JP2010025445A - Control device for diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device suppressing overheat of a glow plug without performing complicated energization control of the glow plug at start of a diesel engine when using a glow plug with the rated voltage lower than the voltage of a battery. <P>SOLUTION: The rated voltage of the glow plug 13 of the diesel engine 5 is lower than the voltage of the battery 17 for applying voltage to the glow plug 13. An electronic control device 20 performs control so that at start of the engine 5, after executing forced cooling of the glow plug 13, the battery 17 starts to apply voltage to the glow plug 13. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for a diesel engine including a glow plug that generates heat when energized.

Conventionally, as described in Patent Document 1, for example, a diesel engine includes a glow plug that promotes ignition of fuel by generating heat when energized.
In the diesel engine described in Patent Document 1, when the engine is started in a state where the combustion chamber is warm, the energization time and the energization current are set so that the power supplied to the glow plug is less than the power supplied during the cold start. The value is controlled to prevent unnecessary power supply to the glow plug.
JP 2001-82266 A

  Some glow plugs have a rated voltage set lower than the voltage of a battery that supplies power to the glow plug. In such a glow plug, for example, a voltage is applied from the battery at a duty ratio of 100% at the start of engine start, the temperature is rapidly raised to the target temperature, and thereafter, the duty ratio is lower than 100% from the battery (for example, 50%). ), A voltage is applied to maintain the target temperature. When such a glow plug is used, for example, when the glow plug is heated by energization, the ignition switch is turned off and the engine is stopped. Since a voltage with a duty ratio of 100% is applied, a situation may occur in which the glow plug exceeds the target temperature and is overheated.

  In addition, in order to suppress such overheating of the glow plug, when the glow plug has already been heated at the time of start-up, as described in Patent Document 1, the power supplied to the glow plug is reduced during normal start-up. It is also conceivable to adjust the applied voltage so as to be smaller than the supplied power. However, when adjusting the voltage applied to the glow plug at the start, the temperature of the glow plug before the start of energization is detected, and the voltage for raising the glow plug to the target temperature based on the detected temperature is set. The control becomes complicated, such as calculating and applying the voltage obtained by the calculation to the glow plug.

  The present invention has been made in view of such circumstances, and its purpose is to perform complicated energization control of the glow plug when starting the engine when using a glow plug whose rated voltage is lower than the voltage of the battery. An object of the present invention is to provide a control device that can suppress overheating of the glow plug.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
The invention according to claim 1 is a control device applied to a diesel engine in which a rated voltage of a glow plug that generates heat by energization is lower than a voltage of a battery that applies a voltage to the glow plug, and when the engine is started The gist of the invention is that control is performed so that application of a voltage from the battery to the glow plug is started after forced cooling of the glow plug is performed.

  According to the above configuration, even when the temperature of the glow plug is high immediately before the engine is started, the glow plug is forcibly cooled when the engine is started and the temperature is lowered. It is possible to prevent the glow plug from being overheated. That is, once the glow plug is cooled, overheating of the glow plug can be suppressed without executing complicated energization control of the glow plug.

  According to a second aspect of the present invention, in the first aspect of the invention, the forced cooling is performed on the condition that the previous operation of the engine was stopped while the glow plug was energized. The gist.

  According to the above configuration, when the glow plug is energized at the time of the previous operation stop, forced cooling at the start is executed, and the glow plug can be appropriately cooled. On the other hand, if the glow plug is not energized at the time of the previous shutdown, it is considered that the temperature of the glow plug is already low at the start of startup. Application of voltage to the plug is started.

  In the invention according to claim 1 or 2, specifically, according to the invention according to claim 3, the forced cooling is performed when the intake air is blown to the glow plug for a predetermined period by cranking. Such a mode can be adopted.

  Accordingly, the glow plug can be cooled by cranking that is normally performed at the time of starting without executing any special control for forced cooling. In addition, when performing forced cooling different from cranking, it is conceivable to start cranking after forcibly cooling the glow plug when starting the engine, but in this case, the start of cranking is delayed. However, according to the above configuration, when starting, cranking is first started as usual, so that the start of the engine is not delayed by cooling of the glow plug.

