JP6794790B2 - Heater control device and heater control system - Google Patents

Description

The present invention relates to a heater control device and a heater control system.

In the fuel supply system of a vehicle, it has been proposed to heat the fuel in order to improve the engine startability at the time of cooling (see, for example, Patent Document 1). In Patent Document 1, the fuel is indirectly heated by providing the fuel injection valve with a heater and actively heating the fuel injection valve with the heater. Further, in Patent Document 1, in order to prevent overheating of the heater, the amount of electric power input to the heater is integrated, and when the accumulated electric energy becomes a predetermined value or more, the amount of electricity supplied to the heater is reduced. ..

JP-A-2002-195110

By the way, light oil used in a diesel engine may solidify (wax) at a relatively high temperature as compared with gasoline. For example, in cold regions, it is assumed that the fuel cannot be properly injected due to the solidification of the fuel. Therefore, in order to melt the solidified fuel, it is conceivable to heat the fuel with a heater as in Patent Document 1.

However, as described above, in Patent Document 1, since the energization control of the heater is performed based on the integrated electric energy, the fuel may not be sufficiently heated depending on the type of fuel used, or conversely, the fuel is heated. There is a risk of consuming extra power due to excessive power consumption.

Further, in the fuel supply system as described above, a fuel filter for filtering fuel is provided in the middle of the fuel supply path. The fuel filter is clogged with the solidification of the fuel, and the clogging is cleared by driving the heater and melting the solidified fuel.

However, the cause of clogging of the fuel filter is not limited to the solidification of the fuel. For example, fuels such as light oil have different properties depending on the country, and in some cases, foreign substances (impurities) may be mixed in the fuel. Therefore, it is assumed that the fuel filter is clogged due to this foreign matter. In this case, even if the heater is driven, the clogging of the fuel filter cannot be cleared, which may cause the heater to be driven unnecessarily.

The present invention has been made in view of such circumstances, and is a heater control device capable of appropriately controlling the drive of the heater to save electric power while considering the type of fuel and impurities in the fuel. One of the purposes is to provide a heater control system.

The heater control device according to the present invention is a heater control device that heats the fuel input to the combustion chamber of the internal combustion engine, and is described above when the temperature of the fuel before passing through the fuel filter is lower than the heater drive threshold. driving the heater, when the temperature of the fuel while driving the heater exceeds the filter clogging determination threshold is defined based on the upstream and downstream of the pressure difference before Symbol fuel filter, driving of the heater Is stopped, and the filter clogging determination threshold value is set to decrease as the pressure difference increases .

The heater control system according to the present invention has a fuel filter that filters the fuel input into the combustion chamber of the internal combustion engine, a heater that heats the fuel, and a temperature that detects the temperature of the fuel before passing through the fuel filter. The control device includes a sensor, a pressure sensor that detects the pressure difference between upstream and downstream of the fuel filter, and a control device that controls the drive of the heater based on the temperature of the fuel and the pressure difference. a heater driving threshold is defined based on the temperature of the fuel, the filter clogging determination threshold is defined based on the pressure difference, stores a case where the temperature of the fuel is below the heater driving threshold If the temperature of the fuel exceeds the filter clogging determination threshold while driving the heater, the driving of the heater is stopped, and the filter clogging determination threshold is the pressure difference. Is characterized in that it is set to decrease as the value increases .

According to the present invention, it is possible to appropriately control the drive of the heater to save electric power while considering the type of fuel and impurities in the fuel.

It is a conceptual diagram which shows the whole structure of the control system of the heater which concerns on this embodiment. It is a graph which shows the relationship between a fuel temperature and a pressure loss. It is a figure which shows the change flow of the threshold value which concerns on this embodiment. It is a graph which shows the specific example of the threshold value change which concerns on this embodiment. It is a figure which shows the pressure measurement condition establishment flow which concerns on this embodiment. It is a figure which shows the drive control flow of the heater which concerns on this embodiment. It is a figure which shows the drive control flow of the heater which concerns on this embodiment. It is a graph which shows the threshold value change which concerns on a modification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following, an example in which the heater control device and the heater control system according to the present invention are applied to a diesel engine for a vehicle will be described, but the application target is not limited to this and can be changed. For example, the heater control device and control system according to the present invention may be applied to a gasoline engine. It is also applicable not only to vehicles but also to outboard motors, for example. In each of the following figures, some configurations are omitted for convenience of explanation.

The schematic configuration of the heater control device and the control system according to the present embodiment will be described with reference to FIG. It is a conceptual diagram which shows the whole structure of the control system of the heater which concerns on this embodiment. In the present embodiment, it is assumed that the vehicle (for example, a four-wheeled vehicle) usually has a configuration, and the description thereof will be omitted.

