JP2009019565A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain reduction in output of an engine, by detecting injection failure of fuel in a fuel injection device. <P>SOLUTION: This fuel injection device 1 has a control chamber 23 controlling back pressure of a needle 36 by discharging the fuel to a return fuel chamber 24 by storing the fuel of pressing the needle 36 in the direction for closing a nozzle port 37 arranged in a nozzle body 11, a control valve 14 changing a communicating state of this control chamber 23 and the return fuel chamber 24, a first piston 12 driven by a piezoelectric actuator 18, a second piston 13 integrally driven with the control valve 14, and an oil tight chamber 15 formed between the first piston 12 and the second piston 13 and transmitting displacement of the first piston 12 to the second piston 13 via the fuel sealed inside. The injection failure of the fuel by a supply shortage of the fuel in the oil tight chamber 15, is detected based on a variation in an engine speed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel injection device that uses a hydraulic pressure of fuel to inject fuel by moving a needle disposed inside an injection nozzle.

  As a fuel injection device that injects high-pressure fuel used in a diesel engine, for example, a device that injects fuel from an injection hole by driving a nozzle needle by an actuator is known. In recent years, a piezo actuator with good response has been used as a drive source for such a fuel injection device, a piezo actuator that expands and contracts, a displacement enlarging mechanism that expands the displacement of the piezo actuator, and a control that controls the back pressure of the nozzle needle A fuel injection device including a valve has been proposed. In such a fuel injection device, the displacement due to expansion and contraction of the piezo actuator is enlarged by a displacement enlargement mechanism, and fuel injection is controlled by operating a control valve.

  An improved version of such a fuel injection device is disclosed in Patent Document 1. A fuel injection device disclosed in Patent Document 1 includes a control chamber that applies pressure in a valve closing direction to a nozzle needle, and a control valve that increases and decreases the pressure in the control chamber by opening and closing between the control chamber and a return passage. And a driving force transmission unit for driving the control valve. The driving force transmission unit includes a large-diameter first piston that slides as the piezoelectric actuator expands and contracts, a small-diameter second piston that contacts the control valve and slides integrally therewith, the first piston, and the first piston It has an oil tight room (displacement expansion room) arranged between two pistons. Further, the fuel injection device includes a check valve that guides fuel to be filled in the oil tight chamber, a fuel filling passage that branches from the leak passage and supplies the filled fuel to the check valve, and the upstream side of the check valve in the fuel filling passage. It has an aperture. According to such a fuel injection device, when the piezo actuator is extended, the fuel that has flowed out of the oil-tight chamber through the clearance of the first piston and the second piston due to an increase in the pressure of the oil-tight chamber is transferred to the oil-tight chamber through the check valve. Can be replenished.

  Further, Patent Document 2 discloses an abnormality detection device that detects an abnormality of a piezo actuator provided in such a fuel injection device. According to the abnormality detection device disclosed in Patent Document 2, it is possible to detect an abnormality such as a partial disconnection or a complete disconnection inside the piezoelectric actuator.

JP 2005-207323 A JP 2002-185056 A

  In the fuel injection device including the displacement enlarging mechanism, when the piezo actuator is extended and the first piston is moved, the pressure in the oil-tight chamber filled with fuel increases due to compression by the first piston. As the pressure rises, the second piston moves the control valve and lowers the pressure in the control chamber, whereby the pressure balance that supports the nozzle needle changes and fuel is injected. However, if there is a shortage of fuel in the oil-tight chamber for some reason, bubbles will be generated in the oil-tight chamber. When bubbles are generated in the oil-tight chamber in this manner, even if the piezo actuator is extended and the first piston is moved, the bubbles in the oil-tight chamber are only compressed, and the pressure in the oil-tight chamber does not increase. For this reason, the second piston is difficult to move and fuel is not normally injected. As described above, if the fuel is not normally injected, it may be difficult to maintain the output of the engine.

  Furthermore, in the fuel injection valve, the operating state of the piezo actuator and the state of the fuel in the oil-tight chamber affect the fuel injection due to its structure. For this reason, it is considered that a fuel injection failure occurs when an abnormality occurs in either of these. The failure of the piezo actuator can be detected by the abnormality detection means of the piezo actuator. However, when an injection failure occurs due to a shortage of fuel in the oil-tight chamber, the abnormality detection means of the piezo actuator cannot detect such an injection failure. Further, by detecting the air-fuel ratio of the exhaust gas from the engine, it can be determined that fuel injection is normally performed. However, it is not possible to equip each cylinder with an air-fuel ratio sensor that detects such an air-fuel ratio. It is difficult in terms of cost.

  Accordingly, an object of the present invention is to detect a fuel injection failure in a fuel injection device and suppress a decrease in engine output.

  The fuel injection device of the present invention that solves such a problem stores the fuel that presses the needle in the direction to close the nozzle injection hole provided in the nozzle body, and discharges the fuel to the return passage, thereby back pressure of the needle. A control chamber that controls the control chamber, a control valve that changes the communication state between the control chamber and the fuel return passage, a first piston that is driven by an actuator, and a second piston that is driven integrally with the control valve An oil-tight chamber that is formed between the first piston and the second piston and that transmits the displacement of the first piston to the second piston via fuel sealed inside, and the nozzle injection hole And detecting means for detecting a fuel injection failure. With such a configuration, it is possible to detect a fuel injection failure. Further, if a fuel injection failure is detected, it is possible to take measures against the fuel injection failure. For example, it is possible to take measures to ensure engine output sufficient to stop the vehicle to a safe place.

