JP2018044532A - Exhaust emission control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission control device which can reduce a variation of an injection amount of an additive from an injection valve with respect to a target injection amount.SOLUTION: An acquisition unit acquires a physical amount of an internal combustion engine. A pulsation calculation unit calculates a valve-closing force F5 which pulses on the basis of an acquisition result. A period calculation unit compares a maximum valve-opening force F2 of an injection valve and the pulsing valve-closing force F5, and calculates a valve-openable period TD2 in which the maximum valve-opening force F2 is larger than the valve-closing force F5, and the injection valve can be opened. Timing (valve-opening force generation timing tf2) at which the maximum valve-opening force F2 is applied after energization start timing ton1 at which energization to the injection valve is started is set as a basic delay period TD4. A post-calculation period calculation unit calculates a period at which the start timing t2 and the finish timing t3 of the valve-openable period TD2 are quickly corrected by the basic delay period TD4 as a post-correction period TD5. An energization start timing setting unit sets the energization start timing ton1 so as to fall within the post-correction period TD5.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an exhaust purification control device.

  Patent Document 1 discloses a technique in which an exhaust valve that injects an additive such as a fuel or a reducing agent into an exhaust pipe is provided in an exhaust gas purification apparatus that purifies exhaust gas using a diesel particulate filter (DPF), a catalyst, or the like. Specific examples of the additive include combustion fuel for DPF regeneration, a reducing agent that reduces NOx on the catalyst, and the like.

  A conventional general injection valve includes a valve body that opens and closes an injection hole, a spring member that applies a spring force to the valve body in the valve closing direction, and an electromagnetic force that is generated by energization to generate the electromagnetic force in the valve opening direction. A solenoid to be applied. When the solenoid is energized, the valve element is opened to inject the additive. An additive supply pump supplies the additive to the injection valve.

Japanese Patent No. 5293279

  In a conventional control device that controls the operation of this type of injection valve, the injection amount of the additive from the injection hole is determined by the pressure applied to the additive by the additive supply pump (supply pressure) and the energization period of the injection valve. And determined by Also, the faster the additive supply pump rotates, the greater the supply pressure and the greater the injection amount. Therefore, when the rotational speed of the additive supply pump is the same and the energization period to the injection valve is the same, the injection amount of the additive into the exhaust pipe is considered to be equal.

  However, the present inventor has found that the phenomenon that the injection amount of the additive varies even when the rotational speed of the additive supply pump is the same and the energization period to the injection valve is equal.

  The present invention has been made in view of the above-described problems, and provides an exhaust purification control apparatus capable of reducing the variation in the injection amount of the additive from the injection valve with respect to the target injection amount. Objective.

  The invention disclosed herein employs the following technical means to achieve the above object. Note that the reference numerals in parentheses described in the claims and in this section indicate the correspondence with the specific means described in the embodiments described later, and do not limit the technical scope of the invention. .

  A valve body (41) for opening and closing a nozzle hole (44) for injecting an exhaust purification additive into the exhaust pipe (3) of the internal combustion engine (2), and a spring force (F3) to the valve body in the valve closing direction. Exhaust gas purification that controls the operation of the injection valve (4), including a spring member (42) to be applied and a solenoid (43) that generates an electromagnetic force (F2) by energization and applies the electromagnetic force in the valve opening direction. The control device (5) includes an acquisition unit (S102) that acquires a physical quantity correlated with the rotational phase of the output shaft (64) of the internal combustion engine, and a positive displacement pump (6) that is connected to and driven by the output shaft. The pressure of the additive pulsating by feeding the additive to the injection valve is defined as the supply pressure (P1), and the combined force of the additive force (F1), which is the force that the valve body receives the supply pressure, and the spring force. Based on the result obtained by the acquisition unit as the pulsating valve closing force (F5) acting on the injection valve The pulsation calculating unit (S103), and the force when the electromagnetic force gradually increases and reaches the maximum value is defined as the maximum valve opening force (F2), and the pulsating valve closing force calculated by the maximum valve opening force and the pulsation calculating unit And a period calculation unit (S104) for calculating a valve opening possible period (TD2) in which the injection valve can be opened by the maximum valve opening force being larger than the valve closing force, and the injection valve The period from the energization start timing (ton1) when energization is started to the timing when the maximum valve opening force is applied to the injection valve is defined as the basic delay period (TD4), and the calculated start timing (t2) and end of the possible valve opening period A corrected period calculation unit (S106) that calculates a period obtained by correcting each of the timings (t3) earlier by the basic delay period as a corrected period (TD5), and an energization start that sets the energization start timing to be within the corrected period Thailand Ring setting unit and (S107), an exhaust purification control device comprising a.

  The present inventor investigated the cause of the above-mentioned phenomenon that “the phenomenon that the injection amount of the additive varies even when the rotational speed of the additive supply pump is the same and the energization period of the injection valve is the same”. Got.

  The injection valve has a needle, a spring member, and a solenoid as a valve body. The needle opens and closes the injection hole of the injection valve. In the needle, a force (additive force) that the supply pressure pushes on the upper surface of the needle and a spring force that is a force that the spring member pushes the needle act as a valve closing force in the valve closing direction. When the injection valve is opened, an electromagnetic force is generated in the needle opening direction by energizing the solenoid. Since the electromagnetic force gradually increases after energization starts, the electromagnetic force when reaching the maximum is defined as the maximum valve opening force. Hereinafter, the maximum valve opening force is expressed as valve opening force. In order to move the needle in the valve opening direction, the valve opening force needs to be larger than the valve closing force.

