JP6642361B2 - Heater drive - Google Patents

Description

  The present invention relates to a heater driving device.

  In an FFV (Flexible-Fuel Vehicle) engine that uses a mixed fuel such as gasoline and ethanol or ethanol as a fuel, the fuel is heated by a heater and then injected into a cylinder of the engine, thereby improving low-temperature startability. Some have been secured. Heating of fuel is performed by providing a heater in the fuel injection device, and the heater is configured to heat fuel injected into a cylinder of the engine. In this case, the heater is controlled by detecting a drive current when the heater is energized and estimating a heater temperature based on the value of the current.

  In such a configuration, it is required to control the energization of the heater while detecting the temperature of the heater, thereby heating the fuel without excess and deficiency, and improving the startability of the engine.

JP 2013-122724 A

  The present invention has been made in consideration of the above circumstances, and an object thereof is to control the energization of the heater while detecting the temperature of the heater, thereby heating the fuel without excess and deficiency, and improving the startability of the engine. An object of the present invention is to provide a heater driving device that can be improved.

The heater drive device according to claim 1, further comprising: detecting a current value at the time of energization of a heater that heats fuel supplied to the internal combustion engine by heating the fuel to be supplied to the internal combustion engine by estimating the temperature of the fuel by estimating the temperature of the fuel. A temperature estimating unit that outputs a temperature, and a control unit that controls energization of the heater based on the estimated fuel temperature of the temperature estimating unit. When the estimated fuel temperature output from the temperature estimating unit is higher than or equal to a preset reference setting level, the power supply to the heater is cut off, and a certain time elapses after the power supply to the heater is cut off. Until there is no request to start the internal combustion engine, the heater is re-energized. When the estimated fuel temperature is lower than the reference set level, the heater is turned on until the estimated fuel temperature reaches the reference set level. To continue the power supply to the motor.

  By adopting the above configuration, the control unit supplies electricity to the heater when the power is turned on, and when the estimated fuel temperature output from the temperature estimating unit is equal to or higher than a preset reference setting level, the control unit supplies the heater with the heater. Cut off the current. Generally, when starting an internal combustion engine such as an FFV engine or a diesel engine, if the temperature of the internal combustion engine and fuel is low, the engine cannot be started normally. Is controlled so as to be at an appropriate level. However, when the time elapsed since the end of the previous operation of the internal combustion engine is small, the fuel temperature may not have dropped much. At this time, if the fuel temperature has reached the reference set level, it is at a level at which the fuel cell can be started. In addition, an appropriate temperature of the fuel can be maintained.

Schematic electrical configuration diagram showing a first embodiment Flowchart of heater control (1) Flowchart of heater control (part 2) Time chart of heater control (Part 1) Time chart of heater control (part 2) Time chart of heater control (part 3) Time chart of heater control (4) Time chart of heater control (part 5) Time chart of heater control (6) Flowchart of heater control showing second embodiment (part 1) Flowchart of heater control (part 2) Flowchart of heater control (part 3) Time chart of heater control (Part 1) Time chart of heater control (part 2) Time chart of heater control (part 3) Time chart of heater control (4)

(1st Embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In the present embodiment, an example in which the present invention is applied to an in-vehicle heater driving device for heating fuel for an engine mounted on a vehicle is shown.

  FIG. 1 shows an electric schematic configuration of the on-vehicle heater driving device 1. The on-vehicle heater driving device 1 controls energization of a heater 3 of a fuel heating unit 2 in a fuel injection device of an FFV engine. . Here, the FFV engine is an engine that uses mixed fuel such as gasoline and ethanol, or ethanol as fuel.

  The fuel before heating flows into the fuel heating unit 2 from the fuel tank, and the fuel heated by the heater 3 is sent to the injector. The heater 3 is composed of, for example, a ceramic heater such as a PCT heater, a metal heater, or the like. Heats the fuel flowing inside. Further, the heater 3 has a characteristic that the resistance value varies according to the temperature, and is configured to detect the temperature using this characteristic.

  The in-vehicle heater driving device 1 is provided with an n-channel MOSFET 4 for energizing the heater 3 from the in-vehicle power supply VB. The MOSFET 4 is supplied with a drive signal from the control circuit 5 to perform on / off drive control. The heater 3 is connected to the output terminal P from the vehicle-mounted power supply VB via the drain and source of the MOSFET 4, and the other terminal of the heater 3 is connected to the ground. The control circuit 5 includes a microcomputer, a memory, an interface circuit, and the like, and stores a program for heating the heater 3 and detecting the temperature. The control circuit 5 has both functions of a temperature estimating unit and a control unit.

  The temperature of the heater 3 is estimated by the control circuit 5 by detecting the terminal voltage Vp of the heater 3 by the detection circuit 6. The detection circuit 6 mainly includes an operational amplifier 7, and an output terminal P is connected to an inverting input terminal of the operational amplifier 7 via a resistor 8. A series circuit of resistors 9 and 10 is connected between the vehicle-mounted power supply VB and the ground, and a common connection point of the resistors 9 and 10 is connected to a non-inverting input terminal of the operational amplifier 7. The resistor 11 is connected between the inverting input terminal and the output terminal of the operational amplifier 7. The detection circuit 6 inputs a detection signal ST corresponding to the drain-source voltage Vds of the MOSFET 4 input to the operational amplifier 7 to the control circuit 5.

