JP6402556B2 - Internal combustion engine, vehicle, and control method for internal combustion engine - Google Patents

Description

  The present invention can accurately detect the leakage of liquefied gas fuel into the internal combustion engine, thereby accurately estimating the occurrence of an abnormality in the seal portion inside each device of the internal combustion engine. The present invention relates to an internal combustion engine, a vehicle, and a control method for an internal combustion engine that prevent abnormal combustion during engine operation due to leakage.

  In a diesel engine using liquefied gas fuel such as DME fuel (dimethyl ether) as the fuel, the liquefied gas fuel has a lower viscosity than that of light oil, so the fuel in the engine fuel system, particularly the injection system used in the engine. The liquefied gas fuel leaks from the seat portion of the injector (injector nozzle) and the seal portion of the sliding portion such as the plunger or cylinder of the high-pressure pump. Although measures against this leak are taken to improve durability and reliability, it is difficult to completely contain the gas leak.

  In particular, in the case of a high-pressure pump using an oil-lubricated cooling method, when the lubricating oil for cooling returns from the lubricating oil outlet of the high-pressure pump to the oil pan, the liquefied gas fuel dissolved in the lubricating oil is blow-by. Leak as gas. The liquefied gas fuel that has leaked into the gas causes deterioration of the lubricating oil for engine cooling, corrosion of the metal (wall surface of the crank chamber, etc.), and air pollution. Then, it returns to the intake passage and intake manifold, mixes with fresh air, flows into the combustion chamber, and is burned with new fuel.

  When the amount of liquefied gas fuel mixed into the blow-by gas is large and the concentration of the liquefied gas fuel in the blow-by gas is increased, if combustion is performed with the intake air in which the blow-by gas is taken in, abnormal fuel is generated, and the cylinder There is a possibility that the internal pressure becomes abnormal and the cylinder liner or the like may be damaged. In the worst case, it is necessary to consider that the engine is damaged.

  In addition, the leakage of liquefied gas fuel from the nozzle seat of the fuel injection valve when the engine is stopped directly enters the cylinder and diffuses not only into the combustion chamber but also into the intake manifold and exhaust manifold. At the next start after the stop, the possibility of abnormal combustion increases.

  In this connection, a fuel injection device for injecting dimethyl ether fuel into the combustion chamber of the engine, and a start control valve that is driven by an actuator and that can open and close the exhaust port regardless of the normal exhaust timing. A sensor for detecting dimethyl ether concentration is provided downstream of the start control valve, and after the starter of the engine is started, the start control valve is kept open until the detected value of the sensor becomes a predetermined value or less. There has been proposed a start control device for a dimethyl ether diesel engine that purges dimethyl ether in a fuel chamber by controlling the injection device to a non-injection state (see, for example, Patent Document 1).

  By using this start control device, even if a small amount of dimethyl ether has leaked, it can be started by purging, but if there is a leak by detecting whether or not liquefied gas fuel has leaked, it will lead to a major failure It is also important to replace or repair parts that have leak points before.

JP 2001-115866 A

  The present invention has been made in view of the above, and an object of the present invention is to accurately detect leakage of liquefied gas fuel into an internal combustion engine. To provide an internal combustion engine, a vehicle, and a control method for an internal combustion engine that can accurately estimate an abnormal state in a seal portion such as a pump and prevent abnormal combustion during engine operation due to leakage of liquefied gas fuel. .

In order to achieve the above object, an internal combustion engine of the present invention detects liquefied gas fuel in an internal combustion engine that uses liquefied gas fuel as a fuel and has a blow-by recirculation passage that recirculates blow-by gas in a crank chamber to an intake passage. the gas detection device which is provided to one of the intake passage and the crank chamber and the blow-by recirculation passage, the abnormality control unit for controlling the internal combustion engine, the concentration of the liquefied gas fuel detected by the gas detector is preset A gas leak determination control is performed to determine that liquefied gas fuel leakage has occurred in the internal combustion engine when the determination threshold value is exceeded, and the abnormality determination threshold is set to a starter for assisting the start of the internal combustion engine. Configured to change based on startup .