  Since the additive supply pump is a positive displacement pump, a periodic change (pulsation) occurs in the supply pressure. Therefore, pulsation is also generated in the force (additive force) caused by the supply pressure pushing the needle. Therefore, pulsation also occurs in the valve closing force applied to the needle. When the positive displacement pump is driven in connection with the output shaft of the engine, the amplitude of the valve closing force, which is the sum of the pulsating additive force and the spring force, is correlated with the engine rotational speed as shown in FIG. As the engine speed increases, the amplitude and average value F5A of the valve closing force F5 increase. That is, the upper limit value F5T and the lower limit value F5D of the valve closing force F5 increase as the engine speed increases. Further, the valve closing force F5 pulsates between an upper limit value F5T and a lower limit value F5D.

  Here, the valve opening force F2 is constant. When the engine speed is lower than NE0, the valve opening force F2 is higher than the upper limit value F5T of the valve closing force F5. On the other hand, when the engine speed is higher than NE0, the valve opening force F2 is between the upper limit value F5T and the lower limit value F5D of the valve closing force F5. Therefore, when the engine speed is higher than NE0, the magnitudes of the valve opening force F2 and the valve closing force F5 are periodically switched by the pulsation of the valve closing force. That is, the period during which the valve opening force F2 is larger than the valve closing force F5 and the injection valve can be opened is defined as the valve opening possible period, and the valve opening force F2 is smaller than the valve closing force F5 and the injection valve opens. When the period during which the valve cannot be opened is the non-valve opening period, the valve opening possible period and the valve opening non-opening period are alternately switched.

  Even if energization of the solenoid for opening the injection valve is started, even if the valve opening force is generated, the valve opening force generation timing that is the timing at which the valve opening force is generated cannot be opened. If it is a period, the injection valve cannot be opened immediately. However, when the valve closing force pulsates, the magnitudes of the valve closing force and the valve opening force are interchanged, and when the valve opening possible period is reached, the injection valve can start to open. In other words, if the valve opening force generation timing is a non-valve opening period, the valve opening cannot be started until the valve opening possible period, and there is a time lag between the energization start timing and the valve opening start timing. Arise. In other words, the valve opening start timing is delayed with respect to the energization start timing. Since the valve opening time of the injection valve is shortened by the delay, only a small amount of the target injection amount can be injected. It is understood that this delay in valve opening is the cause of “a phenomenon in which the injection amount of the additive varies even when the rotational speed of the additive supply pump is the same and the energization period of the injection valve is the same”. It was.

  Based on this knowledge, according to the present invention, the energization start timing setting unit sets the energization start timing within the corrected period. Therefore, even if the electromagnetic force reaches the maximum and the timing at which the valve opening force is generated is delayed by the basic delay period with respect to the energization start timing, the timing at which the valve opening force is generated overlaps the valve opening possible period. Thereby, it is possible to suppress the occurrence of a time delay between the timing at which the valve opening force is generated and the valve opening start timing at which the valve is actually opened. That is, it can be suppressed that the period from the energization start timing to the valve opening start timing is longer than the basic delay period. Thereby, it is possible to provide an exhaust purification control apparatus capable of reducing the variation in the injection amount of the additive from the injection valve with respect to the target injection amount.

1 is a system configuration diagram of a purification system to which an exhaust purification control device of a first embodiment is applied. It is a schematic block diagram which shows the internal action | operation of the positive displacement pump used for 1st Embodiment. It is the figure which showed the correlation with the pulsation of the discharge port pressure which is a pressure of the discharge port vicinity of the positive displacement pump in 1st Embodiment, and a crank angle. It is a figure which shows the phase delay of the supply pressure with respect to the discharge outlet pressure in 1st Embodiment. It is a schematic block diagram of the injection valve of the state in which the valve opening force and the valve closing force are added to the needle of 1st Embodiment. It is a broken line diagram showing the magnitude relationship between the valve closing force and the valve opening force based on the engine rotation speed. It is a time chart which shows an example of the valve opening delay at the time of energizing a solenoid without considering pulsation of valve closing force. It is a time chart at the time of correct | amending the energization start timing before correction | amendment of 1st Embodiment. It is a flowchart which shows the control flow for performing correction | amendment of 1st Embodiment. It is a time chart at the time of correct | amending the electricity supply completion timing before correction | amendment of 2nd Embodiment. It is a flowchart which shows the control flow for performing correction | amendment of 2nd Embodiment. It is a time chart at the time of correct | amending the energization completion timing before correction | amendment of 3rd Embodiment. It is a flowchart at the time of correct | amending the energization end timing before correction | amendment of 3rd Embodiment. It is a flowchart at the time of amending the energization end timing before amendment of a 4th embodiment.

  Hereinafter, a plurality of modes for carrying out the invention will be described with reference to the drawings. In each embodiment, portions corresponding to the matters described in the preceding embodiment may be denoted by the same reference numerals and redundant description may be omitted. In each embodiment, when only a part of the configuration is described, the other configurations described above can be applied to other portions of the configuration.

(First embodiment)
FIG. 1 is a system configuration diagram showing an embodiment in which the present invention is applied to a purification system 1 for a vehicle in which a diesel engine 2 is mounted on an internal combustion engine.