In such a fuel injection means, the detection means may be configured to detect a fuel injection failure based on the torque fluctuation amount of the engine. Further, the detection means may be configured to detect a fuel injection failure based on a fluctuation amount of the engine speed (Claim 3). When the engine operates, engine torque fluctuations and engine speed fluctuations are detected. When fuel injection failure occurs in an operating engine, the engine torque fluctuation amount and the engine rotational speed fluctuation amount are reduced as compared with the case where fuel is normally injected. Therefore, it is possible to detect a fuel injection failure based on such a decrease in the engine torque fluctuation amount and the engine speed fluctuation amount.

  The engine during idle operation maintains a stable state as compared with the engine during vehicle traveling. That is, the engine torque fluctuation amount and the engine rotation fluctuation amount are small. For this reason, when the fluctuation amount of the engine rotation is small, it is difficult to determine whether the state is due to idling or fuel injection failure. Therefore, in the fuel injection device of the present invention, the detection means can detect a fuel injection failure based on vehicle speed information. Since the vehicle is stopped during idling, the vehicle speed is 0 km / h. Based on such vehicle speed information, it can be predicted that the vehicle is idling. As a result, when the fuel injection failure is determined, the idle operation state can be removed based on the vehicle speed. As described above, it is determined that the engine is not in the idling state, and if the engine torque fluctuation amount or the engine rotation fluctuation amount is small, it can be determined that the fuel is poorly injected.

  Moreover, in such a fuel injection device, the detection means may be configured to detect a fuel injection failure for each cylinder. By adopting such a configuration, when a fuel injection failure is detected in all the cylinders, it can be considered that a failure of a component shared by the injection nozzles of each cylinder. For example, when a failure occurs on the downstream side of the joining portion where the return passages provided in the injection nozzles of the cylinders merge, the failure affects the fuel pressure in the return passages, and the fuel of the injection nozzles It is thought to cause injection failure.

  Further, in such a fuel injection device, it is provided with determination means for determining abnormality of the actuator, and the detection means detects a fuel injection failure when the abnormality of the actuator is not determined by the determination means. (Claim 6). With such a configuration, when a malfunction of fuel injection occurs when the actuator is operating normally, a control chamber or an oil tight chamber that controls the pressure on the back of the needle due to the structure of the injection nozzle, etc. It is possible to detect that an abnormality has occurred in. For example, even if the actuator extends normally, fuel injection is not executed unless the control valve is opened due to insufficient pressure rise in the oil-tight chamber, so that an injection failure is detected. Thus, the fuel injection device can detect a shortage of pressure increase in the oil-tight chamber.

  If an injection failure of the fuel injection device occurs, it is considered that the engine output decreases and a running failure occurs. The fuel injection device of the present invention can take measures against such injection failure. The fuel injection device of the present invention comprises control means for controlling the supply of fuel to the control chamber, and the control means supplies the fuel supplied to the control chamber when a fuel injection failure is detected by the detection means. The pressure can be reduced (claim 7). Or the said control means can also be set as the structure which raises the pressure of the fuel supplied to the said control chamber, if the injection failure of a fuel is detected by the said detection means (Claim 8). Furthermore, the control means may be configured to increase the number of times of fuel supplied to the control chamber when a fuel injection failure is detected by the detection means. With such a configuration, when a fuel injection failure is detected, a decrease in engine output can be suppressed, and an engine output sufficient to stop the vehicle at a safe place can be secured.

  The fuel injection device of the present invention can detect not only fuel injection failure due to an abnormality of the actuator but also fuel injection failure due to an abnormality in a control chamber or an oil tight chamber for controlling the pressure on the back surface of the needle.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing a schematic configuration of a four-cylinder engine 100 incorporating a fuel injection device 1 of the present invention. The fuel injection device 1 includes a fuel injection valve 2, an engine speed sensor (NE sensor) 3, an ECU (Electronic Control Unit) 4, and an EDU (Electronic Driver Unit) 5. The ECU 4 constitutes detection means and determination means of the present invention.

  The NE sensor 3 measures the rotation angle of the crankshaft 6. Information on the rotation angle measured by the NE sensor 3 is transmitted to the electrically connected ECU 4. The ECU 4 that has received the information regarding the rotation angle calculates the rotation speed of the engine. Moreover, ECU4 acquires the speed of a vehicle from the vehicle speedometer with which a vehicle is equipped. The EDU 5 is electrically connected to the fuel injection valve 2 and the ECU 4 and is a drive unit that drives the fuel injection valve 2 at the request of the ECU 4. The fuel injection valve 2 is provided in each cylinder of the engine 100, and is disposed in the cylinder head 7 so that the injection hole is exposed in each cylinder. The fuel injection valve 2 is driven based on a command signal from the EDU 5 and injects fuel into the cylinder.

  Next, the fuel injection valve 2 will be described in detail. FIG. 2 is an explanatory view showing a cross section of the fuel injection valve 2 provided in the fuel injection device 1. The fuel injection valve 2 includes a control chamber 14 that stores fuel for pressing the needle 36 in a direction in which a nozzle injection hole 37 provided in the nozzle body 11 is closed. Further, a control valve 23 for changing the communication state between the control chamber 14 and the return fuel chamber 24 and the first passage 26 constituting the fuel return passage is provided. The control valve 23 is disposed in the control chamber 14.

  The fuel injection valve 2 includes a piezoelectric actuator 18 housed in a piezoelectric chamber 16 formed on the proximal end side of the nozzle body 11. The piezo actuator 18 corresponds to the actuator in the present invention. The piezoelectric actuator 18 has a capacitor structure in which piezoelectric ceramic layers such as PZT and electrode layers are alternately stacked, and has a stack structure that expands and contracts in the stacking direction, that is, the vertical direction. The piezo actuator 18 is electrically connected to the EDU 5 and is expanded and contracted by being driven by the EDU 5. A first spring 19 is disposed at the lower end 18 a of the piezo actuator 18, and a constant initial load is applied to the piezo actuator 18.

