JP2007224863A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the freezing of a throttle valve by efficiently transmitting exhaust heat to the throttle valve while inhibiting the increase of weight and the complication of a structure. <P>SOLUTION: A secondary air supply device 58 purifying exhaust gas by supplying secondary air to an exhaust port 20 and accelerating secondary combustion is provided in an exhaust port 20. A warming-up port 65 is formed in a throttle body 46 of an electronic throttle device 44. An air supply passage 59 in the secondary air supply device 58 and the warming-up port 65 of a throttle body 46 are connected by a connection path 68 as a warming-up path and a connection pipe 67. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an internal combustion engine having a throttle valve, and in particular, to prevent the throttle valve from freezing.

  For example, in a cylinder injection internal combustion engine, an intake port and an exhaust port are provided to face a combustion chamber and can be opened and closed by an intake valve and an exhaust valve. An intake pipe is connected to the intake port via an intake manifold, and a throttle valve is provided in the intake pipe. In addition, an injector that injects fuel into the combustion chamber is mounted, and an ignition plug that ignites the air-fuel mixture in the combustion chamber is mounted. On the other hand, an exhaust pipe is connected to the exhaust port via an exhaust manifold, and a three-way catalyst is attached to the exhaust pipe.

  Therefore, by controlling the opening degree of the throttle valve according to the accelerator opening degree of the driver, a predetermined amount of air is sucked into the intake pipe, and when the intake valve is opened, this air is sucked into the combustion chamber from the intake port. The piston is raised and compressed, and fuel is injected from the injector into this high-pressure air. The mixture, which is a mixture of high-pressure air and fuel spray, is led to the vicinity of the spark plug and ignites and explodes, resulting in driving force. When the exhaust valve is opened, the exhaust gas after combustion is discharged from the exhaust port to the exhaust pipe and is purified by the catalyst device.

  In such an internal combustion engine, cold air is sucked into the intake pipe when the throttle valve is opened during cold start or operation in a cold region. For this reason, moisture contained in the air is condensed by boiling under reduced pressure, and it adheres as water droplets to the lower part of the throttle valve, and this water droplet freezes and the throttle valve may freeze. Therefore, conventionally, a circulation pipe that circulates engine cooling water is extended to the throttle body in which the throttle valve is accommodated, and the engine cooling water that has reached a high temperature is circulated to the throttle body through this circulation pipe. Heated to prevent freezing.

  However, in order to circulate hot engine cooling water to the throttle body, a cooling water passage is formed in the cylinder head and the throttle body, and a connecting pipe that connects the cooling water passage of the cylinder head and the cooling water passage of the throttle body. Is required. For this reason, there is a problem that the weight of the entire engine increases due to an increase in various pipes and engine cooling water, leading to a decrease in output performance and a deterioration in fuel consumption. In addition, since the throttle body is generally arranged above the engine body, air tends to accumulate in the circulation pipe that circulates the engine cooling water, and the throttle valve is sufficiently heated by the high-temperature engine cooling water. May be difficult to do.

  Therefore, it has been proposed to prevent the throttle valve from freezing by using the heat of exhaust gas (EGR gas) instead of engine cooling water, which is described in, for example, Patent Documents 1 and 2 below. The spark ignition engine described in Patent Document 1 has an exhaust recirculation passage led out from an exhaust passage, an end thereof is connected to the upstream side of a throttle valve in the intake passage, and an open / close valve is provided in the middle of the exhaust recirculation passage. When the load is equal to or lower than a predetermined set value, the intake valve is heated to return the hot exhaust gas in the exhaust passage to the upstream side of the intake of the throttle valve through the exhaust recirculation passage. This prevents the throttle valve from freezing.

  Further, in the engine throttle device described in Patent Document 2, the upper flange portion of the support is fastened to the valve housing, while the lower flange portion is fastened to the cylinder head and the EGR valve is fastened to the EGR valve. A hole that defines the passage is formed, and this hole communicates with the EGR passage hole of the cylinder head and the EGR valve so that the support is heated by the EGR gas flowing through the hole and heated by the EGR gas flowing through the EGR passage. Heat is transferred by a cylinder head or an EGR valve, and the valve housing is heated through this support to prevent the throttle valve from freezing.

JP 08-158948 A JP 09-105338 A

  In the spark ignition engine described in Patent Document 1 described above, when the engine load is equal to or lower than a predetermined set value, the high-temperature exhaust gas is recirculated from the exhaust gas recirculation passage to the intake upstream side of the throttle valve, Is used to prevent the throttle valve from freezing. However, the hot exhaust gas contains moisture, and even if it is returned to the intake passage to warm the intake air, it is in a negative pressure state downstream of the throttle valve. There is a possibility that the water droplets adhere to the lower portion, and the water droplets freeze to freeze the throttle valve. Further, by returning the exhaust gas to the intake passage, the air-fuel ratio may fluctuate and the combustion may be deteriorated.