  The control circuit 5 is supplied with power of a predetermined voltage VD from a control power generated by a power supply circuit (not shown). The control circuit 5 receives a signal S1 indicating on / off of an IGSW (ignition switch) from the vehicle side, receives an engine start request signal S2 indicating that the starter is on, and further outputs an engine rotation signal from an engine ECU (not shown). S3 is input.

  The control circuit 5 is configured to perform on / off drive control of the MOSFET 4 based on the input signals S1 to S3 and the detection signal ST input from the detection circuit 6 by, for example, PWM control. In this control, the control circuit 5 reads a control program, which will be described later, from the memory and executes it.

  Next, the operation of the above configuration will be described with reference to FIGS. FIG. 2 and FIG. 3 are flowcharts of control of the gate drive of the MOSFET 4 by the vehicle heater drive device 1. After the IGSW is turned on, the in-vehicle heater driving device 1 controls the power supply to the heater 3 of the fuel heating unit 2 in the fuel injection device of the FFV engine to heat the fuel sent to the injector in preparation for an engine start request. . In this case, there are a case where the starter is turned on after the IGSW is turned on and an engine start request is made, and a state where the engine is on standby without issuing the engine start request. The in-vehicle heater driving device 1 controls so as to heat the fuel without any excess or shortage in response to these.

  Prior to the description of the operation, the process of estimating the fuel temperature Tf by the control circuit 5 will be described. When controlling the energization of the heater 3, the control circuit 5 estimates the fuel temperature Tf from a signal detected by energizing the heater 3 as described below, and based on the obtained fuel temperature Tf, Control 3 is performed.

  Since the heater 3 is immersed in the fuel, the fuel temperature Tf is equal to the temperature T of the heater 3. Therefore, if the temperature T of the heater 3 can be calculated, this can be used as the fuel temperature Tf. Since the heater 3 uses a PTC heater, it is a resistor, and the resistance value Rh changes according to the temperature T. By detecting the voltage Vp at the output terminal P when the heater 3 is energized, the fuel temperature Tf can be estimated as follows.

  The resistance value Rho of the heater 3 at the reference temperature To, the resistance temperature coefficient σ, and the previously measured on-resistance Ron of the MOSFET 4 are stored in the memory. The control circuit 5 can read these values from the memory when estimating the fuel temperature Tf.

First, a voltage Vds (= VB-Vp) between the drain and the source of the MOSFET 4 is calculated from the voltage VB of the vehicle-mounted power supply and the detection voltage Vp. As a result, the current Ih supplied to the heater 3 can be calculated as in equation (1). Also, the resistance value Rh of the heater 3 can be calculated from the current Ih of the heater 3 and the voltage Vp as shown in Expression (2).
Ih = (VB−Vp) / Ron (1)
Rh = Vp / Ih (2)
By substituting equation (1) into equation (2), the resistance Rh of the heater 3 can be obtained from the detection voltage Vp as in equation (3).
Rh = Ron · Vp / (VB−Vp) (3)

Since the resistance value Rh at the temperature T of the heater 3 is expressed by the following equation (4), when this is deformed and solved for the temperature T of the heater 3, it is obtained by the equation (5).
Rh = (1 + σ (T−To)) · Ro (4)
T = To + ((Rh / Rho) -1) / σ (5)

  As a result, if the resistance value Rh of the heater 3 can be calculated as in the equation (3), the temperature T of the heater 3, that is, the fuel temperature Tf can be uniquely obtained by substituting this value into the equation (5). it can. Since the estimation process of the fuel temperature Tf can be performed in a short time when the heater 3 is energized, it is possible to determine whether or not to continue the heating before the substantial heating operation is started. it can.

  First, in FIGS. 2 and 3, when the IGSW is turned on, the control circuit 5 starts gate drive control. Immediately after the start, the control circuit 5 performs an initialization process (not shown), and clears various flags and registers. The engine start flag described later is set to the off state, and the setting of the fuel injection is set to the “prohibited” state.

  Thereafter, in step A1, the control circuit 5 energizes the heater 3 to start a heating operation. When the control circuit 5 outputs a gate drive signal based on the PWM signal to the gate of the MOSFET 4, the MOSFET 4 is energized from the vehicle-mounted power supply to the heater 3 via the output terminal P in the ON state. As a result, the voltage VB is applied to the heater 3 and the current flows to generate heat, thereby heating the fuel flowing to the fuel heating unit 2. The fuel flows from the fuel tank into the fuel heating unit 2 and is sent out to the injector while being heated by the heater 3.

  At this time, the control circuit 5 executes step A2 to calculate the voltage Vp at the output terminal P from the digitally converted signal based on the detection signal ST input from the detection circuit 6, and to calculate the fuel temperature Tf by the above-described arithmetic processing. Is estimated. Next, in step A3, the control circuit 5 determines whether or not the estimated fuel temperature Tf is equal to or higher than the reference set level T1 of 60 ° C. This is because the value of 60 ° C. as the reference set level T1 corresponds to the lower limit temperature at which the engine can be started. The temperature range in which the engine can be started is a range from 60 ° C. of the reference set level T1 to 90 ° C. of the boiling point which is the upper limit set level T2.

