JP2017066920A - Engine control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable overflow of cooling water from a radiator sub-tank to be positively prevented.SOLUTION: A radiator sub-tank is connected to a radiator 2 to cool engine cooling water. A storage of heat [qa] of the engine is detected [estimated] by integrating an intake air amount of the engine, for example. When the detected storage of heat [qa] of the engine becomes more than a prescribed value, restriction in operation of the engine [for example, correction to decrease a throttle opening] is carried out to restrict increasing in temperature of the engine. With this arrangement as above, it is possible to prevent over-flow of cooling water positively during travelling of a vehicle as well as its parking or stopping. It is preferable to perform in advance controlling [cooling under utilization of evaporation heat of fuel] for making a value of air fuel ratio rich before performing restriction in operation of the engine.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an engine control apparatus.

  Vehicles, especially commercial vehicles with heavy payloads, are prone to the phenomenon of engine coolant overflowing from the radiator sub tank when the vehicle stops after a long run on a steep uphill. It was. In particular, recently, with the increase in the gear ratio at the low speed stage due to the multi-stage transmission, the above-mentioned overflow is likely to occur due to traveling on an uphill road at a high temperature and a high load. Patent Document 1 discloses that when an abnormal rise of the float in the radiator sub tank is detected, the operation of the engine is limited so as to suppress the rise of the coolant temperature.

Japanese Patent Laid-Open No. 4-94411

  As described in Patent Document 1 described above, when the operation of the engine is limited when an abnormal rise of the float in the radiator sub-tank is detected, a state in which overflow is unavoidable due to a response delay is likely to occur. In other words, while driving, even if no abnormal rise of the float is detected due to cooling by the traveling wind, cooling by the traveling wind cannot be expected when the vehicle stops, while heat dissipation from the engine to the cooling water or from the engine Since the cooling water temperature in the radiator sub-tank further rises with delay due to radiant heat, there is no way to prevent overflow even if an abnormal rise of the float is detected when the vehicle stops.

  On the other hand, it is also conceivable to limit the operation of the engine when the cooling water temperature exceeds a predetermined temperature. However, even in this case, even if the cooling water temperature is lower than the predetermined temperature during traveling, it is not possible to cope with a situation in which the temperature becomes higher than the predetermined temperature after the vehicle stops.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an engine control device that can reliably prevent an overflow of cooling water from a radiator sub tank.

In order to achieve the above object, the present invention basically focuses on the fact that the temperature rise of the cooling water at the time of stopping largely depends on the amount of heat stored in the engine. The engine operation is restricted to prevent this. Specifically, the following solutions have been adopted. That is, as described in claim 1,
An engine control device including a radiator sub tank,
A heat storage amount detecting means for detecting the heat storage amount of the engine;
Engine control means for controlling the engine to be limited to suppress an increase in engine temperature when it is detected that the heat storage amount of the engine detected by the heat storage amount detection means is a predetermined value or more;
It is supposed to be equipped with. According to the above-described solution method, whether or not the cooling water temperature rises that causes the cooling water to overflow from the radiator sub tank is detected (estimated) based on the amount of heat stored, and of course when the vehicle is stopped Even if this occurs, this overflow can be reliably prevented.

A preferred mode based on the above solution is as described in claim 2 and the following claims. That is,
The engine operation restriction by the engine control means is performed by controlling the throttle valve in the closing direction (corresponding to claim 2). In this case, by reducing the throttle opening, it is possible to suppress or reduce the heat generation of the engine, to reliably prevent overflow, and to simplify the control.

  The heat storage amount detection means detects the heat storage amount based on an integrated value of the intake air amount of the engine (corresponding to claim 3). In this case, the heat storage amount can be detected using a general parameter called the intake air amount.

  The radiator cooling fan is driven by the engine, and the cooling fan is stopped when the engine is stopped (corresponding to claim 4). In this case, since the cooling action by the cooling fan cannot be expected when the vehicle is stopped, the overflow can be reliably prevented in a vehicle that is likely to generate an overflow.