  In the engine throttle device described in Patent Document 2, the heat of the support heated by the EGR gas is transmitted to the bubble housing of the throttle valve to prevent the throttle valve from freezing. However, the heat source of the EGR gas and the bubble housing are separated from each other, and it takes a predetermined time to transmit the heat of the EGR gas to the bubble housing through the metal support, and the heat transfer coefficient is insufficient. It is difficult to reliably prevent the throttle valve from freezing.

  The present invention is intended to solve such problems, and prevents the throttle valve from freezing by efficiently transmitting exhaust heat to the throttle valve while suppressing an increase in weight and complication of the structure. An object is to provide an internal combustion engine.

  In order to solve the above-described problems and achieve the object, an internal combustion engine of the present invention includes a combustion chamber, an intake port and an exhaust port communicating with the combustion chamber, and an intake valve that opens and closes the intake port and the exhaust port. And an exhaust valve, fuel injection means for injecting fuel into the combustion chamber or the intake port, ignition means for igniting an air-fuel mixture in the combustion chamber, an intake pipe connected to the intake port, and an intake pipe A throttle valve provided; an exhaust pipe connected to the exhaust port; a catalyst device provided in the exhaust pipe for purifying harmful substances in the exhaust gas; and one end portion of the exhaust port or the exhaust pipe An air supply passage communicating upstream of the catalyst device, an air supply means connected to the other end of the air supply passage, one end communicating with the air supply passage, and the other end of the throttle valve Near It is characterized in that comprises a warm air passage extends to.

  The internal combustion engine of the present invention is characterized in that there is provided control means for supplying air to the exhaust port or the exhaust pipe through the air supply passage by drivingly controlling the air supply means based on the engine temperature. .

  The internal combustion engine of the present invention is characterized in that the warm air passage extends to a throttle body that rotatably supports the throttle valve, and an end portion thereof is closed.

  The internal combustion engine of the present invention is characterized in that the warm air passage extends to a lower portion of a throttle body that rotatably supports the throttle valve.

  In the internal combustion engine of the present invention, the throttle valve is rotatably supported by a throttle body connected to the intake pipe with a horizontal axis, and the warm air passage is formed in the lower part of the throttle body along the horizontal axis. And a connecting passage having one end portion communicating with the air supply passage and the other end portion communicating with the warming port.

  In the internal combustion engine of the present invention, the air supply passage is formed in the engine body along the arrangement direction of the combustion chambers, while a throttle body that rotatably supports the throttle valve is disposed above the engine body. The warm air passage has a connecting pipe that connects the air supply passage and the throttle body.

  According to the internal combustion engine of the present invention, an air supply passage having one end communicating with the upstream side of the catalyst device in the exhaust port or the exhaust pipe is provided, and an air supply means is connected to the other end of the air supply passage. The warm air passage communicates with the exhaust port or the exhaust pipe through the air supply passage when the air supply means is not in operation because the warm air passage with the other portion communicating with the air supply passage and the other end extending to the vicinity of the throttle valve is provided. As a result, the exhaust gas is filled in the warm air passage and is sent to the vicinity of the throttle valve. The high temperature exhaust gas in the warm air passage heats the throttle valve. It is possible to prevent the throttle valve from freezing by suppressing the increase in weight and complication of the structure without freezing, and efficiently transmitting the exhaust heat to the throttle valve. .

  Embodiments of an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this Example.

  1 is a schematic configuration diagram showing an internal combustion engine according to a first embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing a warm air passage in the internal combustion engine of the first embodiment, and FIG. 3 is in the internal combustion engine of the first embodiment. It is a top view showing a warm air passage.

  In the internal combustion engine of the first embodiment, as shown in FIGS. 1 to 3, the engine 10 as the internal combustion engine is a four-cylinder in-cylinder injection type, and a cylinder head 12 is fastened on a cylinder block 11. The pistons 14 are fitted in a plurality of cylinder bores 13 formed in the cylinder block 11 so as to be vertically movable. A crankcase 15 is fastened to the lower part of the cylinder block 11, and a crankshaft 16 is rotatably supported in the crankcase 15. Each piston 14 is connected to the crankshaft 16 via a connecting rod 17. Has been.

  The combustion chamber 18 includes a cylinder block 11, a cylinder head 12, and a piston 14, and has a pent roof shape that is inclined so that the center of the upper portion (the lower surface of the cylinder head 12) is higher. An intake port 19 and an exhaust port 20 are formed on the upper portion of the combustion chamber 18, that is, the lower surface of the cylinder head 12, and the intake valve 21 and the exhaust valve are opposed to the intake port 19 and the exhaust port 20. The lower end portions of 22 are respectively positioned. The intake valve 21 and the exhaust valve 22 are supported by the stem guides 23 and 24 fixed to the cylinder head 12 so as to be movable in the axial direction, and the intake ports 19 and the exhaust ports are supported by the valve springs 25 and 26. It is urged and supported in a direction to close 20. An intake camshaft 27 and an exhaust camshaft 28 are rotatably supported by the cylinder head 12, and the intake cam 29 and the exhaust cam 30 are in contact with the upper end portions of the intake valve 21 and the exhaust valve 22.