  According to this configuration, during operation of the internal combustion engine, it is possible to accurately detect leakage of liquefied gas fuel (for example, DME fuel) from the seal portion inside each device of the internal combustion engine. It is possible to accurately detect an abnormal state due to. As a result, it is possible to suppress leakage by performing repairs such as replacement or repair of parts for these abnormal states, thereby preventing abnormal combustion during operation of the internal combustion engine due to leakage of liquefied gas fuel Can do.

Further, in the internal combustion engine described above, at the start of the internal combustion engine, wherein said control device at key-on of the internal combustion engine performs the gas leakage judgment control, the leakage of the liquefied gas fuel in the internal combustion engine has occurred when it is determined, it configured to perform control not to operate the starter.

  According to this configuration, at the start of the internal combustion engine, the key-on is signaled to start the gas leak determination control, and the gas leak determination control is started. By this gas leak determination control, the leakage of liquefied gas fuel in the internal combustion engine is started. By preventing the starter from operating when it is determined that the liquefied gas has occurred, it is possible to avoid combustion when the leaked liquefied gas fuel is inside the cylinder, intake manifold, exhaust manifold, etc. Thus, abnormal combustion at the start of the internal combustion engine due to leakage of liquefied gas fuel can be reliably prevented.

  In addition, a vehicle of the present invention for achieving the above object includes the above internal combustion engine.

  According to this configuration, the same operational effects as those of the internal combustion engine can be obtained.

  In the above vehicle, a warning light that lights or blinks when the control device determines that the leakage of the liquefied gas fuel is occurring in the internal combustion engine by the gas leak determination control, Configured for the driver's seat.

  According to this configuration, it is possible to notify the driver that the liquefied gas fuel has leaked in the internal combustion engine by turning on or blinking the warning light. By notifying the driver of the leakage state, the driver can know the reason for stopping the starter, and can take measures such as arranging for a repairer.

In addition, the control method for an internal combustion engine of the present invention for achieving the above object is a control of an internal combustion engine having a blow-by recirculation path for returning a blow-by gas in a crank chamber to an intake passage while using liquefied gas fuel as a fuel. In the method, when the concentration of the liquefied gas fuel detected by a gas detection device provided in any of the crank chamber, the blow-by return path, and the intake passage is equal to or higher than a preset abnormality determination threshold value, the internal combustion engine A gas leakage determination control for determining that a leak of liquefied gas fuel has occurred in the engine and changing the abnormality determination threshold based on start of a starter that assists the start of the internal combustion engine It is.

In the control method of the internal combustion engine, during starting of the internal combustion engine, it performs the gas leakage determination control at key-on of the internal combustion engine, the leakage of the liquefied gas fuel in said internal combustion engine has occurred when it is determined, so as not to actuate the starter.

  In the control method for an internal combustion engine, when it is determined by the gas leak determination control that leakage of liquefied gas fuel is occurring in the internal combustion engine, the driver's seat of the vehicle equipped with the internal combustion engine Send a signal to light or blink the warning light provided.

  According to these control methods for the internal combustion engine, the same operational effects as those of the internal combustion engine can be obtained.

  According to the control method for an internal combustion engine, a vehicle, and an internal combustion engine of the present invention, leakage of liquefied gas fuel such as DME fuel during the operation of the internal combustion engine, particularly at the start of start when abnormal combustion due to leaked liquefied gas fuel is likely to occur. Therefore, it is possible to accurately detect abnormal states in the seals of internal combustion engines such as fuel injection valves and high-pressure pumps, thereby preventing abnormal combustion during engine operation due to leakage of liquefied gas fuel. can do.

It is a figure showing typically an example of composition of an internal-combustion engine of an embodiment concerning the present invention. It is a figure which shows typically the structure of the internal combustion engine seen from the X direction of FIG. It is a figure which shows typically an example of a structure of a high pressure pump. It is a figure which shows an example of the control flow at the time of engine starting in the control method of the internal combustion engine of embodiment which concerns on this invention. It is a figure which shows an example of the control flow at the time of engine operation in the control method of the internal combustion engine of embodiment which concerns on this invention. It is a figure which shows an example of a structure of a gas concentration detection sensor. It is a figure which shows an example of the output circuit of a gas concentration detection sensor. It is a figure which shows an example of the correlation of the output voltage Vb of a gas concentration detection sensor, and density | concentration Cb.