  If the fuel temperature Tf has not yet reached the reference set level T1 of 60 ° C., the control circuit 5 determines NO in step A3, and then proceeds to step A4 to continue energizing the heater 3. Become like Thereafter, in step A6, the control circuit 5 determines whether the fuel temperature Tf has reached 90 ° C., which is the upper limit set level T2. When the fuel temperature Tf has not reached the upper limit set level T2, the control circuit 5 proceeds to step A7, and determines whether or not the fuel temperature Tf has reached the reference set level T1.

  Here, when the fuel temperature Tf reaches the reference set level T1 during heating of the fuel, the control circuit 5 changes the setting of the fuel injection from the “prohibited” state to the “permitted” state in step A8. After step A8, or if NO in step A7, the control circuit 5 proceeds to step A9, determines whether or not the signal S2 for requesting engine start has been input. Returning to A4, the above-described processing of steps A4 to A9 is repeated. If YES in step A9, the control circuit 5 proceeds to step A27 in FIG. 3, which will be described later.

  When the fuel temperature Tf reaches the upper limit set level T2 while repeating steps A4 to A9 as described above, the control circuit 5 determines YES in step A6 and proceeds to step A10. If YES in step A6, the control circuit 5 executes YES in step A7 and executes step A8 prior to this.

  The control circuit 5 turns off the power supply to the heater 3 in step A10. Specifically, the control circuit 5 stops the gate signal to the MOSFET 4 and shifts the MOSFET 4 to the off state. Thereby, the power supply to the heater 3 is turned off (cut off).

  If YES in step A3, that is, when the fuel temperature Tf is detected by energizing the heater 3 in steps A1 and A2, the control circuit 5 determines that the fuel temperature Tf has already exceeded the reference set level T1. If there is, the process proceeds to step A10, and the power supply to the heater 3 is turned off. In this case, since the fuel temperature Tf is in a temperature range where the engine can be started at the time when the operation is started by turning on the IGSW, no further heating is performed here, and the heater 3 is immediately turned on. Turn off the power to the

  Thereafter, the control circuit 5 changes the setting of the fuel injection from the “prohibited” state to the “permitted” state in step A11. If the answer is NO in step A3, the process in step A11 has already been executed in step A8, so that the process jumps substantially as already executed.

  Subsequently, the control circuit 5 proceeds to step A12, and determines whether or not the signal S2 of the engine start request has been input. If NO in step A12, the control circuit 5 waits by repeatedly executing steps A12 and A13 until it determines in step A13 that the fixed time Ta has elapsed after the heater is turned off. When the engine start request signal S2 is input, the control circuit 5 proceeds to step A14 shown in FIG. When the time Ta after the heater is turned off has elapsed without input of the engine start request signal S2, the control circuit 5 proceeds to step A25 in FIG. 3, which will be described later.

  When the process proceeds to step A14, the control circuit 5 sets an engine start flag to ON. Thereafter, the control circuit 5 re-energizes the heater 3 in step A15, and performs an estimation process of the fuel temperature Tf in step A16. When the fuel temperature Tf is maintained at or above the reference set level T1, the control circuit 5 determines YES and proceeds to step A18. If the fuel temperature Tf is lower than the reference set level T1, the control circuit 5 determines NO in step A17, proceeds to step A19, continues energizing the heater 3, and proceeds to step A20. The temperature Tf is estimated, and is continued until the fuel temperature Tf reaches the reference set level T1 in step A21.

  Thereafter, when the fuel temperature Tf reaches the reference set level T1, the control circuit 5 sets the fuel injection setting to "permitted" if the setting of the fuel injection is "prohibited" in step A18. In step A18, when the setting of the fuel injection has been changed to "prohibited" through another step described later, the setting is changed to "permitted".

  Thereafter, the control circuit 5 turns off the heater in step A22, that is, turns off the power supply to the heater 3, and determines in step A23 whether or not the engine start flag is on. If the engine start flag is on, the engine is started in step A24 to terminate the control, otherwise, the control is terminated.

  If YES in step A13 described above, that is, if the engine start request signal S2 has not been input until the predetermined time Ta has elapsed after the heater has been turned off, the control circuit 5 determines in step A25 that the fuel injection has been set. Is changed from “permitted” to “prohibited”. Then, thereafter, the control circuit 5 determines in step A26 whether or not the engine start request signal S2 has been input again. In the case of YES, the control circuit 5 proceeds to step A14 described above, and in the case of NO, Proceeds to step A15 described above, and thereafter executes the same processing as described above.

  Further, if YES in step A9 described above, that is, if the engine start request signal S2 is input during fuel heating by the heater 3, the control circuit 5 turns on the engine start flag in step A27. , And thereafter, the process proceeds to step A18 described above, and thereafter, the same processing as described above is executed.

  By performing the gate drive control by the control circuit 5 as described above, the fuel flowing through the fuel heating unit 2 is heated by the heater 3, and the fuel is heated to an appropriate temperature in case the engine start request signal S2 is input. Can be maintained.