  A crank angle sensor 9, a positive displacement pump 6, an intake pipe 11 and a first exhaust pipe 10 are connected to the engine 2. The first exhaust pipe 10 is connected to the second exhaust pipe 3 via a turbocharger 12. This second exhaust pipe 3 corresponds to the exhaust pipe. In the middle of the second exhaust pipe 3, a filter (DPF) 8 for collecting PM, which is particulate matter in the exhaust, is provided. The DPF 8 causes fuel consumption and power performance deterioration due to an increase in exhaust pressure caused by PM accumulation. Therefore, the DPF 8 needs to periodically remove the collected PM (that is, PM regeneration). In order to remove the accumulated PM, fuel is periodically injected into the second exhaust pipe 3 as an additive. The fuel is injected by an injection valve 4 provided upstream of the DPF 8 in the second exhaust pipe 3. The fuel is sent from the positive displacement pump 6 to the injection valve 4 through the fuel pipe 7. The fuel injected along the flow of the exhaust gas passing through the second exhaust pipe 3 reaches the DPF 8 so that the PM deposited on the DPF 8 can be removed by combustion.

  The purification system 1 is provided with an ECU 5 for controlling the operation of the engine 2 and the injection valve 4. This ECU 5 corresponds to an exhaust purification control device. The ECU 5 controls the operating state of the engine 2 according to the driver's request. The ECU 5 includes a memory in which a predetermined program is recorded, a processor that performs arithmetic processing according to the program, an input circuit, and an output circuit. The ECU 5 is connected to the crank angle sensor 9 and the injection valve 4 and the like via electric wiring.

  As shown in FIG. 2, the positive displacement pump 6 is directly connected to the output shaft 64 of the engine 2. The positive displacement pump 6 includes a housing 60, an outer rotor 61, and an inner rotor 62. The housing 60 has a suction port 65 for sucking fuel from a fuel tank (not shown) and a discharge port 66 for discharging fuel. An outer rotor 61 is incorporated in the housing 60. Further, the outer rotor 61 has a storage chamber 63. The fuel sucked into the positive displacement pump 6 is stored in the storage chamber 63. The storage chamber 63 is formed by an outer peripheral surface having seven internal gears. An inner rotor 62 that is rotated by rotation of the output shaft 64 of the engine is disposed in the storage chamber 63. The inner rotor 62 has six external gears that are smaller in diameter than the outer peripheral surface. The external gear of the inner rotor 62 and the internal gear of the outer rotor 61 mesh with each other in a trochoid gear type. When the external gear and the internal gear that rotate together with the output shaft 64 mesh with each other, the outer rotor 61 also rotates. As a result, the fuel stored between the two internal gears of the outer rotor 61 is discharged from the discharge port 66. Pressure (discharge port pressure P0) is applied to the discharged fuel.

  The discharge port 66 of the positive displacement pump 6 is provided with a relief valve (not shown). This relief valve relieves the discharged fuel to the fuel tank when the discharge port pressure P0 rises to a predetermined pressure. This prevents the pressure of the fuel discharged from the positive displacement pump 6 from becoming too high. The discharge port pressure P0 of the present embodiment indicates a pressure upstream of the relief valve.

  The discharge of the fuel from the positive displacement pump 6 is caused by the internal gear and the external gear meshing one by one by the rotation of the output shaft 64. Therefore, a periodic change (pulsation) as shown in FIG. 3 occurs in the pressure applied to the fuel when discharged. Since the inner rotor 62 rotates with the rotation of the output shaft 64, the pulsation characteristics correlate with the engine operating state as shown in FIG. Specifically, the pulsation wavelength is determined by the crank angle that is the rotational phase of the output shaft 64 of the engine 2. The amplitude of the pulsation is determined by the speed of change of the rotational phase of the engine, that is, the rotational speed of the engine. As the engine speed increases, the wavelength decreases and the amplitude increases.

  The fuel discharged from the discharge port 66 is supplied to the injection valve 4 through the fuel pipe 7. At this time, the propagation of fuel pulsation through the fuel pipe 7 causes a phase delay as shown in FIG. Therefore, the pulsation of the fuel pressure becomes a pulsation in which the phase corresponding to the propagation delay phase I 0 has changed with respect to the discharge port pressure P 0 and is supplied to the injection valve 4. The pressure of the fuel supplied to the injection valve 4 in which the phase corresponding to the propagation delay phase I0 has changed is defined as a supply pressure P1. The pulsation wavelength and amplitude of the supply pressure P1 are the same as the discharge port pressure P0.

  Here, the mechanism of the injection valve 4 when the injection valve 4 injects fuel into the second exhaust pipe 3 will be described with reference to FIG. The injection valve 4 has an injection hole 44 for injecting an additive for exhaust gas purification, a needle 41 as a valve body, a spring member 42 and a solenoid 43. The needle 41 opens and closes the injection hole 44 of the injection valve 4. In the needle 41, the force (additive force F1) that the supply pressure P1 pushes the upper surface of the needle 41 and the spring force F3 that is the force that the spring member 42 pushes the needle 41 are closed as the valve closing force F5 (see FIG. 6). Working in the valve direction. Since the supply pressure P1 is pulsating, the additive force F1 is also pulsating. On the other hand, the spring force F3 is constant. That is, the pulsation of the valve closing force F5 is due to the pulsation of the additive force F1. Therefore, the wavelength and amplitude of the pulsation of the valve closing force F5 can be calculated from the supply pressure P1.

  When the injection valve 4 is opened, the solenoid 43 is energized to apply electromagnetic force in the valve opening direction of the needle 41, and the injection valve 4 is opened. Since the electromagnetic force gradually increases after the energization is started, the electromagnetic force when reaching the maximum is defined as the maximum valve opening force and expressed as the valve opening force F2. In order to move the needle 41 in the valve opening direction, the valve opening force F2 by the solenoid 43 needs to be larger than the valve closing force F5.