  According to a fourth aspect of the invention, in the third aspect of the invention, the predetermined period during which the cranking is executed is set to be shorter as the period from the previous operation stop to the current operation start is longer. Is the gist.

  If the period from the previous operation stop to the current operation start is short, it is considered that the temperature has not dropped sufficiently if the glow plug was hot at the time of the previous operation stop. It is necessary to sufficiently cool the glow plug by extending the period during which the intake air is blown to the glow plug. On the other hand, if the period from the previous operation stop to the current operation start is long, even if the glow plug is hot at the time of the previous operation stop, the temperature is considered to decrease. The glow plug can be sufficiently cooled even if the period for blowing the intake air to the plug is not so long. Therefore, according to the said structure, the predetermined period which cools a glow plug by cranking can be set appropriately.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the voltage applied from the battery to the glow plug is such that the glow plug is energized corresponding to the voltage of the battery. The gist of the present invention is that it is executed by energization corresponding to the rated voltage of the glow plug after the period.

  According to the above configuration, in the initial stage of applying a voltage from the battery to the glow plug, the glow plug is energized corresponding to the battery voltage higher than the rated voltage, so that the glow plug can be rapidly heated. Thereafter, energization corresponding to the rated voltage of the glow plug is performed, so that the glow plug is prevented from being overheated.

  In addition, when performing such energization control of the glow plug, if the engine starts with the glow plug heated, a battery voltage higher than the rated voltage of the plug is applied at the initial stage of energization of the glow plug. Therefore, the possibility that the glow plug is overheated is increased. However, according to the above configuration, forced cooling is performed before execution of energization corresponding to the battery voltage, so that the effect of suppressing overheating by forced cooling can be exhibited more remarkably.

Hereinafter, an embodiment of a diesel engine control device according to the present invention will be described in detail with reference to FIGS.
FIG. 1 shows a diesel engine to which the control device of this embodiment is applied and its peripheral mechanism. As shown in FIG. 1, a diesel engine (hereinafter simply referred to as “engine”) 5 to which the control device of this embodiment is applied includes an intake passage 10, a combustion chamber 11, and an exhaust passage 12. Each combustion chamber 11 formed in each cylinder is provided with a glow plug 13 and an injector 14.

  The glow plug 13 is energized and heated when a voltage is applied from a battery 17 mounted on the vehicle, thereby heating the intake air compressed in the combustion chamber 11 at the time of cold start, for example. This promotes the ignition of fuel. In addition, the glow plug 13 of the present embodiment is set to 7V, whose rated voltage is lower than the voltage (12V) of the battery 17. The energization control from the battery 17 to the glow plug will be described in detail later.

  The vehicle is equipped with an electronic control unit 20 that executes various controls of the engine 5 as a control unit for the diesel engine. The electronic control unit 20 includes a CPU that executes arithmetic processing related to the control of the engine 5, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores arithmetic results of the CPU, and an external interface. The input / output port for inputting / outputting the signal is provided. The input port of the electronic control unit 20 has a water temperature sensor 21 for detecting the engine cooling water temperature, a crank sensor 22 for detecting the rotational speed of a crankshaft (not shown), and a switching operation performed by a vehicle driver to correspond to the current operation position. An ignition switch 23 for outputting a signal is connected. The output port of the electronic control unit 20 is connected to a drive circuit for the injector 14 and a drive circuit for executing energization control for the glow plug 13.

  Next, the glow plug 13 provided in the engine 5 of the present embodiment will be described in more detail. When the ignition switch 23 is turned on, the electronic control unit 20 controls the voltage of the battery 17 to be applied to the glow plug 13 through the energization unit 18 at a predetermined duty ratio.