  Next, the above operation will be specifically described with reference to time charts of FIGS. FIGS. 4 and 5 show time charts when the control circuit 5 controls the heater 3 differently depending on the difference in the fuel temperature Tf at the beginning of heating. FIGS. 6 to 9 show time charts in a case where the IGSW is turned on and the heater 3 performs heating, and then the control circuit 5 performs different control with and without an engine start request. In the time chart, the fuel temperature Tf shows the transition of the estimated temperature in the solid line portion, and the broken line portion shows the empirical expected transition because it corresponds to the region where the estimation cannot be performed by energization.

  First, in FIG. 4 corresponding to a state in which the fuel temperature Tf is close to the outside air temperature Tr, when the IGSW is turned on at time t0 as shown in FIG. 4A, the in-vehicle heater driving device 1 shown in FIG. As shown in (1), the internal power supply circuit rises and outputs a predetermined voltage. As a result, the control power supply to the control circuit 5 is turned on, and at time t1, the control circuit 5 starts the gate drive control.

  When the control circuit 5 starts the control, as shown in FIG. 4C, the heater is turned on, that is, the power supply to the heater 3 is started to heat the fuel. The fuel temperature Tf gradually increases as shown in FIG. At this time, the control circuit 5 performs the calculation processing of the fuel temperature Tf at the appropriate time intervals by the processing as described above, as indicated by the broken arrow in the figure. The above corresponds to the operations in steps A1 and A2.

  The control circuit 5 corresponds to a state where the engine has been stopped for a long time because the fuel temperature Tf detected at the start of energization of the heater 3 is close to the outside air temperature Tr. Since the fuel temperature Tf detected at the time of starting the heating is lower than the reference set level T1 and is not in the engine startable area, the above-described step A3 results in NO. As shown in FIG. 4D, the control circuit 5 continues the heating by the heater 3 until the fuel temperature Tf reaches the upper limit set level T2. That is, steps A4 to A9 are repeatedly performed.

  When the fuel temperature Tf reaches the upper limit set level T2 at time t2, the control circuit 5 turns off the power supply to the heater 3, as shown in FIG. 4C. This corresponds to the operation of step A10 as YES in step A6. When the power supply to the heater 3 is turned off, the fuel temperature Tf cannot be estimated thereafter, but the fuel temperature Tf changes gradually as shown in FIG.

  The operation when the IGSW is on has been described above, and the following operation will be described with reference to FIGS. Thereafter, as shown in FIG. 4A, when the IGSW is turned off at time tx, the engine is stopped, the control circuit 5 stops operating, and the control power supply is turned off as shown in FIG. Also turns off.

  On the other hand, in the case where the fuel temperature Tf is in the level of the engine startable region and is equal to or higher than the reference set level T1, when the IGSW is turned on at time t0 as shown in FIG. In the driving device 1, as shown in FIG. 5B, the control power is turned on to the control circuit 5, and at time t1, the control circuit 5 starts the gate drive control. When the control circuit 5 starts the control, as shown in FIG. 5C, the heater is turned on, that is, the power supply to the heater 3 is started to heat the fuel. In this case, as shown in FIG. 5 (d), the fuel temperature Tf detected at the start of heating is within the engine startable region at the reference set level T1 or higher, so the above-mentioned step A3 results in YES. As a result, as shown in FIG. 5C, the control circuit 5 executes step A10 and interrupts the heating by the heater 3 at time t1a slightly elapsed from time t1.

  Next, with reference to FIGS. 6 to 9, an operation subsequent to the above-described operation when the IGSW is turned on will be described for four cases. FIGS. 6 and 7 show the case where the signal S2 for the engine start request is input, and the case where the fuel temperature Tf is lower than or within the engine startable range when the signal S2 is input is divided. FIGS. 8 and 9 show the case where the signal S2 for the engine start request is not input, and similarly, the case where the fuel temperature Tf is lower than or within the engine startable range when the signal S2 is input.

  In the following description, the control circuit 5 shows a case where the level of the fuel temperature Tf near the outside air temperature Tr is estimated by turning on the heater 3 immediately after the control power supply is turned on. Therefore, the operation after the heater 3 is energized by the control circuit 5 until the fuel temperature Tf reaches the upper limit set level T2 is shown. Also, in the description of FIGS. 4 and 5, the injection permission and prohibition states of the injector due to the fuel temperature Tf are not shown, but are shown in response to the engine start request.

  First, a case where the engine start request signal S2 is input will be described with reference to FIG. As described above, while the control circuit 5 starts energizing the heater 3 and continues heating the fuel, as shown in FIG. 6 (g), at time t1b, the fuel temperature Tf reaches the reference set level T1. 6, the fuel temperature-based injection permission is set to the “permitted” state, as shown in FIG.

  The control circuit 5 continues this permission state for a certain time Ta. This time Ta is set to a certain time during which the fuel temperature Tf is within the engine startable region. In the above operation, when steps A4 to A9 are repeatedly performed, step A8 is performed as YES in step A7, and steps A10 to A13 are performed as YES in step A6.

  At time t3 after the elapse of the time Ta, the control circuit 5 sets the fuel temperature-based injection permission from “permitted” to “prohibited” as shown in FIG. This is a result of executing step A25 after YES in step A13. Thereafter, as shown in FIG. 6C, when the engine start request signal S2 is input by the user at time t4, the control circuit 5 turns on the heater 3 as shown in FIG. 6F. It is turned ON, the fuel temperature Tf is detected, and the heating is further continued. At this time, as the signal S3 of the engine speed, as shown in FIG. 6D, the signal of the low speed by the starter is input. This is YES in step A26, and is the operation in steps A14 to A20.