  As described above, as shown in FIG. 6, when the engine speed is lower than NE0, the valve opening force F2 is higher than the upper limit value F5T of the valve closing force F5. On the other hand, when the engine speed is higher than NE0, the valve opening force F2 is between the upper limit value F5T and the lower limit value F5D of the additive force F1. Therefore, when the engine speed is higher than NE0, the magnitude of the valve opening force F2 and the valve closing force F5 is periodically switched by the pulsation of the valve closing force F5. A period in which the valve opening force F2 is larger than the valve closing force F5 and the injection valve 4 can be opened is referred to as an openable period TD2, and a period in which the valve opening force F2 is smaller than the valve closing force F5 and the injection valve cannot be opened is not opened. Let it be a possible period TD1. The valve opening possible period TD2 and the valve opening impossible period TD1 are alternately switched as shown in FIG.

  Assume that the ECU 5 starts energizing the solenoid 43 for opening the injection valve 4 at the energization start timing ton before correction as shown in FIG. As described above, the electromagnetic force gradually increases from the energization start timing ton before correction. Therefore, the valve opening force F2 does not immediately occur immediately after the energization start timing ton before correction, but the valve opening force generation that is the timing at which the electromagnetic force becomes maximum after a predetermined time has elapsed from the energization start timing ton before correction. Occurs at timing tf2. A period from the energization start timing ton before the correction to the valve opening force generation timing tf2 is defined as a basic delay period TD4. This basic delay period TD4 can be said to be the period in which the injection valve 4 can be opened earliest after energization has started, that is, the shortest period until the valve is opened.

  Even when energization of the injection valve 4 is started and the valve opening force generation timing tf2 is reached, the injection valve 4 cannot be opened if the valve opening force generation timing tf2 is the valve opening impossible period TD1. . However, when the valve closing force F5 pulsates, the magnitudes of the valve closing force F5 and the valve opening force F2 are switched, and when the valve opening possible period TD2 is reached, the injection valve 4 starts to open (before correction) Valve opening start timing top). That is, when the valve opening force generation timing tf2 is the valve opening impossible period TD1, the valve opening cannot be started until the valve opening possible period TD2 is reached. Therefore, a valve opening delay period TD3 longer than the basic delay period TD4 occurs between the energization start timing ton before correction and the valve opening start timing top before correction.

  Therefore, in this embodiment, the ECU 5 performs correction as shown in FIG. In this embodiment, the start timing t2 of the valve-openable period TD2 is corrected to be advanced by the basic delay period TD4, and the correction start timing t2a is calculated by the ECU 5. Similarly, the ECU 5 calculates the correction end timing t3a for the end timing t3 of the valve opening delay period TD3. Then, the ECU 5 calculates the corrected period TD5 from the correction start timing t2a and the correction end timing t3a. The ECU 5 sets the energization start timing ton1 so that the energization start timing ton before correction is within the post-correction period TD5. More preferably, the energization start timing ton1 that is earlier than the lower limit timing tB by the basic delay period TD4 is set so that the lower limit timing tB at which the valve closing force F5 becomes the lower limit value F5D coincides with the valve opening start timing top1.

  In addition, when the needle 41 moves in the valve opening direction even a little from the closed state, fuel is filled between the needle 41 and the injection hole 44. Thereby, the force in which the additive force F1 pushes the lower surface of the needle 41 in the valve opening direction is generated. As a result, the force by which the additive force F1 pushes the upper surface of the needle 41 and the force by which the additive force F1 pushes the lower surface of the needle 41 cancel each other. Therefore, it is not necessary to consider the additive force F1 acting on the needle 41 after the needle 41 starts to open. That is, even if the pulsation of the valve closing force F5 increases immediately after the needle starts to open, the needle 41 can be kept open as long as the needle 41 moves in the valve opening direction.

  Next, a correction process performed by the ECU 5 to realize the above correction will be described with reference to FIG. When the operation power is supplied to the ECU 5 and starts its operation, the ECU 5 performs correction processing according to the control flow of FIG.

  When this control flow starts, it is determined whether or not there is a request to drive the injection valve 4 in step S100. Whether or not there is a drive request for the injection valve 4 is determined from the differential pressure between the exhaust pressures detected by the sensors provided upstream and downstream of the DPF 8 attached to the second exhaust pipe 3. When the differential pressure of the exhaust pressure is greater than or equal to a predetermined value, it is considered that the DPF needs to be regenerated and a drive request signal for the injection valve 4 is output. If there is no drive request for the injection valve 4 in step S100, the process returns to step S100 after a predetermined period.

  If there is a drive request for the injection valve 4 in step S100, the process goes to step S101. In step S101, the energization time to the injection valve 4 for injecting a predetermined target injection amount calculated based on the operating state of the engine 2 into the second exhaust pipe 3 is set. In the exhaust purification control apparatus of the present embodiment, the injection valve 4 is not energized immediately after the drive request for the injection valve 4 is received, but energization to the injection valve 4 is started at a timing after a predetermined time from the timing when the drive request is made. The energization start timing ton before correction is provisionally determined. That is, the energization start timing ton before correction is reserved at a timing after a predetermined time from the timing when the drive is requested. At the same time, an energization end timing toff before correction calculated from the energized start timing ton before correction and the injection time are provisionally determined.

  In step S102, a physical quantity having a correlation with the rotational phase of the output shaft 64 of the engine 2 is acquired. Specifically, the detection signal output from the crank angle sensor 9 is acquired. The processor that performs the process of step S102 corresponds to an acquisition unit. The engine state calculation unit calculates the rotation speed of the engine 2 that is the change amount of the rotation phase and the rotation phase per unit time from the physical quantity acquired by the acquisition unit.

