INJECTION CONTROL DEVICE
The present application claims the benefit of priority from Japanese Patent Application No. 2019-164524 filed on Sep. 10, 2019. The entire disclosures of all of the above applications are incorporated herein by reference. The present disclosure relates to an injection control device. An injection control device that controls opening and closing of a fuel injection valve to inject fuel into an internal combustion engine is known. According to an aspect of the present disclosure, an injection control device is configured to control opening and closing of a plurality of fuel injection valves to inject fuel to an internal combustion engine. The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings: Hereinafter, embodiments of the present disclosure will be described. An injection control device according to one embodiment of the present disclosure controls opening and closing of a fuel injection valve to inject fuel to an internal combustion engine. The injection control device supplies a current to the fuel injection valve in accordance with a conduction current profile that is based on a predetermined command injection amount and controls opening and closing of the fuel injection valve. In a direct injection control according to an embodiment of the present disclosure, multi-stage injection control is performed in which fuel required for one combustion is divided into multiple times to form an ideal spray in a cylinder of the engine. At that time, the multi-stage injection control is performed by combining multiple injections which are different in injection time. Among them, accuracy of an injection amount of a minute injection, which is shorter in injection time than that of the normal injection, has a large influence on achievement of exhaust gas regulations. A valve closing detection is a technique is to learn a valve closing time to enhance the accuracy of the injection amount of this minute injection. When the multi-stage injection control is performed, overlap occurs in injections of the cylinders. In particular, minute injection is generally performed at the end of an intake stroke or in a compression stole of the engine. Therefore, an issue could arises that the learning of the valve closing time cannot be properly performed due to an overlap which could frequently occur with injection in another cylinder. For example, in a 4-cylinder configuration, in a 4-cycle engine, injections of cylinders, which are not in the antiphase relationship, may overlap with each other. The cylinders which are not in the antiphase relationship are the cylinder in the combustion stroke and the cylinder in the intake stroke and are the cylinder in the exhaust stroke and the cylinder in the compression stroke. To the contrary, injections of the cylinders in the antiphase relationship do not overlap. In consideration of this, in order to address the issue that the learning of the valve closing time cannot be properly performed, it is conceivable to provide two valve closing detection circuits at maximum to detect the valve closing. However, in the configuration described above, a concern arises that a manufacturing cost may increase due to the increase in the valve closing detection circuit. According to an example of the present disclosure, an injection control device is configured to control opening and closing of a plurality of fuel injection valves to inject fuel to an internal combustion engine. The injection control device comprises an energization instruction switch configured to switch a plurality of energization instruction signals ON and OFF to instruct energization of the plurality of fuel injection valves. The injection control device further comprises a first cylinder designation switch configured to designate one of the plurality of energization instruction signals, which correspond to the plurality of fuel injection valves respectively, to designate a valve closing detection cylinder. The injection control device further comprises a valve closing detection unit configured to monitor a plurality of downstream voltages of the fuel injection valve to detect occurrence of an inflection point in change of the plurality of downstream voltages and to detect valve closing. The injection control device further comprises a second cylinder designation switch configured to designate one of the plurality of downstream voltages, which correspond to the plurality of fuel injection valves respectively, and to designate the valve closing detection cylinder. The injection control device further comprises a stage number designation unit configured to designate a valve closing detection stage number to a plurality of injections of the valve closing detection cylinder. The injection control device further comprises a valve closing time measuring unit configured to measure a valve closing time, which is from a switching timing at which the energization instruction signal is switched from ON to OFF to a valve closing detection timing at which the valve closing detection unit detects the valve closing, for injection of the valve closing detection stage number among the plurality of injections of the valve closing detection cylinder. The injection control device further comprises a valve closing time learning unit configured to learn the valve closing time measured by the valve closing time measuring unit. The configuration designates the valve closing detection cylinder among the multiple cylinders. The configuration designates the valve