  When the fuel temperature Tf reaches the reference set level T1, which is the lower limit of the engine startable region, as shown in FIG. 6G, the control circuit 5 energizes the heater 3 as shown in FIG. Then, as shown in FIG. 6E, the permission of fuel temperature-induced injection is changed from “prohibited” to “permitted”. As a result, fuel is injected from the injector to the engine, and the engine speed signal S3 increases as shown in FIG. 6D, and the engine is started. This is the operation when YES is obtained in step A20, the process proceeds to steps A21 to A23, and step A24 is performed.

  When the engine is started and the engine start request signal S2 is cleared, the engine speed signal S3 settles at a certain level. Note that once the engine is started, the fuel is heated at the temperature of the engine itself, and thereafter, the heating by the heater 3 is not required. Therefore, as shown in FIG. The temperature-based injection permission is maintained in the “permitted” state.

Thereafter, as shown in FIG. 6A, when the IGSW is turned off at time tx, the engine is stopped, the control circuit 5 stops operating, and the control power supply is turned off as shown in FIG. 6B. Becomes
Next, a case where the engine start request signal S2 is inputted and which is inputted at a timing earlier than the time t3 in FIG. 6 will be described with reference to FIG. In the same manner as in the above case, the control circuit 5 starts energizing the heater 3 to heat the fuel, and as shown in FIG. Set to "Allowed" state.

  After that, before the time t3, that is, before the time Ta elapses, as shown in FIG. 7C, when the engine start request signal S2 is input by the user at the time t4a, the control circuit 5 executes the processing shown in FIG. As shown in (f), the power supply to the heater 3 is turned on, and the fuel temperature Tf is detected. At this time, the fuel temperature Tf is still higher than the lower limit of the engine startable region and exceeds the reference set level T1. As shown in FIG. 7 (g), the control circuit 5 turns off the power supply to the heater 3 at time t5a when a short time has elapsed from time t4a. This corresponds to the case of YES in step A17. Further, as shown in FIG. 7E, the control circuit 5 continues the fuel temperature-based injection permission as “permitted”.

  As a result, fuel is injected from the injector to the engine, the engine speed signal S3 increases as shown in FIG. 7D, and the engine is started. When the engine is started and the engine start request signal S2 is cleared, the engine speed signal S3 settles at a certain level. Further, as shown in FIG. 7E, the control circuit 5 holds the fuel temperature-based injection permission in the “permitted” state.

  Next, a case where the IGSW is turned off without input of the engine start request signal S2 after the IGSW is turned on will be described with reference to FIGS. First, in the case shown in FIG. 8, the control circuit 5 starts energizing the heater 3 and continues heating the fuel, and as shown in FIG. When the reference set level T1 is reached, as shown in FIG. 8E, the fuel temperature-based injection permission is set to the “permitted” state. The control circuit 5 continues this permission state for a certain time Ta.

  In this case, since the engine start request signal S2 is not input, the control circuit 5 sets the fuel temperature-based injection permission to “permit” as shown in FIG. "" To "Prohibited". Thereafter, the control circuit 5 re-energizes the heater 3 as shown in FIG. 8 (f) at a time t4b when a certain time Tb has elapsed after the heater 3 was turned off. The control circuit 5 detects the fuel temperature Tf by energizing the heater 3, and further continues heating when the fuel temperature Tf at this time is lower than the reference set level T1, which is the lower limit of the engine startable region.

  When the fuel temperature Tf reaches the reference set level T1 at time t5b as shown in FIG. 8G, the control circuit 5 turns off the power supply to the heater 3 as shown in FIG. 8F. As shown in FIG. 8 (e), the fuel temperature-based injection permission is changed from “prohibited” to “permitted”. Thus, when the engine start request signal S2 is input, the engine can be started. However, in this case, as shown in FIG. 8A, if the IGSW is turned off at time tx without inputting the engine start request signal S2, the engine is stopped, and the control circuit 5 stops operating. The control power is also turned off as shown in FIG.

  FIG. 9 shows a case in which the control circuit 5 re-energizes the heater 3 as shown in FIG. 9F at a time t4c after a certain time Tb has elapsed after the heater 3 has been turned off. The case where the detected fuel temperature Tf is equal to or higher than the reference set level T1 and is within the engine startable region is shown.

  In this case, the control circuit 5 turns off the power supply to the heater 3 as shown in FIG. 9F at a time t5c when a short time has elapsed from the time t4c, and further as shown in FIG. 9E. The fuel temperature-based injection permission is changed from “prohibited” to “permitted”. Thus, when the engine start request signal S2 is input, the engine can be started. However, in this case, as shown in FIG. 9A, if the IGSW is turned off at time tx without inputting the engine start request signal S2, the engine is stopped, and the control circuit 5 stops operating. 9B, the control power is also turned off.

  According to the first embodiment, the gate drive control is executed by the control circuit 5. Thus, the control circuit 5 detects the fuel temperature Tf by energizing the fuel flowing through the fuel heating unit 2 for heating by the heater 3, and supplies the fuel in case the engine start request signal S 2 is input. By controlling so as to be equal to or higher than the reference set level T1, which is the lower limit of the engine startable region, the startability of the engine can be improved while heating the fuel without excess or deficiency.

