JP2009156228A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of quickly thawing ice adhered to a throttle valve even immediately after starting the internal combustion engine. <P>SOLUTION: A rotating position detector 202 is assembled in a stepping motor 201 which changes opening of a throttle valve 20, and opening of the throttle valve 20 is detected by the rotating position detector 202. A control computer C controls rotating position of the stepping motor 201 by specifying opening θy of the throttle valve 20 based on a grasped engine load and engine speed. In the case wherein the detected opening and the specified opening do not correspond to each other, the control computer C regulates adjusting condition of an exhaust side variable valve timing mechanism 41 by controlling a hydraulic supply adjusting mechanism 42 to advance the opening/closing timing of an exhaust valve 28. With this structure, burned gas inside of a combustion chamber 111 is blown back to an intake path 18 side through an intake port 121. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an internal combustion engine in which a throttle valve is disposed on an intake passage leading to a combustion chamber.

  When the outside air temperature is low, moisture contained in the air in the intake passage may freeze. Alternatively, in an internal combustion engine that purifies exhaust gas by recirculating part of the exhaust gas to the intake passage, moisture contained in the recirculated exhaust gas may mix with low-temperature fresh air in the intake passage and freeze. is there. Due to the above-mentioned icing, if ice adheres between the throttle valve disposed on the intake passage and the throttle body that forms the casing that houses the throttle valve, the throttle valve may stick and not rotate properly. is there.

As a means for solving such a problem, for example, in the throttle device disclosed in Patent Document 1, the throttle body has a double structure including an outer pipe and an inner pipe, and the outlet side of the EGR passage is between the outer pipe and the inner pipe. Is provided over the entire circumference of the throttle valve. The exhaust gas recirculated to the passage is used to warm the throttle body and melt ice adhering to the throttle valve.
JP-A-10-169474

  However, the throttle device disclosed in Patent Document 1 has a problem that it takes time to function sufficiently immediately after the engine is started. Specifically, immediately after starting the engine, the temperature of the exhaust gas discharged from the combustion chamber itself is relatively low. In addition, since the wall surface temperature of the pipe structure that forms the exhaust passage and the EGR passage is also low, the exhaust gas temperature is further lowered until the exhaust passage and the EGR passage are recirculated to the intake passage. For this reason, immediately after the engine is started, the temperature of the exhaust gas recirculated to the passage becomes low, and it takes time to eliminate the sticking of the throttle valve due to freezing.

  An object of the present invention is to provide an internal combustion engine that can quickly melt ice adhering to a throttle valve even immediately after the start of the internal combustion engine.

  The present invention is directed to an internal combustion engine in which a throttle valve is disposed on an intake passage leading to a combustion chamber, and the invention of claim 1 includes blow-back means that blows back already burned gas in the combustion chamber toward the intake passage. And a sticking detecting means for detecting sticking of the throttle valve, and when sticking of the throttle valve is detected by the sticking detecting means, the blow-back means is turned back to bring the burned gas into the intake passage side. And a control means for controlling to blow back.

  The burnt gas in the combustion chamber is hot, and the temperature drop of the burnt gas blown back to the intake passage is small. For this reason, even immediately after the internal combustion engine is started, the ice adhering to the throttle valve quickly melts.

  In a preferred example, the sticking detection means includes an opening degree specifying means for specifying the opening degree of the throttle valve, and an opening degree detecting means for detecting the opening degree of the throttle valve, and is detected by the opening degree detecting means. When the detected opening degree does not coincide with the designated opening degree designated by the opening degree designation means, the control means turns the blowing means back and blows the burnt gas back to the intake passage side. To control.

  When the detected opening degree does not coincide with the designated opening degree, the blow-back means is turned back and the already burned gas in the combustion chamber is blown back to the intake passage side. The burnt gas in the combustion chamber is hot and the temperature drop of the burnt gas blown back to the intake passage is small. Therefore, even immediately after starting the internal combustion engine, the ice adhering to the throttle valve is quickly melted.

  In a preferred example, the control means generates a failure when a state in which the detected opening detected by the opening detecting means does not coincide with the specified opening specified by the opening specifying means continues for a predetermined time. Is determined.

  The occurrence of a failure here means a case where the throttle valve does not move normally due to a cause other than freezing. Such a determination makes it possible to distinguish between a malfunction of the original throttle valve due to a cause other than freezing and a malfunction of the throttle valve due to freezing that is different from this failure.