  Therefore, when the intake camshaft 27 and the exhaust camshaft 28 rotate in synchronization with the engine 10, the intake cam 29 and the exhaust cam 30 press the intake valve 21 and the exhaust valve 22 against the urging force of the valve springs 25 and 26. When the valves 21 and 22 move up and down at a predetermined timing, the intake port 19 and the exhaust port 20 are opened and closed, and the intake port 19 and the combustion chamber 18, and the combustion chamber 18 and the exhaust port 20 communicate with each other. be able to.

  The valve mechanism of the engine 10 is variable intake valve / valve valve mechanism (VVT: Variable Valve Timing-intelligent) 31 and 32 that controls the intake valve 21 and the exhaust valve 22 at the optimum opening / closing timing according to the operating state. ing. The intake / exhaust variable valve mechanisms 31, 32 are configured by providing VVT controllers 33, 34 at the shaft ends of the intake camshaft 27 and the exhaust camshaft 28. The phases of the camshafts 27 and 28 with respect to the cam sprocket are changed by acting on the advance chamber and retard chamber (not shown) of the VVT controllers 33 and 34, and the opening / closing timing of the intake valve 21 and the exhaust valve 22 is advanced or retarded. Is something that can be done. In this case, the intake / exhaust variable valve mechanism 31, 32 advances or retards the opening / closing timing with the operating angle (opening period) of the intake valve 21 and the exhaust valve 22 being constant. In addition, the intake camshaft 27 and the exhaust camshaft 28 are provided with cam position sensors 37 and 38 for detecting their rotational phases.

  A surge tank 40 is connected to the intake port 19 via an intake manifold 39, and an intake pipe 41 is connected to the surge tank 40. An air cleaner 42 is attached to an air intake port of the intake pipe 41. . An electronic throttle device 44 having a throttle valve 43 is provided downstream of the air cleaner 42 and immediately upstream of the surge tank 40. In this electronic throttle device 44, a throttle valve 43 is rotatably supported by a horizontal support shaft 47 on a throttle body 46 having an opening 45 communicating with a surge tank 40 and an intake pipe 41. A drive motor 48 supports the support shaft. The throttle valve 43 is configured to be rotatable via 47, and the opening amount (throttle opening) of the opening 45 is adjusted by driving the drive motor 48 and rotating the throttle valve 43. be able to.

  The cylinder head 12 is provided with an injector (fuel injection means) 49 that directly injects fuel into the combustion chamber 18, and the injector 49 is located on the intake port 19 side and is inclined at a predetermined angle in the vertical direction. ing. An injector 49 mounted on each cylinder is connected by a delivery pipe 50. A high pressure pump 52 is connected to the delivery pipe 50 via a fuel supply pipe 51. The high pressure pump 52 is connected to a fuel supply pipe (not shown). A low pressure feed pump and a fuel tank are connected. Further, a spark plug (ignition means) 53 that is positioned above the combustion chamber 18 and ignites the air-fuel mixture is mounted on the cylinder head 12.

  On the other hand, an exhaust pipe 55 is connected to the exhaust port 20 via an exhaust manifold 54. The exhaust pipe 55 is a catalyst device that purifies harmful substances such as HC, CO, and NOx contained in the exhaust gas. (Three-way catalyst) 56 and 57 are mounted.

  Further, the secondary air is supplied to the engine 10 of the present embodiment by supplying secondary air to the exhaust port 20 in a state where the catalyst devices 56 and 57 are not sufficiently activated, such as when the engine 10 is cold started. A secondary air supply device 58 that promotes secondary combustion and purifies exhaust gas is provided. In the secondary air supply device 58, an air supply passage 59 is formed in the cylinder head 12 between the intake port 19 and the exhaust port 20 along the arrangement direction of the cylinder bores 13 (combustion chambers 18). In addition, the air supply passage 59 communicates with each exhaust port 20 via a plurality of communication passages 60. In FIG. 1, the engine 10 is schematically shown, and the air supply passage 59 is shown on the side of the exhaust port 20. The air supply passage 59 is connected to an air pump 62 as air supply means via a connecting pipe 61, and an electromagnetic valve 63 is attached to the connecting pipe 61. In the cylinder head 12, a plurality of water jackets 64 are formed at the periphery of the air supply passage 59.

  Accordingly, when the air pump 62 is driven with the solenoid valve 63 opened, air is supplied to the air supply passage 59 through the connecting pipe 61, and the air in the air supply passage 59 is supplied to each exhaust port 20 through each communication passage 60. can do. That is, air is supplied to each exhaust port 20 in a state where the catalyst devices 56 and 57 are not sufficiently activated, such as when the engine 10 is cold started, so that the exhaust pipe 20 is led to the exhaust pipe 55. Air can increase the oxygen concentration in the exhaust gas to increase the air-fuel ratio (A / F), promote secondary combustion in HC and CO in the exhaust gas, and promote the purification of the exhaust gas. Thus, the activation of the catalyst devices 56 and 57 can be promoted to suppress the deterioration of exhaust emission.