  Next, in step S103, the pulsation of the valve closing force F5 is calculated based on the acquisition result acquired in step S102. As described above, the wavelength and amplitude of the pulsation of the valve closing force F5 can be obtained from the supply pressure P1. Since the supply pressure P1 is a pulsation that has changed by a propagation delay phase I0 with respect to the discharge port pressure P0, the supply pressure P1 can be obtained from the discharge port pressure P0.

  As described above, the discharge port pressure P0 can be calculated based on the acquisition result obtained by the acquisition unit. The propagation delay phase I0 is determined by the shape of the fuel pipe 7, the temperature of the fuel, and the like. The fuel temperature can be calculated by, for example, a water temperature sensor (not shown) that detects the cooling water temperature of the engine 2 attached to the engine 2. The propagation delay phase I0 can be calculated by recording in advance a map of the correspondence between the delay due to the fuel temperature and the delay due to the shape of the fuel pipe 7. The pulsation of the valve closing force F5 is calculated by recording in advance a map of the correspondence relationship between the pulsation of the propagation delay phase I0, the crank angle sensor 9, and the discharge port pressure P0. The processor that performs the process of step S103 corresponds to a pulsation calculation unit.

  In step S104, a valve opening possible period TD2 is calculated. The processor that performs the process of step S104 corresponds to a period calculation unit. During the valve opening possible period TD2, the pulsating valve closing force F5 calculated by the pulsation calculating unit in step S103 is compared with the valve opening force F2, and the valve opening force F2 becomes larger than the valve closing force F5. It is calculated as a valve opening possible period TD2 in which the injection valve 4 can be opened.

  In step S105, a basic delay period TD4 is calculated. Since the basic delay period TD4 changes according to the battery voltage mounted on the vehicle, the basic delay period TD4 increases as the battery voltage decreases. It is calculated by recording the correspondence between the battery voltage and the basic delay period TD4 in advance as a map.

  In step S106, a correction start timing t2a and a correction end timing t3a are calculated, in which the start timing t2 and the end timing t3 of the valve opening possible period TD2 calculated by the period calculation unit are respectively advanced by the basic delay period TD4. The period from the correction start timing t2a to the correction end timing t3a is the post-correction period TD5. The processor that performs the process of step S106 corresponds to the corrected period calculation unit.

  Next, in step S107, the energization start timing ton1 is set so that the energization start timing ton before correction falls within the period after correction. The processor that performs the process of step S107 corresponds to an energization start timing setting unit. More preferably, the energization start timing ton1 to the injection valve 4 is set so that the lower limit timing tB at which the value of the valve closing force F5 becomes the lower limit value F5D coincides with the valve opening start timing top1. Specifically, the energization start timing ton before correction is corrected and set as the energization start timing ton1 so that the injection valve 4 is energized at a timing earlier than the lower limit timing tB by the basic delay period TD4.

  When the energization start timing ton1 is set, the control flow in FIG. 9 ends.

  As described above, according to the present embodiment, the energization timing to the injection valve 4 is corrected and set as the energization start timing ton1 so that the energization start timing ton before correction is within the corrected period TD5. Thus, even when it takes a basic delay period TD4 minutes from the start of energization until the valve opening force F2 is generated, the valve opening force generation timing tf2, which is the timing at which the valve opening force F2 is generated, is the valve opening possible period. Overlaps TD2. That is, the valve opening force generation timing tf2 coincides with the valve opening start timing top1. Therefore, it is possible to suppress a time delay between the valve opening force generation timing tf2 and the valve opening start timing top1 that actually starts the valve opening. That is, it can be suppressed that the period from the energization start timing ton1 to the valve opening start timing top1 is longer than the basic delay period TD4. Thereby, it is possible to provide an exhaust purification control apparatus capable of reducing the variation in the injection amount of the additive from the injection valve 4 with respect to the target injection amount.

  Further, if an attempt is made to generate a valve opening force F2 larger than the upper limit value F5T of the valve closing force F5, the voltage generated in the solenoid 43 needs to be increased. Therefore, the injection valve 4 needs to be enlarged. However, as in the present embodiment, the energization start timing ton before correction is corrected and the energization start timing ton1 is set in the valve opening possible period TD2, so that the injection valve 4 can be opened without increasing the size of the injection valve 4. It is possible to control the valve start timing top1. That is, it is possible to provide an exhaust purification control device capable of reducing the variation in the injection amount of the additive from the injection valve 4 with respect to the target injection amount without increasing the size of the injection valve 4.

  Furthermore, the energization start timing setting unit in step S107 energizes the injection valve 4 so that the lower limit timing tB and the valve opening start timing top1 coincide. Since the lower limit timing tB is an intermediate point of the valve opening possible period TD2, energization is started even when an error occurs in the calculated value of the pulsation of the valve closing force F5 and a slight deviation occurs in the valve opening possible period TD2. Timing ton1 is a corrected period TD5. That is, it is possible to shorten the period from the energization start timing ton1 to the valve opening start timing top1 more reliably.

(Second Embodiment)
In the present embodiment, as shown in FIG. 10, control is performed to set an energization end timing toff1 that is corrected so that the temporarily determined energization end timing toff before correction is delayed by the valve opening delay period TD3. Thereby, the energization end timing toff before correction estimated is changed to the energization end timing toff1.

  Next, a correction process performed by the ECU 5 to realize the above correction will be described with reference to FIG.