  Hereinafter, an internal combustion engine, a vehicle, and a control method for an internal combustion engine according to embodiments of the present invention will be described with reference to the drawings. In this embodiment, DME fuel is used as the liquefied gas fuel injected into the cylinder. The vehicle according to the embodiment of the present invention includes the engine (internal combustion engine) 1 according to the embodiment of the present invention.

  As shown in FIG. 1, an engine (internal combustion engine) 1 according to an embodiment of the present invention includes an engine main body 10, an intake passage 12, and an exhaust passage 13, and further includes a turbocharger ( A turbo-type supercharger) 15 and a high-pressure EGR system that recirculates the exhaust gas G passing through the exhaust passage 13 to the intake passage 12 via the high-pressure EGR passage 14 as EGR gas Ge.

  The intake passage 12 is connected to an intake manifold 11a, and is provided with an air flow rate (MAF) sensor (not shown), a compressor 15b of a turbocharger 15, and an intercooler 16 in order from the upstream side. The exhaust passage 13 is connected to the exhaust manifold 11b and is provided with a turbine 15a of the turbocharger 15 and an exhaust gas purification processing device (not shown) in order from the upstream side. The high pressure EGR passage 14 is provided by connecting the exhaust passage 13 on the upstream side of the turbine 15a and the intake passage 12 on the downstream side of the intercooler 16, and an EGR cooler 17 and an EGR valve 18 are provided in order from the upstream side. ing.

  The fresh air A introduced from the atmosphere is sent to the intake manifold 11a together with the EGR gas Ge flowing from the high pressure EGR passage 14 into the intake passage 12 as necessary, and is sent to the combustion chamber in the cylinder (cylinder). The fuel 1 is mixed and compressed with fuel F injected from a fuel injection device (not shown), and the fuel F burns to generate power in the engine 1. Then, the exhaust gas G generated by the combustion in the engine 1 flows out to the exhaust passage 13, a part of which flows as the EGR gas Ge to the high-pressure EGR passage 14, and the remaining exhaust gas Ga (= G-Ge) is After being purified by the exhaust gas purification device via the turbine 15a, it is discharged to the atmosphere via a muffler (not shown).

  Further, a blow-by recirculation passage 20 is provided for recirculating the blow-by gas Gb in the crank chamber 10 a of the engine body 10 to the intake passage 12. In order to more clearly show the relationship among the crank chamber 10a, the intake manifold 11a, and the blow-by recirculation path 20, the configuration of the engine body 10 viewed from the X direction in FIG. 1 is shown in FIG.

  Further, a gas concentration detection sensor (gas detection device) 30 for detecting the concentration Cb of the DME fuel F is provided in any of the inside of the crank chamber 10a, the blow-by recirculation passage 20, and the intake passage 12 including the intake manifold 11a. In addition, in the structure of FIG. 2, it has provided in the inside of the crank chamber 10a.

  As this gas concentration detection sensor 30, for example, a contact combustion type sensor whose structure is shown in FIG. 6 can be used. This contact combustion type sensor includes a gas sensitive element package 30a having a combustible gas sensitive element such as a metal oxide semiconductor, an O-ring 30b, an epoxy resin (in a thick line portion) 30c, a load resistance 30d, and the like. An example of the output circuit of the gas concentration detection sensor 30 is shown in FIG. In this output circuit, the output voltage Vb between the sensor output voltage 30h and the ground 30i is determined by the heater resistance 30f and the sensor resistance 30g with respect to the voltage between the circuit voltage 30e and the ground 30i.

  This gas concentration detection sensor 30 is a sensor that uses the amount of heat generated when the combustible gas burns on the oxidation catalyst. When a combustible gas such as fuel F is introduced therein, the introduced combustible gas is detected. The gas enters the gas sensitive element package 30a and burns by being heated to about 350 ° C. to 450 ° C. by the heat generated by the heater resistance 30f, and this combustion raises the temperature of the sensor resistance 30g to increase the resistance value. Change. Since the change in the resistance value is substantially proportional to the combustible gas concentration Cb as shown in FIG. 8, the concentration Cb can be detected by the output voltage Vb as the sensor output voltage 30h.