  Incidentally, when the engine 10 is cold-started or operated in a cold region, low-temperature air is sucked into the intake pipe 41 when the throttle valve 43 is opened. For this reason, moisture contained in the air is condensed by boiling under reduced pressure and adheres to the lower portion of the throttle valve 43 as water droplets. The water droplets freeze and the throttle valve 43 may freeze.

  Therefore, in this embodiment, the exhaust gas staying in the air supply passage 59 in the secondary air supply device 58 is circulated to the vicinity of the electronic throttle device 44 through the warm air passage, thereby heating the throttle valve 43 and freezing. It is preventing. That is, an electronic throttle device 44 is disposed above the engine 10, and a warm-up port 65 whose end is closed is provided below the throttle valve 43 of the electronic throttle device 44, that is, below the throttle body 46. Is formed. On the other hand, the engine 10 is provided with a connecting pipe (connecting passage) 67 passing through the cylinder head 12 and the head cover 66 in the vertical direction, and a lower end portion of the connecting pipe 67 is connected to the air supply passage via the connecting path 68. 59, and the upper end portion communicates with the warm air port 65. In the present embodiment, the connecting passage 68, the connecting pipe 67, and the warming port 65 constitute the warm air passage of the present invention.

  Therefore, when the solenoid valve 63 of the secondary air supply device 58 is closed and the air pump 62 is not driven, the exhaust gas enters and stays in the air supply passage 59. This exhaust gas is connected to the connection path 68 and the connection pipe 67. Since the throttle body 46 is heated by the exhaust gas in the warm air port 65 and the throttle valve 46 is frozen, the throttle valve 43 can be prevented from freezing.

  Incidentally, an electronic control unit (ECU) 71 is mounted on the vehicle, and the ECU 71 can control the injector 49, the spark plug 53, and the like. That is, an air flow sensor 72 and an intake air temperature sensor 73 are mounted on the upstream side of the intake pipe 41, and an intake pressure sensor 74 is provided in the surge tank 40. The measured intake air amount, intake air temperature, intake air pressure Is output to the ECU 71. The electronic throttle device 44 is equipped with a throttle position sensor 75, which outputs the current throttle opening to the ECU 71. The accelerator position sensor 76 outputs the current accelerator opening to the ECU 71. Further, the crank angle sensor 77 outputs the detected crank angle of each cylinder to the ECU 71, and the ECU 71 determines each stroke of intake, compression, expansion (explosion), and exhaust in each cylinder based on the detected crank angle. At the same time, the engine speed is calculated. The cylinder block 11 is provided with a water temperature sensor 78 for detecting the engine coolant temperature, and outputs the detected engine coolant temperature to the ECU 71. In addition, a fuel pressure sensor 79 is provided in the delivery pipe 50 communicating with each injector 49, and the detected fuel pressure is output to the ECU 71.

  Therefore, the ECU 71 drives the high-pressure pump 52 based on the detected fuel pressure so that the fuel pressure becomes a predetermined pressure, and also detects the detected intake air amount, intake air temperature, intake pressure, throttle opening, accelerator opening, A fuel injection amount, injection timing, ignition timing, and the like are determined based on engine operating conditions such as engine speed and engine coolant temperature, and the injector 49 and spark plug 53 are driven to execute fuel injection and ignition.

  The ECU 71 can control the intake / exhaust variable valve mechanisms 31 and 32 based on the engine operating state. That is, when the temperature is low, the engine is started, the engine is idle, or the load is light, the exhaust gas blows back into the intake port 19 or the combustion chamber 18 by eliminating the overlap between the exhaust valve 22 closing timing and the intake valve 21 opening timing. Reduce the amount to enable stable combustion and improved fuel efficiency. Further, at the time of medium load, by increasing the overlap, the internal EGR rate is increased to improve the exhaust gas purification efficiency, and the pumping loss is reduced to improve the fuel consumption. Further, at the time of high-load low-medium rotation, the closing timing of the intake valve 21 is advanced, thereby reducing the amount of intake air that blows back to the intake port 19 and improving the volume efficiency. At the time of high load and high rotation, the closing timing of the intake valve 21 is retarded in accordance with the rotation speed, so that the timing is adjusted to the inertial force of the intake air and the volume efficiency is improved.