  From step S100 to step S105, the same arithmetic processing as in the first embodiment is performed. In step S208, a period from the energization start timing ton before correction to the valve opening start timing top before correction is opened from the provisionally determined energization start timing ton before correction and the valve closing force F5 calculated in step S103. Calculated as the valve delay period TD3. Specifically, when the energization of the injection valve 4 is started and the valve opening force generation timing tf2 is the valve opening possible period TD2, the valve opening delay period TD3 is determined from the current start timing ton before correction. Up to the generation timing tf2. That is, the valve opening delay period TD3 is the basic delay period TD4.

  On the other hand, when the valve opening force generation timing tf2 is the valve opening impossible period TD1, the valve opening force generation timing tf2 cannot be opened, and the valve opening impossible period TD1 and the valve opening possible period TD2 cannot be opened. The valve opens at the timing when and are replaced. Therefore, when the valve opening force generation timing tf2 is the valve opening impossible period TD1, the valve opening start timing top before correction is the start timing of the valve opening possible period TD2 closest to the energization start timing ton before correction. t2. Therefore, the valve opening delay period TD3 is calculated as a period from the energization start timing ton before the correction to the start timing t2. The processor that performs the process of step S208 corresponds to a valve opening delay period calculation unit.

  Next, in step S209, the energization end timing toff1 is set based on the valve opening delay period TD3 calculated in step S208. Specifically, the energization end timing toff1 is set by delaying the energization end timing toff before correction for the calculated valve opening delay period TD3. The processor that performs the process of step S209 corresponds to an energization end timing setting unit.

  According to the present invention, the period from the energization start timing ton before correction to the valve opening start timing top before correction is calculated as the valve opening delay period TD3 based on the energization start timing ton and pulsation before correction. Further, the target injection amount of fuel as an additive calculated based on the operating state of the engine 2 and the energization end timing toff before correction to the injection valve 4 from the energization start timing ton before correction are calculated and provisionally determined. Then, the pre-correction energization end timing setting unit sets the energization end timing toff1 so that the temporarily determined energization end timing toff before correction is delayed by the valve opening delay period TD3.

  If the energization to the injection valve 4 is stopped at the estimated energization end timing toff before correction without considering the valve opening delay period TD3, the injection valve 4 is opened for the valve opening delay period TD3. The period is shortened. When the valve opening period is shortened, the actual injection amount becomes smaller than the target injection amount.

  However, in the present invention, the energization end timing toff before correction is delayed by the valve opening delay period TD3, so that the amount of fuel that could not be injected from the energization start timing ton before correction to the valve opening start timing top before correction. Can be injected. As a result, it is possible to inject an amount close to the target injection amount into the exhaust pipe. Therefore, it is possible to reduce the variation in the injection amount with respect to the target injection amount.

(Third embodiment)
In the present embodiment, as shown in FIG. 12, a period from the estimated energization end timing toff before correction to the valve closing completion timing tcle at which the injection valve 4 completes valve closing is calculated as the valve closing period TD6. Based on the calculated length of the valve closing period TD6, the energization end timing toff before correction is corrected to set the energization end timing toff1. Thereby, the valve closing completion timing tcle is corrected to the corrected valve closing completion timing tcle1.

  A correction process performed by the ECU 5 to realize the correction will be described with reference to FIG.

  From step S100 to step S103, the same arithmetic processing as in the first embodiment is performed. In step S310, based on the valve closing force F5 calculated in step S103, the period from the energization end timing toff before correction to the valve closing completion timing tcle for completing the closing of the injection valve 4 is calculated as the valve closing period TD6. . The valve closing period TD6 is calculated by recording a map of the correspondence relationship between the valve closing force F5 and the valve closing period TD6 in the memory of the ECU 5. Specifically, first, the magnitude of the closing force F5 at the energization end timing toff before correction from the pulsation of the valve closing force F5 calculated at step S103 and the temporarily determined energization end timing toff before correction. Is calculated. The valve closing period TD6 is calculated by referring to a map recorded in advance based on the calculated valve closing force F5. The processor that performs the process of step S310 corresponds to a valve closing period calculation unit.

  In step S311, the energization end timing toff before correction temporarily determined in step S101 is corrected based on the valve closing period TD6, and the energization end timing toff1 is set. More specifically, the longer the calculated valve closing period TD6 is, the faster the energization end timing toff before correction is corrected, and the shorter the valve closing period TD6 is, the longer the energization end timing toff before correction is corrected. The correction amount is calculated by previously recording a correspondence relationship between the valve closing period TD6 and the energization end timing toff1 as a map in the memory of the ECU 5, and referring to the map based on the valve closing period TD6 calculated in step S310. . The processor that performs the process of step S311 corresponds to the valve closing setting unit.

  The gap between the needle 41 and the nozzle hole 44 is filled with fuel at the energization end timing toff before correction. Therefore, even when the energization is stopped and the valve opening force F2 by the solenoid 43 becomes zero, the fuel pressure filled between the needle 41 and the injection hole 44 is opened on the lower surface of the needle 41 in the valve opening direction. Acts as a force. On the other hand, on the upper surface of the needle 41, the additive force F1 and the spring force F3 due to the pulsating supply pressure P1 act as the valve closing force F5.

  Here, at the energization end timing toff before correction, the fuel opening force and the additive force F1 cancel each other. However, as described above, the spring force F3 is also applied to the upper surface of the needle 41. Therefore, when energization stops, the needle 41 gradually moves in the valve closing direction by the spring force F3. When the needle 41 moves in the valve closing direction, the fuel filled between the needle 41 and the injection hole 44 decreases. Therefore, the fuel opening force is reduced. That is, the valve closing force F5 that is the sum of the additive force F1 and the spring force F3 is relatively large with respect to the fuel opening force. At this time, the valve closing force F5 applied to the needle 41 increases as the fuel pressure increases, so that the valve closing of the needle 41 is accelerated. That is, the magnitude of the valve closing force F5 at the energization end timing toff before correction is the length of the period from the energization end timing toff before correction to the valve closing completion timing tcle at which the needle 41 completely closes the nozzle hole 44. Affects.