  As shown in FIG. 1, a control device 40 called an engine control unit (ECU) that controls the engine 1 is provided. The control device 40 converts the output voltage Vb detected by the gas concentration detection sensor 30 into a concentration Cb (see FIG. 8). In addition, the control device 40 normally controls the engine 1 and the vehicle as a whole based on information from various sensors provided in the engine 1 or various sensors provided in a vehicle equipped with the engine 1. It is carried out.

  In the present invention, when the control device 40 converts the output voltage Vb detected by the gas concentration detection sensor 30 and the concentration Cb of the DME fuel F is equal to or higher than a preset abnormality determination threshold Cbc. The gas leak determination control for determining that the leakage of the DME fuel F has occurred in the engine 1 is performed. The gas concentration detection sensor 30 is preferably provided in the intake passage 12 at a position closer to the engine body 10 in order to avoid abnormal combustion in the combustion chamber, and the position closer to the cylinder such as the intake manifold 11a is also more preferable. preferable.

  Here, the abnormality determination threshold value Cbc is calculated in advance through experiments or the like and is stored in the control device 40. Considering a value at which abnormal combustion occurs in the engine 1 and the engine 1 does not fail, for example, 8000 ppm. It is preferable to set to a value of ˜12000 ppm. Further, this gas leak determination control is performed by comparing the concentration Cb with the abnormality determination threshold Cbc every preset control time (for example, 0.5 seconds to 1.5 seconds).

  Although not shown, a plurality of gas concentration detection sensors 30 are provided in any one of a plurality of locations of the inside of the crank chamber 10a, the blow-by recirculation passage 20 and the intake passage 12 (including the intake manifold 11a). The average value Cbm = ΣCbi / I) of the concentration Cbi obtained by converting the output voltage Vbi (i = 1, 2,... I) detected by these gas concentration detection sensors 30 is compared with the abnormality determination threshold Cbc. If comprised in this way, since said gas leak determination control can be performed more correctly, it is more preferable.

  Thereby, during the operation of the engine 1, leakage of DME fuel F from the seal portion inside each device of the engine 1, for example, the nozzle seat portion of the fuel injection valve (not shown) or the inside of the high pressure pump 21 (see FIG. 3). Since the leakage of the DME fuel F from the plunger 21b and the sliding portion of the cylinder 21i can be accurately detected, abnormalities such as peeling of these seal portions can be accurately detected. As a result, it is possible to perform repairs such as replacement or repair of parts for damage such as peeling of these seals, so abnormal combustion during operation of the engine 1 due to leakage of the DME fuel F, particularly starting Abnormal combustion at the start can be prevented.

  Further, when the control device 40 starts up the engine 1, the control device 40 performs gas leakage determination control by turning on the engine key, and it is determined that the leakage of the DME fuel F in the engine 1 has occurred. The starter (not shown) is controlled so as not to operate.

  Thereby, when the engine 1 is started, the key-on is signaled to start the gas leakage determination control, and the gas leakage determination control is started. Due to this gas leakage determination control, the leakage of the DME fuel F in the engine 1 occurs. When it is determined that the starter is not operated, combustion in a state where the leaked DME fuel F is in the cylinder, the intake manifold 11a, the exhaust manifold 11b, etc. can be avoided. Abnormal combustion at the start of the engine 1 due to leakage of the DME fuel F can be reliably prevented.

  Further, the vehicle according to the present invention is configured to include the engine 1 having the above-described configuration. In this vehicle, the control device 40 causes the leakage of the DME fuel F in the engine 1 due to the gas leak determination control. A warning light (not shown) that lights up or flashes when it is determined that the vehicle is driving is provided in the driver's seat of the vehicle.

  Accordingly, the driver can be notified that the DME fuel F has leaked in the engine 1 by turning on or flashing the warning light. Therefore, in particular, the leakage state of the DME fuel F at the start of the engine 1 can be detected. By notifying the driver, the driver can know the reason for stopping the starter and can take measures such as arranging for a repairer.

  Next, a control method for an internal combustion engine according to an embodiment of the present invention will be described with reference to the control flows of FIGS. The control flow in FIG. 4 is a control flow that “starts” when the engine 1 is started (“START” in FIG. 4 is when the engine key is turned on), and the control flow in FIG. It is a control flow performed when shifting to operation, that is, a control flow performed during normal operation of the engine 1.