As shown in FIG. 1, the control system 1 of the heater 10 according to the present embodiment is configured to control the heater 10 for heating the fuel used in the internal combustion engine (not shown) of the vehicle. Specifically, the control system 1 of the heater 10 includes a fuel filter 11 for filtering fuel, a heater 10 for heating the fuel filter 11, an ECU 12 (Electronic Control Unit) as a control device for controlling the drive of the heater 10, and the like. Will be done.

The internal combustion engine is, for example, a diesel engine, and is configured to inject (inject) fuel into the combustion chamber from an injector 13 as a fuel injection device. A fuel tank 14 and a fuel filter 11 are connected to the internal combustion engine. Diesel fuel such as light oil is stored in the fuel tank 14. In the fuel tank 14, a low-pressure pump 15 for pumping fuel and a temperature sensor 16 for detecting the temperature of the fuel are provided. The operation of the low pressure pump 15 is controlled by the ECU 12.

The temperature sensor 16 detects the temperature of the fuel in the fuel tank 14, that is, the temperature of the fuel before passing through the fuel filter 11. The detected value of the temperature sensor 16 is output to the ECU 12. The fuel filter 11 filters the fuel pumped from the fuel tank 14. The fuel filter 11 has a built-in heater 10 for heating the fuel. Although the details will be described later, the heater 10 indirectly heats the fuel in the fuel filter 11 by heating the fuel filter 11.

A high-pressure pump 17 and a fuel accumulator pipe 18 are provided between the fuel filter 11 and the injector 13 from the downstream side. The high-pressure pump 17 operates in conjunction with a valve operating mechanism (not shown). The fuel accumulator pipe 18 is connected to an injector 13 provided for each cylinder. The fuel filtered by the fuel filter 11 is increased in pressure by the high-pressure pump 17, and is temporarily stored in the fuel accumulator pipe 18. By opening and closing each injector 13 at a predetermined timing, high-pressure fuel is injected into the combustion chamber from the tip of each injector 13. Further, a part of the fuel in the fuel accumulator pipe 18 and the injector 13 is returned to the fuel tank 14.

A first pressure sensor 19 and a second pressure sensor 20 are provided upstream and downstream (front and back) of the fuel filter 11. The first pressure sensor 19 detects the pressure of the fuel before passing through the fuel filter 11. The second pressure sensor 20 detects the pressure of the fuel after passing through the fuel filter 11. The detected values of the first pressure sensor 19 and the second pressure sensor 20 are output to the ECU 12. Although the details will be described later, the ECU 12 calculates the pressure loss (pressure difference) before and after the fuel filter 11 from the detected values of the first pressure sensor 19 and the second pressure sensor 20.

The ECU 12 controls various configurations in the vehicle in an integrated manner, and is composed of a processor, a memory, and the like that execute various processes in the vehicle. The memory is composed of a storage medium such as a ROM (Read Only Memory) or a RAM (Random Access Memory) depending on the application. A control program or the like that controls each part in the vehicle is stored in the memory. In particular, in the present embodiment, the ECU 12 is configured to control the drive of the heater 10 according to the temperature and pressure of the fuel. Although details will be described later, the ECU 12 stores a temperature map (see FIG. 2) based on the fuel temperature and the pressure loss before and after the fuel filter 11 in the memory. The ECU 12 controls the drive of the heater 10 based on this temperature map.

By the way, light oil used as a fuel for a diesel engine is composed of a hydrocarbon component having a boiling point of about 170 to 370 ° C. Light oil is used, for example, for diesel engines for vehicles such as trucks and buses, diesel engines for power generation, agriculture, and construction machinery, and for heating boilers.

As described above, while light oil is liquid at room temperature, it has a higher solidification temperature (easier to solidify) than gasoline or the like due to the characteristics of fuel. Further, in the JIS standard (JIS K 2204), the types of fuels are finely classified according to the parameters that are indicators of the fuel properties of light oil. Specifically, light oil is classified into five types, Special No. 1, No. 1, No. 2, No. 3, and Special No. 3, according to the "pour point" and "clogging point".

Here, the "pour point" is a numerical value indicating the low temperature fluidity of the liquid, and indicates the temperature immediately before the liquid solidifies. Specifically, it shows the minimum temperature at which a liquid can flow when cooled without stirring. For example, in the special No. 1 light oil, the pour point is set to 5 ° C. or lower, and in the special No. 3 light oil, the pour point is set to −30 ° C. or lower. In this way, the pour point is used as an index for knowing the solidification (waxing) of the fuel at low temperature.