  That is, in the present embodiment, as indicated by a solid line A in FIG. 2A, for example, application of voltage to the glow plug 13 starts from time t1, and during a predetermined period Δt1 in the initial energization period, the battery 17 and glow plug 13 The voltage is applied at a duty ratio of 100%, and thereafter, the voltage is applied at a duty ratio of 60%. The duty ratio here defines the ratio of the time during which a voltage is applied to the glow plug 13 with respect to a predetermined very short unit time. When the engine 5 is warmed up after the engine 5 is started, the application of voltage to the glow plug 13 is stopped. The period from when the voltage applied from the battery 17 to the glow plug 13 is changed to the duty ratio of 60% until the warm-up is completed, that is, the period during which the voltage is applied to the glow plug 13 at the duty ratio of 60%. For example, the period Δt2 is set by experiment.

  In the present embodiment, by applying a voltage to the glow plug 13 in this manner, as shown by a solid line A in FIG. 2B, the glow plug is applied during a predetermined period Δt1 in which the voltage is applied with a duty ratio of 100%. 13 rises rapidly and reaches a target temperature Ta ° C. (eg, 1200 ° C.) at time t2. Further, after time t2, a voltage corresponding to the rated voltage of the glow plug 13 is applied, and the glow plug 13 is maintained at the target temperature Ta ° C. Note that if the period during which the voltage is applied from the battery 17 to the glow plug 13 at a duty ratio of 100% exceeds the predetermined period Δt1, the glow plug 13 may be overheated exceeding the target temperature Ta ° C. The voltage is applied at 100% for this predetermined period Δt1. This predetermined period Δt1 is appropriately set in advance through experiments or the like.

  In the present embodiment, the glow plug 13 having a rated voltage lower than the voltage of the battery 17 is used. For example, when a glow plug having a rated voltage similar to the voltage of the battery 17 is used, the glow plug shown in FIG. ) And (b) as indicated by the alternate long and short dash line B, the temperature rise of the glow plug is moderate even when the voltage of the battery 17 is applied at a duty ratio of 100%. When such a glow plug is used, the voltage of the battery 17 is applied with a duty ratio of 100% even after the target temperature is reached, whereby the temperature of the glow plug is maintained at the target temperature.

  Here, in this embodiment, a glow plug 13 having a rated voltage lower than the voltage of the battery 17 is used, and as described above, the voltage is applied at a duty ratio of 100% in the initial stage of energization to perform rapid temperature rise. Therefore, there is a risk of overheating when energization is started while the glow plug 13 is at a high temperature.

  That is, for example, as shown in FIG. 3A, when the ignition switch 23 is turned on at time t1, application of a voltage to the glow plug 13 is started, and a duty ratio of 60 starts from time t2 after a predetermined period Δt1. The voltage is applied in%. In this way, when the voltage is applied to the glow plug 13, the ignition switch 23 is turned off at time t3, and then the ignition switch 23 is turned on at time t4 without sufficiently decreasing the temperature of the glow plug 13. The voltage is again applied to the glow plug 13 at a duty ratio of 100% from time t4 while the glow plug 13 remains at a high temperature. For this reason, the glow plug 13 exceeds the target temperature Ta ° C., and the glow plug 13 may be overheated as shown in FIG.

  Therefore, in the present embodiment, when the electronic control device 20 applies a voltage to the glow plug 13 to raise the temperature of the plug 13, if the glow plug 13 is at a high temperature, the glow plug 13 is forcibly cooled and then the glow plug 13 is heated. Control is performed so that a voltage is applied to the plug 13. Specifically, when the glow plug 13 is at a high temperature, the glow plug 13 is forcibly cooled by blowing the intake air to the glow plug 13 by cranking in a state where no voltage is applied to the glow plug 13. . The electronic control unit 20 controls the voltage to be applied to the glow plug 13 without cooling the glow plug 13 when the glow plug 13 is not at a high temperature. Hereinafter, energization control of the glow plug executed by the electronic control unit 20 will be described based on the flowchart of FIG. FIG. 4 is a flowchart showing an execution procedure of energization control of the glow plug 13 by the electronic control unit 20. This series of processing is repeatedly executed at predetermined intervals.