  For example, the larger the valve closing force F5, the shorter the valve closing period TD6 that is the period from the energization end timing toff before correction to the valve closing completion timing tcle. Therefore, the actual injection amount may be smaller than the target injection amount.

  However, according to the present embodiment, the period from the energization end timing toff before correction to the valve closing completion timing tcle at which the injection valve 4 is completely closed is calculated as the valve closing period TD6. The energization end timing toff1 is advanced with respect to the energization end timing toff before correction as the valve closing period TD6 is longer, and the energization end timing toff1 is delayed with respect to the energization end timing toff before correction as the valve closing period TD6 is smaller. Make corrections. Thereby, it is possible to reduce the variation in the injection amount injected during the period from the energization end timing toff before correction to the valve closing completion timing tcle. Therefore, the accuracy of the target injection amount can be improved.

(Fourth embodiment)
Exhaust gas flows in the second exhaust pipe 3 to which the injection valve 4 is attached. The pressure of the exhaust gas passing through the second exhaust pipe 3 pulsates in synchronization with the rotational speed of the engine 2. The needle 41 that closes the injection hole 44 of the injection valve 4 receives pressure from the exhaust. Specifically, when the exhaust pressure is high, the exhaust pressure acts in the valve opening direction with respect to the needle 41. Therefore, the nozzle hole 44 is easy to open when the exhaust pressure is high. On the other hand, when the exhaust pressure is low, the nozzle hole 44 is difficult to open. Therefore, the ease of opening the nozzle hole 44 changes according to the magnitude of the pulsating exhaust pressure. Therefore, a variation in the valve opening delay period TD3, which is a period from the energization start timing ton before correction to the valve opening start timing top before correction, occurs.

  Therefore, in this embodiment, the valve opening delay period TD3 is calculated in consideration of the pulsation of the exhaust pressure in addition to the pulsation of the valve closing force F5. In this embodiment, the energization end timing toff before correction is set based on the calculated valve opening delay period TD3.

  A correction process performed by the ECU 5 to realize the correction will be described with reference to FIG.

  From step S100 to step S103, the same arithmetic processing as in the first embodiment is performed. In step S412, the pressure pulsation of the exhaust gas flowing through the second exhaust pipe 3 is calculated. The processor that performs the process of step S412 corresponds to a pressure calculation unit. The pulsation of the exhaust pressure flowing in the second exhaust pipe 3 is synchronized with the rotational speed of the engine 2 as described above. Therefore, it is possible to calculate the exhaust pressure pulsation from the detected value of the crank angle sensor 9.

  In step S408, the valve opening delay period TD3 is calculated based on the valve closing force F5 and the exhaust pressure. The delay in valve opening due to the exhaust pressure is calculated by recording a map in the ECU 5 in advance for the correspondence between the exhaust pressure and the ease of opening the injection valve 4. The valve opening delay due to the valve closing force F5 is calculated from the calculated valve closing force F5 and the energization start timing ton before correction. Then, the valve opening delay period TD3 is calculated from the valve opening delay due to the valve closing force F5 and the valve opening delay due to the exhaust pressure.

  In step S209, the energization end timing toff before correction is set to the energization end timing toff1 delayed by the calculated valve opening delay period TD3. When the energization end timing toff1 is set, the control flow in FIG. 14 ends.

  Here, according to the present embodiment, the pressure calculation unit calculates the pulsating exhaust pressure passing through the second exhaust pipe 3. A period from the energization start timing ton before correction to the valve opening start timing top before correction is estimated based on the calculated exhaust pressure, and the energization end timing toff before correction is determined from the estimated period.

  Thereby, it is possible to correct the variation in the period from the energization start timing ton before correction based on the pulsation due to the valve closing force F5 and the pulsation due to the exhaust pressure to the valve opening start timing top before correction. Therefore, variation in the injection amount can be reduced, and the accuracy of the injection amount can be improved.

(Other embodiments)
The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made as illustrated below. Not only combinations of parts that clearly show that combinations are possible in each embodiment, but also combinations of the embodiments even if they are not explicitly stated unless there is a problem with the combination. Is also possible.

  In the first to fourth embodiments, the example in which the exhaust purification control device of the present invention is applied to the device for injecting fuel into the DPF has been shown. However, for example, the present invention may be applied to a vehicle provided with an NOx storage reduction catalyst, a selective reduction NOx catalyst, an oxidation catalyst, a three-way catalyst, or the like instead of the DPF. In that case, fuel or urea is used as the additive.

  In the first to fourth embodiments, the positive displacement pump 6 is driven by being directly connected to the output shaft 64 of the engine 2, but may be connected via a pulley or the like, for example. In the above embodiment, the positive displacement pump 6 is a trochoid gear type which is one of rotary pumps, but may be a gear pump or a screw pump. Alternatively, a reciprocating pump such as a piston pump may be used instead of the rotary pump.

  In the first to fourth embodiments, when it is determined in step S100 that there is a drive request for the injection valve 4, the energization start timing ton before correction is a drive request for the injection valve 4 in step S101. Reserved at a timing after a predetermined time from the timing. However, in the second embodiment to the fourth embodiment, energization may be started at the same time when there is a drive request to the injection valve 4.