In a preferred example, the control means performs fail-safe control for preventing the engine from being stopped when the blow-back means is in the blow-back state.
The fail safe control is a control that gives priority to the continued operation of the engine over the contents of the driver's operation (depressing the accelerator pedal). By performing such fail-safe control, the engine will not stop even when the throttle valve is malfunctioning.

  In a preferred example, the blow-back means includes an exhaust valve that opens and closes an exhaust port that communicates with the combustion chamber, and an exhaust-side variable valve timing mechanism that can adjust the opening and closing timing of the exhaust valve. Is blown back by advancing the closing timing of the exhaust valve from the top dead center by the exhaust side variable valve timing mechanism.

  When the timing of closing the exhaust valve is changed to the advance position where the burnt gas can be trapped in the combustion chamber, when the intake passage and the combustion chamber communicate with each other, a part of the burnt gas trapped in the combustion chamber Is blown back to the intake passage side. The exhaust side variable valve timing mechanism is suitable as a mechanism constituting the blowback means.

  In a preferred example, the blow-back means includes an exhaust valve that opens and closes an exhaust port that communicates with the combustion chamber, an exhaust-side variable valve timing mechanism that can adjust an opening and closing timing of the exhaust valve, and an intake port that communicates with the combustion chamber. An intake valve that opens and closes, and an intake side variable valve timing mechanism that can adjust the opening and closing timing of the intake valve, and the blowback of the burned gas is performed by the exhaust side variable valve timing mechanism to close the exhaust valve. Is advanced from the top dead center, and the opening timing of the intake valve is retarded from the top dead center by the intake side variable valve timing mechanism.

  If the opening timing of the intake valve is retarded, the pressure in the combustion chamber immediately before blow-back becomes lower than when only the closing timing of the exhaust valve is advanced. That is, the pressure in the combustion chamber immediately before blow-back can be adjusted by adjusting the retard of the opening timing of the intake valve. The lower the pressure in the combustion chamber immediately before blow-back, the lower the blow-back pressure of the burned gas.

  The internal combustion engine of the present invention has an excellent effect that ice adhering to the throttle valve can be quickly melted even immediately after the start of the internal combustion engine.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 2A, the cylinder block 49 constituting the diesel engine 10 (internal combustion engine) includes a plurality of cylinders 11 [four in this embodiment as shown in FIG. 1A]. The cylinder head 12 connected to the cylinder block 49 is provided with a fuel injection nozzle 13 for each cylinder 11.

As shown in FIG. 1A, the fuel is supplied to the fuel injection nozzle 13 via the fuel pump 14 and the common rail 15, and the fuel injection nozzle 13 injects the fuel into each cylinder 11.
An intake manifold 16 is connected to the cylinder head 12. An intake pipe 17 is connected to the intake manifold 16, and an air cleaner 171 is connected to the intake pipe 17. The intake pipe 17 and the intake manifold 16 constitute an intake passage 18. A compressor unit 191, an intercooler 50, and a throttle valve 20 of the supercharger 19 are disposed in the middle of the intake pipe 17 from the upstream side. The supercharger 19 is a known variable nozzle turbocharger that is operated by an exhaust gas flow, and the intercooler 50 is a heat exchanger that cools the intake air whose temperature has been raised by supercharging by heat exchange with engine cooling water. It is.

  The throttle valve 20 is for adjusting the flow rate of air sucked into the intake passage 18. The opening degree of the throttle valve 20 is changed by the stepping motor 201. The stepping motor 201 is controlled by the control computer C. A rotational position detector 202 is incorporated in the stepping motor 201, and the opening degree θx of the throttle valve 20 is detected by a rotational position detector 202 as opening degree detection means. Information on the throttle opening degree θx detected by the rotational position detector 202 is sent to the control computer C. Even when the opening degree of the throttle valve 20 is the minimum, the throttle valve 20 does not completely close the intake pipe 17. That is, even when the opening degree of the throttle valve 20 is the minimum, air can pass around the throttle valve 20.

  An exhaust manifold 21 is connected to the cylinder head 12. An exhaust pipe 22 is connected to the exhaust manifold 21. A particulate filter 23 is interposed on the exhaust pipe 22. The exhaust gas discharged from the cylinder 11 is released to the atmosphere via the exhaust manifold 21, the exhaust pipe 22, and the particulate filter 23. The exhaust manifold 21, the exhaust pipe 22, and the particulate filter 23 constitute an exhaust passage.

  As shown in FIG. 2A, a piston 24 is accommodated in the cylinder 11 so as to be able to reciprocate. The piston 24 that defines the combustion chamber 111 in the cylinder 11 is connected to the crankshaft 26 via a connecting rod 25. The reciprocating motion of the piston 24 is converted into the rotational motion of the crankshaft 26 via the connecting rod 25.