  When the energization control of the glow plug 13 is started, it is first determined in step S11 whether or not the ignition switch 23 is in an on state. If the ignition switch 23 is in the off state, it is not necessary to apply a voltage to the glow plug 13, so that the process is terminated and the process is terminated. If the ignition switch 23 is in the on state, the process proceeds to step S12. In step S12, it is determined whether or not the previous ignition switch 23 was on. If it is determined in step S12 that the ignition switch 23 was previously turned on, the energization of the glow plug after the ignition switch 23 is turned on has already started or the energization of the glow plug 13 has already been completed. Therefore, the process moves to the end and the process is temporarily terminated.

  If it is determined in step S12 that the previous ignition switch 23 has not been turned on, it is determined in step S13 whether or not the previous operation of the engine 5 is within a predetermined operation period. Specifically, in this step S13, it is determined whether or not the previous operation was within the period (Δt1 + Δt2). That is, as described above, in the glow plug 13 of the present embodiment, the voltage from the battery 17 is applied at a duty ratio of 100% in the period Δt1 from the start of energization, and the voltage from the battery 17 is then applied to the duty ratio in the period Δt2. It is applied at 60%, and energization of the glow plug 13 is completed. Therefore, in this step S13, it is determined whether or not the previous operation was finished during the energization period of the glow plug 13 by determining whether or not the previous operation was within a predetermined period (Δt1 + Δt2). The electronic control unit 20 stores, for example, the time when the ignition switch 23 is changed from the off state to the on state, and the time when the ignition switch 23 is changed from the on state to the off state, whereby the previous operation period is the period (Δt1 + Δt2). It can be determined whether it was within or not.

  In step S13, if it is determined that the previous operation has exceeded the predetermined operation period, the previous operation has ended after the glow plug 13 has been energized, so it is determined that the glow plug 13 is not at a high temperature. Moving to S17, energization of the glow plug 13 is started. On the other hand, if it is determined in step S13 that the previous operation is within the predetermined operation period, it is considered that the previous operation was energized by the glow plug 13 and the glow plug 13 was terminated at a high temperature. Control goes to step S14.

  In step S14, it is determined whether or not the previous stop period is within a predetermined stop period. That is, if the stop period from the previous operation stop to the current operation start is long, even if the glow plug 13 is at a high temperature at the previous operation stop, the temperature is sufficiently lowered, and the glow plug 13 There is no need to cool the plug 13 before the plug 13 is energized. Therefore, if it is determined that the previous stop period exceeds the predetermined stop period, the process proceeds to step S17 and energization of the glow plug 13 is started. On the other hand, if it is determined in step S14 that the period from the previous operation stop to the current operation start is short and within the predetermined stop period, the temperature of the glow plug 13 has not yet decreased and the plug 13 is at a high temperature. Therefore, the process proceeds to step S15 to perform forced cooling of the glow plug 13.

  In step S15, a predetermined period during which cranking is performed to cool the glow plug 13 is set based on the previous stop period. That is, when the previous stop period is short, it is considered that the temperature of the glow plug has hardly decreased during the stop period of the engine 5. Therefore, the glow plug is extended by increasing the period of blowing the intake air to the glow plug 13 by cranking. 13 needs to be cooled sufficiently. On the other hand, if the previous stop period is long, it is considered that the temperature is lowered to some extent even when the glow plug is hot at the time of the previous operation stop. The glow plug 13 can be sufficiently cooled even if the period for blowing the intake air is not so long. Therefore, in step S15, the predetermined period during which cranking is executed is set shorter as the previous stop period is longer. For example, when the glow plug 13 is hardly cooled, the cranking for forced cooling can be set to 10 revolutions of the crankshaft.

  Then, the process proceeds to step S16, the starter is turned on to rotate the crankshaft of the engine 5, and cranking is performed for the predetermined period set in step S15. Then, after cranking is performed for a predetermined period, the process proceeds to step S17 and energization of the glow plug 13 is started. After starting the energization of the glow plug 13 in this way, the process proceeds to the end and the present process is terminated.

