JP6223818B2 - Intake heater temperature estimation device and engine start assist system - Google Patents

Description

  The technology of the present disclosure includes an intake heater temperature estimation device that estimates the temperature of an intake heater that heats intake air, and an engine start assist system that assists engine start.

  2. Description of the Related Art Conventionally, an automobile equipped with a diesel engine has been provided with an intake heater for heating intake air for the purpose of improving engine startability in a cold region. The intake heater includes a heating element that generates heat when power is supplied from a battery, and improves the startability of the engine by raising the temperature of intake air taken into the engine. In relation to such an intake heater, Patent Document 1 discloses a technique for setting the energization time to the intake heater to a predetermined time.

Japanese Utility Model Publication No. 3-65851

  Incidentally, in recent years, there are a wide variety of electrical devices mounted on automobiles, and the timing at which each electrical device is activated varies from device to device. For this reason, there are various patterns of battery voltage change during the energization period, and simply determining the energization time may cause the intake heater temperature not to reach the target temperature or, on the contrary, exceed the target temperature. was there.

  An object of the technology of the present disclosure is to provide an intake heater temperature estimation device and an engine start assist system capable of estimating the temperature of the intake heater with high accuracy.

  An intake heater temperature estimation device that solves the above-described problem is a temperature estimation device for an intake heater that estimates a temperature of an intake heater that includes a heating element that generates heat upon receiving power supply from a battery, the voltage value of the battery A voltage detection unit that detects a resistance value of the heating element, a resistance value acquisition unit that acquires a resistance value of the heating element, and a power calculation unit that calculates power consumption for each cycle based on the voltage value and the resistance value A power amount calculation unit that calculates a power consumption amount for each cycle based on the power consumption and the cycle; and a total power amount calculation unit that calculates a total power consumption amount obtained by integrating the power consumption amount for each cycle. The temperature of the intake heater is estimated based on the total power consumption.

  An engine start assist system that solves the above problem includes an intake heater that heats intake air, and a temperature estimation device that estimates a temperature of the intake heater, and the engine start assist system is based on the temperature estimated by the temperature estimation device. An engine start assist system that performs the above-described operation, wherein the temperature estimation device is the above-described intake heater temperature estimation device.

  According to the above configuration, the power consumption in the heating element is calculated for each period based on the voltage value of the battery, and the temperature of the heating element is estimated from the integrated value of the power consumption. Moreover, temperature is estimated for every period when the voltage value of a battery is detected. Therefore, the temperature of the heating element can be estimated with high accuracy.

In the intake heater temperature estimation apparatus, it is preferable that the resistance value acquisition unit acquires a constant value as the resistance value.
According to the above configuration, the resistance value acquisition unit acquires the resistance value of the heating element as a constant value regardless of the temperature of the heating element. This simplifies the calculation process.

The intake heater temperature estimation device preferably estimates the temperature by dividing the total power consumption by the heat capacity of the heating element.
According to the above configuration, even if the material of the heating element is changed, the temperature of the heating element can be estimated with high accuracy only by changing the heat capacity.

  The engine start assist system further includes an outside air temperature detecting unit that detects an outside air temperature, and a cooling water temperature detecting unit that detects a cooling water temperature that is a temperature of cooling water for cooling the engine, and the outside air temperature and the It is preferable to start power supply to the heating element when at least one of the cooling water temperatures is equal to or lower than a threshold value.

  According to the above configuration, power supply to the heating element is started when at least one of the outside air temperature and the cooling water temperature is lower than the threshold value. In other words, since the intake air can be heated as necessary, the power consumption of the battery can be suppressed.

The schematic block diagram which showed the schematic structure of one Embodiment which actualized the starting assistance system of the engine provided with the temperature estimation apparatus of the intake heater in the technique of this indication with the engine. The functional block diagram which shows the structure of a control part. The flowchart which shows the process sequence of a start assistance process. The graph which shows an example of transition of estimated temperature typically.

Hereinafter, an embodiment of an intake heater temperature estimation device and an engine start assist system according to the present disclosure will be described with reference to FIGS.
As shown in FIG. 1, the start assist system 10 includes an intake heater 11 attached in the middle of the intake passage 6 of the engine 5. The intake heater 11 is connected to the battery 7 by an electric circuit 12. A relay 14 that opens and closes the electric circuit 12 is provided in the middle of the electric circuit 12. When the relay 14 is in the off state, the intake heater 11 is cut off from the power supply from the battery 7. On the other hand, when the relay 14 is in the ON state, the intake heater 11 generates heat by supplying power from the battery 7 and heats the intake air that passes through the intake heater 11. On / off of the relay 14 is controlled by the control unit 20.

