JP5050864B2 - Glow plug control device - Google Patents

Description

  The present invention relates to a technique for controlling a glow plug provided in a cylinder of an internal combustion engine.

  Conventionally, glow plugs arranged in cylinders have been used for the purpose of promoting ignition at the start of a diesel engine. For example, Patent Document 1 describes a technique for detecting a current flowing in ions generated by combustion using an electrode of a glow plug after the glow plug is deenergized. In this technique, soot that adheres to and accumulates on the electrode portion by energizing the glow plug is burned off to suppress the influence of soot, thereby improving the detection accuracy of the ignition timing by the ion current. In addition, Patent Documents 2 and 3 describe techniques related to the present invention.

JP-A-11-82149 JP 2007-16788 A JP 11-44285 A

  By the way, it is considered that the amount of soot accumulated in the cylinder (for example, around the glow plug) varies depending on the operating conditions. That is, it is considered that a difference in the soot accumulation amount occurs due to a difference in engine speed, fuel injection amount, and the like. However, Patent Documents 1 to 3 described above do not describe removing accumulated soot in consideration of such changes in operating conditions.

  The present invention has been made to solve the above-described problems, and a glow plug capable of appropriately removing soot accumulated around the glow plug in consideration of operating conditions of the internal combustion engine. An object of the present invention is to provide a control device.

In one aspect of the present invention, a glow plug control device that controls a glow plug provided in a cylinder of an internal combustion engine includes a soot in a cylinder in the cylinder based on a rotational speed and a fuel injection amount of the internal combustion engine. A soot accumulation amount estimating means for estimating the accumulation amount, and a glow control for energizing the glow plug after the internal combustion engine is stopped when the soot accumulation amount estimated by the soot accumulation amount estimation means is larger than a predetermined value. Plug control means.

The glow plug control device is preferably used for controlling the glow plug provided in the cylinder of the internal combustion engine. Specifically, the soot accumulation amount estimation means estimates the soot accumulation amount in the cylinder (such as around the glow plug) based on the rotational speed of the internal combustion engine and the fuel injection amount, and the glow plug control means estimates When the soot accumulation amount is larger than a predetermined value, the glow plug is energized. Thereby, it is possible to appropriately energize the glow plug in a situation where the accumulated soot should be removed. Therefore, the soot accumulated around the glow plug can be burned out, and the soot can be appropriately removed. Accordingly, it is possible to appropriately prevent deterioration of the operating state due to a drop in the tip temperature of the glow plug due to accumulation of soot around the glow plug, breakage when replacing the glow plug, and the like.
Further, the glow plug control means may perform control to energize the glow plug when the estimated soot accumulation amount is larger than a predetermined value not only during the operation of the internal combustion engine but also after the internal combustion engine is stopped. it can.

  In one aspect of the above glow plug control device, the glow plug control device further comprises temperature acquisition means for acquiring at least one of a water temperature and an outside air temperature in the internal combustion engine, and the glow plug control means is estimated by the soot accumulation amount estimation means. When the soot accumulation amount is larger than a predetermined value, the energization time of the glow plug is made longer when the temperature acquired by the temperature acquisition means is low than when it is high.

  In this aspect, the glow plug control means lengthens the energization time of the glow plug as the water temperature and / or the outside air temperature is lower. This makes it possible to appropriately remove soot accumulated around the glow plug when cold.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment]
First, a first embodiment of the present invention will be described.

(overall structure)
FIG. 1 is a schematic diagram showing a configuration of a vehicle 50 to which a glow plug control device according to the first embodiment is applied. In FIG. 1, solid arrows indicate gas flows, and broken arrows indicate input / output of signals.

  The vehicle 50 mainly includes an intake passage 3, a throttle valve 4, an engine (internal combustion engine) 5, an exhaust passage 9, a glow plug 11, a rotation speed sensor 15, an ECU (Engine Control Unit) 20, Have The engine 5 includes a cylinder 6a, an intake valve 7, an exhaust valve 8, a fuel injection valve 10, and the like, and corresponds to, for example, a diesel engine. In FIG. 1, only one cylinder 6a is shown for convenience of explanation, but the engine 5 actually has a plurality of cylinders 6a.