  The fuel injection valve 2 includes a large-diameter first piston 12 that is driven by the piezoelectric actuator 18 and a small-diameter second piston 13 that is driven integrally with the control valve 23. Further, an oil-tight chamber 15 is formed between the first piston 12 and the second piston 13 and transmits the displacement in the moving direction of the first piston 12 to the second piston 13. Here, the ratio of the cross-sectional areas of the first piston 12 and the second piston 13 is 2: 1. As a result, the displacement of the first piston 12 is doubled and transmitted to the second piston 13. Note that the piezo chamber 16 and the first passage 26 communicate with each other via the nozzle return passage 17. This nozzle return passage 17 constitutes a return passage in the present invention.

  The first piston 12 is in contact with the lower end 18 a of the piezo actuator 18 and moves up and down as the piezo actuator 18 expands and contracts. A fuel filling passage 20 that branches from the nozzle return passage 17 and supplies fuel to the oil tight chamber 15 is formed inside the first piston 12. In the fuel filling passage 20, an orifice 22 is formed on the downstream side, and a check ball storage portion 12 b is formed on the further downstream side of the orifice 22. A check ball 21 is stored in the check ball storage portion 12b.

  Further, inside the nozzle body 11, a fuel accumulator chamber 38 formed around the tip portion 36 a of the needle 36 is provided. Further, a back pressure chamber 33 in which a second spring 39 is housed is formed on the back side of the needle 36. An in-orifice 33a is formed at the inlet of the back pressure chamber 33, and an out-orifice 33b is formed at the outlet. The fuel accumulator chamber 38, the back pressure chamber 33, and the control chamber 14 communicate with each other through high-pressure fuel passages 27, 34, and 35, and high-pressure fuel is supplied through the fuel supply passage 28.

  A control valve 23 is built in the control chamber 14 as described above. The control valve 23 forms a three-way valve. The control chamber 14 is formed with a communication port 14a with the return fuel chamber 24 on its upper surface that becomes the upper seat surface, and further, a tapered portion 14b that decreases in diameter toward the front end side that becomes the lower seat surface, and continues to this. A small diameter portion 14c is formed. On the other hand, the control valve 23 is formed with an upper end 23 a having a tapered lower surface and a lower end 23 b that slides within the reduced diameter portion 14 c of the control chamber 14. A slight gap for fuel leakage is formed between the reduced diameter portion 14c and the lower end portion 23b.

  A leak fuel chamber 30 is provided adjacent to the downstream side of the control chamber 14. The fuel leaked from the control chamber 14 flows into the leak fuel chamber 30. A third spring 31 is housed in the leak fuel chamber 30. Such a leak fuel chamber 30 communicates with the return fuel chamber 24 and the piezo chamber 16 via the nozzle return passage 17.

  The fuel injection device 1 also includes a proximal end return passage 9 that constitutes the return passage of the present invention. The proximal-side return passage 9 is a passage that returns an overflow of the fuel supplied to the fuel injection valve 2 to a fuel tank (not shown). One end of the proximal end side return passage 9 is connected to the stack chamber 16. The other end of the base end side return passage 9 is connected to a merging portion 10 with the base end side return passage 9 returning from the fuel injection valve 2 having the same configuration attached to another cylinder. A fuel tank side return passage 41 that constitutes a return passage of the present invention is connected to the merging portion 10. The fuel tank side return passage 41 is connected to the back end that keeps the pressure in the base end side return passage 9 constant. A pressure regulating valve 40 is arranged.

  Next, the operation of the fuel injection device 1 configured as described above will be described while showing the movement of each part in the fuel injection valve 2, the movement of fuel, the balance of fuel pressure, and the like.

  First, when the nozzle injection hole 37 is closed and fuel is not being injected, that is, when the voltage is not applied to the piezo actuator 18 by the EDU 5, the control valve 23 is pressed against the upper seat surface, and the communication port 14a is blocked. As a result, high-pressure fuel is held in the control chamber 14. At this time, since the high pressure fuel is similarly held in the back pressure chamber 33, the needle 36 is pressed to the front end side, and the front end portion 36a of the needle 36 is seated on the seat portion so that the fuel is not injected. In such a state, when a voltage from the EDU 5 is applied to the piezo actuator 18, the piezo actuator 18 expands and moves the large-diameter first piston 12 downward. An oil-tight chamber 15 is formed on the lower side of the first piston 12. Since the oil-tight chamber 15 is normally filled with fuel, the displacement of the first piston 12 is a small-diameter second piston 13. Is transmitted to. Here, since the ratio of the cross-sectional areas of the first piston 12 and the second piston 13 is 2: 1, the displacement of the first piston 12 is transmitted to the second piston 13 according to the ratio of the cross-sectional areas. The second piston 13 moving in this way presses the control valve 23 against the tip end side of the nozzle body 11. As a result, the control valve 23 opens the communication port 14a and sits on the tapered portion 14b that forms the lower seat surface. As a result, the high-pressure fuel in the control chamber 14 begins to flow to the return fuel chamber 24 through the communication port 14a. As a result, the pressure in the back pressure chamber 33 that is in communication with the control chamber 14 and whose flow rate is managed by the in-orifice 33a and the out-orifice 33b decreases. When the pressure in the back pressure chamber 33 decreases, the pressing force of the needle 36 decreases, so the needle 36 moves to the proximal end side and injection is started.

  On the other hand, when the injection ends, the following operation is performed. That is, when the voltage load on the piezoelectric actuator 18 by the EDU 5 is stopped, the first piston 12, the second piston 13 and the control valve 23 move to the proximal end side by the urging force of the first spring 19 and the third spring 31. . As a result, the control valve 23 is seated on the upper seat and closes the communication port 14a. As a result, the outflow of fuel from the control chamber 14 stops and the pressure in the control chamber 14 begins to rise. When the pressure in the control chamber 14 increases, the pressure in the back pressure chamber 33 also increases. Therefore, the needle 36 is pressed to the front end side and is seated on the seat portion, the nozzle injection hole 37 is closed, and injection stops. To do.