  The control unit 20 is mainly configured by a microcomputer having a central processing unit (CPU), a nonvolatile memory (ROM), and a volatile memory (RAM). The control unit 20 executes a start assist process based on various control programs and various data stored in the ROM. The various data include a start temperature Tst at which power supply to the intake heater 11 is started, a resistance value R of the intake heater 11 that is a constant value, a coefficient K based on a heat capacity C of the intake heater 11 described later, and the intake heater. 11 target temperatures Ttar are stored.

  The start temperature Tst is a temperature at which start assistance is preferably performed for the engine 5, and is 0 ° C., for example. The target temperature Ttar is a temperature at which the intake air passing through the intake heater 11 can be sufficiently heated, and is 800 ° C., for example.

  An ignition switch 21 is electrically connected to the control unit 20. A key-on signal is input to the control unit 20 from the ignition switch 21 when the ignition switch 21 is turned on. When the key-on signal is input from the ignition switch 21, the control unit 20 starts the start control process.

  The controller 20 is electrically connected to an outside air temperature sensor 22 that is an outside air temperature detecting unit that detects an outside air temperature Ta that is the temperature of the outside air. The control unit 20 acquires the outside air temperature Ta by performing various calculations based on the detection signal from the outside air temperature sensor 22.

  A cooling water temperature sensor 23 that is a cooling water temperature detecting unit that detects a cooling water temperature Tcw that is a temperature of cooling water for cooling the engine 5 is electrically connected to the control unit 20. The control unit 20 acquires the coolant temperature Tcw by performing various calculations based on the detection signal from the coolant temperature sensor 23.

  The control unit 20 is electrically connected to a voltage sensor 24 as a voltage detection unit that detects a voltage value Ei that is a voltage of the battery 7. The control unit 20 obtains the voltage value Ei every predetermined cycle T, for example, 50 msec, by performing various calculations based on the detection signal from the voltage sensor 24.

  The control unit 20 is electrically connected to a notification lamp 25 that notifies the driver that power is being supplied to the intake heater 11. The notification lamp 25 is a lamp that can be visually recognized by the driver. The control unit 20 turns on the notification lamp 25 when the relay 14 is controlled to the on state, and turns off the notification lamp 25 when the relay 14 is controlled to the off state.

With reference to FIG. 2, the structure of the control part 20 is demonstrated in detail.
As shown in FIG. 2, the control unit 20 includes a necessity determination unit 31 that determines whether or not assistance from the intake heater 11 is necessary when starting the engine 5. The necessity determination unit 31 acquires the outside air temperature Ta and the cooling water temperature Tcw through the sensors 22 and 23 when the start assist process is started.

  The necessity determining unit 31 determines that assistance by the intake heater 11 is necessary for starting the engine 5 when at least one of the outside air temperature Ta and the cooling water temperature Tcw is lower than the start temperature Tst. In this case, the necessity determining unit 31 outputs a control signal for controlling the relay 14 to the ON state to the relay driving unit 37 and outputs a control signal for lighting the notification lamp 25 to the lamp driving unit 38. On the other hand, the necessity determining unit 31 determines that the assistance by the intake heater 11 is not necessary for starting the engine 5 when both the outside air temperature Ta and the cooling water temperature Tcw are equal to or higher than the start temperature Tst. In this case, the control unit 20 ends the start assist process.

  The control unit 20 includes a power calculation unit 32 that calculates power consumption in the intake heater 11. When the relay 14 is in the ON state, the power calculation unit 32 calculates the power consumption Pi based on the voltage value Ei of the battery 7 and the resistance value R of the intake heater 11 stored in the various data for each period T. . The power consumption Pi is calculated based on the voltage value Ei and the resistance value R according to Ohm's law.

  The control unit 20 includes a power amount calculation unit 33 that calculates the power consumption amount Wi of the intake heater 11 in each period T. The power amount calculation unit 33 calculates a power consumption amount Wi based on the power consumption Pi and the cycle T for each cycle T. The power consumption amount Wi is calculated by multiplying the power consumption Pi by the period T.