  Air (fresh air) introduced from the outside passes through the intake passage 3, and the throttle valve 4 adjusts the flow rate of air passing through the intake passage 3. The air that has passed through the intake passage 3 is supplied to the combustion chamber 6 b in the engine 5. Further, the fuel injected by the fuel injection valve 10 is supplied to the combustion chamber 6b. In the combustion chamber 6b, the air-fuel mixture thus supplied is combusted. In this case, the piston 6c reciprocates by combustion, and this reciprocating motion is transmitted to the crankshaft (not shown) via the connecting rod 6d, and the crankshaft rotates. Further, an exhaust passage 9 is connected to the engine 5, and exhaust gas generated by combustion is discharged from the exhaust passage 9.

  An intake valve 7 and an exhaust valve 8 are provided in the combustion chamber 6 b of the engine 5. The intake valve 7 controls conduction / interruption between the intake passage 3 and the combustion chamber 6b by opening and closing. The exhaust valve 8 controls opening / closing of the exhaust passage 9 and the combustion chamber 6b by opening and closing.

  Further, the cylinder 6 a of the engine 5 is provided with a glow plug 11 (hereinafter also simply referred to as “glow”) that can promote ignition when the engine 5 is started. Energization of the glow plug 11 is controlled by a control signal supplied from the ECU 20, as indicated by a broken-line arrow in FIG. The glow plug 11 is disposed for each of the plurality of cylinders 6a.

  The rotational speed sensor 15 is configured to be able to detect the rotational speed of the engine 5 (engine rotational speed). The rotational speed sensor 15 supplies a detection signal corresponding to the detected engine rotational speed to the ECU 20 as indicated by a broken line arrow in FIG.

  The ECU 20 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown). The ECU 20 acquires signals from various sensors provided in the vehicle 50 and controls components in the vehicle 50. In the first embodiment, the ECU 20 mainly functions as a soot accumulation amount estimation unit and a glow plug control unit to control the glow plug 11. That is, the ECU 20 corresponds to a glow plug control device in the present invention. The ECU 20 also controls other components in the vehicle 50, but a description of portions that are not particularly related to the present embodiment is omitted.

(Glow plug control method)
Next, a control method that the ECU 20 performs on the glow plug 11 in the first embodiment will be described.

  In the first embodiment, the ECU 20 estimates the amount of soot accumulated in the cylinder 6a (for example, around the glow plug 11) based on the operating conditions of the engine 5, and the estimated amount of soot accumulated. (Hereinafter referred to as “estimated deposition amount”) is controlled so that the glow plug 11 is energized. That is, in the first embodiment, the soot accumulation amount estimated in consideration of the difference in the soot accumulation amount due to the difference in operating conditions is obtained, and the accumulated soot is removed based on the estimated soot accumulation amount. Control for. Specifically, the ECU 20 obtains an estimated accumulation amount based on the engine speed and the fuel injection amount, and energizes the glow plug 11 when the estimated accumulation amount is larger than a predetermined value. As a result, the soot accumulated around the glow plug 11 can be burned out, and the soot can be appropriately removed.

  With reference to FIG.2 and FIG.3, the control method of the glow plug 11 is demonstrated concretely.

  In the present embodiment, the ECU 20 creates in advance a map (hereinafter referred to as “soot accumulation map”) representing the amount of soot accumulated for each engine speed and fuel injection amount, and the soot accumulation map is created. Obtain the estimated soot accumulation amount. Specifically, the ECU 20 refers to the soot accumulation map to obtain the soot amount corresponding to the current engine speed and fuel injection amount, and calculates the estimated soot accumulation amount by integrating the obtained soot amount. The soot accumulation map corresponds to a map showing the amount of soot accumulated in a predetermined time (in other words, the amount of soot accumulated per unit time) according to the current engine speed and fuel injection amount, and is measured and analyzed. It is created by performing in advance.

  FIG. 2 shows an example of a soot deposition map. FIG. 2 shows the engine speed in the horizontal direction and the fuel injection amount in the vertical direction. As illustrated, in the soot accumulation map, the soot accumulation amount is indicated by a numerical value for each engine speed and fuel injection amount. From this, it can be seen that when the engine speed is high and the fuel injection amount is large, the amount of accumulated soot is large.