  The operation of the glow plug energization control performed in the above procedure will be described with reference to FIG. As shown in FIG. 5A, when the ignition switch 23 is turned on at time t5, the energization of the glow plug 13 is started, and the voltage is applied at a duty ratio of 60% from time t6 after a predetermined period Δt1. Applied. In this state where the glow plug 13 is energized, for example, at time t7, the ignition switch 23 is changed to an off state. Thereafter, as shown in FIG. 5 (b), when the ignition switch 23 is turned on at time t8 in a state where the temperature of the glow plug 13 is not sufficiently lowered, in step S13 in the flowchart shown in FIG. It is determined whether or not the previous operation period is within a predetermined operation period. In the example shown in FIG. 5, it is determined whether or not the previous operation period (Δt1 + Δt3) is within a period (Δt1 + Δt2) that is a normal energization period, and the operation period (Δt1 + Δt3) is within an energization period (Δt1 + Δt2). Therefore, at the previous operation end time t3, it is determined that the temperature of the glow plug 13 is still a high temperature of the target temperature Ta ° C.

  Then, the process proceeds to step S14 in FIG. 4 and whether or not the period Δt4 from time t7 to t8, which is the previous stop period in FIG. 5, is equal to or shorter than the predetermined stop period sufficient for cooling the glow plug 13. Is determined. When it is determined that the period Δt4 is within the predetermined stop period, at time t8 when the ignition switch 23 is turned on, the temperature of the glow plug 13 is still sufficiently lowered as shown in FIG. 5B. Therefore, the cranking period Δt5 for forced cooling of the glow plug 13 is set based on the stop period Δt4.

  Thereby, after the ignition switch 23 is turned on at time t8, first, Δt5 cranking is performed for a predetermined period, whereby the glow plug 13 is sufficiently cooled during the synchronization period Δt5 as shown in FIG. 5B. The Then, energization of the glow plug 13 is started at time t9 after a period Δt5 has elapsed since the ignition switch 23 was turned on. After energization of the glow plug 13 is started, the voltage from the battery 17 is applied to the glow plug 13 at a duty ratio of 100% for a predetermined period Δt1 as usual, and then the voltage from the battery 17 is applied for a predetermined period Δt2. Applied at a duty ratio of 60%.

  As described above, according to the present embodiment, when the glow plug 13 is considered to be hot at the start of operation of the engine 5, the energization is started after the glow plug 13 is cooled by cranking. Therefore, when the glow plug 13 is at a high temperature, the plug 13 is once cooled to raise the glow plug 13 to the target temperature Ta ° C. by normal energization control without performing complicated energization control. And the overheating of the plug 13 can be suppressed. In the present embodiment, in the initial energization of the glow plug 13, energization control is performed in which a battery voltage with a duty ratio of 100% higher than the rated voltage of the plug 13 is applied, so that the glow plug 13 is at a high temperature. Although the possibility of overheating due to energization is increased, the effect of suppressing overheating can be exhibited more significantly by performing such forced cooling.

According to this embodiment explained in full detail above, the following effects can be obtained.
(1) In the present embodiment, the engine 5 includes the glow plug 13 having a rated voltage lower than the voltage of the battery 17. Then, the electronic control unit 20 performs control so that application of a voltage from the battery 17 to the glow plug 13 is started after forced cooling of the glow plug 13 is performed when the engine 5 is started. As a result, even if the temperature of the glow plug 13 is high immediately before the engine 5 is started, the glow plug 13 is forcibly cooled when the engine 5 is started and the temperature is lowered. In this case, the glow plug 13 can be prevented from being overheated. That is, once the glow plug 13 is cooled, overheating of the glow plug 13 can be suppressed without executing complicated energization control of the glow plug 13.

  (2) In the present embodiment, forced cooling is executed on condition that the previous operation of the engine 5 was stopped while the glow plug 13 was energized. Specifically, forced cooling before the start of energization of the glow plug 13 is executed on condition that the previous operation of the engine 5 has been completed within a predetermined operation period (Δt1 + Δt2). Thereby, when the glow plug 13 is energized and considered to be high temperature at the time of the previous operation stop, forced cooling at the start is executed, and the glow plug 13 can be appropriately cooled. Further, when the glow plug 13 is not energized at the time of the previous operation stop, it is considered that the temperature of the glow plug 13 is already low at the start of the start, so unnecessary unnecessary cooling is not performed. Application of a voltage to the glow plug 13 is started.