  The control unit 20 includes a total power amount calculation unit 34 that calculates the total power consumption amount Wn that is the total amount of power consumption in the intake heater 11 by integrating the power consumption amount Wi. The total power consumption calculating unit 34 calculates the total power consumption Wn by integrating the power consumption Wi for each period T.

  The control unit 20 includes a temperature estimation unit 35 that calculates the estimated temperature Tes of the intake heater 11 from the total power consumption Wn. The temperature estimation unit 35 calculates the estimated temperature Tes (= Wn / K) by dividing the total power consumption Wn by the coefficient K based on the heat capacity C of the intake heater 11. An example of the coefficient K is the heat capacity C of the intake heater 11. The control unit 20 calculates the temperature increase of the intake heater 11 based on the total power consumption Wn and the heat capacity C as the estimated temperature Tes.

  The coefficient K may be a value calculated in consideration of the amount of heat release according to the temperature difference ΔT between the estimated temperature Tes and the outside air temperature Ta, and the value of the coefficient K in such a case is an experiment performed in advance. Or based on simulation. Further, the temperature estimation unit 35 may calculate the estimated temperature Tes by adding, for example, the temperature rise based on the total power consumption Wn to the initial temperature, with the outside temperature Ta as the initial temperature of the intake heater 11.

  The control unit 20 includes a comparison determination unit 36 that compares the estimated temperature Tes with the target temperature Ttar of the intake heater 11 to determine whether the estimated temperature Tes has reached the target temperature Ttar. When the comparison determination unit 36 determines that the estimated temperature Tes has reached the target temperature Ttar, the comparison determination unit 36 outputs a control signal for controlling the relay 14 to the OFF state to the relay drive unit 37 and notifies the lamp drive unit 38 of the notification lamp. A control signal for turning off 25 is output to the lamp drive unit 38.

  The control unit 20 includes a relay driving unit 37 that drives the relay 14. When the control signal is input from the necessity determination unit 31, the relay drive unit 37 generates a drive signal for controlling the relay 14 to be in an ON state, and outputs the generated drive signal to the relay 14. In addition, when a control signal is input from comparison determination unit 36, relay drive unit 37 generates a drive signal for controlling relay 14 to be in an OFF state, and outputs the generated drive signal to relay 14.

  The control unit 20 includes a lamp driving unit 38 that drives the notification lamp 25. When the control signal is input from the necessity determination unit 31, the lamp driving unit 38 generates a driving signal for lighting the notification lamp 25, and outputs the generated driving signal to the notification lamp 25. In addition, when the control signal is input from the comparison determination unit 36, the lamp driving unit 38 generates a driving signal for turning off the notification lamp 25 and outputs the generated driving signal to the notification lamp 25.

  With reference to FIG. 3, the process procedure of the start assistance process which the control part 20 performs is demonstrated. When the key-on signal is input from the ignition switch 21, the control unit 20 starts the start assist process.

  As shown in FIG. 3, when the start assist process is started, the control unit 20 acquires the outside air temperature Ta and the cooling water temperature Tcw (step S11). Then, the control unit 20 determines whether or not at least one of the outside air temperature Ta and the cooling water temperature Tcw acquired in Step S11 is lower than the start temperature Tst (Step S12).

  When both the outside air temperature Ta and the cooling water temperature Tcw are higher than the start temperature Tst (step S12: NO), the control unit 20 ends the start assist process on the assumption that the engine 5 does not need start assist. On the other hand, when at least one of the outside air temperature Ta and the cooling water temperature Tcw is lower than the start temperature Tst (step S12: YES), the control unit 20 controls the relay 14 to be turned on and turns on the notification lamp 25 (step S13). ). The controller 20 notifies the driver that starting assistance is performed by turning on the notification lamp 25.

  Next, after acquiring the voltage value Ei of the battery 7 based on the detection signal from the voltage sensor 24 (step S14), the control unit 20 consumes based on the voltage value Ei and the resistance value R of the intake heater 11. The electric power Pi is calculated (step S15).

  Subsequently, after calculating the power consumption amount Wi in the current cycle T based on the power consumption Pi and the cycle T (step S16), the control unit 20 uses the integrated value of the power consumption amount Wi up to the current cycle T. A certain total power consumption Wn is calculated (step S17). In the next step S18, the control unit 20 calculates the estimated temperature Tes of the intake heater 11 based on the total power consumption Wn and the heat capacity C.