  An intake port 121 and an exhaust port 122 are formed in the cylinder head 12 connected to the cylinder block 49. An intake valve 27 is provided in the cylinder head 12 so as to open and close the intake port 121, and an exhaust valve 28 is provided in the cylinder head 12 so as to open and close the exhaust port 122. A branch pipe of the intake manifold 16 is connected to the intake port 121, and a branch pipe of the exhaust manifold 21 is connected to the exhaust port 122.

  An intake cam shaft 29 and an exhaust cam shaft 30 are disposed above the cylinder head 12. The intake camshaft 29 is provided with an intake cam 31, and the exhaust camshaft 30 is provided with an exhaust cam 32. The intake cam 31 can drive the intake cam lever 33, and the exhaust cam 32 can drive the exhaust cam lever 34.

  Air in the intake passage 18 is sucked into the combustion chamber 111 when the intake port 121 is open during the stroke of the piston 24 from the top dead center to the bottom dead center. The air (fresh air) in the combustion chamber 111 is generated when the intake valve 27 closes the intake port 121 and the exhaust valve 28 closes the exhaust port 122 during the stroke of the piston 24 from the bottom dead center to the top dead center. When it is, it is compressed. When the piston 24 reaches the upper start point in the compression stroke from the bottom dead center to the top dead center, the fuel is injected from the fuel injection nozzle 13 into the compressed high-temperature air in the combustion chamber 111. The fuel injected into the compressed high-temperature air burns sequentially, and the piston 24 moves from the top dead center to the bottom dead center.

  The burnt gas in the combustion chamber 111 is discharged to the exhaust manifold 21 when the exhaust valve 28 opens the exhaust port 122 during the stroke of the piston 24 from the bottom dead center to the top dead center.

A crank angle detector 35, an accelerator sensor 36, a pressure detector 37, an air flow meter 38, a water temperature detector 39, and a warning lamp 40 are signal-connected to the control computer C.
The crank angle detector 35 detects the rotation angle (crank angle) of the crankshaft 26. The crank angle information detected by the crank angle detector 35 is sent to the control computer C. The control computer C calculates the engine speed based on the crank angle information detected by the crank angle detector 35.

  The accelerator sensor 36 detects the amount of depression of an accelerator pedal (not shown). The depression amount detection information detected by the accelerator sensor 36 is sent to the control computer C. The control computer C calculates and controls the fuel injection amount in the fuel injection nozzle 13 based on the depression amount detection information and the engine speed information. The control computer C grasps the calculated fuel injection amount as the engine load. The control computer C controls the rotational position of the stepping motor 201 by designating the opening θy of the throttle valve 20 based on the grasped engine load and the engine speed. That is, the control computer C controls the rotational position of the stepping motor 201 so that the opening degree of the throttle valve 20 becomes the specified opening degree θy. The crank angle detector 35, the accelerator sensor 36, and the control computer C constitute opening degree specifying means for specifying the opening degree of the throttle valve 20.

  The pressure detector 37 detects the pressure (supercharging pressure) in the intake manifold 16. Information on the supercharging pressure detected by the pressure detector 37 is sent to the control computer C. The control computer C determines the target boost pressure from a preset map based on the engine speed, the fuel injection amount, and the like. The control computer C controls the vane opening degree in the turbine unit 192 of the supercharger 19 so that the supercharging pressure detected by the pressure detector 37 becomes the target supercharging pressure.

  The air flow meter 38 detects the flow rate of the intake air flowing through the intake passage 18. The intake flow rate information obtained by the air flow meter 38 is sent to the control computer C. The control computer C limits the maximum fuel injection amount in the fuel injection nozzle 13 based on the intake flow rate information obtained by the air flow meter 38, the supercharging pressure information detected by the pressure detector 37, the engine speed information, and the like. .

  The water temperature detector 39 detects the temperature of the cooling water for cooling the engine. The control computer C determines whether the warm-up has been completed based on the water temperature information obtained by the water temperature detector 39.

  As shown in FIGS. 1B and 2A, a known hydraulic exhaust side variable valve timing mechanism 41 is provided on the end side of the exhaust camshaft 30. The exhaust side variable valve timing mechanism 41 is configured to transmit the rotational driving force of the crankshaft 26 to the exhaust camshaft 30 and to change the rotational phase of the exhaust camshaft 30 by hydraulic pressure.