Further, the "clogging point" is a numerical value indicating the low temperature fluidity of the liquid as well as the pour point, and indicates the temperature at which the liquid becomes difficult to flow through the filter when the temperature is lowered. Specifically, it indicates the temperature at which clogging occurs when suction filtration is performed while cooling the fuel. For example, in the light oil of No. 1, the clogging point is set to -1 ° C. or lower, and in the light oil of Special No. 3, the clogging point is set to -19 ° C. or lower. In this way, the clogging point is used as an index for knowing the clogging (clogging) of the fuel filter.

Especially in Japan, the temperature difference is large depending on the season and region, so for example, use No. 1 or Toku No. 1 light oil in summer and No. 2 (No. 3 or Toku No. 3 in cold regions) light oil in winter. , Fuel is used properly according to the season and region. That is, light oil having a relatively high pour point is used in summer, and light oil having a relatively low pour point is used in winter. Therefore, in winter and cold regions, measures are taken to prevent the fuel from solidifying due to the ambient temperature.

However, even though the fuels are used properly as described above, the fuel suitable for the area is not always used, for example, when moving from a relatively hot area to a cold area. Therefore, the solidification of the fuel is suppressed by heating the fuel with a heater.

In the conventional heater control system, the integrated electric energy of the heater is monitored, and when the integrated electric energy exceeds a predetermined value, the power supply to the heater is suppressed or stopped. However, since the drive of the heater is uniformly controlled by a constant amount of electric energy, it is assumed that appropriate heating may not be performed depending on the type of fuel.

For example, when fuel with a high pour point or clogging point solidifies, if the drive of the heater is controlled with a fixed amount of electric energy, the heater may stop before the solidified fuel completely melts. The clogging of the fuel filter may not be cleared. On the other hand, when fuel with a low flow point or clogging point solidifies, even after the fuel is completely melted by the heat of the heater and the clogging of the fuel filter is cleared, the accumulated electric power reaches a predetermined value. Further heating of the heater may consume extra power.

Further, the cause of clogging of the fuel filter is not limited to the solidification component of the fuel. For example, fuels such as light oil have different properties depending on the country, and in some cases, impurities may be mixed in the fuel. Therefore, it is possible that the fuel filter is clogged due to this impurity. When such impurities are accumulated in the fuel filter, even if the solidified component of the fuel is sufficiently melted by heating the heater, the impurities themselves remain, so that the clogging of the fuel filter cannot be eliminated. In this case, it is necessary to replace the fuel filter itself, and it is considered meaningless to heat the fuel with a heater any more. Therefore, as described above, if the drive of the heater is uniformly controlled by a constant amount of electric energy, the heater will be unnecessarily driven.

In view of the above points, the present inventor focused on the pressure loss before and after the fuel filter, and found that the molten state (fuel viscosity) of the solidified component of the fuel correlates with the pressure loss. Specifically, in the present embodiment, the drive of the heater 10 is controlled based on the pressure loss and the fuel temperature.

For example, when the fuel temperature at which the fuel is assumed to have solidified is detected, that is, when the temperature of the fuel falls below a predetermined temperature, the fuel is warmed by driving the heater 10, and the solidified component of the fuel is melted. Along with this, the viscosity (pressure loss) of the fuel gradually decreases, and the temperature of the fuel gradually increases. As described above, if the cause of the clogging of the fuel filter 11 is the solidification component of the fuel, the solidification component can be melted by heating the fuel with the heater 10.

On the other hand, when the cause of clogging of the fuel filter 11 is not a solidification component of the fuel but impurities in the fuel, the pressure difference before and after the fuel filter does not change even if the temperature of the fuel rises with the driving of the heater 10. Or hard to change). Therefore, in the present embodiment, a "filter clogging determination threshold value" based on the fuel temperature and pressure loss is defined, and when the fuel temperature exceeds the "filter clogging determination threshold value" while the heater 10 is being driven, the heater 10 is used. It was configured to stop the drive of.

As a result, when the fuel contains a solidifying component, the solidifying component can be melted by the heat of the heater 10, and the startability of the engine can be improved. Further, when impurities are mixed in the fuel, the driving of the heater 10 can be stopped, so that it is possible to prevent the heater 10 from being driven more than necessary. By setting the "filter clogging determination threshold value" in this way, it is possible to appropriately determine whether the cause of clogging of the fuel filter 11 is due to the solidification component of the fuel or due to impurities in the fuel. .. Therefore, it has become possible to appropriately control the drive of the heater 10 to save electric power while considering the type of fuel and impurities in the fuel.

Next, with reference to FIG. 2, the “filter clogging determination threshold value” used for the drive control of the heater according to the present embodiment will be described. FIG. 2 is a graph showing the relationship between fuel temperature and pressure loss. In the graph shown in FIG. 2, the horizontal axis represents the pressure loss (pressure difference) before and after the fuel filter, and the vertical axis represents the fuel temperature.