  The engine operation restriction by the engine control means is executed on condition that the climbing rate is equal to or higher than a predetermined value, the predetermined low speed stage, and the cooling water temperature is equal to or higher than a predetermined temperature. ). In this case, it is preferable to prevent engine operation as much as possible while reliably preventing overflow.

  The engine operation restriction by the engine control means is further executed on condition that the accelerator opening is fully open and the outside air temperature is equal to or higher than a predetermined temperature (corresponding to claim 6). In this case, it is preferable to further improve the effect corresponding to the fifth aspect.

  The engine control means performs control to increase the fuel injection amount and enrich the air-fuel ratio in advance before executing the engine operation restriction (corresponding to claim 7). In this case, it is preferable to avoid the engine operation restriction as much as possible by performing the engine cooling action by enriching the air-fuel ratio.

The transmission connected to the engine is an automatic transmission that can be switched between a manual transmission mode and an automatic transmission mode that are fixed to a selected gear stage,
The engine control means, when controlling the throttle valve in the closing direction, gradually decreases the throttle opening in the manual shift mode, and decreases the throttle opening at once in the automatic shift mode.
This is done (corresponding to claim 8). In this case, it is preferable to prevent a situation in which an upshift is unnecessarily accompanied by a correction of a decrease in the throttle opening, and a situation in which an overflow is caused by repeating the upshift and the downshift. Become.

  ADVANTAGE OF THE INVENTION According to this invention, the overflow of the cooling water from a radiator sub tank can be prevented, and especially the overflow at the time of a stop can be prevented reliably.

The simplified side view which shows the mode of a radiator and the vicinity of a radiator sub tank. The figure which shows the example of a control system of this invention in a block diagram. The time chart which shows the example of control of this invention. The flowchart which shows the example of control of this invention. The flowchart which shows the continuation of FIG.

  In FIG. 1, 1 is an engine, and in the embodiment, it is a gasoline engine used in a one-box type commercial vehicle. In the figure, 2 is a radiator and 3 is a radiator sub tank. The cooling fan 4 of the radiator 2 is mechanically driven by the crankshaft 1a of the engine 1, and cannot be expected to be cooled by the cooling fan 4 when the engine is stopped.

  In FIG. 1, 11 is a cooling water circulation path from the engine 1 to the radiator 2, 12 is a cooling water circulation path from the radiator 2 to the engine 1, and 13 is a circulation path between the radiator 2 and the radiator sub tank 3. In addition, although the said circulation paths 11-13 are simply shown in FIG. 1, the general path | route conventionally adopted can be employ | adopted for this circulation path suitably.

  FIG. 2 shows an example of a control system of the present invention, and U in the figure is a controller (control unit) configured using a microcomputer. As will be described later, the controller U constitutes means for detecting the amount of heat stored in the engine and engine control means for appropriately restricting the operation of the engine.

  Signals from various sensors or devices S1 to S7 are input to the controller U. The sensor S1 is a water temperature sensor that detects the cooling water temperature of the engine. The sensor S2 is a vehicle speed sensor that detects the vehicle speed. S3 is a rotation speed sensor that detects the engine rotation speed. S4 is an intake air temperature sensor that detects the intake air temperature of the engine, and is used to estimate the outside air temperature. S5 is an intake air amount sensor for detecting the intake air amount of the engine, and is used for calculating the filling amount. S6 is a transmission. In the embodiment, for example, an automatic transmission with five forward speeds is used, and a manual transmission mode that is fixed to an arbitrary gear stage and between the first speed and the fifth speed (highest speed gear stage). It is possible to manually select the automatic shift mode in which the shift is automatically performed. Information regarding the current shift speed and the selected shift mode is output to the controller U from the transmission S6. S7 is an accelerator sensor that detects the accelerator opening.

  The controller U controls the throttle actuator S11 and the fuel injection valve 12. That is, as will be described later, the controller U controls the throttle actuator S11 so as to reduce the current throttle opening corresponding to the accelerator opening to limit the operation of the engine. Further, the controller U is configured to perform an engine cooling operation using the heat of vaporization of the fuel by correcting the increase in the fuel injection amount in order to suppress an increase in the engine temperature.