  A hydraulic pressure supply adjusting mechanism 42 is connected to the exhaust side variable valve timing mechanism 41 through a hydraulic passage. The hydraulic pressure supply adjustment mechanism 42 defines an adjustment state of the exhaust side variable valve timing mechanism 41 that adjusts the rotation phase of the exhaust camshaft 30. The hydraulic supply adjustment mechanism 42 is controlled by the control computer C.

  The intake valve 27 is driven at an opening / closing timing indicated by a curve D1 in FIGS. 2 (b), (c), and (d). The exhaust valve 28 is driven at an opening / closing timing indicated by curves E1, E2, E3 in FIGS. 2B, 2C, and 2D, for example. The opening / closing timing of the exhaust valve 28 shown by these curves E1, E2, E3 is brought about by controlling the hydraulic pressure supply adjusting mechanism 42 to define the adjustment state of the exhaust side variable valve timing mechanism 41.

  In a state in which the exhaust valve 28 is driven, for example, at the opening / closing timing indicated by the curve E1 in FIG. 2B, the exhaust valve 28 does not close the exhaust port 122 before the piston 24 reaches top dead center, and the already burned gas Is not trapped in the combustion chamber 111.

  In a state in which the exhaust valve 28 is driven, for example, at the opening / closing timing indicated by a curve E2 in FIG. 2B, the exhaust valve 28 closes the exhaust port 122 before the piston 24 reaches the top dead center, and a part of the burned gas. Is confined in the combustion chamber 111. The confinement of the burnt gas in this case is performed in order to suppress the generation of nitrogen oxides. In the following, control including confinement of already burned gas performed according to a set of engine load and engine speed (engine operating state) is referred to as “normal internal EGR control”. The opening / closing timing of the exhaust valve 28 for performing the normal internal EGR control is specified in advance according to the set of the engine load and the engine speed representing the operating state. Normal internal EGR control is performed after warm-up is complete.

  FIG. 3 is a flowchart showing a blowback control program for performing control to blow back the already burned gas in the combustion chamber 111 to the intake passage 18 side. The control computer C performs blowback control based on the blowback control program shown in the flowchart of FIG. To do. Hereinafter, the blowback control will be described based on the flowchart shown in FIG.

  The control computer C determines whether or not the designated opening θy matches the opening θx of the throttle valve 20 detected by the rotational position detector 202 (step S1). If θy−α ≦ θx ≦ θy + α (YES in step S1), control computer C repeats the determination in step S1. α represents an allowable error. In the present embodiment, when θy−α ≦ θx ≦ θy + α, the detected opening degree θx is regarded as matching the specified opening degree θy.

  If θy−α ≦ θx ≦ θy + α is not satisfied (NO in step S1), the control computer C controls the hydraulic pressure supply adjustment mechanism 42 so as to advance the opening / closing timing of the exhaust valve 28, thereby adjusting the exhaust side variable valve timing mechanism 41. The adjustment state is defined (step S2). The determination of NO in step S2 is a determination that the detected opening θx and the specified opening θy do not match. A curve E3 in FIG. 2D represents the opening / closing timing of the exhaust valve 28 that is advanced, and the closing timing of the exhaust valve 28 is advanced from the top dead center. When the opening / closing timing of the exhaust valve 28 is advanced as shown by the curve E3, the exhaust valve 28 closes the exhaust port 122 before the piston 24 reaches top dead center, and a part of the burned gas is in the combustion chamber 111. Be trapped in. The intake valve 27 opens and closes the intake port 121 as shown by a curve D1 in FIG. 2D, and when the intake port 121 is opened, the burned gas in the combustion chamber 111 passes through the intake port 121 and the intake passage. It blows back to the 18th side. The already burned gas blown back to the intake passage 18 side warms the vicinity of the throttle valve 20.

  The exhaust side variable valve timing mechanism 41 and the exhaust valve 28 constitute a blow-back means for blowing back the already burned gas in the combustion chamber 111 to the intake passage 18 side. The state in which the opening / closing timing of the exhaust valve 28 is advanced as shown by the curve E3 is the blowback state of the blowback means.

  The control computer C determines whether or not the predetermined time t has elapsed since the determination of NO in step S1 (step S3). When the predetermined time t has elapsed (YES in step S3), the control computer C determines whether or not the designated opening θy and the detected opening θx match (step S4). If θy−α ≦ θx ≦ θy + α is not satisfied (NO in step S4), the control computer C turns on the warning lamp 40 (step S5). The situation where θy−α ≦ θx ≦ θy + α does not occur after the elapse of the predetermined time t indicates the occurrence of sticking of the throttle valve 20 (failure of the throttle valve 20) not caused by freezing. The determination of NO in step S4 is a determination that the throttle valve 20 has failed due to freezing, and the control computer C determines that the detected opening θx does not coincide with the specified opening θy for a predetermined time t. Determines that a failure has occurred.