As described above, the ECU 12 (see FIG. 1) stores the fuel temperature and the temperature map based on the pressure loss upstream and downstream of the fuel filter 11 (see FIG. 1) in the memory. As shown in FIG. 2, in the temperature map, the first predetermined pressure difference P1 (hereinafter, may be referred to as pressure loss P1) and the second predetermined pressure difference P2 (hereinafter, pressure loss) that define the drive range of the heater are defined. (P2) and the filter clogging determination threshold value L (hereinafter, may be simply referred to as the threshold value L) are shown.

In the present embodiment, the points (ΔP, T) plotted on the graph based on the fuel temperature and pressure loss detected at a predetermined timing, that is, the parameters defined based on the fuel temperature and pressure loss are linear. When it exists in the region surrounded by P1, P2, and L (see the dot hatching portion in FIG. 2), the heater 10 is controlled to be continuously driven. This region is referred to as a heater drive continuation region R1.

Specifically, the pressure loss P1 represents a pressure loss corresponding to the fuel viscosity that does not affect the clogging of the fuel filter 11. In the region below the pressure loss P1, it can be determined that the solidified component of the fuel is sufficiently melted and the clogging of the fuel filter 11 is cleared. That is, it can be determined that the condition of the fuel filter 11 is good. Therefore, when the detected pressure loss ΔP is less than the pressure loss P1, the ECU 12 does not drive the heater 10 (if the heater 10 is being driven, the driving of the heater 10 is stopped). This makes it possible to prevent unnecessary heater drive.

Here, the region below the pressure P1 is defined as the "normal operation region R2" at which the engine can be started appropriately. The pressure loss P1 is not limited to the pressure loss when the solidified component of the fuel is completely melted, and is appropriately changed to the extent that the clogging of the fuel filter 11 is not affected (the engine startability is not affected). Is possible.

The pressure loss P2 is set to be larger than the pressure loss P1. The pressure loss P2 represents a pressure loss in which the fuel filter 11 is clogged and it is assumed that the clogging of the fuel filter 11 cannot be cleared even if the heater 10 is driven. In the region where the pressure loss exceeds P2, it can be predicted that foreign substances (impurities) other than the solidified component of the fuel are accumulated in the fuel filter 11. That is, the state of the fuel filter 11 has deteriorated (deteriorated), and it can be predicted that the fuel filter 11 needs to be replaced. Therefore, when the detected pressure loss ΔP exceeds P2, the heater 10 is not driven (if the heater 10 is being driven, the driving of the heater 10 is stopped). This makes it possible to prevent unnecessary heater drive.

Here, the region exceeding the pressure loss P2 is referred to as a "filter clogging region R3" in which the clogging of the fuel filter 11 is not cleared regardless of whether the heater 10 is driven or not. The pressure loss P2 can be appropriately changed in the same manner as the pressure loss P1. As described above, in the normal operation region R2 and the filter clogging region R3, the stop of the heater 10 is determined only by the pressure loss ΔP regardless of the fuel temperature T.

The “filter clogging determination threshold value L” is a threshold value for determining whether or not the ECU 12 drives the heater 10 according to the fuel temperature T, and determining the cause of clogging of the fuel filter 11 after the heater is driven. The threshold value L is represented by a straight line (including a broken line portion) in which the fuel temperature drops to T2-T1 between the pressure losses P1-P2. That is, the threshold value L is set so that the fuel temperature decreases as the pressure loss increases.

When the engine is started, the heater 10 is driven when the fuel temperature T falls below the threshold value L. After the heater is driven, the heater drive is driven depending on whether or not the points (ΔP, T) plotted on the graph based on the fuel temperature and pressure loss detected at a predetermined timing exist in the heater drive continuation region R1. Whether or not to continue is determined. Specifically, when the points (ΔP, T) plotted on the graph exist in the heater drive continuation region R1, the heater 10 is continuously driven, and the points (ΔP, T) are in the heater drive continuation region R1. If it does not exist, the driving of the heater 10 is stopped. The specific drive control flow of the heater 10 will be described later.

The above threshold value L is obtained in advance by an experiment or the like and stored in the ECU 12. For example, the threshold value L can be obtained by driving the heater 10 and actually measuring the pressure loss ΔP and the fuel temperature T using a new fuel filter 11 and a fuel containing no impurities and having good fuel properties.

In this way, by letting the ECU 12 learn the tendency of the pressure loss and the change in the fuel temperature when the heater 10 is driven in a good condition in advance, the pressure loss and the change in the temperature when the solidified component of the fuel melts can be changed. It is possible to predict trends.