  Next, an example of control for preventing overflow from the radiator sub tank 3 by the controller U will be described with reference to the time chart of FIG. Note that this time chart is based on the assumption that the gear stage is the second speed with a low speed, the climbing rate is 6% or more, and the accelerator is fully open (the load weight is large).

  Here, the climbing rate is theoretically calculated based on the vehicle speed and the gear ratio at the second speed. Further, the heat storage amount of the engine is obtained as an integrated value qa of the filling amount of the engine based on the intake air amount. When the heat storage amount (integrated value) qa becomes the maximum guard value, it is assumed that the possibility of overflowing from the radiator sub tank 3 when the vehicle is stopped is extremely high.

  In FIG. 3, the vehicle travels at about 55 km / h before the time t1, the engine speed is 4500 rpm, and the water temperature is considerably lower than 100 ° C. At a time point before the time point t1, it is normal traveling itself, and control for restricting the operation of the engine is not performed.

  When the traveling on the uphill road is continued and the time point t1 is reached, the heat storage amount qa reaches the predetermined reference value A. Even in this state, the engine operation restriction is not executed. The reference value A is set as a smaller value as the outside air temperature estimated based on the intake air temperature is higher. Under one condition that the heat storage amount qa is equal to or greater than a reference value, air-fuel ratio enrichment control and engine operation restriction control (control to reduce the throttle opening in the embodiment), which will be described later, are performed. .

  The time point at which the cooling water temperature reaches 100 ° C. after t1 is the time point t2. At time t2, the execution counter is set to 1 for heat damage control (that is, control for preventing overflow of cooling water), and the enrich control flag is turned on. By setting the enrich control flag to 1, the fuel injection amount from the fuel injection valve S12 is increased (for example, 35% increase). As a result, an increase in the engine temperature, that is, the cooling water temperature is suppressed by the cooling action utilizing the heat of vaporization of the fuel. At time t3, the heat storage amount qa reaches the maximum guard value, but the engine operation restriction control is not yet executed.

  Note that the time when the coolant temperature reaches 101 ° C. while continuing to travel on the uphill road is the time t4. At time t4, the increase in the coolant temperature cannot be suppressed by the enrichment control alone, and the throttle opening is corrected to decrease. That is, the throttle opening is reduced by a predetermined amount from the state where the throttle opening is 100% corresponding to the fully open accelerator opening (corresponding to engine operation restriction). The throttle opening after the reduction is set, for example, to such a size that the vehicle speed can be maintained at 50 km / h with full loading, 2-speed traveling, and a climbing rate of 6%. Due to the decrease in the throttle opening, the engine temperature, that is, the cooling water temperature is lowered or maintained.

  In the embodiment, when the throttle opening is corrected to be decreased, the throttle opening reduction method is made different depending on the shift mode so as not to be unnecessarily shifted up to the third speed where the driving force is insufficient. It is. That is, in the manual shift mode, the speed is fixed at the second speed, so that the throttle opening is gradually decreased from the viewpoint of preventing torque shock accompanying the decrease in the throttle opening (see the solid line in (h)). . On the other hand, in the automatic transmission mode, the throttle opening is greatly decreased at a stroke and then gradually changed to the throttle opening after the reduction in order to reliably prevent upshifting to the third speed. Yes (see broken line in (h)). The prevention of upshifting to the 3rd speed may cause an overflow in the future because the conditions for restricting the operation of the engine are released and the gears are frequently shifted between the 2nd and 3rd speeds. Is taken into account.

  Details of the control related to the engine operation restriction described above will be described with reference to the flowcharts shown in FIGS. In the following description, Q indicates a step.

  First, the process of FIG. 4 is a process of determining whether or not a precondition for executing a heat damage countermeasure (overflow countermeasure) is satisfied. That is, in Q1, it is determined that the cooling water temperature is 90 ° C. or higher, in Q2, it is determined that the vehicle speed is 70 km / h or lower, and in Q3, it is determined that the engine speed is in a range between 2500 and 4500 rpm. If it is determined in Q4 that the climbing rate is 6% or more, and it is determined in Q5 that the charging efficiency is 0.5 or more, the process proceeds to Q6. If NO is determined in any of Q1 to Q5, the process returns to Q1.