(2nd Embodiment)
FIGS. 10 to 16 show the second embodiment. Hereinafter, portions different from the first embodiment will be described. In this embodiment, after the energization control of the heater 3 is performed after the IGSW is turned on, the fuel temperature Tf is detected the next time the heater 3 is energized, and thereafter, the fuel temperature Tf is detected until the upper set level T2 is reached. The heating is continued.

  The control circuit 5 performs a control operation according to the gate drive control flowcharts shown in FIGS. In this case, steps B1 to B13 in FIG. 10 implement the same contents as steps A1 to A13 in FIG. 2 of the first embodiment. Steps B14 to B21 in FIG. 11 implement the same contents as steps A14 to A21 in FIG. 3 of the first embodiment. Further, steps B28 to B30 in FIG. 11 implement the same contents as steps A25 to A27 in FIG. 3 of the first embodiment.

  In the following description, the contents after step B22 in FIGS. 11 and 12 will be mainly described. In the first embodiment, the control circuit 5 changes the setting of the fuel injection from “prohibited” to “permitted” in step A21, and then turns off the power supply to the heater 3 in step A22. On the other hand, in this embodiment, after changing the fuel injection setting from “prohibited” to “permitted” in step B21, the state of the engine start flag is determined first in step B22. If the engine start flag is on, the control circuit 5 proceeds to step B23 and starts the engine.

  Thereafter, the control circuit 5 proceeds to step B24, estimates the fuel temperature Tf, and determines in a subsequent step B25 whether or not the obtained fuel temperature Tf is equal to or higher than the upper limit set level T2. If the fuel temperature Tf has not reached the upper limit set level T2, the control circuit 5 determines NO and proceeds to step B26 to continue energizing the heater 3 to perform a heating operation. To B26 are repeatedly executed.

  Then, when the fuel temperature Tf reaches the upper limit set level T2, the control circuit 5 determines YES in step B25, shifts to step B27, turns off the power supply to the heater 3, and ends the heating operation.

  As described above, in this embodiment, even after the fuel temperature Tf has entered the engine startable region, the heating by the heater 3 is continued until it reaches the upper limit set level T2. Thus, by raising the fuel temperature Tf to the upper limit of the engine startable region, the fuel can be sufficiently heated even after the engine is started. Further, when the engine has not been started, the engine can be quickly started even if it takes time until the engine start request is input.

  Next, differences from the cases of FIGS. 6 to 9 shown in the first embodiment will be described with reference to FIGS. First, FIG. 13 and FIG. 14 show the case where the signal S2 for the engine start request is input, and the case where the fuel temperature Tf is lower than or within the engine startable range when the signal S2 is input is divided.

  In FIG. 13, when an engine start request signal S2 is input by the user at time t4, the control circuit 5 turns on the power supply to the heater 3 as shown in FIG. 13 (f), and detects the fuel temperature Tf. To continue heating. Thereafter, as shown in FIG. 13 (g), when the fuel temperature Tf reaches the reference set level T1, which is the lower limit of the engine startable region, as shown in FIG. Is changed from "prohibited" to "permitted". As a result, fuel is injected from the injector into the engine, and the engine speed signal S3 increases as shown in FIG. 13D, and the engine is started.

  At this time, in this embodiment, the control circuit 5 continues energizing the heater 3 as shown in FIG. Then, as shown in FIG. 13 (g), when the fuel temperature Tf reaches the upper limit setting example bell T2 at time t6, the control circuit 5 turns off the power supply to the heater 3 at this time. As a result, the fuel temperature Tf is maintained thereafter in the range of the engine startable region.

  Next, a case where the engine start request signal S2 is inputted and which is inputted at a timing earlier than the time t3 in FIG. 13 will be described with reference to FIG. In this case, when the engine start request signal S2 is input by the user at time t4a before the time t3, that is, before the time Ta has elapsed, as shown in FIG. As shown in FIG. 14F, the power supply to the heater 3 is turned on, and the fuel temperature Tf is detected.

  At this time, since the fuel temperature Tf is still higher than the lower limit of the engine startable region and exceeds the reference set level T1, the control circuit 5 performs the fuel temperature-induced injection as shown in FIG. Continue with "permitted" permission. As a result, fuel is injected from the injector into the engine, and the engine speed signal S3 increases as shown in FIG. 13D, and the engine is started.

  At this time, the control circuit 5 keeps energizing the heater 3 as shown in FIG. Then, as shown in FIG. 14G, when the fuel temperature Tf reaches the upper limit setting example bell T2 at time t5as, the control circuit 5 turns off the power supply to the heater 3 at this time. As a result, the fuel temperature Tf is maintained thereafter in the range of the engine startable region.

  Next, a case where the IGSW is turned off without input of the engine start request signal S2 after the IGSW is turned on will be described with reference to FIGS. 15 and 16. First, in the case shown in FIG. 15, the heater 3 is re-energized as shown in FIG. 15 (f) at a time t4b when a certain time Tb has elapsed after the heater 3 was turned off. The control circuit 5 detects the fuel temperature Tf by energizing the heater 3, and further continues heating when the fuel temperature Tf at this time is lower than the reference set level T1, which is the lower limit of the engine startable region.