  Furthermore, the ECU 71 can control the secondary air supply device 58 based on the engine operating state. That is, the ECU 71 applies the water temperature sensor 78 as means for detecting the engine temperature of the engine 10, and the engine cooling water temperature detected by the water temperature sensor 78 when the engine 10 is cold started or the like is predetermined engine cooling. When the temperature is lower than the water temperature, the solenoid valve 63 is opened and the air pump 62 is driven to supply air to the air supply passage 59 through the connecting pipe 61 and supply air to the exhaust ports 20 from the air supply passage 59 through the communication passages 60. To do. Therefore, while the air supplied to the exhaust port 20 reaches the catalyst devices 56 and 57 through the exhaust pipe 55, the secondary combustion of HC and CO in the exhaust gas is increased by increasing the oxygen concentration in the exhaust gas. The catalyst is promoted to promote purification, and the exhaust gas temperature is raised to promote the activation of the catalyst devices 56 and 57.

  On the other hand, after the warming up of the engine 10 is finished, the ECU 71 closes the electromagnetic valve 63 and stops the driving of the air pump 62 when the engine cooling water temperature detected by the water temperature sensor 78 is preset and becomes higher than a predetermined engine cooling water temperature. Then, air is not supplied from the air supply passage 59 to each exhaust port 20, and conversely, the air in each exhaust port 20 enters the air supply passage 59 through the communication passage 60. Since some exhaust gas enters the warm air port 65 through the connection path 68 and the connection pipe 67, the throttle body 46 is heated by the exhaust gas in the warm air port 65, and the throttle valve 43 is prevented from freezing.

  As described above, in the internal combustion engine of the first embodiment, the engine 10 is provided with the secondary air supply device 58 for purifying the exhaust gas by promoting the secondary combustion by supplying the secondary air to the exhaust port 20. The warm air port 65 is formed in the throttle body 46 of the electronic throttle device 44, and the air supply passage 59 and the warm air port 65 of the throttle body 46 in the secondary air supply device 58 are connected to the connecting path 68 and the connecting pipe. 67 is connected.

  Therefore, when the solenoid valve 63 of the secondary air supply device 58 is closed and the driving of the air pump 62 is stopped, the exhaust gas of the exhaust port 20 enters the air supply passage 59 and the exhaust gas of the air supply passage 59 is connected. Since the throttle body 46 is heated by the exhaust gas in the warm air port 65 through the passage 68 and the connecting pipe 67 and the exhaust gas in the warm air port 65 is heated, the water adhering to the periphery of the throttle valve 43 is not frozen. By efficiently transmitting the heat of the exhaust gas to the throttle valve 43, the throttle valve 43 can be prevented from freezing.

  In this case, in order to introduce the exhaust gas to the vicinity of the throttle valve 43, the air supply passage 59 of the secondary air supply device 58 is used. From the air supply passage 59 to the vicinity of the throttle valve 43, the connecting passage 68 and the warm air passage are provided. A connecting pipe 67 is provided. Therefore, it is possible to reliably prevent the throttle valve 43 from freezing by suppressing an increase in weight and a complicated structure.

  In addition, since the end of the warm air port 65 formed in the throttle body 46 is closed, the exhaust gas is not introduced into the intake pipe 41, and solidification of moisture contained in the exhaust gas can be prevented. Combustion deterioration due to fluctuations in the intake flow rate can be prevented.

  Further, a warm air port 65 is formed in the lower part of the throttle body 46, and water condensed near the throttle valve 43 tends to accumulate below the throttle valve 43. However, the exhaust gas in the warm air port 65 causes the throttle valve 43 to Since the lower part, that is, the lower part of the throttle body 46 is heated, it is possible to reliably prevent freezing of water adhering to the lower part of the throttle valve 43.

  The connecting pipe 67 is provided through the cylinder head 12 and the head cover 66 in the vertical direction, so that the air supply passage 59 and the warm air port 65 can be easily communicated with each other.

  FIG. 4 is a schematic plan view showing the internal combustion engine according to the second embodiment of the present invention, and FIG. 5 is a longitudinal sectional view showing a warm air passage in the internal combustion engine of the second embodiment.

  In the internal combustion engine of the second embodiment, as shown in FIGS. 4 and 5, the engine 110 as the internal combustion engine is a V-type 6-cylinder engine, and the left and right banks 112 inclined on the cylinder block 111 at a predetermined angle. 113, three cylinder bores 114, 115 are formed in each of the banks 112, 113, and pistons 116, 117 are fitted to the cylinder bores 114, 115 so as to be movable up and down. A crankshaft (not shown) is rotatably supported at the lower part of the cylinder block 111, and the pistons 116 and 117 are connected to the crankshaft via connecting rods 118 and 119, respectively.

  On the other hand, cylinder heads 120 and 121 are fastened to the upper portions of the banks 112 and 113 of the cylinder block 111, and the combustion chambers 122 and 123 are configured by the cylinder block 111, the pistons 116 and 117, and the cylinder heads 120 and 121. ing. The intake ports 124 and 125 and the exhaust ports 126 and 127 are formed to face the upper portions of the combustion chambers 122 and 123, that is, the lower surfaces of the cylinder heads 120 and 121. The intake ports 124 and 125 and the exhaust ports 126 and 127 127, the lower end portions of the intake valves 128 and 129 and the exhaust valves 130 and 131 are located. The intake valves 128 and 129 and the exhaust valves 130 and 131 are supported by the cylinder heads 120 and 121 so as to be movable in the axial direction, and are attached in a direction to close the intake ports 124 and 125 and the exhaust ports 126 and 127. It is supported. In addition, intake camshafts 132 and 133 and exhaust camshafts 134 and 135 are rotatably supported on the cylinder heads 120 and 121, and intake cams 136 and 137 and exhaust cams 138 and 139 are provided with intake valves 128, 129 and The upper end portions of the exhaust valves 130 and 131 are in contact with each other.