  In the control flow of FIG. 4, when started, the output voltage Vb detected by the gas concentration detection sensor 30 is converted into the concentration Cb of the DME fuel F and detected in step S11. After detecting the concentration Cb of the DME fuel F, the process proceeds to step S12.

  In step S12, it is determined in the gas leakage determination control in step S11 whether or not the detected concentration Cb of the DME fuel F is equal to or higher than a preset abnormality determination threshold Cbc. Here, the abnormality determination threshold value Cbc is set in advance through experiments or the like, but is preferably set to a value of, for example, 8000 ppm to 12000 ppm in consideration of a value that does not cause abnormal combustion in the engine 1.

  When the concentration Cb is equal to or higher than the abnormality determination threshold Cbc in step S12 (YES), it is determined that the leakage of DME fuel F in the engine 1 has occurred, the process proceeds to step S13, and in step S13. The starter is not operated (OFF state), and a warning light (not shown) provided in the driver's seat of the vehicle is turned on or blinked (ON state), and then the control flow ends in FIG. This control flow ends.

  When the concentration Cb is less than the abnormality determination threshold Cbc in step S12 (NO), it is determined that no DME fuel F leaks in the engine 1, and the process proceeds to step S14. In step S14 Since the engine 1 is normally operated after the starter is started (ON state) without turning on or blinking the warning light (OFF state), step S21 in the control flow during normal operation of the engine 1 (see FIG. 5). Proceed to

  When the process proceeds from step S14 in the control flow in FIG. 4 to step S14 in the control flow in FIG. 5, the output voltage Vb detected by the gas concentration detection sensor 30 is converted into the concentration Cb of the DME fuel F and detected in step S21. To do. After detecting the concentration Cb of the DME fuel F, the process proceeds to step S22. In step S22, it is determined in the gas leak determination control in step S21 whether or not the detected concentration Cb of the DME fuel F is equal to or higher than a preset abnormality determination threshold Cbc.

  In step S22, when the concentration Cb is equal to or higher than the abnormality determination threshold Cbc (YES), it is determined that leakage of the DME fuel F in the engine 1 has occurred, and the process proceeds to step S23, and in step S23. After the warning lamp is turned on or blinking (ON state), the process proceeds to the end, and this control flow ends. Although not shown, it is preferable to provide a load limit in step S23 so that the engine 1 is not subjected to a certain load so as to be able to travel while minimizing damage due to abnormal combustion in the engine 1. .

  When the concentration Cb is less than the abnormality determination threshold Cbc in step S22 (NO), it is determined that no DME fuel F leaks in the engine 1, and the process proceeds to step S24. In step S24 Without turning on or blinking the warning lamp (OFF state), the process returns to step S21, and steps S21 to S24 are repeated every preset control time (preferably 0.5 to 1.5 seconds). Then, when the engine 1 stops operating, an interrupt to the control flow of FIG. 5 is generated, and the control flow of FIG. 5 ends.

  In the gas leak determination control described above, the concentration Cb of the DME fuel F is compared with the abnormality determination threshold value Cbc, but the output voltage Vb of the gas concentration detection sensor 30 is compared with the abnormality determination threshold value Vbc for output voltage. You may do it. This abnormality determination threshold value Vbc is also calculated in advance by experiments or the like, similarly to the abnormality determination threshold value Cbc.

  Further, the abnormality determination threshold Cbc is set to the same value at the start of the engine 1 (step S12 in the control flow in FIG. 4) and the normal operation after the start (step S22 in the control flow in FIG. 5). By setting the abnormality determination threshold value Cbc to different values at the time of starting and normal operation after starting, the influence of the concentration Cb of the leakage amount of DME fuel F is generally different at the time of starting and normal operation. , You will be able to control more finely.

  By these controls, the concentration Cb of the DME fuel F detected by the gas concentration detection sensor 30 provided in the crank chamber 10a, any of the blow-by recirculation passage 20 and the intake passage 12 becomes equal to or higher than a preset abnormality determination threshold Cbc. Sometimes, it is possible to perform gas leak determination control for determining that the DME fuel F has leaked in the engine 1.

  Further, when the engine 1 is started, gas leak determination control is performed by key-on, and when it is determined that the DME fuel F has leaked in the engine 1, the starter is not operated.