  When the fuel temperature Tf reaches the reference set level T1 at time t5b, as shown in FIG. 15G, the control circuit 5 sets the fuel temperature-based injection permission from “prohibited” as shown in FIG. Change the setting to "Allow". At this time, the control circuit 5 keeps energizing the heater 3 as shown in FIG. Then, as shown in FIG. 15 (g), when the fuel temperature Tf reaches the upper limit setting example bell T2 at time t6b, the control circuit 5 turns off the power supply to the heater 3 at this time. As a result, the fuel temperature Tf is maintained thereafter in the range of the engine startable region.

  FIG. 16 shows a case where the control circuit 5 re-energizes the heater 3 as shown in FIG. 9F at a time t4c after a certain time Tb has elapsed after the heater 3 has been turned off, as shown in FIG. The case where the detected fuel temperature Tf is equal to or higher than the reference set level T1 and is within the engine startable region is shown.

  In this case, the control circuit 5 changes the fuel temperature-based injection permission from “prohibited” to “permitted” at time t5c after a short time has elapsed from time t4c, as shown in FIG. At this time, the control circuit 5 continues energizing the heater 3 as shown in FIG. Then, as shown in FIG. 16G, when the fuel temperature Tf reaches the upper limit setting example bell T2 at time t6b, the control circuit 5 turns off the power supply to the heater 3 at this time. As a result, the fuel temperature Tf is maintained thereafter in the range of the engine startable region.

  Also according to the second embodiment, heating is performed until the fuel temperature Tf reaches the upper limit set level T2 by energizing the heater 3 by inputting the engine start request signal S2 or re-energizing the heater 3 after the time Tb has elapsed. Since the operation is continued, the same operation and effect as the first embodiment can be obtained.

(Other embodiments)
Note that the present invention is not limited to only the above-described embodiment, and can be applied to various embodiments without departing from the gist thereof. For example, the present invention can be modified or expanded as follows.

  The reference set level T1 is not limited to 60 ° C., and the upper limit set level T2 is not limited to the boiling point of 90 ° C., but can be set to a level corresponding to an appropriate temperature according to fuel or conditions.

  Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments and the structures. The present disclosure also encompasses various modifications and variations within an equivalent range. In addition, various combinations and forms, and other combinations and forms including only one element, more or less, are also included in the scope and spirit of the present disclosure.

  In the drawings, reference numeral 1 denotes an on-vehicle heater driving device, 3 denotes a heater, 4 denotes an n-channel MOSFET, 5 denotes a control circuit, and 6 denotes a detection circuit.

Claims (13)