  If θy−α ≦ θx ≦ θy + α (YES in step S4), control computer C shifts to normal control (step S6) and shifts to step S1. The situation of θy−α ≦ θx ≦ θy + α after the elapse of the predetermined time t indicates that the throttle valve 20 is stuck due to icing. The determination of YES in step S4 is a determination of the occurrence of sticking of the throttle valve 20 due to icing. The normal control is the opening / closing timing control of the exhaust valve 28 shown in the timing chart of FIG. 2 (b) or FIG. 2 (c).

  The opening degree detection means and the opening degree designation means described above constitute sticking detection means for detecting sticking of the throttle valve 20. When the detected opening degree θx detected by the opening degree detecting means does not coincide with the designated opening degree θy specified by the opening degree specifying means, the control computer C constituting the opening degree specifying means sets the blowback means to the blowback state. And control means for controlling the burned gas to blow back to the intake passage 18 side.

In the first embodiment, the following effects can be obtained.
(1) When the detected opening degree θx does not coincide with the specified opening degree θy, the already burned gas in the combustion chamber 111 is blown back to the intake passage 18 side. The burnt gas in the combustion chamber 111 has a high temperature, and the temperature drop of the burnt gas blown back to the intake passage 18 side is small. Therefore, the ice adhering to the throttle valve 20 melts quickly.

  (2) The burnt gas in the combustion chamber 111 is still hot immediately after the engine is started, and the temperature drop of the burnt gas blown back to the intake passage 18 side is small. Therefore, the ice adhering to the throttle valve 20 while the engine is stopped also melts quickly.

  (3) When the state where the detected opening degree θx does not coincide with the specified opening degree θy continues for a predetermined time t, the control computer C determines that a failure has occurred. The occurrence of failure in this case refers to a case where foreign matter other than ice adheres to the throttle valve and the throttle valve does not move normally, or the throttle valve does not move normally due to a failure of the stepping motor 201. As the foreign matter other than ice, for example, in the case of an internal combustion engine in which a supercharger is used, oil leaked from the supercharger is adhered and solidified, or a part of exhaust gas is returned to the intake passage. If it is an internal combustion engine, the thing etc. which the soot in exhaust gas adhered and solidified are mentioned.

  Such a determination makes it possible to distinguish between an original failure of the throttle valve 20 due to the adhesion of foreign matter or the failure of the stepping motor 201 and a malfunction of the throttle valve 20 due to freezing that is different from this failure. Therefore, since the control computer C turns on the warning lamp 40 only when the original trouble of the throttle valve 20 occurs, the warning lamp 40 does not malfunction due to freezing.

(4) The exhaust-side variable valve timing mechanism 41 used for exhaust gas purification is suitable as a mechanism constituting the blow-back means.
Next, a second embodiment shown in the flowchart of FIG. 4 will be described. The apparatus configuration is the same as in the first embodiment. The same steps as those in the flowchart in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  If NO in step S1 (if not θy−α ≦ θx ≦ θy + α), the control computer C shifts to failsafe control (step S2a). The fail-safe control here is control that gives priority to the continued operation of the engine over the contents of the driver's operation (depressing the accelerator pedal). For example, the fuel injection amount is set to a predetermined amount regardless of the depressing operation of the accelerator pedal. The control is limited to the following, and the supercharging pressure is reduced by fully opening the vane opening in the turbine section 192 of the turbocharger 19 of the variable nozzle turbocharger type. The predetermined amount is a maximum fuel injection amount specified in advance according to the intake flow rate detected by the air flow meter 38.

  If NO in step S4 (if not θy−α ≦ θx ≦ θy + α), the control computer C continues fail-safe control (step S5b). The fail safe control here includes the fail safe control in step S2a and the control for stopping the normal internal EGR control. If θy−α ≦ θx ≦ θy + α (YES in step S4), the control computer C cancels fail-safe control and shifts to normal control (step S6e), and shifts to step S1. The fail safe control in step S2a is performed while the state in which the detected opening degree θx does not coincide with the designated opening degree θy continues. That is, the control computer C performs fail-safe control in step S2a when the blow-back means is in the blow-back state.