  In the first embodiment, the third embodiment, and the fourth embodiment, the calculation is performed using a map such as the propagation delay phase I0 or the valve closing force F5. However, the calculation may be performed using a pre-recorded arithmetic expression. Good.

  In the third embodiment, the valve closing period TD6 is calculated from the valve closing force F5 in step S310, and then the correction amount is calculated based on the valve closing period TD6 in step S311. However, the correction amount may be calculated directly from the valve closing force F5. In that case, the calculation is performed by referring to a map recorded in advance based on the correspondence between the valve closing force F5 and the correction amount.

  A part or all of the functions executed by the ECU 5 may be configured by hardware using one or a plurality of ICs.

  The ECU 5 executes a program stored in a non-transitional tangible recording medium. By executing this program, a method corresponding to the program is executed.

DESCRIPTION OF SYMBOLS 1 ... Purification system, 2 ... Internal combustion engine, 3 ... Second exhaust pipe, 4 ... Injection valve, 41 ... Valve body,
42 ... Spring member, 43 ... Solenoid, 44 ... Injection hole, 64 ... Output shaft

Claims (5)

A valve body (41) for opening and closing a nozzle hole (44) for injecting an exhaust purification additive into the exhaust pipe (3) of the internal combustion engine (2), and a spring force (F3) to the valve body in the valve closing direction The operation of the injection valve (4) comprising: a spring member (42) for applying pressure; and a solenoid (43) for generating an electromagnetic force (F2) by energization and applying the electromagnetic force in the valve opening direction of the valve body. An exhaust purification control device (5) for
An acquisition unit (S102) for acquiring a physical quantity correlated with the rotational phase of the output shaft (64) of the internal combustion engine;
A positive displacement pump (6) connected to and driven by the output shaft feeds and supplies the additive to the injection valve. The pressure of the additive that pulsates is defined as a supply pressure (P1), and the supply pressure is defined as the valve. Pulsation that is calculated based on the acquisition result by the acquisition unit as a pulsation closing force (F5) acting on the injection valve, which is a combination of the additive force (F1), which is a force received by the body, and the spring force A calculation unit (S103);
The force when the electromagnetic force gradually increases and reaches the maximum is set as the maximum valve opening force (F2), and the maximum valve opening force is compared with the valve closing force calculated by the pulsation calculating unit, A period calculation unit (S104) for calculating a valve opening possible period (TD2) in which the injection valve can be opened by the maximum valve opening force being larger than the valve closing force;
The period from the energization start timing (ton1) when energization to the injection valve is started to the timing at which the maximum valve opening force is applied to the injection valve is defined as a basic delay period (TD4), and the calculated valve opening possible period A corrected period calculation unit (S106) that calculates a period obtained by correcting each of the start timing (t2) and the end timing (t3) earlier by the basic delay period as a corrected period (TD5);
An exhaust purification control apparatus comprising: an energization start timing setting unit (S107) that sets the energization start timing to be within the corrected period.   The energization start timing setting unit performs the energization so that a lower limit timing (tB) at which the calculated valve closing force becomes a lower limit value coincides with a valve opening start timing (top1) at which the injection valve starts opening. The exhaust purification control apparatus according to claim 1, wherein a start timing is set. A valve body (41) for opening and closing a nozzle hole (44) for injecting an exhaust purification additive into the exhaust pipe (3) of the internal combustion engine (2), and a spring force (F3) to the valve body in the valve closing direction The operation of the injection valve (4) comprising: a spring member (42) for applying pressure; and a solenoid (43) for generating an electromagnetic force (F2) by energization and applying the electromagnetic force in the valve opening direction of the valve body. An exhaust purification control device (5) for
An acquisition unit (S102) for acquiring a physical quantity correlated with the rotational phase of the output shaft (64) of the internal combustion engine;
A positive displacement pump (6) connected to and driven by the output shaft feeds and supplies the additive to the injection valve. The pressure of the additive that pulsates is defined as a supply pressure (P1), and the supply pressure is defined as the valve. Pulsation that is calculated based on the acquisition result by the acquisition unit as a pulsation closing force (F5) acting on the injection valve, which is a combination of the additive force (F1), which is a force received by the body, and the spring force A calculation unit (S103);
A valve opening start timing (top1) at which the injection valve starts to open is calculated from an energization start timing (ton1) at which energization to the injection valve starts and the valve closing force, and the valve opening from the power supply start timing is calculated. A valve opening delay period calculation unit (S208) that calculates a period until the start timing as a valve opening delay period (TD3);
An energization end timing (toff) before correction to the injection valve calculated from the target injection amount of the additive calculated based on the operating state of the internal combustion engine and the energization start timing is delayed by the valve opening delay period. An exhaust gas purification control apparatus comprising: an energization end timing setting unit (S209) that corrects and sets the timing so as to be the same. Based on the valve closing force that pulsates, a valve closing period (i.e., a period from the energization end timing set in the energization end timing setting unit to the valve closing completion timing (tcle) at which the injection valve completes closing) A valve closing period calculation unit (S310) for calculating TD6);
The exhaust gas purification control according to claim 3, further comprising: a valve closing setting unit (S311) configured to correct and set again the energization end timing set in the energization end timing setting unit as the valve closing period is longer. apparatus. A pressure calculation unit (S412) for calculating an exhaust pressure pulsating in the exhaust pipe;
The exhaust purification control apparatus according to claim 3 or 4, wherein the valve opening delay period calculation unit calculates the valve opening delay period based on the valve closing force and the exhaust pressure.

Images