closing detection stage number among the multiple injections of the designated valve closing detection cylinder. The configuration measures the valve closing time from the timing, at which the energization instruction signal is switched from ON to OFF, to the valve closing detection timing for the injection of the valve closing detection stage number of the designated valve closing detection cylinder and performs the learning of the valve closing time. The configuration designates the valve closing detection cylinder from the plurality of cylinders, thereby to enable to avoid increase in the number of the valve closing detection circuit in advance. The configuration enables to appropriately learn the closing time and to appropriately increase the injection amount accuracy, while eliminating the concern of cost increase due to the increase in the number of the valve closing detection circuit. Further, the configuration designates the valve closing detection stage number among the multiple injections, thereby to enable to measure selectively (only) the valve closing time of injection required to learn the valve closing time and to reduce the calculation processing load and communication frequency. Hereinafter, embodiments of the present disclosure will be described with reference to drawings. In the embodiments, elements corresponding to those which have been described in the preceding embodiments are denoted by the same reference numerals, and redundant description may be omitted. A first embodiment will be described with reference to The injector 2 Each of the injectors 2 The injection control device 1 includes a control unit 3, an energization control unit 4, an upstream switch 5, a downstream switch 6, a cylinder designation circuit 7, a first cylinder designation switch 8, a second cylinder designation switch 9, a stage number designation circuit 10, a valve closing detection circuit 11, and a valve closing time counter 12. The stage number designation circuit 10 corresponds to a stage number designating unit. The valve closing detection circuit 11 corresponds to a valve closing detection unit. The valve closing time counter 12 corresponds to a valve closing time measuring unit. The control unit 3 mainly includes a microcomputer and further includes a CPU, a ROM, a RAM, an I/O, and the like. The control unit 3 performs various processing operations based on a program stored in, for example, the ROM. The control unit 3 has a configuration for performing various processing operations and includes an energization instruction switching unit 3 The function produced by the control unit 3 may be provided by software stored in the ROM, which is a substantial memory device, by a computer that executes the software, by only software, by only hardware, or by a combination thereof. The energization instruction switching unit 3 The energization control unit 4 acquires the energization current profile from the control unit 3 via a serial communication path and stores the acquired energization current profile in its internal memory. When the energization control unit 4 detects the ON/OFF switching of the TQ signals 1 to 4, the energization control unit 4 drives the upstream switch 5 and the downstream switch 6 according to the energization current profile stored in the internal memory. The upstream switch 5 is a switch provided on the upstream side of the injectors 2 The downstream switch 6 is a switch provided on the downstream side of the injectors 2 The first cylinder designation switch 8 inputs the TQ signals 1 to 4. When the first cylinder designation switch 8 inputs the cylinder designation signal from the cylinder designation circuit 7, the first cylinder designation switch 8 designates the valve closing detection cylinder based on the input cylinder designation signal. The first cylinder designation switch 8 outputs he TQ signal corresponding to the designated valve closing detection cylinder to an injection stage number counter 10 The second cylinder designation switch 9 inputs a downstream voltage of the injectors 2 The stage number designation circuit 10 includes a stage number designation register 10 When the designated stage number input from the stage number designation register 10 The valve closing detection circuit 11 includes an operational amplifier 11 The valve closing time counter 12 measures the valve closing time based on the TQ signal input from the stage number designation circuit 10 and the inflection point detection notification input from the second cylinder designation switch 9 via the waveform inflection point logic 11 When the valve closing time learning unit 3 A function of the configuration will be described with reference to In this case, the control unit 3 outputs the cylinder designation signal for designating the injector 2 The control unit 3 outputs the stage number designation signal for designating the third stage of injection as the designated stage number to the stage number designation circuit 10. When the stage number designation circuit 10 inputs the stage number designation signal from the control unit 3, the stage number designation circuit 10 stores the designated stage number, which is designated based on the input stage umber designation signal, in the stage number designation register 10 When the control unit 3 specifies the injection command timing of the normal injection for the injector 2 When the control unit 3 specifies the injection stop timing of the normal injection of the injector 2 Subsequently, when