  When the estimated temperature Tes is calculated, the control unit 20 compares the estimated temperature Tes with the target temperature Ttar (step S19). When the estimated temperature Tes is lower than the target temperature Ttar (step S19: NO), the control unit 20 repeatedly executes the processing from step S14 to step S19 every cycle T until the estimated temperature Tes becomes equal to or higher than the target temperature Ttar. On the other hand, when the estimated temperature Tes is equal to or higher than the target temperature Ttar (step S19: YES), the control unit 20 controls the relay 14 to the off state and turns off the notification lamp 25 and ends the start assist process (step S20). ). The control unit 20 notifies the driver that start-up assistance has been completed by turning off the notification lamp 25.

  With reference to FIG. 4, the operation of the start assist system 10 will be described. FIG. 4 is a graph schematically showing an example of the transition of the estimated temperature, and shows the transition of the estimated temperature Tes when power supply is started to another electrical device on the way. In FIG. 4, the solid line indicates the transition of the estimated temperature Tes, and the portion indicated by dots in the region from time tk to time tk + 1 indicates the total power consumption Wn until time tk + 1.

  As shown in FIG. 4, when the start assist process is started at time t <b> 1 and the relay 14 is controlled to be on, power supply from the battery 7 to the intake heater 11 is started.

  In each cycle T from time t1 to time t4, the voltage value Ei of the battery 7 is stable because there is no power supply to other electrical devices. Therefore, in the period from time t1 to time t4, the power consumption amount Wi in each cycle T becomes substantially equal, and the total power consumption amount Wn increases under a constant increase amount. That is, during this period, the estimated temperature Tes rises at a constant rate of increase. Note that the rate of increase of the estimated temperature Tes at this time is referred to as a reference rate of increase.

  When power supply to another electrical device such as an air conditioning fan is started at time t4, a voltage drop occurs in the battery 7 due to an inrush current to the other electrical device. Therefore, in the period from time t4 to time t6, the power consumption amount Wi in each cycle T is smaller than the power consumption amount Wi in each cycle T before time t4. Therefore, in the period from time t4 to time t6, the estimated temperature Tes rises at an increase rate lower than the reference increase rate.

  Eventually, when the output voltage of the battery 7 becomes stable at time t6, the power consumption amount Wi in each period T in the period from time t6 to time t7 is changed in each period T in the period from time t4 to time t6. It becomes larger than the power consumption amount Wi. Thereby, the rate of increase of the estimated temperature Tes approaches the reference rate of increase.

  Then, when the output voltage of the battery 7 is stabilized at time t7, the estimated temperature Tes rises under a rate of increase substantially equal to the reference rate of increase after time t7. Eventually, when the estimated temperature Tes reaches the target temperature Ttar at time t9, the relay 14 is controlled to be in the OFF state, whereby the power supply from the battery 7 is cut off, and the cold start process is completed. Note that “Tmin” in the figure is the lowest auxiliary temperature that is the lowest value of the temperature of the intake heater 11 that can assist the start of the engine 5.

  As described above, the start assist system 10 obtains the power consumption amount Wi in each cycle T based on the voltage value Ei of the battery 7, so that even if a voltage drop occurs in the battery 7 on the way, the total power consumption amount Wn. The accuracy of the estimated temperature Tes of the intake heater 11 based on is increased. As a result, it is determined with high accuracy whether the intake heater 11 has reached the target temperature Ttar.

  Here, the total power consumption Wn in the intake heater 11 can be calculated using the current value of the intake heater 11. However, while the voltage sensor 24 is generally mounted on the vehicle, a current sensor for detecting the current flowing through the intake heater 11 needs to be separately incorporated in the electric circuit 12. In consideration of versatility of the control unit 20, simplification of wiring, and the like, it is preferable that the above-described current sensor is attached to a substrate constituting the control unit 20. If the current sensor is incorporated in the control unit 20 in this way, not only the inrush current to the intake heater 11 but also a large current flows in the control unit 20, and the durability of the control unit 20 against such current is taken into consideration. Then, even the mechanical design change of the control unit 20 may be necessary.

  In this respect, in the above-described start assist system 10, the total power consumption Wn in the intake heater 11 is calculated by the voltage value Ei of the battery 7, so that the number of components can be reduced and the electrical load on the control unit 20 can be reduced. And mechanical load is reduced.

According to the above embodiment, the effects listed below can be obtained.
(1) By calculating the estimated temperature Tes for each cycle according to the voltage value Ei of the battery 7, the temperature of the intake heater 11 can be estimated with high accuracy. Further, it can be determined with high accuracy whether or not the temperature of the intake heater 11 has reached the target temperature Ttar.