That is, if the fuel has few impurities and good fuel properties, the point (ΔP, T) that exceeds the threshold value L does not change (see the solid arrow in FIG. 2). Therefore, the heater 10 can be continuously driven until the pressure loss ΔP reaches P1. As a result, the solidifying component of the fuel can be appropriately melted, and the startability of the engine is improved.

On the other hand, if the fuel contains impurities and has poor fuel properties, impurities may be accumulated in the fuel filter 11. In this case, even if the fuel temperature T is raised by driving the heater 10, the pressure loss ΔP does not change (decrease), or the degree of change in the pressure loss ΔP becomes small. That is, a change (movement) of a point (ΔP, T) that exceeds the threshold value L occurs (see the broken line arrow in FIG. 2).

In this case, impurities are accumulated in the fuel filter 11, and it can be determined that the clogging of the fuel filter 11 cannot be cleared even if the heater 10 is driven further. By providing the threshold value L in this way, it is possible to appropriately determine whether the cause of clogging of the fuel filter 11 is due to the solidification component of the fuel or due to impurities in the fuel. As a result, it is possible to appropriately determine the replacement timing of the fuel filter 11.

Further, when the point (ΔP, T) that exceeds the threshold value L is changed, the drive of the heater 10 is stopped, so that unnecessary heater drive can be suppressed. Therefore, it is possible to appropriately control the drive of the heater 10 to save electric power while considering the type of fuel and impurities in the fuel.

Next, various control flows according to the present embodiment will be described with reference to FIGS. 3 to 7. FIG. 3 is a diagram showing a threshold change flow according to the present embodiment. FIG. 4 is a graph showing a specific example of threshold value change according to the present embodiment, and the vertical and horizontal axes of the graph correspond to the graph of FIG. FIG. 5 is a diagram showing a flow for establishing pressure measurement conditions according to the present embodiment. 6 and 7 are diagrams showing a drive control flow of the heater according to the present embodiment. In each of the following flows, the main body of the determination is the ECU unless otherwise specified. The "threshold value" to be changed in FIG. 3 represents the "filter clogging determination threshold value L" described in FIG.

First, the threshold change flow will be described. The threshold value is appropriately changed when it is assumed that the driving conditions of the heater 10 need to be changed, for example, when the type of fuel is changed or when the fuel filter 11 (see FIG. 1) is replaced with a new one. Will be done. As shown in FIG. 3, when the control is started, it is determined in step ST101 whether or not the ignition is turned on. If the ignition is turned on (step ST101: YES), the process proceeds to step ST102. If the ignition is not turned on (step ST101: NO), the process of step ST101 is repeated.

In step ST102, it is determined whether or not the pressure measurement condition is satisfied. The establishment of the pressure measurement condition will be described later with reference to FIG. If the pressure measurement condition is satisfied (step ST102: YES), the process proceeds to step ST103. If the pressure measurement condition is not satisfied (step ST102: NO), the threshold value is not changed and the control ends. In step ST103, the threshold is initialized. Here, it is assumed that the threshold value L stored in the ECU 12 (see FIG. 1) is initialized in advance. When the threshold value is initialized, the process proceeds to step ST104.

In step ST104, it is determined whether the engine is stopped or the fuel flow rate is stable. That is, it is determined whether the engine can be started, or whether the engine cannot be started due to solidification of fuel or clogging of the filter. For example, it is determined whether the fuel flow rate is stable during the period from the ignition ON state to the starter drive, during idling stop, or during idling. If the engine is stopped or the fuel flow rate is stable (step ST104: YES), the process proceeds to step ST105. On the other hand, when the engine is not stopped and the fuel flow rate is not stable (step ST104: NO), the threshold value is not changed and the control ends.

In step 105, the low pressure pump 15 is driven. As a result, fuel is supplied from the fuel tank 14 toward the fuel filter 11. In the next step ST106, the pressure loss before and after the fuel filter 11 and the fuel temperature are detected (measured). For example, the pressure loss is calculated by the ECU 12 based on the difference between the detected values of the first pressure sensor 19 and the second pressure sensor 20.

Next, the threshold value is changed based on the pressure loss and the fuel temperature detected in step ST106 (step ST107). In step ST107, as shown in FIG. 4, the pressure loss and the fuel temperature are detected, so that the points (ΔP, T) can be plotted on the fuel temperature-pressure loss graph. For example, in FIG. 4, points (ΔP, T) are plotted in a region above the initialized threshold value L. That is, points (ΔP, T) are plotted outside the heater drive continuation region R1 (see FIG. 2).

As described above, if the drive control of the heater 10 is executed in the state of the initialized threshold value L, there is a possibility that the first heater drive is not executed when the engine is started. Therefore, in the present embodiment, the points (ΔP, T) first plotted at the time of starting the engine are set to be lower than the heater drive threshold value (threshold value L) which is the heater drive condition, that is, the points (ΔP, T). The threshold value is changed (corrected) from the threshold value L to the threshold value L1 so that is included in the heater drive continuation region.