  Further, when it is determined by the gas leak determination control that the DME fuel F is leaking in the engine 1, a signal for turning on or blinking a warning lamp provided in the driver's seat of the vehicle equipped with the engine 1 is transmitted. To do.

  According to the internal combustion engine, the vehicle, and the control method for the internal combustion engine having the above-described configuration, when the engine 1 is operated, particularly at the start of starting when abnormal combustion due to the leaked DME fuel F is likely to occur, leakage of the DME fuel F, for example, Since the leakage of the liquefied gas fuel F from the nozzle seat portion of the fuel injection valve (not shown), the plunger 21b inside the high-pressure pump 21 (see FIG. 3), the sliding portion of the cylinder 21i, and the like can be accurately detected. Thus, it is possible to accurately estimate an abnormal state in the seal portion of the engine 1 such as a fuel injection valve or a high pressure pump, and to prevent abnormal combustion during engine operation due to leakage of the DME fuel F.

1 engine (internal combustion engine)
10 Engine body 10a Crank chamber 11a Intake manifold 11b Exhaust manifold 12 Intake passage 13 Exhaust passage 14 High-pressure EGR passage 15 Turbocharger (turbo supercharger)
15a Turbine 15b Compressor 16 Intercooler 17 EGR cooler 18 EGR valve 20 Blow-by recirculation path 21 High-pressure pump 30 Gas concentration detection sensor (gas detection device)
40 Control device A Fresh air A + Ge + Gb Intake gas G Exhaust gas Ga Exhaust gas (G-Ge) flowing into the turbine of the turbocharger
Gb Blow-by gas Gc Purified exhaust gas Ge EGR gas F DME fuel (liquefied gas fuel)
Vb, Vbi Gas concentration detection sensor output voltage Cb, Cbi Liquefied gas fuel concentration (detection value)
Cbc, Vbc abnormality determination threshold

Claims (7)

In an internal combustion engine provided with a blow-by return passage that uses liquefied gas fuel as a fuel and returns the blow-by gas in the crank chamber to the intake passage.
A gas detection device for detecting liquefied gas fuel is provided in any of the crank chamber, the blow-by return path, and the intake path,
Control device for controlling the internal combustion engine,
When the concentration of the liquefied gas fuel detected by the gas detection device is equal to or higher than a preset abnormality determination threshold value, gas leak determination control is performed to determine that the liquefied gas fuel leaks in the internal combustion engine. In addition, the internal combustion engine configured to change the abnormality determination threshold based on start of a starter that assists start of the internal combustion engine. During startup of the internal combustion engine, performs the control device the gas leak judgment control at key-on of the internal combustion engine, when the leakage of the liquefied gas fuel in the internal combustion engine is determined to have occurred, the starter The internal combustion engine of claim 1, configured to perform control that does not operate.   A vehicle comprising the internal combustion engine according to claim 1. The control device is
The warning seat that is turned on or flashes when it is determined by the gas leakage determination control that leakage of liquefied gas fuel is occurring in the internal combustion engine is provided in the driver's seat of the vehicle. 3. The vehicle according to 3. In a control method for an internal combustion engine that uses a liquefied gas fuel as a fuel and includes a blow-by return passage for returning a blow-by gas in a crank chamber to an intake passage,
When the concentration of the liquefied gas fuel detected by a gas detection device provided in any of the crank chamber, the blow-by return path, and the intake passage is equal to or higher than a preset abnormality determination threshold, Control of an internal combustion engine characterized by performing gas leak determination control for determining that a leak of liquefied gas fuel has occurred, and changing the abnormality determination threshold based on start of a starter that assists start of the internal combustion engine Method. During startup of the internal combustion engine, performs the gas leakage determination control at key-on of the internal combustion engine, when the leakage of the liquefied gas fuel in said internal combustion engine is determined to have occurred, so as not to actuate the starter The method for controlling an internal combustion engine according to claim 5, wherein:   When the gas leak determination control determines that a leak of liquefied gas fuel has occurred in the internal combustion engine, a signal for turning on or blinking a warning lamp provided in a driver's seat of a vehicle equipped with the internal combustion engine 7. The method for controlling an internal combustion engine according to claim 5, wherein transmission is performed.

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