  Here, the operation of the oil-tight chamber 15 will be described in detail. When the piezo actuator 18 is extended at the time of injection, the check ball 21 provided in the first piston 12 is pressed against the inner peripheral wall of the check ball storage portion 12b, and the oil tight chamber 15 is sealed. Since the oil-tight chamber 15 is filled with fuel, the displacement of the first piston 12 is transmitted to the second piston 13 via the oil-tight chamber 15. The fuel in the oil-tight chamber 15 in such a state is at a high pressure because it is pressed against the first piston 12. For this reason, the fuel in the oil-tight chamber 15 slightly leaks from the clearance of the sliding portion of the first piston 12 to the piezo chamber 16. Further, the return fuel chamber 24 is slightly leaked from the clearance of the sliding portion of the second piston 13. When the application of voltage to the piezo actuator 18 is stopped to stop the injection, the piezo actuator 18 returns to the original state, and the first piston 12 also moves to the proximal end side. As a result, the oil-tight chamber 15 returns to its original capacity, but since the amount of fuel in the oil-tight chamber 15 is reduced due to leakage during injection, the oil-tight chamber 15 has a negative pressure. At this time, a gap is formed between the check ball 21 in the first piston 12 and the check ball storage portion 12b, and the fuel reduced by the leak is replenished to prepare for the next injection.

  In the fuel injection device 1 that injects fuel in this way, the ECU 4 performs oil-tight chamber supply error failure determination. The oil-tight chamber supply error means that the fuel in the oil-tight chamber 15 of the fuel injection valve 2 is insufficient, so that the extension of the piezo actuator 18 is not transmitted to the control valve 23 and the control valve 23 does not operate normally. This indicates a state in which is not performed. Here, the control of the oil-tight chamber supply error failure determination performed by the ECU 4 will be described with reference to the flow shown in FIG. FIG. 3 is a control flow of oil-tight chamber supply error failure determination performed by the ECU 4.

  First, in step S11, the ECU 4 determines whether or not an injector body hardware system fail flag recorded in a RAM (Random Access Memory) included in the ECU 4 is ON. The injector body hard system fail indicates the normal state and abnormal state of the piezo actuator 18. That is, if the piezo actuator 18 is operating normally, the injector body hard system fail is OFF, and if the piezo actuator 18 is abnormal, the injector body hard system fail is ON. Such an abnormality determination of the piezo actuator 18 is performed by the ECU 4. If there is an abnormality in the piezo actuator 18, the ECU 4 sets the injector body hardware system fail flag to ON and records it in the RAM.

  In step S11, if the ECU 4 determines YES, that is, if the ECU 4 determines that the flag of the injector main body hardware system fail is ON, the ECU 4 ends the process and returns. On the other hand, if the ECU 4 determines NO in step S11, that is, if the ECU 4 determines that the flag of the injector main body hardware system fail is not ON, the ECU 4 proceeds to step S12.

  In step S12, the ECU 4 detects a change in the rotational speed of the engine 100 and the vehicle speed. The ECU 4 acquires the rotational speed of the engine 100 from the NE sensor 3 and acquires the vehicle speed from the vehicle speed meter. FIG. 4 is an explanatory diagram showing an example of engine speed fluctuations and vehicle speeds detected in this way. FIG. 4A shows the relationship between the fluctuation of the rotational speed and time, and shows the fluctuation of the rotational speed for each cylinder. FIG. 4B shows the relationship between the vehicle speed and time. The time shown in FIG. 4A and the time shown in FIG. 4B represent the same time, and the interval between the horizontal axis in FIG. 4A and the horizontal axis in FIG. 4B is also equal. After finishing the process of step S12, the ECU 4 proceeds to step S13.

  In step S13, the ECU 4 determines whether or not the transmission is neutral and the vehicle speed is 0 km / h. When the transmission is in the neutral range and the vehicle speed is 0 km / h, the engine 100 is in an idle operation state. In the idle operation state, the fluctuation amount of the rotational speed of the engine 100 is small. If the ECU 4 determines NO in step S13, that is, determines that the transmission is not neutral or determines that the vehicle speed is not 0 km / h, the ECU 4 proceeds to step S14. Moreover, ECU4 repeats the process of step S13 until it determines NO in step S13.

  In step S14, the ECU 4 determines whether or not there is a fuel injection request. ECU4 has the information regarding a fuel-injection request | requirement. The ECU 4 determines whether there is a fuel injection request based on this information. Such a fuel injection request can also be determined based on the throttle opening. If the ECU 4 determines YES in step S14, that is, if there is a fuel injection request, the process proceeds to step S15.

At step S15, ECU 4 is the rotation variation value [Delta] [omega ^2, it is determined whether there is a predetermined change amount A hereinafter become cylinder. Here, rotation fluctuation value Δω ² is a value obtained from the fluctuation amount of the rotational speed of engine 100. FIG. 5 is an explanatory diagram in which one cylinder is selected from the relationship between the change in the rotational speed of the four cylinders shown in FIG. The rotation fluctuation value Δω ² is larger than the fluctuation amount A in the vicinity of time t1 in FIG. On the other hand, the rotation fluctuation value Δω ² is smaller than the fluctuation amount A in the vicinity of time t2 in FIG. Note that the fluctuation amount A is a smaller value than the average value of the fluctuation amount of the rotational speed of the running engine 100. Further, the fluctuation amount A is a value set in advance based on the specifications of the engine 100 and the operating condition.