the control unit 3 specifies the injection command timing of the normal injection for the injector 2 When the control unit 3 specifies the injection stop timing of the normal injection of the injector 2 Subsequently, when the control unit 3 specifies the injection command timing of the minute injection for the injector 2 When the control unit 3 specifies the injection stop timing of the minute injection of the injector 2 When the injector 2 Subsequently, the energization control unit 4 stops energization of the injector 2 At this time, the injector 2 Subsequently, due to the stop of the energization of the injector 2 When the valve closing time counter 12 inputs the inflection point detection notification from the valve closing detection circuit 11, the valve closing time counter 12 ends the measurement of the time. The valve closing time counter 12 outputs the measured time as the valve closing time to the control unit 3. Subsequently to this point, when the control unit 3 inputs the valve closing time from the valve closing time counter 12, the control unit 3 combines the input valve closing time and the valve closing time, which has been input in the past, and performs learning of the valve closing time by using a learning algorithm stored in advance. In the above-described configuration, the engine has the four-cylinder configuration including the four injectors 2 Next, a pattern for designating the valve closing detection cylinder will be described. Herein, as the pattern for designating the valve closing detection cylinder, a pattern for designating the valve closing detection cylinder following minute injection, a pattern, in which the valve closing detection cylinder is switched and designated every ½ cycle (360° CA) of the injection cycle, and a pattern, in which the valve closing detection cylinder is switched and designated for each one cycle (720° CA) of the injection cycle will be sequentially described. (1) Pattern for designating the valve closing detection cylinder following minute injection In the pattern for designating the valve closing detection cylinder following the minute injection, as shown in In the pattern for designating the valve closing detection cylinder following the minute injection, the valve closing time of the minute injection can be constantly acquired, and the learning speed of the valve closing time of the minute injection can be increased. (2) Pattern in which the valve closing detection cylinder is switched and designated at every ½ cycle of the injection cycle In the pattern, in which the valve closing detection cylinder is switched and designated at every ½ cycle of the injection cycle, as shown in Subsequently, the control unit 3 repeats a cycle in which the valve closing detection cylinder is alternately switched between the injector 2 In the pattern in which the valve closing detection cylinder is switched and designated at every ½ cycle of the injection cycle, frequency to acquire the valve closing time can be increased, and detection frequency can be increased, thereby to enable to appropriately detect a failure of the injectors 2 (3) Pattern in which the valve closing detection cylinder is switched and designated at every 1 cycle of the injection cycle In the pattern, in which the valve closing detection cylinder is switched and designated at every 1 cycle of the injection cycle, as shown in In the pattern in which the valve closing detection cylinder is switched and designated at every 1 cycle of the injection cycle, the valve closing detection can be easily synchronized with an air-fuel ratio control, compared with the (2) pattern in which the valve closing detection cylinder is switched and designated at every ½ cycle of the injection cycle as described above. It is noted that, the control unit 3 may switch, within one trip, the patterns including the pattern to designate the valve closing detection cylinder following minute injection, the pattern to switch and designate the valve closing detection cylinder at every ½ cycle of the injection cycle, and the pattern to switch and designate the valve closing detection cylinder at every 1 cycle of the injection cycle. Immediately after starting the engine, the control unit 3 may adopt, for example, the pattern for designating the valve closing detection cylinder following minute injection in order to increase the learning speed of the valve closing time of minute injection. After a certain period of time has elapsed subsequent to the immediately after starting the engine, the control unit 3 may adopt, for example, the pattern in which the valve closing detection cylinder is switched and designated at every ½ cycle of the injection cycle in order to increase the detection frequency or may adopt the pattern in which the valve closing detection cylinder is switched and designated at every 1 cycle of the injection cycle in order to facilitate synchronization of valve closing detection with the air-fuel ratio control. Separately from these patterns, a pattern for designating the valve closing detection cylinder following normal injection may be adopted, and a pattern in which the valve closing time of the normal injection is constantly acquired may be used. The first embodiment as described above produces the following operational effects. The injection control device 1 designates the valve closing detection cylinder among the multiple cylinders. The injection control device 1 designates the valve closing detection stage number among the multiple