  Accordingly, when the intake camshafts 132 and 133 and the exhaust camshafts 134 and 135 rotate in synchronization with the engine 110, the intake cams 136 and 137 and the exhaust cams 138 and 139 cause the intake valves 128 and 129 and the exhaust valves 130 and 131 to be predetermined. The intake ports 124 and 125 and the exhaust ports 126 and 127 are opened and closed by moving the intake port 124 and 125 and the combustion chambers 122 and 123, and the combustion chambers 122 and 123 and the exhaust ports 126 and 127, respectively. You can communicate.

  In addition, the valve operating mechanism of this engine is a variable intake valve operating mechanism (VVT: Variable Valve Timing-intelligent) 140, 141 for controlling the intake valves 128, 129 and the exhaust valves 130, 131 at the optimum opening / closing timing according to the operating state. The exhaust variable valve mechanisms 142 and 143 are configured. The intake camshafts 132 and 133 and the exhaust camshafts 134 and 135 are provided with cam position sensors 144, 145, 146, and 147 for detecting their rotational phases. The intake variable valve mechanisms 140 and 141 and the exhaust variable valve mechanisms 142 and 143 are substantially the same as those of the first embodiment described above, and thus detailed description thereof is omitted.

  A surge tank 150 is connected to the intake ports 124 and 125 of the cylinder heads 120 and 121 via intake manifolds 148 and 149, and an intake pipe 151 is connected to the surge tank 150. An air cleaner 152 is attached to the intake port. The intake pipe 151 is provided with an electronic throttle device 154 having a throttle valve 153 located on the downstream side of the air cleaner 152. The electronic throttle device 154 has a throttle body 155 communicating with the surge tank 150 and the intake pipe 151, and a throttle valve 153 is rotatably supported on the throttle body 155 by a horizontal support shaft 156. A drive motor (not shown) Thus, the throttle opening can be adjusted by rotating the throttle valve 153.

  On the other hand, a connection pipe 161 is connected to the exhaust ports 126 and 127 via exhaust manifolds 157 and 158 and catalyst devices 159 and 160, and an exhaust pipe 162 is connected to the connection pipe 161. A catalyst device 163 is mounted.

  Further, each cylinder head 120, 121 is provided with an injector (fuel injection means) 164, 165 for injecting fuel (gasoline) directly into each combustion chamber 122, 123, and each injector 164, 165 has a delivery pipe. 166 and 167 are connected, and a fuel of a predetermined pressure can be supplied from the high-pressure fuel pump 168 to each of the delivery pipes 166 and 167. In addition, ignition plugs (ignition means) 169 and 170 that are located above the combustion chambers 122 and 123 and ignite the air-fuel mixture are mounted on the cylinder heads 120 and 121, respectively.

  Further, the secondary air is supplied to the exhaust ports 126 and 127 to the engine 110 of the present embodiment in a state where the catalyst devices 159 and 160 are not sufficiently activated, such as when the engine 110 is cold started. Are provided with secondary air supply devices 171 and 172 for purifying exhaust gas by promoting secondary combustion. In the secondary air supply devices 171, 172, air supply passages 173, 174 are formed in the cylinder heads 120, 121 along the arrangement direction of the cylinder bores 114, 115 (combustion chambers 122, 123). The supply passages 173 and 174 communicate with the exhaust ports 126 and 127 via a plurality of communication passages 175 and 176. The air supply passages 173 and 174 are connected to an air pump 178 as air supply means via a connecting pipe 177, and an electromagnetic valve 179 is attached to the connecting pipe 178.

  Accordingly, when the air pump 178 is driven with the electromagnetic valve 179 opened, air is supplied to the air supply passages 173 and 174 through the connecting pipe 177, and the air in the air supply passages 173 and 174 is supplied to the communication passages 175 and 176. It can supply to each exhaust port 126,127 through. That is, by supplying air to the exhaust ports 126 and 127 in a state where the catalyst devices 159 and 160 are not sufficiently activated, such as when the engine 110 is cold started, the exhaust pipes 162 and 127 are connected to the exhaust pipes 162. The air guided to the air can raise the oxygen concentration in the exhaust gas to increase the air-fuel ratio (A / F), and promote the secondary combustion in HC and CO in the exhaust gas to promote the purification of the exhaust gas. In addition, the exhaust gas temperature can be raised to promote the activation of the catalyst devices 159 and 160, thereby suppressing the deterioration of exhaust emission.