The rotation fluctuation value Δω ² is equal to or less than the fluctuation amount A when the engine 100 is in the idling operation state. The ECU 4 makes a determination for excluding such an idle operation state in step S13 in order not to determine such an idle operation state as an oil-tight chamber supply error failure. The ECU 4 performs control so that the engine 100 does not proceed to step S13 and subsequent steps when the engine 100 is in the idling operation state.

Even when fuel is not injected from the fuel injection valve 2, the rotation fluctuation value Δω ² may be considered to be equal to or less than the fluctuation amount A. There are various reasons why fuel is not injected from the fuel injection valve 2. For example, a fuel injection failure occurs due to a foreign matter biting of the fuel injection valve 2 or a malfunction of the needle 36 of the fuel injection valve 2. Due to such fuel injection failure, the driving force of the crankshaft 6 decreases, and the rotational fluctuation value Δω ² becomes the fluctuation amount A or less.

ECU4, when it is determined as YES in step S15, i.e., if the rotation variation value [Delta] [omega ² is less become cylinder change amount A, the process proceeds to step S16.

At step S16, ECU 4 in all the cylinders, it is determined whether or not the rotational variation value [Delta] [omega ² is less than or equal to the variation amount A. If ECU4 in step S16 it is determined that YES, that, in all the cylinders, when the rotational fluctuation value [Delta] [omega ² is less than or equal to the change amount A, the process proceeds to step S17.

  In step S17, the ECU 4 turns on the oil-tight chamber supply error fail. The oil-tight chamber supply error failure indicates an abnormal state in the oil-tight chamber 15. The ECU 4 sets the oil-tight chamber supply error fail flag to ON and records it in its own RAM when fuel is not injected due to air bubbles entering the oil-tight chamber 15.

Here, if the processing in step S17 is performed, i.e., in all the cylinders in step S16, it will be described when the rotation variation value [Delta] [omega ² is determined to equal to or less than the variation amount A. In all the cylinders, the rotational fluctuation value Δω ² is equal to or less than the fluctuation amount A because of the failure of the back pressure adjusting valve 40 disposed in the fuel tank return passage 41. If the fuel tank-side return passage 41, that is, the back pressure adjusting valve 40 disposed downstream of the merging portion 10 is out of order, the pressure adjustment of the proximal-side return passage 9 in the fuel injection valves 2 of all the cylinders is performed. It becomes deficient. If the pressure in the proximal end return passage 9 is not adjusted in this way, the fuel in the oil-tight chamber 15 is insufficient. It is desirable that the oil-tight chamber 15 is always in a state where fuel is supplied because the internal fuel leaks and decreases due to sliding of the first piston 12 and the second piston 13. However, if the pressure in the base end side return passage 9 is not adjusted, the pressure in the return passage decreases and fuel is not supplied to the oil tight chamber 15. When the fuel in the oil-tight chamber 15 is insufficient, bubbles are mixed into the oil-tight chamber 15. Thereby, the displacement of the first piston 12 cannot be transmitted to the second piston 13, and the control valve 23 does not operate normally. That is, when the fuel in which air bubbles are mixed is sealed in the oil-tight chamber 15, even if the first piston 12 pushes the fuel in the oil-tight chamber 15, the air bubbles are only compressed, and until the second piston 13 is pushed down. I cannot expect the pressure to rise. Therefore, since the control valve 23 is not opened, the needle 36 does not rise, and fuel injection failure occurs. Further, since the base end side return passage 9 provided in the fuel injection valve 2 of each cylinder is connected at the junction 10, the pressure of the fuel in the base end side return passage 9 of the fuel injection valve 2 of each cylinder is Equally, such fuel injection failure occurs in all cylinders. As described above, when the back pressure regulating valve 40 is out of order, the rotational fluctuation value Δω ² becomes equal to or less than the fluctuation amount A in all the cylinders.

  When the ECU 4 turns on the oil-tight chamber supply error fail flag in step S17, the process ends and the process returns.

By the way, when the ECU 4 determines NO in step S14, that is, when there is no fuel injection request, the process returns to step S13. Also, if ECU4 determines as NO in step S15, i.e., if the rotation variation value [Delta] [omega ² is no less become cylinder variation A also returns to step S13.

Also, if ECU4 determines as NO in step S16, i.e., in all the cylinders, when the rotational fluctuation value [Delta] [omega ² is not equal to or less than the change amount A, the process proceeds to step S18.

In step S18, the ECU 4 turns on the other error fail flags. The other error failure indicates that a fuel injection failure has occurred due to a cause different from the failure of the back pressure regulating valve 40. In step S16, if the rotation variation value [Delta] [omega ² in all cylinders determines that it has not become less variation amount A, the cylinder fuel injection valve rotation variation value [Delta] [omega ² determines that following the change amount A in step S15 2 Therefore, it can be determined that some abnormality has occurred except for the abnormality of the piezo actuator 18. For example, it can be considered that a fuel injection failure has occurred due to a foreign matter being caught or a bubble mixed in the oil-tight chamber 15. Here, the ECU 4 sets other error fail flags to ON and records them in the RAM provided therein.

  When the ECU 4 turns on the other error fail in step S18, the process ends and returns.

  As described above, the fuel injection failure can be detected by the control performed by the ECU 4, and necessary measures can be taken against the fuel injection failure. For example, it is possible to take an evacuation operation in which the output of the engine that decreases due to poor fuel injection is maintained and the vehicle is stopped at a safe place.