  (3) In this embodiment, forced cooling of the glow plug 13 is performed by the intake air being blown to the glow plug 13 for a predetermined period by cranking. Thereby, the glow plug 13 can be cooled by cranking normally performed at the time of starting, without performing special control for forced cooling. In addition, when forced cooling different from cranking is performed, if cranking is started after the glow plug 13 is forcibly cooled when the engine 5 is started, the cranking start is delayed. Since the cranking is started, the start of the engine 5 is not delayed by the cooling of the glow plug 13.

  (4) In this embodiment, the predetermined period during which cranking is executed is set shorter as the previous stop period is longer. That is, if the previous operation stop period is short, the temperature is not sufficiently lowered when the glow plug 13 is at a high temperature at the time of the previous operation stop, so that intake air is blown to the glow plug 13 by cranking. It is necessary to sufficiently cool the glow plug 13 by extending the period. On the other hand, if the previous operation stop period is long, it is considered that the temperature is sufficiently lowered even when the glow plug 13 is at a high temperature at the time of the previous operation stop. The glow plug 13 can be sufficiently cooled even if the period of blowing the air is not so long. Therefore, the predetermined period during which the glow plug 13 is cooled by cranking can be set appropriately.

  (5) In this embodiment, the voltage from the battery 17 to the glow plug 13 is applied by first applying the voltage of the battery 17 to the glow plug 13 at a duty ratio of 100% for a predetermined period Δt1 so that the glow plug 13 has the target temperature Ta. After the temperature is rapidly raised to ° C., the voltage of the battery 17 is applied to the glow plug 13 at a duty ratio of 60%. That is, in this embodiment, first, energization corresponding to the rated voltage of the glow plug 13 is performed after the glow plug 13 is energized corresponding to the voltage of the battery 17 for a predetermined period Δt1. Thus, in the initial stage of applying a voltage from the battery 17 to the glow plug 13, the glow plug 13 is energized corresponding to the voltage of the battery 17 higher than the rated voltage, so that the glow plug 13 can be rapidly heated. it can. Thereafter, energization corresponding to the rated voltage of the glow plug 13 is performed, so that the glow plug 13 is prevented from being overheated.

  Further, in the case of adopting such a mode in which energization corresponding to the voltage of the battery 17 is applied at the initial stage when the voltage to the glow plug 13 is applied, when the engine 5 is started with the glow plug 13 heated, Since energization of the battery 17 voltage higher than the rated voltage of the glow plug 13 is performed, there is a high possibility that the glow plug 13 is overheated. However, according to the above configuration, forced cooling is performed before the energization corresponding to the voltage of the battery 17 is performed, so that the effect of suppressing overheating by forced cooling can be exhibited more remarkably.

(Other embodiments)
In addition, you may change the said embodiment suitably as follows.
In the above-described embodiment, the energization corresponding to the rated voltage of the glow plug 13 is performed after the energization corresponding to the voltage of the battery 17 is performed to the glow plug 13 for the predetermined period Δt1, and then the voltage is applied from the battery 17 to the glow plug 13. Although it is made to apply, the electricity supply aspect is not specifically limited. For example, even when a voltage higher than the rated voltage of the glow plug is applied at the initial stage of energization of the glow plug, the battery voltage is applied not at a duty ratio of 100% but at a duty ratio of 80%. May be. Alternatively, the voltage of the battery may be applied to the glow plug from the beginning of energization with a duty ratio of 60%, and the voltage corresponding to the rated voltage of the glow plug may be applied from the beginning of energization.

  In each of the above embodiments, the rated voltage of the glow plug 13 is 7V, but the rated voltage is not limited to 7V, and the rated voltage may be lower than 7V or higher than 7V. May be. The duty ratio of the voltage applied from the battery to the glow plug in order to maintain the glow plug at the target temperature is not limited to 60% shown in the above embodiment, and is set as appropriate according to the rated voltage of the glow plug. Is done.