injections of the designated valve closing detection cylinder. The injection control device 1 measures the valve closing time from the timing, at which the energization instruction signal is switched from ON to OFF, to the valve closing detection timing for the injection of the valve closing detection stage number of the designated valve closing detection cylinder and performs the learning of the valve closing time. The configuration designates the valve closing detection cylinder, thereby to enable to avoid increase in the number of the valve closing detection circuit 11 in advance. The configuration enables to appropriately learn the closing time and to appropriately increase the injection amount accuracy, while eliminating the concern of cost increase due to the increase in the number of the valve closing detection circuit 11. Further, the configuration designates the valve closing detection stage number, thereby to enable to measure selectively (only) the valve closing time of injection required to learn the valve closing time and to reduce the calculation processing load and communication frequency. The injection control device 1 designates, as the valve closing detection stage number, the stage number of the minute injection among the multiple injections of the valve closing detection cylinder, thereby to enable to appropriately learn the valve closing time of the minute injection. The injection control device 1 designates, as the valve closing detection stage number, the stage number of the normal injection among the multiple injections of the valve closing detection cylinder, thereby to enable to appropriately learn the valve closing time of the normal injection. When the cylinder designated as the next valve closing detection cylinder is not performing fuel injection, the injection control device 1 designates the valve closing detection cylinder. The configuration enables to avoid a situation in which a cylinder in which fuel injection is being performed is designated as the valve closing detection cylinder, thereby to appropriately designate the cylinder that is to perform fuel injection as the valve closing detection cylinder and to appropriately learn the valve closing time. When fuel injection is not being performed at the stage designated as the next valve closing detection stage number, the injection control device 1 designates the valve closing detection stage number. The configuration enables to avoid a situation in which the stage in which fuel injection is being performed is designated as the valve closing detection stage number, thereby to appropriately designate the stage that is to perform fuel injection as the valve closing detection stage number and to appropriately learn the valve closing time. The injection control device 1 designates the valve closing detection cylinder at every time, when detecting the valve closing detection of the valve closing detection cylinder, and designates the valve closing detection cylinder following the minute injection. In this way, the configuration enables to constantly acquire the valve closing time for the minute injection, thereby to enable to increase the learning speed of the valve closing time for the minute injection. The injection control device 1 switches and designates the valve closing detection cylinder at every ½ cycle (360° CA) of the injection cycle, thereby to enable to increase the detection frequency and to appropriately detect failure of the injectors 2 The injection control device 1 switches and designates the valve closing detection cylinder at every cycle (720° CA) of the injection cycle, thereby to enable to easily synchronize the valve closing detection with another control such as the air-fuel ratio control. A second embodiment will be described with reference to An injection control device 21 includes the control unit 3, the energization control unit 4, the upstream switch 5, the downstream switch 6, the cylinder designation circuit 7, the first cylinder designation switch 8, the second cylinder designation switch 9, the stage number designation circuit 10, the valve closing detection circuit 11, and the valve closing time counter 12, as described in the first embodiment. The injection control device 21 further includes a boost prohibition zone generation unit 22, a boost circuit 23, and a boost control unit 24. When the cylinder designation circuit 7 inputs the cylinder designation signal from the control unit 3, the cylinder designation circuit 7 outputs the input cylinder designation signal to the first cylinder designation switch 8 and the second cylinder designation switch 9 and further outputs the input cylinder designation signal to the boost prohibition zone generation unit 22. The stage number designation circuit 10 outputs the TQ signal to the valve closing time counter 12 and further outputs the TQ signal to the boost prohibition zone generation unit 22. The boost circuit 23 is a circuit that generates a boost power supply for peak current driving. The boost circuit 23 includes a DC-DC converter including a boost chopper circuit. The boost chopper circuit includes, for example, an inductor 25, a MOS transistor 26 as a switching element, a current detection resistor 27, a diode 28, and a boost capacitor 29, which are connected in the illustrated form. The boost circuit 23 is not limited to the illustrated form, and various forms may be employable. The boost control unit 24 acquires the boost control profile from the control unit 3 via the serial