  In the second embodiment, the same effect as in the first embodiment can be obtained. Further, by performing fail-safe control, the engine does not stop even when the throttle valve 20 malfunctions in an icing state or when the throttle valve 20 is out of order.

  Next, a third embodiment of FIGS. 5 and 6 will be described. 5, the same reference numerals are used for the same components as those in the first embodiment, and in FIG. 6, the same reference numerals are used for the same steps as those in the flowchart of the second embodiment, and detailed descriptions thereof are omitted.

  As shown in FIG. 5A, a known hydraulic intake side variable valve timing mechanism 43 is provided on the end side of the intake camshaft 29. The intake side variable valve timing mechanism 43 is configured to transmit the rotational driving force of the crankshaft 26 to the intake camshaft 29 and to change the rotational phase of the intake camshaft 29 by hydraulic pressure. A hydraulic pressure supply adjusting mechanism 44 is connected to the intake side variable valve timing mechanism 43 via a hydraulic passage. The hydraulic pressure supply adjustment mechanism 44 defines the adjustment state of the intake side variable valve timing mechanism 43 that adjusts the rotation phase of the intake camshaft 29. The hydraulic supply adjustment mechanism 44 is controlled by the control computer C.

  The exhaust valve 28 is driven at an opening / closing timing indicated by curves E1, E2, E3 in FIGS. 5B, 5C, and 5D, for example. The opening / closing timing of the exhaust valve 28 shown by these curves E1, E2, E3 is brought about by controlling the hydraulic pressure supply adjusting mechanism 42 to define the adjustment state of the exhaust side variable valve timing mechanism 41. The intake valve 27 is driven at an opening / closing timing indicated by curves D1, D2, D3 in FIGS. 5B, 5C, and 5D, for example. The opening / closing timing of the intake valve 27 shown by these curves D1, D2, D3 is brought about by controlling the hydraulic pressure supply adjusting mechanism 44 to define the adjustment state of the intake side variable valve timing mechanism 43.

  In a state where the intake valve 27 is driven at an opening / closing timing indicated by a curve D2 in FIG. 5B, for example, the exhaust valve 28 closes the exhaust port 122 before the piston 24 reaches the top dead center, and the piston 24 remains at the top dead center. The intake valve 27 opens the intake port 121 in the middle of reaching the bottom dead center after reaching. Therefore, a part of the burnt gas is trapped in the combustion chamber 111, and a part of the trapped burnt gas is blown back to the intake passage 18 side. In this case, the burnt gas is confined and blown back in order to suppress the generation of nitrogen oxides. Hereinafter, control including confinement of burned gas and blowback performed in accordance with a set of engine load and engine speed (engine operating state) will be referred to as “normal internal EGR control”.

  If NO in step S1 in the flowchart of FIG. 6 (when θy−α ≦ θx ≦ θy + α is not satisfied), the control computer C shifts to fail-safe control (step S2a). Then, the control computer C controls the hydraulic pressure supply adjustment mechanism 42 so as to advance the opening / closing timing of the exhaust valve 28 to define the adjustment state of the exhaust side variable valve timing mechanism 41, and the opening / closing timing of the intake valve 27. The hydraulic pressure supply adjustment mechanism 44 is controlled so as to retard the angle of the intake side, and the adjustment state of the intake side variable valve timing mechanism 43 is defined (step S2e).

  A curve D3 in FIG. 5D represents the open / close timing of the intake valve 27 that is retarded. When the opening timing of the intake valve 27 is retarded from the top dead center as shown by the curve D3, the intake valve 27 opens the intake port 121 while the piston 24 is moving toward the bottom dead center after reaching the top dead center. open. Accordingly, the burnt gas in the combustion chamber 111 starts to blow back to the intake passage 18 side via the intake port 121 from the middle of the piston 24 toward the bottom dead center after reaching the top dead center. The already burned gas blown back to the intake passage 18 side warms the vicinity of the throttle valve 20.

  The exhaust-side variable valve timing mechanism 41, the intake-side variable valve timing mechanism 43, the exhaust valve 28, and the intake valve 27 constitute a blow-back means that blows back the already burned gas in the combustion chamber 111 to the intake passage 18 side. The state in which the closing timing of the exhaust valve 28 is advanced from the top dead center as shown by the curve E3 and the opening timing of the intake valve 27 is retarded from the top dead center as shown by the curve D3 is the blow back of the blow back means. State.