  In each of the above embodiments, the cranking execution period for forced cooling of the glow plug 13 is set to be shorter as the previous stop period is longer. However, the cranking execution period for forced cooling of the glow plug 13 may be set to a fixed period regardless of the length of the previous stop period.

  In each of the above embodiments, the glow plug 13 is forcibly cooled by blowing intake air to the glow plug 13 by cranking. However, forced cooling may be performed by a method other than cranking, such as injecting fuel from an injector in the vicinity of the glow plug and cooling the glow plug using the heat of vaporization that vaporizes the fuel.

  In each of the above embodiments, forced cooling is executed on the condition that the previous operation of the engine 5 was stopped while the glow plug 13 was energized. However, even if the previous operation was stopped after the glow plug was energized, for example, when the glow plug was hot, such as when it was stopped immediately after the glow plug was energized, the engine stopped operating For example, the glow plug may be forcibly cooled at the start and then energization of the plug may be started. That is, in each of the above embodiments, the forced cooling of the glow plug 13 is performed on the condition that the previous operation of the engine 5 is within the period (Δt1 + Δt2), but the previous operation of the engine 5 is performed during the period (Δt1 + Δt2 + Δt6). ) (The time required for the glow plug at the target temperature Ta ° C. to cool to a temperature that does not hinder energization when the glow plug is at the target temperature Ta ° C.) is forcibly cooled. Good.

  The above embodiments have been described on the assumption that the glow plug is energized at the start. However, as is well known, since it is not necessary to energize the glow plug when restarting after warming up, for example, the cooling water temperature is determined by the water temperature sensor 21 between step S12 and step S13 in the flowchart of FIG. Thus, the glow plug may not be energized at the start of warm-up.

The schematic diagram which shows the diesel engine which concerns on one Embodiment of the control apparatus of the diesel engine of this invention, and its periphery mechanism. In the embodiment, (a) and (b) are timing charts showing changes in the duty ratio of the battery voltage applied to the glow plug and the temperature of the glow plug in normal glow plug energization control. In the embodiment, (a) and (b) are timing charts showing changes in the duty ratio of the battery voltage and the temperature of the glow plug when a voltage is applied to the glow plug when the glow plug is at a high temperature. 6 is a flowchart showing an execution procedure of glow plug energization control in the embodiment. In the embodiment, (a) and (b) are timing charts showing changes in the duty ratio of the battery voltage applied to the glow plug and the temperature of the glow plug when forced cooling is performed before the energization of the glow plug is started.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 5 ... Diesel engine, 10 ... Intake passage, 11 ... Combustion chamber, 12 ... Exhaust passage, 13 ... Glow plug, 14 ... Injector, 17 ... Battery, 18 ... Current supply unit, 20 ... Electronic control unit, 21 ... Water temperature sensor, 22 ... Crank sensor, 23 ... Ignition switch.

Claims (5)

A control device applied to a diesel engine in which a rated voltage of a glow plug that generates heat by energization is lower than a voltage of a battery that applies a voltage to the glow plug,
A diesel engine control device, wherein, at the time of starting the engine, control is performed so that application of a voltage from the battery to the glow plug is started after forced cooling of the glow plug is executed. In claim 1,
The diesel engine control apparatus, wherein the forced cooling is executed on condition that the previous operation of the engine was stopped while the glow plug was energized. In claim 1 or 2,
The diesel engine control device according to claim 1, wherein the forced cooling is performed by blowing air into the glow plug for a predetermined period by cranking. In claim 3,
The control apparatus for a diesel engine, wherein the predetermined period during which the cranking is executed is set shorter as the period from the previous operation stop to the current operation start is longer. In any one of Claims 1-4,
Application of a voltage from the battery to the glow plug is performed by energizing the glow plug corresponding to the rated voltage of the glow plug after energization corresponding to the voltage of the battery is performed for a predetermined period. A control device for a diesel engine.

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