  FIG. 3 shows an example of the elapsed time of the estimated soot accumulation amount. FIG. 3 shows time on the horizontal axis and the estimated amount of soot on the vertical axis. Here, the graphs A1 and A2 illustrate the difference in the estimated soot accumulation amount due to the difference in operating conditions. From this, it can be seen that the graph A1 has a larger degree of increase in the estimated soot deposition amount than the graph A2, in other words, the rate at which soot is deposited is faster. The plurality of dots in the graphs A1 and A2 correspond to the estimated soot accumulation amount calculated from the soot amount obtained from the soot accumulation map at each time point. As described above, the estimated soot accumulation amount is calculated by obtaining the soot amount corresponding to the current engine speed and the fuel injection amount with reference to the soot accumulation map and integrating the soot amount.

  Further, an alternate long and short dash line A <b> 3 in FIG. 3 indicates a predetermined value (hereinafter referred to as “specified value”) used for determination on the estimated accumulation amount. This specified value A3 corresponds to a soot accumulation amount that desirably removes soot accumulated by energizing the glow plug 11, and is a value set in advance. The ECU 20 energizes the glow plug 11 when the estimated soot accumulation amount is larger than the prescribed value A3, and energizes the glow plug 11 when the estimated soot accumulation amount is equal to or less than the prescribed value A3. Absent. That is, the ECU 20 burns off the soot deposited around the glow plug 11 by energizing the glow plug 11 when the estimated soot accumulation amount is larger than the specified value A3.

  Next, a glow plug control process executed by the ECU 20 will be described with reference to FIG. FIG. 4 is a flowchart showing glow plug control processing according to the first embodiment. This process is repeatedly executed by the ECU 20 at a predetermined cycle.

  First, in step S101, the ECU 20 acquires the current engine speed and fuel injection amount. Specifically, the ECU 20 acquires the current engine speed from the speed sensor 15 and also acquires the current fuel injection amount from the control signal supplied to the fuel injection valve 10. Then, the process proceeds to step S102.

  In step S102, the ECU 20 reads a soot accumulation map. Specifically, the ECU 20 reads a soot accumulation map (see FIG. 2) stored in advance in a ROM or the like. Next, the ECU 20 refers to the soot accumulation map to obtain the soot amount corresponding to the engine speed and the fuel injection amount acquired in step S101. That is, the amount of soot accumulated at the current engine speed and fuel injection amount is obtained. When the above process ends, the process proceeds to step S103.

  In step S103, the ECU 20 calculates the estimated soot accumulation amount based on the soot amount obtained from the soot accumulation map in step S102. Specifically, the ECU 20 calculates the estimated soot accumulation amount by integrating the soot amount obtained in step S102. For example, the ECU 20 calculates the estimated soot accumulation amount by adding the soot amount obtained in step S102 to the estimated soot accumulation amount calculated in the previous step S103. When the above process ends, the process proceeds to step S104.

  In step S104, the ECU 20 determines whether or not the estimated soot accumulation amount calculated in step S103 is equal to or less than a specified value. That is, in step S104, the glow plug 11 is energized to determine whether or not the accumulated soot should be removed. The specified value used in the determination in step S104 corresponds to a soot deposition amount in which it is desirable to remove soot accumulated by energizing the glow plug 11, and a result of measurement or analysis or the like. It is preset according to

  If the estimated soot accumulation amount is equal to or less than the specified value (step S104; Yes), the process exits the flow. In this case, it is considered unnecessary to remove soot. Therefore, the ECU 20 does not energize the glow plug 11.

  On the other hand, when the estimated soot accumulation amount is larger than the specified value (step S104; No), the process proceeds to step S105. In this case, it is considered that soot should be removed. Therefore, in step S105, the ECU 20 energizes the glow plug 11. Specifically, the ECU 20 performs control to energize the glow plug 11 for a predetermined time. The predetermined time for energization is set based on the time for energizing the glow plug 11 in order to properly burn off the accumulated soot. For example, the predetermined time is set in advance according to the result of measurement or analysis. When the above process ends, the process exits the flow.

  According to the first embodiment described above, it is possible to appropriately energize the glow plug 11 in a situation where accumulated soot is to be removed. Therefore, the soot accumulated around the glow plug 11 can be burned out and the soot can be appropriately removed. Therefore, it is possible to appropriately prevent deterioration of the operation state due to the temperature drop of the tip of the glow plug 11 due to the accumulation of soot around the glow plug 11 and damage when the glow plug 11 is replaced. .