Specifically, as shown in FIG. 4, the threshold value is above the threshold value L (the fuel temperature becomes higher) so that the points (ΔP, T) are included on a straight line having the same inclination as the threshold value L at the time of initialization. It is changed to the threshold value L1 which is translated in the direction). Here, the region below the threshold value L1 after the change is designated as a new heater drive continuation region R4. By translating the threshold value L in this way, it becomes possible to carry out drive control of the heater 10 under new conditions. The ECU 12 stores the changed threshold value L1 in the memory, and uses the threshold value L1 for the subsequent heater drive control. As a result, the threshold change flow is completed.

In FIG. 4, the case where the threshold value is changed so that the point (ΔP, T) is on the threshold value L1 has been described, but the present invention is not limited to this, and the threshold value can be changed as appropriate. The point (ΔP, T) may be included in the heater drive continuation region. For example, the threshold value is changed (translation of the threshold value L) so that the point (ΔP, T) is located in the region below the threshold value L1. You may.

Next, the flow for satisfying the pressure measurement conditions will be described. At the start of control, it is assumed that the refueling flag and the chiller flag, which will be described later, are not set (refueling flag 0, chiller flag 0). As shown in FIG. 5, first, in step ST201, it is determined whether or not the ignition is turned on. If the ignition is turned on (step ST201: YES), the process proceeds to step ST202. If the ignition is not turned on (step ST201: NO), the process of step ST201 is repeated.

In step ST202, it is determined whether or not the fuel tank 14 is sufficiently refueled. Whether or not the fuel tank 14 is sufficiently refueled can be determined by the ECU 12 from a float and a fuel sensor (both not shown) provided in the fuel tank 14.

When the fuel tank 14 is sufficiently refueled (step ST202: YES), the refueling flag 1 is set in step ST203, and the process proceeds to step ST204. If the fuel tank 14 is not sufficiently refueled (step ST202: NO), the process proceeds to step ST204.

In step ST204, it is determined whether or not the engine is in a cold state. Whether or not it is in the cold state can be determined by the ECU 12 from, for example, the engine temperature, the cooling water temperature, and the like.

When the engine is in the cold state (step ST204: YES), the cold flag 1 is set in step ST205, and the process proceeds to step ST206. If the engine is not in the cold state (step ST204: NO), the process proceeds to step ST206.

In step ST206, it is determined whether or not the refueling flag 1 and the colder flag 1 are set. When the refueling flag 1 and the colder flag 1 are set (step ST206: YES), it is determined that the pressure measurement condition is satisfied in step ST207. If the refueling flag 1 and the colder flag 1 are not set (step ST206: NO), it is assumed that the pressure measurement condition is not satisfied, and the process proceeds to step ST209.

In step ST208, the refueling flag 1 and the chiller flag 1 are reset (refueling flag 1 → 0, chiller flag 1 → 0), and the control ends. In step ST209, the cold machine flag is reset (cold machine flag → 0), and the control ends. As described above, according to the flow of FIG. 5, it is possible to determine whether or not to measure the pressure based on the fuel refueling state and the engine cold state.

In the flow of FIG. 5, it is assumed that the pressure measurement condition is satisfied when the refueling flag 1 and the cooler flag 1 are set, but the present invention is not limited to this. For example, the pressure measurement condition may be satisfied when either the refueling flag 1 or the colder flag 1 is set.

Next, the drive control flow of the heater 10 will be described. In the flow shown in FIGS. 6 and 7, the threshold value L is used as the threshold value. Further, the "heater drive threshold value" used for determining the first heater drive at the time of starting the engine shall show the same value as the "filter clogging determination threshold value L", and shall be used only in step ST302. The heater drive threshold value does not necessarily have to be the same value as the filter clogging determination threshold value L, and a dedicated value may be specified separately.

As shown in FIG. 6, the engine (see FIG. 1) is first started in step ST301, and in step ST302, it is determined whether or not the fuel temperature T is below the heater drive threshold value. That is, in the ECU 12, the points (ΔP, T) plotted on the fuel temperature-pressure loss graph (hereinafter, simply referred to as a graph) are any one of the heater drive continuous region R1, the normal operation region R2, and the filter clogging region R3. Judge whether or not it is included in the area of. When the fuel temperature T is smaller than the threshold value L, that is, when the points (ΔP, T) are included in the above three regions (step ST302: YES), the process proceeds to step ST303. In this case, it can be determined that the fuel may have solidified. When the fuel temperature is equal to or higher than the threshold value L (step ST302: NO), it is assumed that the heater 10 does not need to be driven, and the control ends.