  In Q6, it is determined that the intake air temperature is 34 ° C. or higher. In Q7, it is determined that the integrated value of the intake air amount, that is, the heat storage amount qa, is equal to or higher than the predetermined reference value A. In Q8, the cooling water temperature is 100 ° C. or higher. If it is discriminated, it is determined that all the preconditions for executing the heat damage countermeasure are satisfied, and the process proceeds to Q11 in FIG. If NO in Q6 to Q8, the process returns to Q1.

  The time point of shifting to Q11 in FIG. 5 is the time point t2 in FIG. At this time, the heat damage countermeasure control execution counter is set to a predetermined time (for example, 15 seconds), and enrich control is started.

  After Q12, it is determined whether or not the gear position is the second speed. If the determination in Q12 is YES, it is determined in Q13 whether or not the cooling water temperature is 101 ° C. or higher (confirmation as to whether or not it is time t4 in FIG. 3). If YES in Q13, if it is confirmed by Q14 and Q15 that the vehicle speed is 45 km or more and 75 km / h or less, whether or not the climbing rate is 5% or more in Q16. Determined. If YES in Q16, the throttle opening is corrected to decrease in Q17 (engine operation restriction execution). If NO in any of Q12 to Q16, it is determined that there is no risk of overflow even when the vehicle is stopped as well as during traveling, and the process returns to Q1 without passing through Q17. The counter at Q11 is set for 15 seconds, for example, and after the set time has elapsed, the process returns to Q1 in FIG.

  Although the embodiments have been described above, the present invention is not limited to the embodiments, and appropriate modifications can be made within the scope of the claims. As a condition for executing the engine operation restriction, in addition to the heat storage amount qa, a parameter to be added can include any one or a plurality of combinations among the plurality of elements shown in the embodiment. Only qa may be used as a condition for restricting engine operation. Of course, the object of the present invention is not limited to what is explicitly stated, but also implicitly includes providing what is substantially preferred or expressed as an advantage.

  The present invention can reliably prevent an overflow of cooling water from the radiator sub tank when the vehicle is stopped.

1: Engine 2: 4 Radiator 3: Radiator sub tank 4: Cooling fan U: Controller S1: Water temperature sensor S2: Vehicle speed sensor S3: Engine speed sensor S4: Intake air temperature sensor S5: Intake air amount sensor S6: Transmission S7: Accelerator opened Degree sensor S11: throttle actuator S12: fuel injection valve

Claims (8)

An engine control device including a radiator sub tank,
A heat storage amount detecting means for detecting the heat storage amount of the engine;
Engine control means for controlling the engine to be limited to suppress an increase in engine temperature when it is detected that the heat storage amount of the engine detected by the heat storage amount detection means is a predetermined value or more;
An engine control device comprising: In claim 1,
An engine control device according to claim 1, wherein the engine operation restriction by the engine control means is performed by controlling a throttle valve in a closing direction. In claim 1 or claim 2,
The engine control apparatus according to claim 1, wherein the heat storage amount detection means detects a heat storage amount based on an integrated value of an intake air amount of the engine. In any one of Claims 1 thru | or 3,
An engine control device, wherein a radiator cooling fan is driven by an engine, and the cooling fan is stopped when the engine is stopped. In any one of Claims 1 thru | or 4,
Engine control by the engine control means is executed on condition that the climbing rate is equal to or higher than a predetermined value, a predetermined low speed stage, and a coolant temperature is equal to or higher than a predetermined temperature. . In claim 5,
An engine control device according to claim 1, wherein the engine operation restriction by the engine control means is executed on condition that the accelerator opening is fully open and the outside air temperature is equal to or higher than a predetermined temperature. In any one of Claims 1 thru | or 6,
The engine control device, wherein the engine control means performs control to increase the fuel injection amount and enrich the air-fuel ratio in advance before executing the engine operation restriction. In claim 2,
The transmission connected to the engine is an automatic transmission that can be switched between a manual transmission mode and an automatic transmission mode that are fixed to a selected gear stage,
The engine control means, when controlling the throttle valve in the closing direction, gradually decreases the throttle opening in the manual shift mode, and decreases the throttle opening at once in the automatic shift mode.
An engine control device.

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