  Next, a second embodiment of the present invention will be described. The fuel injection device of the present embodiment has the same configuration as that of the fuel injection device 1 of the first embodiment. However, this embodiment differs from the first embodiment in the control performed by the ECU 4. In addition to the oil-tight chamber supply error fail determination control, the ECU 4 according to this embodiment performs control for retreat travel that is a countermeasure after the oil-tight chamber supply error fail flag is turned ON in the fail determination control. . In addition, since the structure of the fuel-injection apparatus of a present Example is the same as Example 1, the same reference number as Example 1 is attached | subjected and the detailed description is abbreviate | omitted.

  In this embodiment, the ECU 4 functions as the control means of the present invention. Here, the control for retreat travel performed by the ECU 4 after the oil-tight chamber supply error fail flag is turned ON in the oil-tight chamber supply error fail determination control shown in FIG. 3 will be described. FIG. 6 is a control flow for retreat travel performed by the ECU 4.

  First, in step S21, the ECU 4 determines whether or not the oil-tight chamber supply error failure flag recorded in its own RAM is ON. If the ECU 4 determines YES in step S21, that is, if it is determined that the oil-tight chamber supply error fail flag is ON, the ECU 4 proceeds to step S22. On the other hand, if the ECU 4 determines NO in step S21, that is, if it is determined that the oil-tight chamber supply error fail flag is OFF, the ECU 4 ends the process and returns.

  In step S22, the ECU 4 decreases the fuel supply pressure P by ΔP2. Here, the fuel supply pressure P is the pressure of the fuel supplied through the fuel supply passage 28. As a result, the pressures in the high pressure fuel passages 27, 34, 35 on the high pressure side of the fuel injection valve 2, the back pressure chamber 33, the fuel pressure accumulation chamber 38, and the control chamber 14 are reduced. Thus, when the pressure in the control chamber 14 decreases, the second piston 13 integrated with the control valve 23 can move with a smaller force than before the pressure in the control chamber 14 decreases. . That is, the pressure for pushing down the second piston 13 decreases. In the oil-tight chamber 15, the amount of pressure increase decreases due to a shortage of fuel. Thus, when the pressure in the control chamber 14 decreases, the second piston 13 can be pushed down. As a result, the control valve 23 integrated with the second piston 13 is opened, so that fuel is supplied from the control chamber 14 to the return fuel chamber 24, and thus to the nozzle return passage 17 and the oil tight chamber 15, The fuel can be injected. Here, ΔP2 is a preset value, and can be set to 10 (MPa), for example.

  When the ECU 4 decreases the fuel supply pressure P by ΔP2 in step S22, the ECU 4 proceeds to step S23.

  In step S23, the ECU 4 determines whether or not the fuel injection has been restored. Here, the ECU 4 determines whether or not the fuel injection has been restored from the fluctuation amount of the engine speed, as performed by the oil-tight chamber supply error failure determination. If the ECU 4 determines YES in step S23, that is, if it determines that the fuel injection has returned, it proceeds to step S24.

  In step S24, the ECU 4 determines a fuel supply pressure for retreat travel. This fuel supply pressure is the fuel injection pressure that allows the vehicle to travel until it stops at a safe position. That is, the engine 100 can inject fuel at the fuel supply pressure determined here and can run until the vehicle is stopped. When the fuel supply pressure for retreat travel is determined in step S24, the ECU 4 finishes the process and returns.

  Incidentally, if the ECU 4 determines NO in step S23, that is, if it determines that the fuel injection has not returned, it returns to step S22. Once the fuel supply pressure P is decreased in step S22, if the fuel injection does not return, the fuel supply pressure P is further decreased by ΔP2 to facilitate the opening of the control valve 23 of the fuel injection valve 2. .

  As described above, the engine 100 incorporating the fuel injection device 1 of the present embodiment can travel as much as possible to evacuate the vehicle even when a fuel injection failure occurs, and the vehicle can be placed in a safe place. Can be stopped.

  Next, Embodiment 3 of the present invention will be described. The fuel injection device of the present embodiment has the same configuration as that of the fuel injection device 1 of the first embodiment. Similar to the second embodiment, the ECU 4 of the present embodiment deals with the problem after the oil-tight chamber supply error fail flag is turned ON in the fail-decision control in addition to the control of the oil-tight chamber supply error fail determination. Control for evacuation travel is performed. In the second embodiment, when the flag of the oil tight chamber supply error fail is ON, the fuel supply pressure is decreased. On the other hand, the second embodiment is different from the second embodiment in that the fuel supply pressure is increased. Is different. In addition, since the structure of the fuel-injection apparatus of a present Example is the same as Example 1, the same reference number as Example 1 is attached | subjected and the detailed description is abbreviate | omitted.

  In this embodiment, the ECU 4 corresponds to the control means of the present invention. Here, the control for retreat travel performed by the ECU 4 after the oil-tight chamber supply error fail flag is turned ON in the oil-tight chamber supply error fail determination control shown in FIG. 3 will be described. FIG. 7 is a control flow for retreat travel performed by the ECU 4.

  First, in step S31, the ECU 4 determines whether or not the oil-tight chamber supply error failure flag recorded in its own RAM is ON. If the ECU 4 determines YES in step S31, that is, if it is determined that the oil-tight chamber supply error fail flag is ON, the ECU 4 proceeds to step S32. On the other hand, when the ECU 4 determines NO in step S31, that is, when it is determined that the oil-tight chamber supply error fail flag is OFF, the ECU 4 finishes the process and returns.

  In step S32, the ECU 4 increases the fuel supply pressure P by ΔP3. As a result, the pressures in the high pressure fuel passages 27, 34, 35 on the high pressure side of the fuel injection valve 2, the back pressure chamber 33, the fuel pressure accumulation chamber 38, and the control chamber 14 increase. As the pressure in the control chamber 14 increases in this way, the amount of fuel leaking from the control chamber 14 into the leak fuel chamber 30 increases. As a result, fuel is supplied to the nozzle return passage 17 and thus to the oil-tight chamber 15. Thus, by supplying fuel into the oil-tight chamber 15, the second piston can be pushed down by the internal pressure raised by the first piston 12. In this way, fuel can be injected. Here, ΔP3 is a preset value, and can be set to, for example, 5 (MPa).