In step ST303, the heater 10 is driven. As a result, the fuel is warmed, the temperature of the fuel is gradually raised, and the solidification of the fuel is gradually eliminated. In step ST304, it is determined whether or not the pressure loss ΔP is larger than the pressure loss P1 and smaller than the pressure loss P2. That is, the ECU 12 determines whether or not the points (ΔP, T) plotted on the graph are included in the heater drive continuation region R1.

When the pressure loss ΔP is larger than the pressure loss P1 and smaller than the pressure loss P2, that is, when the point (ΔP, T) is included in the heater drive continuation region R1 (step ST304: YES), the process proceeds to step ST305. When the pressure loss ΔP is less than or equal to the pressure loss P1 or more than or equal to the pressure loss P2, that is, when the point (ΔP, T) is not included in the heater drive continuation region R1 (step ST304: NO), step ST308 (see FIG. 7). Proceed to processing.

In step ST305, the driving of the heater 10 is continued. In this case, it can be determined that the solidified component in the fuel is in the process of melting. Next, in step ST306, it is determined whether or not the pressure loss ΔP is below the pressure loss P1 or the fuel temperature T is above the threshold value L. That is, the ECU 12 determines whether or not the points (ΔP, T) plotted on the graph deviate from the heater drive continuation region R1. When the pressure loss ΔP is lower than the pressure loss P1 or the fuel temperature T is higher than the threshold value L, that is, the point (ΔP, T) is out of the heater drive continuation region R1 (step ST306: YES), the step ST307. Proceed to processing. In step ST307, the drive of the heater 10 is stopped, and the control ends.

For example, when the pressure loss ΔP is less than the pressure loss P1, it can be determined that the solidifying component in the fuel is sufficiently melted, that is, the clogging of the fuel filter 11 is cleared. Further, when the fuel temperature T exceeds the threshold value L, the solidified component in the fuel is sufficiently melted, but impurities are accumulated in the fuel filter 11, and even if the heater 10 is driven further, the fuel filter 11 It can be determined that the clogging cannot be eliminated. In this case, for example, the ECU 12 may prompt the filter replacement by lighting the lamp on the meter. In this way, when the points (ΔP, T) deviate from the heater drive continuation region R1, the drive of the heater 10 is stopped, so that unnecessary heater drive can be prevented. In step 306, when the pressure loss ΔP does not fall below the pressure loss P1 and the fuel temperature T does not exceed the threshold value L, that is, the point (ΔP, T) is in the heater drive continuation region R1 (step ST306: NO), the process of step ST306 is repeated while continuing the heater drive.

As shown in FIG. 7, in step ST308, the driving of the heater 10 is stopped, and the process proceeds to step ST309. In step ST309, it is determined whether or not the pressure loss ΔP is less than the pressure loss P1, that is, whether or not the points (ΔP, T) are included in the normal operation region R2. If the pressure loss ΔP is less than the pressure loss P1 (step ST309: YES), the process proceeds to step ST310. When the pressure loss ΔP does not fall below the pressure loss P1 (step ST309: NO), that is, when the pressure loss ΔP is larger than the pressure loss P2 (points (ΔP, T) are included in the filter clogging region R3). ), Proceed to the process of step ST311.

In step ST310, the ECU 12 determines that the fuel filter 11 is normal, that is, the fuel filter 11 is not clogged or has been cleared, and ends the control. In step ST311 the ECU 12 determines that the fuel filter 11 is abnormal, that is, the fuel filter 11 is clogged, and proceeds to the process of step ST312. In step ST312, the ECU 12 notifies the driver and the like. For example, the ECU 12 prompts the driver to replace the filter by lighting the lamp on the meter. With the above, the control is completed.

In the above embodiment, the size and shape of each configuration shown in the accompanying drawings are not limited to this, and can be appropriately changed within the range in which the effects of the present invention are exhibited. In addition, the present invention can be appropriately modified and implemented as long as it does not deviate from the scope of the object.

For example, in the above embodiment, when the threshold value is changed, the threshold value L is translated to form a new threshold value L1, but the configuration is not limited to this. For example, the configuration shown in FIG. 8 is also possible. FIG. 8 is a graph showing a threshold change according to a modified example. The vertical and horizontal axes of the graph shown in FIG. 8 correspond to FIGS. 2 and 4.

As shown in FIG. 8, points (ΔP, T) are plotted on the graph, and while actually driving the heater 10 to heat the fuel, the pressure loss and the fuel temperature are generated at a plurality of timings (twice in FIG. 8). Is detected. Then, a plurality of points (point 1, point 2) are plotted on the graph. The ECU 12 calculates an approximate curve of the threshold value from a plurality of points, and stores the approximate curve as a new threshold value L2 in the memory. The region defined by the threshold value L2 (the region below the threshold value L2) is designated as a new heater drive continuation region R5.