  In this embodiment, the exhaust gas staying in the air supply passage 173 in the secondary air supply device 171 described above is circulated to the vicinity of the electronic throttle device 154 through the warm air passage, thereby heating the throttle valve 153 and freezing it. It is preventing. That is, an electronic throttle device 154 is disposed above the engine 110, and a warm air port 180 whose end is closed is provided below the throttle valve 153 of the electronic throttle device 154, that is, below the throttle body 155. Is formed. On the other hand, a connecting path 181 communicating with the air supply path 173 is formed in the cylinder head 120, and the warm air port 180 and the connecting path 181 are connected by a connecting pipe 182. In the present embodiment, the connecting passage 181, the connecting pipe 182, and the warming port 180 constitute the warming passage of the present invention.

  Therefore, when the solenoid valve 179 of the secondary air supply device 171 is closed and the air pump 178 is not driven, the exhaust gas enters and stays in the air supply passage 173. This exhaust gas is connected to the connection path 181 and the connection pipe. Since the air enters the warm air port 180 through 182 and the throttle body 155 is heated by the exhaust gas in the warm air port 180, the throttle valve 153 can be prevented from freezing.

  Incidentally, an electronic control unit (ECU) 183 is mounted on the vehicle, and this ECU 183 can control the fuel injection timing of the injectors 164 and 165, the ignition timing of the spark plugs 169 and 170, and the like. The fuel injection amount, the injection timing, the ignition timing, and the like are determined based on the engine operating conditions such as the intake air amount, intake air temperature, throttle opening, accelerator opening, engine speed, and coolant temperature. Therefore, an airflow sensor 184 and an intake air temperature sensor 185 are mounted on the upstream side of the intake pipe 151, and the measured intake air amount and intake air temperature are output to the ECU 183. The electronic throttle device 154 is provided with a throttle position sensor 186, and the accelerator pedal is provided with an accelerator position sensor 187, which outputs the current throttle opening and accelerator opening to the ECU 183. Further, a crank angle sensor 188 is provided on the crankshaft, and the detected crank angle is output to the ECU 183. The ECU 183 calculates the engine speed based on the crank angle. The cylinder block 111 is provided with a water temperature sensor 189 and outputs the detected engine cooling water temperature to the ECU 183.

  Further, the ECU 183 can control the intake variable valve operating mechanisms 140 and 141 and the exhaust variable valve operating mechanisms 142 and 143 based on the engine operating state.

  Further, the ECU 183 can control the secondary air supply devices 171 and 172 based on the engine operating state. That is, the ECU 183 applies the water temperature sensor 189 as a means for detecting the engine temperature of the engine 110, and the engine cooling water temperature detected by the water temperature sensor 189 is set in advance when the engine 110 is cold started. When the pressure is lower, the electromagnetic valve 179 is opened and the air pump 178 is driven to supply air to the air supply passages 173 and 174 through the connecting pipe 177, and from the air supply passages 173 and 174 to the respective exhaust passages 175 and 176. Air is supplied to the ports 126 and 127. Therefore, while the air supplied to the exhaust ports 126 and 127 reaches the catalyst devices 159 and 160 through the exhaust manifolds 157 and 158, the oxygen concentration in the exhaust gas is increased to increase the HC and CO in the exhaust gas. The secondary combustion is promoted to promote purification, and the exhaust gas temperature is increased to promote the activation of the catalyst devices 159 and 160.

  On the other hand, when the engine 110 is warmed up, the ECU 183 closes the solenoid valve 179 and stops driving the air pump 178 when the engine coolant temperature detected by the water temperature sensor 189 is preset and becomes higher than a predetermined engine coolant temperature. Then, the supply of air from the air supply passages 173 and 174 to the exhaust ports 126 and 127 is stopped. Then, the air in the exhaust port 126 enters the air supply passage 173 through the communication passage 175, and the exhaust gas in the air supply passage 173 enters the warm air port 180 through the connection path 181 and the connection pipe 182. The throttle body 155 is heated by the exhaust gas in the port 180, and the throttle valve 153 is prevented from freezing.

  Thus, in the internal combustion engine of the second embodiment, the secondary air supply device 171 that purifies exhaust gas by promoting secondary combustion by supplying secondary air to the engine 110 to the exhaust ports 126 and 127. , 172, a warm air port 180 is formed in the throttle body 155 of the electronic throttle device 154, and the air supply passage 173 in the secondary air supply device 171 and the warm air port 180 of the throttle body 155 are connected as a warm air passage 181. And a connecting pipe 182.

  Therefore, when the solenoid valve 179 of the secondary air supply device 171 is closed and the driving of the air pump 178 is stopped, the exhaust gas of the exhaust port 126 enters the air supply passage 173, and the exhaust gas of the air supply passage 173 is connected. Since the throttle body 155 is heated by the exhaust gas in the warm air port 180 through the passage 181 and the connecting pipe 182, the water adhering to the periphery of the throttle valve 153 is not frozen. By efficiently transferring the heat of the exhaust gas to the throttle valve 153, the throttle valve 153 can be prevented from freezing.