  When the ECU 4 increases the fuel supply pressure P by ΔP3 in step S32, the ECU 4 proceeds to step S33.

  In step S33, the ECU 4 determines whether or not the fuel supply pressure P is less than or equal to the allowable supply pressure B. This allowable supply pressure B is set in a range where the engine does not cause overrun.

  If the ECU 4 determines YES in step S33, that is, if the ECU 4 determines that the fuel supply pressure P is equal to or lower than the allowable supply pressure B, the ECU 4 proceeds to step S34.

  In step S34, the ECU 4 determines whether or not the fuel injection has been restored. Here, the ECU 4 determines whether or not the fuel injection has been restored from the fluctuation amount of the engine speed, as performed by the oil-tight chamber supply error failure determination. If the ECU 4 determines YES in step S34, that is, if it determines that the fuel injection has returned, it proceeds to step S35.

  In step S35, the ECU 4 determines the fuel supply pressure for retreat travel. This fuel supply pressure is the fuel injection pressure that allows the vehicle to travel until it stops at a safe position. Here, the fuel supply pressure P at the time of starting the process of step S35 is determined as the fuel supply pressure for retreat travel. When the fuel supply pressure for retreat travel is determined in step S35, the ECU 4 finishes the process and returns.

  By the way, when the ECU 4 determines NO in step S33, that is, when it is determined that the fuel supply pressure P exceeds the allowable supply pressure B, the ECU 4 proceeds to step S36.

  In step S36, the ECU 4 sets the fuel supply pressure P to the allowable supply pressure B. When performing the process of step S36, the fuel supply pressure P exceeds the allowable supply pressure B. If the operation is continued in this state, it is conceivable that the engine 100 may malfunction such as seizure. For this reason, the fuel supply pressure P is reduced to the allowable supply pressure B. When the fuel supply pressure P is set to the allowable supply pressure B in step S36, the ECU 4 proceeds to step S35.

  If the ECU 4 determines NO in step S34, that is, if it determines that fuel injection has not returned, it returns to step S32. Once the fuel supply pressure P is increased in step S32, if the fuel injection does not return, the fuel supply pressure P is further increased by ΔP3, and the amount of fuel leaking from the control chamber 14 is increased.

  As described above, the fuel injection device 1 according to the present embodiment retracts the vehicle by supplying fuel at a fuel supply pressure at which the engine 100 does not generate overrun even when fuel injection failure occurs. Therefore, the vehicle can be stopped at a safe place.

  Next, a fourth embodiment of the present invention will be described. The fuel injection device of the present embodiment has the same configuration as that of the fuel injection device 1 of the first embodiment. In the same manner as in the second embodiment, the ECU 4 in this embodiment, in addition to the control in the oil-tight chamber supply error fail determination in the first embodiment, after the oil-tight chamber supply error fail flag is turned ON in the fail determination control, The control for evacuation travel which is the countermeasure is performed. In the second embodiment, when the flag of the oil tight chamber supply error fail is ON, the fuel supply pressure is decreased, whereas in the second embodiment, the number of fuel injections is increased. Is different. In addition, since the structure of the fuel-injection apparatus of a present Example is the same as Example 1, the same reference number as Example 1 is attached | subjected and the detailed description is abbreviate | omitted.

  In this embodiment, the ECU 4 corresponds to the control means of the present invention. Here, the control for retreat travel performed by the ECU 4 after the oil-tight chamber supply error fail flag is turned ON in the oil-tight chamber supply error fail determination control shown in FIG. 3 will be described. FIG. 8 is a control flow for retreat travel performed by the ECU 4.

  First, in step S41, the ECU 4 determines whether or not an oil-tight chamber supply error failure flag recorded in its own RAM is ON. If the ECU 4 determines YES in step S41, that is, if it is determined that the oil-tight chamber supply error fail flag is ON, the ECU 4 proceeds to step S42. On the other hand, if the ECU 4 determines NO in step S41, that is, if it is determined that the oil-tight chamber supply error fail flag is OFF, the ECU 4 ends the process and returns.

  In step S42, the ECU 4 increases the number of fuel injections. The fuel injection device 1 performs fuel injection into the cylinder by performing pilot injection that performs injection before main injection or post injection that performs injection after main injection, in addition to main injection, in one combustion stroke. The number of injections can be increased. In the fuel injection valve 2, even if fuel cannot be injected due to air bubbles mixed in the oil-tight chamber 15, if the small-diameter piston 13 moves even slightly, the control valve 23 opens and the return fuel chamber 24. Fuel can flow into the It is conceivable that when the fuel injection valve 2 increases the number of injections, that is, the number of expansion / contractions of the piezo actuator 18, the control valve 23 opens and the amount of fuel supplied to the return passage increases. As a result, the fuel is supplied to the nozzle return passage 17 and thus the oil-tight chamber 15, so that the amount of pressure increase in the oil-tight chamber 15 is returned, and the control valve 23 integrated with the second piston 13 is sufficiently provided. The valve can be opened, thereby reducing the back pressure of the needle 36, so that injection can be performed.

  If ECU4 increases the frequency | count of injection in step S42, it will progress to step S43.

  In step S43, the ECU 4 determines whether or not the total fuel injection amount Q is less than or equal to the allowable injection amount C. This allowable injection amount C is set within a range in which the engine does not cause overrun. The total injection amount Q is the total amount of fuel injected in a single combustion stroke.

  If the ECU 4 determines YES in step S43, that is, if it is determined that the total fuel injection amount Q is less than or equal to the allowable injection amount C, the ECU 4 proceeds to step S44.