  The control computer C makes a determination in step S4 following step S2e. If NO in step S4 (not θy−α ≦ θx ≦ θy + α), the control computer C turns on the warning lamp 40 when the predetermined time t has elapsed (YES in step S3) (step S5). ). That is, the control computer C determines that a failure has occurred when the detected opening degree θx does not coincide with the specified opening degree θy for a predetermined time t.

  If YES in step S4 (when θy−α ≦ θx ≦ θy + α), the control computer C cancels failsafe control and shifts to normal control (step S6e). That is, the control computer C performs fail-safe control for preventing the engine from being stopped when the blow-back means is in the blow-back state.

  In the third embodiment, the same effect as in the second embodiment can be obtained. In the third embodiment, the opening timing of the intake valve 27 can be adjusted. Therefore, the delay in the opening timing of the intake valve 27 can be adjusted to adjust the pressure in the combustion chamber 111 just before the blowback. That is, if the opening timing of the intake valve 27 is retarded, the pressure in the combustion chamber 111 immediately before the blow-back is lower than when only the closing timing of the exhaust valve 28 is advanced. Therefore, even if the burned-back amount of the burnt gas is the same as in the first and second embodiments, the burn-up pressure of the burned gas blown back to the intake passage 18 side can be adjusted to be reduced. This means that the blow-back pressure can be appropriately controlled so that soot does not adhere to the throttle valve 20 due to the blow-back of the burned gas.

Next, a fourth embodiment shown in FIGS. 7A, 7B, and 7C will be described. The same reference numerals are used for the same components as those in the first embodiment, and detailed description thereof is omitted.
As shown in FIG. 7B, the intake cam shaft 29 is provided with an intake cam 45 and an intake cam 31 that are opened twice. The intake cam 31 can drive the intake cam lever 33, and the intake cam 45 that opens twice can drive the intake cam lever 46 that opens twice. The intake camshaft 29, the intake cam 31, the intake cam lever 33, the double-open intake cam 45, and the double-open intake cam lever 46 constitute an intake-side variable valve mechanism 47. The intake cam lever 46 opened twice can be separated from the intake cam lever 33.

  As shown in FIG. 7A, the intake side variable valve mechanism 47 can be supplied with hydraulic pressure from a hydraulic pressure supply adjustment mechanism 48. The hydraulic supply adjustment mechanism 48 is controlled by the control computer C. When hydraulic pressure is supplied from the hydraulic supply adjustment mechanism 48 to the intake side variable valve mechanism 47, the intake cam lever 46 that is opened twice is connected to the intake cam lever 33, and the intake cam lever 46 that is opened twice is opened by the intake cam 45 that is opened twice. Driven. Curves D4 and D1 in FIG. 7C are examples of opening / closing timings of the intake valve 27 when the intake cam lever 46 is driven twice with the intake cam lever 46 opened twice. Show.

  When the intake valve 27 is opened and closed at the opening and closing timings indicated by curves D4 and D1, the intake valve 27 once opens the intake port 121 before the piston 24 reaches top dead center, and a part of the burned gas in the combustion chamber 111 Is blown back to the intake passage 18 side. The already burned gas blown back to the intake passage 18 side warms the vicinity of the throttle valve 20.

  The intake valve 27 is opened / closed by the double-open intake cam 45 and the double-open intake cam lever 46 at the opening / closing timings indicated by the curves D4, D1 in the case of NO in step S1 in the flowcharts of FIGS. (when θy−α ≦ θx ≦ θy + α is not satisfied).

  The intake side variable valve mechanism 47 and the intake valve 27 constitute a blow-back means that blows back the already burned gas in the combustion chamber 111 to the intake passage 18 side. The state in which the intake valve 27 opens the intake port 121 twice as shown by the curves D4 and D1 is the blowback state of the blowback means.

  When the supply of hydraulic pressure from the hydraulic supply adjustment mechanism 48 to the intake side variable valve mechanism 47 is stopped, the intake cam lever 46 that opens twice is disconnected from the intake cam lever 33. As a result, the intake cam lever 46 is opened twice, and the intake cam lever 33 is driven by the intake cam 31. A curve D1 in FIG. 7C is also an opening / closing timing of the intake valve 27 when the intake cam lever 33 is driven.

In the fourth embodiment, the same effects as the items (1) to (3) in the first embodiment can be obtained.
In the present invention, the following embodiments are also possible.

  If the detected opening θx and the specified opening θy do not match even after a predetermined time t has elapsed from step S2 in the flowcharts of FIGS. 3 and 4 or step S2e in the flowchart of FIG. You may make it determine.