  Then, the air supply passage 173 of the secondary air supply device 171 is used to introduce the exhaust gas to the lower side of the throttle valve 153, and the connection passage 181 and the connection passage 181 are connected as a warm air passage from the air supply passage 173 to the lower portion of the throttle body 155. A pipe 182 is provided. Therefore, it is possible to reliably prevent the throttle valve 153 from freezing by suppressing an increase in weight and complication of the structure.

  In each of the above-described embodiments, the warm air passage of the present invention is constituted by the connecting passages 68 and 181, the connecting pipes 67 and 182, and the warm air ports 65 and 180. However, if the distance between the air supply passage and the throttle valve is short. The warm air passage that continues from the cylinder head to the throttle body may be formed directly, and if the distance between the air supply passage and the throttle valve is long, the air supply passage and the warm air port may be connected only by a connecting pipe.

  In each of the above-described embodiments, the internal combustion engine of the present invention has been described as applied to a direct injection internal combustion engine. However, the present invention may be applied to a port injection internal combustion engine that injects fuel into an intake port. The same effects as those of the embodiment can be obtained. Furthermore, the form of the internal combustion engine may be an in-line multi-cylinder or a V-type.

  As described above, the internal combustion engine according to the present invention prevents exhaust of the throttle valve by guiding the exhaust gas to the vicinity of the throttle valve using the air supply passage in the secondary air supply device. It is also suitable for use in other internal combustion engines.

1 is a schematic configuration diagram illustrating an internal combustion engine according to a first embodiment of the present invention. FIG. 3 is a longitudinal sectional view showing a warm air passage in the internal combustion engine of the first embodiment. FIG. 2 is a plan view illustrating a warm air passage in the internal combustion engine of the first embodiment. It is a schematic plan view showing the internal combustion engine which concerns on Example 2 of this invention. 6 is a longitudinal sectional view showing a warm air passage in the internal combustion engine of Embodiment 2. FIG.

Explanation of symbols

10, 110 Engine 18122, 123 Combustion chamber 19, 124, 125 Intake port 20, 126, 127 Exhaust port 21, 128, 129 Intake valve 22, 130, 131 Exhaust valve 41, 151 Intake pipe 43, 153 Throttle valve 44, 154 Electronic throttle device 46,155 Throttle body 49,164,165 Injector (fuel injection means)
53, 169, 170 Spark plug (ignition means)
54,157,158 Exhaust manifold 55,162 Exhaust pipe 56,57,159,160,163 Catalyst device 58,171,172 Secondary air supply device 59,173,174 Air supply passage 60175,176 Communication passage 61,177 Connection Pipe 62,178 Air pump 63,179 Solenoid valve 65,180 Warm air port (warm air passage)
67,182 Connection piping (warm air passage, connection passage)
68,181 connection path (warm air passage)
71,183 Electronic control unit, ECU (control means)
78,189 Water temperature sensor

Claims (6)

  A combustion chamber, an intake port and an exhaust port communicating with the combustion chamber, an intake valve and an exhaust valve that open and close the intake port and the exhaust port, and a fuel injection unit that injects fuel into the combustion chamber or the intake port; Ignition means for igniting the air-fuel mixture in the combustion chamber, an intake pipe connected to the intake port, a throttle valve provided in the intake pipe, an exhaust pipe connected to the exhaust port, and the exhaust pipe A catalyst device for purifying a harmful substance in exhaust gas, an air supply passage having one end communicating with the upstream side of the exhaust port or the exhaust pipe from the catalyst device, and other air supply passages. An internal combustion engine comprising: an air supply means connected to an end; and a warm air passage having one end communicating with the air supply passage and the other end extending to the vicinity of the throttle valve.   2. The internal combustion engine according to claim 1, further comprising control means for supplying air to the exhaust port or the exhaust pipe through the air supply passage by drivingly controlling the air supply means based on engine temperature. A characteristic internal combustion engine.   3. The internal combustion engine according to claim 1, wherein the warm air passage is extended to a throttle body that rotatably supports the throttle valve, and an end portion thereof is closed.   4. The internal combustion engine according to claim 1, wherein the warm air passage extends to a lower portion of a throttle body that rotatably supports the throttle valve.   5. The internal combustion engine according to claim 1, wherein the throttle valve is rotatably supported by a throttle body connected to the intake pipe with a horizontal axis, and the warm air passage is connected to the throttle body. An internal combustion engine having a warm air port formed at the bottom along the horizontal axis, and a connecting passage having one end communicating with the air supply passage and the other end communicating with the warm air port. .   6. The internal combustion engine according to claim 1, wherein the air supply passage is formed in the engine body along the arrangement direction of the combustion chambers, while the throttle valve is rotatably supported. An internal combustion engine, wherein a body is disposed above the engine body, and the warm air passage has a connecting pipe that connects the air supply passage and the throttle body.

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