[Second Embodiment]
Next, a second embodiment of the present invention will be described.

  In the second embodiment, when the glow plug 11 is energized, the glow plug 11 is heated according to at least one of the temperature of the cooling water in the engine 5 (hereinafter simply referred to as “water temperature”) and the outside air temperature. It differs from the first embodiment in that the energization time of the plug 11 is changed. Specifically, in the second embodiment, the energization time of the glow plug 11 is made longer than when the temperature is high when at least one of the water temperature and the outside air temperature is low. This is because when the water temperature and the outside air temperature are low (in other words, when it is cold), the time to energize the glow plug 11 to properly burn out the accumulated soot is compared. This is because it tends to take a long time.

(overall structure)
FIG. 5 is a schematic diagram illustrating a configuration of a vehicle 51 to which the glow plug control device according to the second embodiment is applied. In FIG. 5, the solid line arrows indicate the gas flow, and the broken line arrows indicate the signal input / output. Moreover, the same code | symbol is attached | subjected to the component same as the vehicle 50 (refer FIG. 1) shown in 1st Embodiment, and the description is abbreviate | omitted.

  The vehicle 51 is different from the vehicle 50 described above in that it has a water temperature sensor 16 and an outside air temperature sensor 17 in addition to the rotational speed sensor 15 and has an ECU 21 instead of the ECU 20. The water temperature sensor 16 detects the temperature (water temperature) of cooling water that cools the engine 5 and the like, and supplies a detection signal corresponding to the detected water temperature to the ECU 21. The outside air temperature sensor 17 detects the temperature of the outside air in the vehicle 51 and supplies a detection signal corresponding to the detected outside air temperature to the ECU 21.

  The ECU 21 includes a CPU, a ROM, a RAM, and the like (not shown). The ECU 21 acquires signals from various sensors provided in the vehicle 51 and controls the components in the vehicle 51. In the second embodiment, the ECU 21 functions as a temperature acquisition unit, a soot accumulation amount estimation unit, and a glow plug control unit, and controls the glow plug 11. That is, the ECU 21 corresponds to a glow plug control device in the present invention. The ECU 21 also controls other components in the vehicle 51, but a description of portions that are not particularly related to the present embodiment is omitted.

(Glow plug control method)
Next, a control method that the ECU 21 performs on the glow plug 11 in the second embodiment will be described. In the second embodiment, the ECU 21 makes the energization time of the glow plug 11 longer than when it is high when at least one of the water temperature and the outside air temperature is low. That is, the ECU 21 increases the energization time of the glow plug 11 as it is colder.

  FIG. 6 is a diagram illustrating an example of the energization time for each water temperature. In FIG. 6, the horizontal axis represents the water temperature of the engine 5, and the vertical axis represents the energization time of the glow plug 11. In addition, the energization time in the graph generally represents the time to energize the glow plug 11 in order to properly burn out the accumulated soot. As shown in the figure, it can be seen that the energization time of the glow plug 11 becomes longer as the water temperature is lower. This is because when the water temperature is low, energization of the glow plug 11 tends to take a long time to burn off the accumulated soot.

  FIG. 7 is a flowchart showing glow plug control processing according to the second embodiment. This process is repeatedly executed by the ECU 21 at a predetermined cycle. Note that the processes in steps S201 to S204 are the same as the processes in steps S101 to S104 in the glow plug control process (see FIG. 4) according to the first embodiment described above, and thus the description thereof is omitted. Here, the processing after step S205 will be described.

  The processing after step S205 is executed when it is determined that the estimated soot accumulation amount is larger than the prescribed value (step S204; No), that is, when it is determined that the soot should be removed. In step S205, the ECU 21 acquires the water temperature and the outside air temperature of the engine 5. Specifically, the ECU 21 acquires the water temperature from the water temperature sensor 16 and acquires the outside air temperature from the outside air temperature sensor 17. Then, the process proceeds to step S206.

  In step S206, the ECU 21 determines whether or not the temperature acquired in step S205 is equal to or lower than a predetermined temperature. Here, it is determined whether or not it is cold based on at least one of the water temperature and the outside air temperature. For example, the ECU 21 determines that it is cold when the water temperature is equal to or lower than the first predetermined temperature and / or when the outside air temperature is equal to or lower than the second predetermined temperature.