  (2) The calculation of the power consumption Pi can be simplified by setting the resistance value R of the intake heater 11 to a constant value. The reason for this configuration is that although the resistance value R of the intake heater 11 varies depending on the temperature, the target temperature Ttar is a very high temperature of, for example, 800 ° C., so that the power consumption amount Wi caused by the change in the resistance value R This is because the influence of this error on the estimated temperature Tes is very small.

  (3) The estimated temperature Tes is calculated by dividing the total power consumption Wn by the heat capacity C. Therefore, when the material of the intake heater 11 is changed, it is possible to reach the intake heater 11 to the same target temperature Ttar only by changing the setting of the heat capacity C.

  (4) Power supply to the intake heater 11 is performed when at least one of the outside air temperature Ta and the cooling water temperature Tcw is lower than the start temperature Tst which is a threshold value. That is, since the cold start operation is performed only when necessary, the power consumption of the battery can be suppressed.

  (5) The target temperature Ttar is higher than the minimum auxiliary temperature Tmin of the engine 5. Therefore, even if the estimated temperature Tes is higher than the actual temperature, the possibility that the actual temperature is higher than the minimum auxiliary temperature Tmin is increased by the estimated temperature Tes reaching the target temperature Ttar.

In addition, the said embodiment can also be suitably changed and implemented as follows.
-The control part 20 has memorize | stored the resistance value R of the intake heater 11 as a fixed value as a resistance value acquisition part. Not only this but the control part 20 may be provided with the resistance value acquisition part which calculates resistance value R based on the estimated temperature Tes. According to such a configuration, the accuracy of the estimated temperature Tes is further increased.

The necessity determination unit 31 may determine whether or not starting assistance is necessary based on not only the outside air temperature Ta and the cooling water temperature Tcw but also other information such as the remaining amount of the battery 7.
The intake heater only needs to have a heating element that heats the intake air before combustion, and is not limited to the intake heater 11 that heats the intake air that passes through the intake passage 6, for example, air in the combustion chamber of the engine 5 A glow plug for heating may be used.

  DESCRIPTION OF SYMBOLS 5 ... Engine, 6 ... Intake passage, 7 ... Battery, 10 ... Start-up assistance system, 11 ... Intake heater, 12 ... Electric circuit, 14 ... Relay, 20 ... Control part, 21 ... Ignition switch, 22 ... Outside temperature sensor, 23 ... Cooling water temperature sensor, 24 ... voltage sensor, 25 ... notification lamp, 31 ... necessity determination unit, 32 ... power calculation unit, 33 ... power amount calculation unit, 34 ... total power amount calculation unit, 35 ... temperature estimation unit, 36 ... Comparison judging unit 37... Relay driving unit 38. Lamp driving unit.

Claims (5)

A temperature estimation device for an intake heater that estimates a temperature of an intake heater having a heating element that generates heat upon receiving power supply from a battery,
A voltage detector for detecting the voltage value of the battery at a predetermined period;
A resistance value acquisition unit for acquiring a resistance value of the heating element;
A power calculator that calculates power consumption for each cycle based on the voltage value and the resistance value;
A power amount calculation unit for calculating a power consumption amount for each cycle based on the power consumption and the cycle;
A total power amount calculation unit that calculates the total power consumption obtained by integrating the power consumption for each cycle;
An intake heater temperature estimation device that estimates the temperature of the intake heater based on the total power consumption. The intake heater temperature estimation device according to claim 1, wherein the resistance value acquisition unit acquires a constant value as the resistance value. The temperature estimation device for an intake heater according to claim 1 or 2, wherein the temperature is estimated by dividing the total power consumption by the heat capacity of the heating element. An intake heater for heating the intake air;
A temperature estimation device for estimating the temperature of the intake heater,
An engine start assist system for assisting engine start based on the temperature estimated by the temperature estimation device,
The temperature estimation device is
An engine start assist system, which is the intake heater temperature estimation device according to any one of claims 1 to 3. An outside air temperature detector for detecting outside air temperature,
A cooling water temperature detection unit that detects a cooling water temperature that is a temperature of cooling water for cooling the engine, and
The engine start assist system according to claim 4, wherein power supply to the heating element is started when at least one of the outside air temperature and the cooling water temperature is equal to or lower than a threshold value.

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