  In step S44, the ECU 4 determines whether or not the fuel injection has been restored. Here, the ECU 4 determines whether or not the fuel injection has been restored from the fluctuation amount of the engine speed, as performed by the oil-tight chamber supply error failure determination. If the ECU 4 determines YES in step S44, that is, if it determines that the fuel injection has returned, it proceeds to step S45.

  In step S45, the ECU 4 determines the number of times of retreat traveling injection. The number of injections is the number of fuel injections that enables the vehicle to travel until it stops at a safe position. Here, the number of fuel injections at the time of starting the process of step S45 is determined as the number of times of retreat travel injections. When the fuel supply pressure for retreat travel is determined in step S45, the ECU 4 finishes the process and returns.

  By the way, if the ECU 4 determines NO in step S43, that is, if it determines that the total fuel injection amount Q exceeds the allowable injection amount C, the ECU 4 proceeds to step S46.

  In step S46, the ECU 4 sets the total fuel injection amount Q to be the allowable injection amount C or less. That is, the number of fuel injections is reduced so that the total fuel injection amount Q is equal to or less than the allowable injection amount C. When the process of step S46 is performed, the total fuel injection amount Q exceeds the allowable injection amount C. If the operation is continued in this state, it is conceivable that the engine 100 may malfunction such as seizure. For this reason, the total fuel injection amount Q is set to the allowable injection amount C or less. After finishing the process of step S46, the ECU 4 proceeds to step S45.

  If the ECU 4 determines NO in step S44, that is, if it determines that the fuel injection has not returned, it returns to step S42. Once the number of fuel injections is increased in step S42, if the fuel injection does not return, the number of fuel injections is further increased to promote the fuel flow to the return passage.

  In this way, the fuel injection device 1 is capable of running only enough to retract the vehicle by supplying fuel at a fuel injection amount that does not cause an overrun even when a fuel injection failure occurs. The vehicle can be stopped at a safe place.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited thereto. Various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope.

  For example, in the oil-tight chamber supply error fail determination control performed by the ECU 4, detection of fuel injection failure is performed based on the fluctuation amount of the engine speed, but instead, based on the fluctuation amount of the engine torque. A fuel injection failure can be detected.

It is explanatory drawing which showed schematic structure of the 4-cylinder engine incorporating the fuel injection apparatus. It is explanatory drawing which showed the fuel injection valve with which a fuel injection apparatus is provided in the cross section. It is a control flow of oil-tight chamber supply error failure determination performed by the ECU. It is explanatory drawing which showed an example of the fluctuation | variation of the rotation speed of an engine, and an example of a vehicle speed, Comprising: (a) shows the relationship between the fluctuation | variation of a rotation speed, and time for every cylinder, (b) shows the relationship between a vehicle speed and time. Is shown. FIG. 5 is an explanatory diagram in which one cylinder is selected from the relationship between fluctuations in the rotational speed of the four cylinders and time shown in FIG. This is a control flow for evacuation travel performed by the ECU, which lowers the fuel supply pressure. This is a control flow for evacuation travel performed by the ECU, and increases the fuel supply pressure. This is a control flow for evacuation travel performed by the ECU, and increases the number of fuel injections.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection apparatus 2 Fuel injection valve 3 NE sensor 4 ECU
5 EDU
9 Proximal return passage 11 Nozzle body 12 First piston 13 Second piston 14 Control chamber 15 Oil tight chamber 17 Nozzle return passage 18 Piezo actuator 20 Fuel filling passage 21 Check ball 23 Control valve 24 Return fuel chamber 33 Back pressure chamber 36 Needle 37 Nozzle nozzle hole 40 Differential pressure valve 41 Fuel tank side return passage 100 Engine

Claims (9)

A control chamber for controlling the back pressure of the needle by storing fuel that presses the needle in a direction to close the nozzle nozzle hole provided in the nozzle body and discharging the fuel to the return passage;
A control valve for changing the communication state between the control chamber and the fuel return passage;
A first piston driven by an actuator;
A second piston driven integrally with the control valve;
An oil-tight chamber that is formed between the first piston and the second piston and that transmits the displacement of the first piston to the second piston via fuel sealed inside;
Detecting means for detecting poor fuel injection in the nozzle nozzle hole;
A fuel injection device comprising: The fuel injection device according to claim 1, wherein
The fuel injection device according to claim 1, wherein the detection means detects a fuel injection failure based on an engine torque fluctuation amount. The fuel injection device according to claim 1, wherein
The fuel injection device according to claim 1, wherein the detecting means detects a fuel injection failure based on a fluctuation amount of an engine speed. The fuel injection device according to claim 1, wherein
The fuel injection device according to claim 1, wherein the detection means detects fuel injection failure based on vehicle speed information. The fuel injection device according to claim 1, wherein
The fuel injection device characterized in that the detection means detects a fuel injection failure for each cylinder. The fuel injection device according to claim 1, wherein
A determination means for determining an abnormality of the actuator;
The fuel injection device according to claim 1, wherein the detection unit detects a fuel injection failure when the determination unit does not determine abnormality of the actuator. The fuel injection device according to claim 1, wherein
Control means for controlling the supply of fuel to the control chamber;
The control means reduces the pressure of the fuel supplied to the control chamber when a fuel injection failure is detected by the detection means. The fuel injection device according to claim 1, wherein
Control means for controlling the supply of fuel to the control chamber;
The control means increases the pressure of the fuel supplied to the control chamber when a fuel injection failure is detected by the detection means. The fuel injection device according to claim 1, wherein
Control means for controlling the supply of fuel to the control chamber;
The control means increases the number of times of fuel supplied to the control chamber when a fuel injection failure is detected by the detection means.

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