In this way, the threshold value L2 may be changed to a threshold value L2 whose point movement tendency is different from the threshold value L at the time of initialization. Even in this case, it becomes possible to carry out drive control of the heater 10 under new conditions. As a result, it is possible to carry out heater control corresponding to the actual pressure loss and the change over time of the fuel temperature. The ECU 12 can calculate the approximate curve in step ST107 of FIG. 3, for example.

Further, in the above embodiment, the heater 10 is built in the fuel filter 11, but the present invention is not limited to this configuration. The heater 10 may be arranged at another place, for example, may be provided in the fuel tank 14.

Further, in the above embodiment, the temperature sensor 16 is arranged in the fuel tank 14 to detect the temperature of the fuel in the fuel tank 14, but the configuration is not limited to this. The temperature sensor 16 may be arranged on the fuel filter 11.

Further, in the above embodiment, the pressure loss (pressure difference) is calculated from the detected values of the first and second pressure sensors, but the present invention is not limited to this configuration. For example, the pressure loss may be detected by a single pressure sensor (differential pressure sensor).

Further, in the above embodiment, the drive control of the heater 10 is performed based on the temperature of the fuel, but the present invention is not limited to this configuration. For example, the drive control of the heater 10 may be performed based on the engine water temperature in the warm-up state of the internal combustion engine (engine) and the temperature of the lubricating oil.

Further, in the above embodiment, after determining whether or not the heater 10 is driven by the fuel temperature T, the continuous drive or drive stop of the heater 10 is determined by the pressure loss ΔP, but the order of determination is this. It is not limited and can be changed as appropriate. For example, the ECU 12 may first determine whether or not the heater 10 is driven by the pressure loss ΔP.

The present invention has the effect of appropriately controlling the drive of the heater to save electric power while considering the type of fuel and impurities in the fuel, and in particular, the control device for the heater in the vehicle engine and the heater control device. It is useful for heater control systems.

1 Control system 10 Heater 11 Fuel filter 12 ECU (control device)
16 Temperature sensor 19 First pressure sensor (pressure sensor)
20 Second pressure sensor (pressure sensor)
L, L1, L2 Filter clogging judgment threshold P1 First predetermined pressure difference (pressure loss)
P2 Second predetermined pressure difference (pressure loss)
ΔP pressure loss (pressure difference)
T Fuel temperature (fuel temperature)
R1, R4, R5 Heater drive continuous area R2 Normal operation area R3 Filter clogging area

Claims (7)

A controller for a heater that heats the fuel input into the combustion chamber of an internal combustion engine.
Temperature of the fuel before passing through the fuel filter to drive the heater when below the heater driving threshold, the temperature of the fuel while driving the heater, upstream and downstream of the pressure difference before Symbol fuel filter If the filter clogging determination threshold value specified based on the above is exceeded, the drive of the heater is stopped .
A heater control device, wherein the filter clogging determination threshold value is set so as to decrease as the pressure difference increases . The heater control device according to claim 1 , wherein the heater is not driven when the pressure difference is less than the first predetermined pressure difference. The heater control device according to claim 2 , wherein after driving the heater, the driving of the heater is continued until the pressure difference drops to the first predetermined pressure difference. The heater control device according to claim 2 or 3 , wherein the heater is not driven when the pressure difference exceeds the second predetermined pressure difference larger than the first predetermined pressure difference. The filter clogging determination threshold is characterized in that the temperature of the fuel and the pressure difference detected when the engine is started are changed so as to be included in the heater drive continuation region defined by the filter clogging determination threshold. The heater control device according to any one of claims 1 to 4 . The heater according to claim 5 , wherein the change of the filter clogging determination threshold value is performed based on the time course of the fuel temperature and the pressure difference when the heater is driven from the time of starting the engine. Control device. A fuel filter that filters the fuel input into the combustion chamber of an internal combustion engine,
A heater that heats the fuel and
A temperature sensor that detects the temperature of the fuel before it passes through the fuel filter,
A pressure sensor that detects the pressure difference between the upstream and downstream of the fuel filter,
A control device for controlling the drive of the heater based on the temperature of the fuel and the pressure difference is provided.
The control device includes a heater driving threshold defined based on the temperature of the fuel, the filter clogging determination threshold is defined based on the pressure difference, stores a temperature of the fuel is the heater If the temperature is below the drive threshold value, the heater is driven, and if the temperature of the fuel exceeds the filter clogging determination threshold value while the heater is being driven, the drive of the heater is stopped .
A heater control system, wherein the filter clogging determination threshold value is set so as to decrease as the pressure difference increases .

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