A temperature estimating unit (5) for detecting a current value at the time of energization of a heater for heating fuel to be supplied to the internal combustion engine by generating heat by flowing an electric current, estimating the temperature of the fuel, and outputting an estimated fuel temperature; ,
A control unit (5) for controlling energization of the heater based on the estimated fuel temperature of the temperature estimating unit;
When the power is turned on, the controller energizes the heater and shuts off energization to the heater when the estimated fuel temperature output from the temperature estimating unit is equal to or higher than a preset reference set level. Until a predetermined time has elapsed after the supply of power to the heater has been interrupted, when there is no request to start the internal combustion engine, the heater is re-energized, and when the estimated fuel temperature is lower than the reference set level, A heater driving device that continues to supply power to the heater until the estimated fuel temperature reaches the reference set level . A temperature estimating unit (5) for detecting a current value at the time of energization of a heater for heating fuel to be supplied to the internal combustion engine by generating heat by flowing an electric current, estimating the temperature of the fuel, and outputting an estimated fuel temperature; ,
A control unit (5) for controlling energization of the heater based on the estimated fuel temperature of the temperature estimating unit;
When the power is turned on, the controller energizes the heater and shuts off energization to the heater when the estimated fuel temperature output from the temperature estimating unit is equal to or higher than a preset reference set level. Until a predetermined time elapses after the energization of the heater is interrupted, the heater is re-energized when there is no request for starting the internal combustion engine, and when the estimated fuel temperature is equal to or higher than the reference set level, the heater Heater drive device that cuts off current to the heater. A temperature estimating unit (5) for detecting a current value at the time of energization of a heater for heating fuel supplied to the internal combustion engine by generating heat by flowing an electric current, estimating the temperature of the fuel, and outputting an estimated fuel temperature; ,
A control unit (5) for controlling energization of the heater based on the estimated fuel temperature of the temperature estimating unit;
When the power is turned on, the controller energizes the heater and shuts off energization to the heater when the estimated fuel temperature output from the temperature estimator is equal to or higher than a preset reference set level. Until a predetermined time has elapsed after the supply of power to the heater has been interrupted, when there is no request to start the internal combustion engine, the heater is re-energized, and when the estimated fuel temperature is lower than the reference set level, A heater driving device that continues to supply power to the heater until the estimated fuel temperature reaches a higher set level set higher than the reference set level . A temperature estimating unit (5) for detecting a current value at the time of energization of a heater for heating fuel to be supplied to the internal combustion engine by generating heat by flowing an electric current, estimating the temperature of the fuel, and outputting an estimated fuel temperature; ,
A control unit (5) for controlling energization of the heater based on the estimated fuel temperature of the temperature estimating unit;
When the power is turned on, the controller energizes the heater and shuts off energization to the heater when the estimated fuel temperature output from the temperature estimating unit is equal to or higher than a preset reference set level. Until a predetermined time elapses after the power supply to the heater is interrupted, when there is no request to start the internal combustion engine, the heater is re-energized, and the estimated fuel temperature is equal to or higher than the reference setting level and the reference setting is performed. A heater driving device that continues energizing the heater until the estimated fuel temperature reaches the upper set level when the fuel temperature is lower than the upper set level set higher than the level . A temperature estimating unit (5) for detecting a current value at the time of energization of a heater for heating fuel to be supplied to the internal combustion engine by generating heat by flowing an electric current, estimating the temperature of the fuel, and outputting an estimated fuel temperature; ,
A control unit (5) for controlling energization of the heater based on the estimated fuel temperature of the temperature estimating unit;
The control unit is configured such that, when power is turned on, when the estimated fuel temperature output from the temperature estimating unit by energizing the heater is lower than a preset reference set level, the estimated fuel temperature is set to The energization to the heater is continued until the upper set level set higher than the reference set level is reached, and until a predetermined time has elapsed after the energization to the heater has been interrupted, when there is no request to start the internal combustion engine, A heater driving device that re-energizes the heater and continues to energize the heater until the estimated fuel temperature reaches the reference set level when the estimated fuel temperature is lower than the reference set level . A temperature estimating unit (5) for detecting a current value at the time of energization of a heater for heating fuel to be supplied to the internal combustion engine by generating heat by flowing an electric current, estimating the temperature of the fuel, and outputting an estimated fuel temperature; ,
A control unit (5) for controlling energization of the heater based on the estimated fuel temperature of the temperature estimating unit;
The control unit is configured such that, when power is turned on, when the estimated fuel temperature output from the temperature estimating unit by energizing the heater is lower than a preset reference set level, the estimated fuel temperature is set to The energization to the heater is continued until the upper set level set higher than the reference set level is reached, and until a predetermined time has elapsed after the energization to the heater has been interrupted, when there is no request to start the internal combustion engine, A heater driving device that re-energizes the heater and interrupts energization of the heater when the estimated fuel temperature is equal to or higher than the reference set level . A temperature estimating unit (5) for detecting a current value at the time of energization of a heater for heating fuel to be supplied to the internal combustion engine by generating heat by flowing an electric current, estimating the temperature of the fuel, and outputting an estimated fuel temperature; ,
A control unit (5) for controlling energization of the heater based on the estimated fuel temperature of the temperature estimating unit;
The control unit is configured such that, when power is turned on, when the estimated fuel temperature output from the temperature estimating unit by energizing the heater is lower than a preset reference set level, the estimated fuel temperature is set to The energization to the heater is continued until the upper set level set higher than the reference set level is reached, and until a predetermined time has elapsed after the energization to the heater has been interrupted, when there is no request to start the internal combustion engine, A heater driving device that re-energizes the heater and, when the estimated fuel temperature is lower than the reference set level, continues energizing the heater until the estimated fuel temperature reaches the upper set level . A temperature estimating unit (5) for detecting a current value at the time of energization of a heater for heating fuel to be supplied to the internal combustion engine by generating heat by flowing an electric current, estimating the temperature of the fuel, and outputting an estimated fuel temperature; ,
A control unit (5) for controlling energization of the heater based on the estimated fuel temperature of the temperature estimating unit;
The control unit is configured such that, when power is turned on, when the estimated fuel temperature output from the temperature estimating unit by energizing the heater is lower than a preset reference set level, the estimated fuel temperature is set to The energization to the heater is continued until the upper set level set higher than the reference set level is reached, and until a predetermined time has elapsed after the energization to the heater has been interrupted, when there is no request to start the internal combustion engine, A heater driving device that re-energizes the heater and continues energizing the heater until the estimated fuel temperature reaches the upper set level when the estimated fuel temperature is equal to or higher than the reference set level and lower than the upper set level. . 9. The control unit according to claim 5 , wherein when the power is turned on, the heater is energized and the energization to the heater is shut off when the estimated fuel temperature is equal to or higher than the reference set level. 9. 4. The heater driving device according to claim 1. Wherein, said at start request of the internal combustion engine, wherein when the estimated fuel temperature is lower than the reference set level, according to claim 1, wherein the estimated fuel temperature continues to energization of the heater to reach the reference set level The heater driving device according to any one of claims 2, 5, and 6 . 7. The control unit according to claim 1 , wherein when the estimated fuel temperature is equal to or higher than the reference set level at the time of a start request of the internal combustion engine, energization to the heater is cut off. 8. of the heater driving device. Wherein the control unit, the at start request of the internal combustion engine, wherein when the estimated fuel temperature is lower than the reference set level, said estimated fuel temperature continues to energization of the heater until it reaches before Symbol upper level set level Item 9. The heater driving device according to any one of items 3, 4, 7, and 8 . When the estimated fuel temperature is equal to or higher than the reference set level and lower than the upper set level at the time of the start request of the internal combustion engine, the control unit supplies power to the heater until the estimated fuel temperature reaches the upper set level. The heater driving device according to any one of claims 3, 4, 7, and 8, wherein

Images