communication path and stores the acquired boost control profile in the internal memory. The boost control unit 24 performs a boost switching control of the boost circuit 23 according to the boost control profile stored in the internal memory. When the tor 22 receives the cylinder designation signal from the cylinder designation circuit 7, the boost prohibition zone generation unit 22 designates the valve closing detection cylinder based on the input cylinder designation signal. The boost prohibition zone generation unit 22 generates the boost prohibition zone based on the TQ signal input from the stage number designation circuit 10. The boost prohibition zone generation unit 22 outputs the boost control prohibition signal to the boost control unit 24. Specifically, when the boost prohibition zone generation unit 22 detects switching of the TQ signal, which is input from the stage number designation circuit 10, from ON to OFF, the boost prohibition zone generation unit 22 outputs a boost control prohibition signal to the boost control unit 24 for a certain time from that time point, when detecting the switching of the TQ signal, as a starting point. The boost prohibition zone generation unit 22 prohibits the boost switching control for the valve closing detection cylinder, thereby not to perform the boost switching control. The boost prohibition zone generation unit 22 permits the boost switching control for cylinders other than the valve closing detection cylinder and performs the boost switching control. A function of the configuration will be described with reference to In this case, the control unit 3 outputs the cylinder designation signal for designating the injector 2 When the control unit 3 specifies the injection command timing of the normal injection for the injector 2 When the control unit 3 specifies the injection stop timing of the normal injection of the injector 2 Subsequently, when the control unit 3 specifies the injection command timing of the normal injection of the injector 2 When the control unit 3 specifies the injection stop timing of the normal injection of the injector 2 Specifically, a description will be made about a mode, in which a charge prohibition zone is generated, for a case in which the valve closing detection cylinder is switched that has been described in the first embodiment. As shown in Further, modes of generating the charge prohibition zone will be described for the pattern for designating the valve closing detection cylinder following minute injection, the pattern in which the valve closing detection cylinder is switched and designated at every ½ cycle of the injection cycle, and the pattern in which the valve closing detection cylinder is switched and designated at every 1 cycle of the injection cycle, as described in the first embodiment. As shown in Although the present disclosure has been described in accordance with the examples, it is understood that the present disclosure is not limited to such examples or structures. The present disclosure encompasses various modifications and variations within the scope of equivalents. Additionally, various combinations and configurations, as well as other combinations and configurations including more, less, or only a single element, are within the scope and spirit of the present disclosure. The control circuit and method described in the present disclosure may be implemented by a special purpose computer which is configured with a memory and a processor programmed to execute one or more particular functions embodied in computer programs of the memory. Alternatively, the control circuit described in the present disclosure and the method thereof may be realized by a dedicated computer configured as a processor with one or more dedicated hardware logic circuits. Alternatively, the control circuit and method described in the present disclosure may be realized by one or more dedicated computer, which is configured as a combination of a processor and a memory, which are programmed to perform one or more functions, and a processor which is configured with one or more hardware logic circuits. The computer program may also be stored on a computer readable non-transitory tangible recording medium as instructions to be executed by a computer. It should be appreciated that while the processes of the embodiments of the present disclosure have been described herein as including a specific sequence of steps, further alternative embodiments including various other sequences of these steps and/or additional steps not disclosed herein are intended to be within the steps of the present disclosure. While the present disclosure has been described with reference to preferred embodiments thereof, it is to be understood that the disclosure is not limited to the preferred embodiments and constructions. The present disclosure is intended to cover various modification and equivalent arrangements. In addition, while the various combinations and configurations, which are preferred, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the present disclosure. A first switch designates one of energization instruction signals to designate a valve closing detection cylinder. A valve closing detection unit monitors downstream voltages of the fuel injection valves to detect occurrence of an inflection point in change of the downstream voltages and detects valve closing. A second switch designates one of the downstream voltages and designates the valve closing detection cylinder. A stage number designation unit designates a valve closing detection stage number. A valve closing time measuring unit measures a valve closing time, which is from a switching timing at which the energization instruction signal is switched from ON to OFF to a valve closing detection timing of the valve closing, for injection of the valve closing detection stage number of the valve closing detection cylinder. A valve closing time learning unit learns the valve closing time measured by the valve closing time measuring unit. 1. An injection control device configured to control opening and closing of a plurality of fuel injection valves to inject fuel to an internal combustion engine, the injection control device comprising:
an energization instruction switch configured to switch a plurality of energization instruction signals ON and OFF to instruct energization of the plurality of fuel injection valves; a first cylinder designation switch configured to designate one of the plurality of energization instruction signals, which correspond to the plurality of fuel injection valves respectively, to designate a valve closing detection cylinder; a valve closing detection unit configured to monitor a plurality of downstream voltages of the fuel injection valve to detect occurrence of an inflection point in change of the plurality of downstream voltages and to detect valve closing; a second cylinder designation switch configured to designate one of the plurality of downstream voltages, which correspond to the plurality of fuel injection valves respectively, and to designate the valve closing detection cylinder; a stage number designation unit configured to designate a valve closing detection stage number to a plurality of injections of the valve closing detection cylinder; a valve closing time measuring unit configured to measure a valve closing time, which is from a switching timing at which the energization instruction signal is switched from ON to OFF to a valve closing detection timing at which the valve closing detection unit detects the valve closing, for injection of the valve closing detection stage number among the plurality of injections of the valve closing detection cylinder; and a valve closing time learning unit configured to learn the valve closing time measured by the valve closing time measuring unit. 2. The injection control device according to the first cylinder designation switch and the second cylinder designation switch are configured to designate, when injections of a plurality of cylinders overlap, one of the plurality of cylinders, in which the injections overlap, as the valve closing detection cylinder. 3. The injection control device according to the stage number designation unit is configured to designate, as the valve closing detection stage number, the stage number of injection with a shortest injection time among the plurality of injections of the valve closing detection cylinder. 4. The injection control device according to the stage number designation unit is configured to designate, as the valve closing detection stage number, the stage number of injection with a longest injection time among the plurality of injections of the valve closing detection cylinder. 5. The injection control device according to the first cylinder designation switch and the second cylinder designation switch are configured to designate the valve closing detection cylinder when injection is not performed for the cylinder which is designated as a next valve closing detection cylinder, and the stage number designation unit is configured to designate the valve closing detection stage number when injection is not performed at the stage number designated as a next valve closing detection stage number. 6. The injection control device according to the first cylinder designation switch and the second cylinder designation switch are configured to designate the valve closing detection cylinder at every time when the valve closing detection unit detects valve closing of the valve closing detection cylinder, and the stage number designation unit is configured to designate the valve closing detection stage number at every time when the valve closing detection unit detects valve closing of the valve closing detection cylinder. 7. The injection control device according to the first cylinder designation switch and the second cylinder designation switch are configured to switch and designate the valve closing detection cylinder at every ½ cycle of the injection cycle. 8. The injection control device according to the first cylinder designation switch and the second cylinder designation switch are configured to switch and designate the valve closing detection cylinder at every 1 cycle of the injection cycle. 9. The injection control device according to a boost circuit configured to generate a booster power supply for peak current driving; and a boost control unit configured to perform a boost switching control of the boost circuit, wherein the injection control unit is configured not to perform the boost switching control for the valve closing detection cylinder and to perform the boost switching control for a cylinder other than the valve closing detection cylinder in a period in which the valve closing detection unit detects the valve closing of the valve closing detection cylinder.CROSS REFERENCE TO RELATED APPLICATION
TECHNICAL FIELD
BACKGROUND
SUMMARY
BRIEF DESCRIPTION OF THE DRAWINGS
DETAILED DESCRIPTION
First Embodiment
Second Embodiment
Other Embodiments