In an internal combustion engine capable of external EGR, fail-safe control may include control for stopping execution of external EGR.
The exhaust side variable valve timing mechanism and the intake side variable valve timing mechanism may be driven by an electric motor.

A sticking detection means that detects sticking of the throttle valve 20 by detecting an abnormality in the current in the stepping motor that drives the throttle valve 20 is also possible.
The present invention may be applied to a gasoline engine equipped with a fuel injection nozzle.

The technical idea that can be grasped from the embodiment described above will be described below.
[1] The internal combustion engine according to any one of claims 1 to 6, wherein the blowback means is an intake side variable valve mechanism.

1 is a schematic configuration diagram of an internal combustion engine according to a first embodiment. (B) is a partial plan view showing an exhaust side variable valve timing mechanism. (A) is a sectional side view of an internal combustion engine. (B) is a timing chart showing the opening and closing timing of the exhaust valve and the intake valve during normal operation. (C) is a timing chart showing opening and closing timings of the exhaust valve and the intake valve during normal internal EGR control. (D) is a timing chart showing opening and closing timings of the exhaust valve and the intake valve during the blow-back control. The flowchart which shows a blow-back control program. The flowchart which shows the blow-back control program which shows 2nd Embodiment. A 3rd embodiment is shown and (a) is a sectional side view of an internal-combustion engine. (B) is a timing chart showing the opening and closing timing of the exhaust valve and the intake valve during normal operation. (C) is a timing chart showing opening and closing timings of the exhaust valve and the intake valve during normal internal EGR control. (D) is a timing chart showing opening and closing timings of the exhaust valve and the intake valve during the blow-back control. The flowchart which shows a blow-back control program. A 4th embodiment is shown and (a) is a partial plane sectional view. (B) is a perspective view showing an intake side variable valve mechanism. (C) is a timing chart showing opening and closing timings of the exhaust valve and the intake valve during the blow-back control.

Explanation of symbols

  10: A diesel engine as an internal combustion engine. 111 ... Combustion chamber. 121: Intake port. 122: Exhaust port. 18 ... Intake passage. 20 ... Throttle valve. 202: A rotational position detector as an opening degree detecting means. 27: An intake valve constituting blow-back means. 28: An exhaust valve constituting blow-back means. 35 ... Crank angle detector constituting the opening degree specifying means. 36: An accelerator sensor constituting opening degree specifying means. 41. Exhaust-side variable valve timing mechanism constituting blow-back means. 43. Intake side variable valve timing mechanism constituting blow-back means. C: A control computer as control means constituting opening degree specifying means. t: A predetermined time. θx is the detected opening. θy: Designated opening.

Claims (6)

In an internal combustion engine in which a throttle valve is arranged on the intake passage leading to the combustion chamber,
Blow-back means for blowing the burnt gas in the combustion chamber back to the intake passage;
Sticking detection means for detecting sticking of the throttle valve;
An internal combustion engine comprising: control means for controlling the blowback means to blow back to the intake passage side when the sticking detection means detects sticking of the throttle valve.   The sticking detection means includes an opening degree specifying means for specifying the opening degree of the throttle valve, and an opening degree detecting means for detecting the opening degree of the throttle valve, and the detected opening degree detected by the opening degree detecting means. The control means controls the blow-back means to be blown back to blow the burned gas back to the intake passage when the opening does not coincide with the designated opening designated by the opening designation means. 2. An internal combustion engine according to 1.   The control means determines that a failure has occurred when a state in which the detected opening detected by the opening detecting means does not coincide with the designated opening designated by the opening designation means continues for a predetermined time. The internal combustion engine according to claim 2.   The internal combustion engine according to any one of claims 1 and 2, wherein the control means performs fail-safe control for preventing the engine from being stopped when the blow-back means is in a blow-back state.   The blow-back means includes an exhaust valve that opens and closes an exhaust port that communicates with the combustion chamber, and an exhaust-side variable valve timing mechanism that can adjust the opening and closing timing of the exhaust valve. 5. The internal combustion engine according to claim 1, wherein the internal combustion engine is performed by advancing a closing timing of the exhaust valve from a top dead center by an exhaust side variable valve timing mechanism.   The blow-back means includes an intake valve that opens and closes an intake port that communicates with the combustion chamber, and an intake-side variable valve timing mechanism that can adjust the opening and closing timing of the intake valve. The exhaust side variable valve timing mechanism is used to advance the closing timing of the exhaust valve from top dead center, and the intake side variable valve timing mechanism is used to retard the opening timing of the intake valve from top dead center. Item 6. The internal combustion engine according to Item 5.

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