  If the acquired temperature is higher than the predetermined temperature (step S206; No), the process proceeds to step S207. In this case, it can be said that it is not cold. Accordingly, in step S207, the ECU 21 performs control to energize the glow plug 11 for a predetermined time. When the above process ends, the process exits the flow.

  On the other hand, when the acquired temperature is equal to or lower than the predetermined temperature (step S206; Yes), the process proceeds to step S208. In this case, it can be said that it is cold. Therefore, in step S208, the ECU 21 performs control to energize the glow plug 11 for the time “predetermined time + α”. That is, the glow plug 11 is energized for a time longer than the energization time in step S207. The time “α” for extending the energization time is set based on the time during which the glow plug 11 should be energized in order to properly burn off the accumulated soot. For example, the time “α” is set in advance according to the result of measurement or analysis. When the above process ends, the process exits the flow.

  Thus, in 2nd Embodiment, the energization time of the glow plug 11 can be lengthened at the time of cold. Therefore, according to the second embodiment, it is possible to appropriately remove the soot deposited around the glow plug 11 even when it is cold.

  In the glow plug control process described above, the energization time of the glow plug 11 is set to one of “predetermined time” and “predetermined time + α” depending on whether or not the acquired temperature is equal to or lower than the predetermined temperature. Although an example of setting is shown, the present invention is not limited to this. That is, the present invention is not limited to switching between the two types of energization time according to the determination result of whether or not it is cold. In another example, three or more types of energization time can be switched or the energization time can be changed continuously according to at least one of the water temperature and the outside air temperature. For example, the energization time of the glow plug 11 is set in a map or the like for each water temperature and outside air temperature, and the energizing time according to the acquired water temperature and outside air temperature is obtained from the map, and the glow plug 11 is energized. be able to.

[Modification]
In the above description, the embodiment in which the glow plug 11 is controlled to be energized during the operation of the engine 5 has been described. However, the present invention is not limited to this. In another example, it is possible to perform control to energize the glow plug 11 as described above during at least one of the operation of the engine 5 and after the engine 5 is stopped. That is, not only during the operation of the engine 5 but also after the engine 5 is stopped, in order to remove the soot accumulated around the glow plug 11 when the estimated soot accumulation amount is larger than the prescribed value, Control to energize the plug 11 can be performed. When energization is performed after the engine 5 is stopped, control for energizing the glow plug 11 is performed based on the estimated soot accumulation amount obtained from the engine speed and the fuel injection amount during operation of the engine 5.

  Moreover, this invention is not limited to application to a diesel engine, It can apply also to a gasoline engine.

1 is a schematic configuration diagram of a vehicle to which a glow plug control device according to a first embodiment is applied. FIG. An example of a soot deposition map is shown. An example of the elapsed time of the estimated soot accumulation amount is shown. It is a flowchart which shows the glow plug control process which concerns on 1st Embodiment. The schematic block diagram of the vehicle to which the control apparatus of the glow plug which concerns on 2nd Embodiment was applied is shown. An example of the energization time for each water temperature is shown. It is a flowchart which shows the glow plug control process which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Intake passage 4 Throttle valve 5 Engine 6a Cylinder 10 Fuel injection valve 11 Glow plug 15 Revolution sensor 16 Water temperature sensor 17 Outside temperature sensor 20, 21 ECU
50, 51 vehicles

Claims (2)

A glow plug control device for controlling a glow plug provided in a cylinder of an internal combustion engine,
Soot accumulation amount estimating means for estimating the amount of soot accumulation in the cylinder in the cylinder based on the rotational speed of the internal combustion engine and the fuel injection amount;
Glow plug control means for performing control to energize the glow plug after the internal combustion engine is stopped when the soot accumulation amount estimated by the soot accumulation amount estimation means is larger than a predetermined value. Glow plug control device. A temperature acquisition means for acquiring at least one of a water temperature and an outside air temperature in the internal combustion engine;
The glow plug control means is configured such that when the soot accumulation amount estimated by the soot accumulation amount estimation means is greater than a predetermined value, the glow plug control means is more effective when the temperature acquired by the temperature acquisition means is lower than when it is high. The glow plug control device according to claim 1, wherein the energizing time of the glow plug is increased.

Images