Throttle control device

Abstract

To suppress fixing of a throttle valve due to freezing during stopping of an engine.SOLUTION: A microcontroller 21 variably sets execution timing of opening and closing drive on the basis of an outside air temperature T1 and an engine water temperature T2 at stopping of an engine 10 so as to execute the opening and closing drive in a period in which icing of a throttle valve 12 after stopping of the engine 10 is melted.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a throttle control device that controls a throttle valve of an in-vehicle engine.

Background Art

[0002] In a low-temperature environment, the throttle valve may freeze during engine shutdown, resulting in malfunction. Patent Document 1 describes a technique for suppressing sticking of the throttle valve due to freezing by driving the throttle valve to open and close every time a certain period of time elapses since the engine stopped.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a low-temperature environment, cold intake air is blown onto the throttle valve during engine operation. Then, moisture in the intake air may freeze on the surface of the throttle valve that has become cold. Even in such a case, when the engine stops, the cold intake air is no longer blown onto the throttle valve. On the other hand, the throttle valve after engine shutdown is warmed by the residual heat of the engine. Therefore, the temperature of the throttle valve may rise after engine shutdown, and the ice formation on the valve surface may melt. The melted water drips along the surface of the throttle valve and accumulates in the gap between the throttle valve and the throttle body. Then, as time passes and the engine cools down, the temperature of the throttle valve and the throttle body becomes sub-zero again. And the water accumulated in the gap may freeze again, and the throttle valve may become stuck.

[0005] In the opening and closing drive of the throttle valve, water adhering to the throttle valve and its surroundings can be easily shaken off, but freezing may not be completely removed in some cases. On the other hand, the timing of ice melting on the throttle valve surface and the timing of refreezing of the melted water vary depending on the situation. Therefore, simply driving the throttle valve to open and close at regular intervals after the engine stops may not be able to suppress sticking of the throttle valve.

Means for Solving the Problem

[0006] The throttle control device for solving the above problem performs sticking suppression control to suppress sticking of the throttle valve due to freezing by driving the throttle valve to open and close after the engine stops. And the throttle control device variably sets the execution timing of the sticking suppression control based on the outside air temperature at the time of engine stop, which is the stop-time outside air temperature, and the coolant water temperature of the engine at the time of engine stop, which is the stop-time water temperature.

[0007] The timing when the ice on the throttle valve melts after the engine stops and the timing when the melted water refreezes can be predicted from the stop-time outside air temperature and the stop-time water temperature. Therefore, in the above throttle control device, the opening and closing drive of the throttle valve after the engine stops by the sticking suppression control can be performed during the period when the ice is in a melted state. Thus, sticking of the throttle valve due to freezing during engine stop can be suppressed.

[0008] In addition, when the stop-time outside air temperature and the stop-time water temperature are values at which ice formation on the throttle valve does not occur, it is advisable not to perform the opening and closing drive of the throttle valve in the above sticking suppression control. Also, when the stop-time outside air temperature and the stop-time water temperature are values at which ice formation on the throttle valve can occur and the ice is maintained without melting even after the engine stops, it is advisable not to perform the opening and closing drive of the throttle valve in the above sticking suppression control. In such cases, the opening and closing drive of the throttle valve for sticking suppression is less likely to be unnecessarily performed in a situation where sticking does not occur.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiment for Carrying Out the Invention

[0010] Hereinafter, an embodiment of the throttle control device will be described in detail with reference to FIGS. 1 to 5. <Configuration of Throttle Control Device> First, with reference to FIG. 1, the configuration of the throttle control device of this embodiment will be described. As shown in FIG. 1, the throttle valve 12 is installed inside a throttle body 13 provided in an intake passage 11 of an engine 10 mounted on a vehicle. The throttle valve 12 is connected to a throttle motor 14. And the throttle valve 12 is driven to open and close by the throttle motor 14.

[0011] The operation control of the engine 10 is performed by the ECM (Engine Control Module) 20. In this embodiment, this ECM 20 corresponds to the throttle control device. The ECM 20 includes a microcontroller 21. The microcontroller 21 includes a processing device 22 that executes various arithmetic processes for the operation control of the engine 10, and a storage device 23 that stores control programs and data. Further, the ECM 20 includes a motor drive circuit 24. The motor drive circuit 24 adjusts the drive current of the throttle motor 14 according to the command of the microcontroller 21. Various sensors for checking the operation status of the engine 10 are connected to the ECM 20. The sensors connected to the ECM 20 include an outside air temperature sensor 26 that detects the outside air temperature T1, and a water temperature sensor 27 that detects the engine water temperature T2, which is the temperature of the cooling water of the engine 10.

[0012] The ECM 20 performs the operation control of the engine 10 according to the detection results of various sensors. Specifically, the ECM 20 performs the operation control of the engine 10 by having the processing device 22 read and execute the program stored in the storage device 23. And the ECM 20 performs the drive control of the throttle valve 12 as part of the operation control of the engine 10.

[0013] The microcontroller 21 is connected to the battery 29 via the main relay 28. And when the main relay 28 is closed, power is supplied from the battery 29 to the microcontroller 21. On the other hand, when the main relay 28 is open, the power supply from the battery 29 to the microcontroller 21 is cut off. Note that the power of the battery 29 is supplied to the motor drive circuit 24 and the throttle motor 14 via the microcontroller 21.

[0014] When the driver turns on the ignition switch 30, the main relay 28 is closed in conjunction with it, and the microcontroller 21 is activated. On the other hand, when the ignition switch 30 is turned off, the microcontroller 21 performs stop control of the engine 10. Then, after the engine 10 stops, the microcontroller 21 opens the main relay 28. Note that the microcontroller 21 stops the engine 10 with the opening degree of the throttle valve 12 as the opener opening degree. The opener opening degree is a degree slightly on the opening side from the fully closed degree where the throttle valve 12 closes the intake passage 11.

[0015] Also, the ECM 20 is provided with a soak timer 25. The battery 29 constantly supplies power to the soak timer 25 regardless of the open / closed state of the main relay 28. The soak timer 25 is provided with a counter for measuring the elapsed time after the engine 10 stops. Then, when a preset time elapses after the engine 10 stops, the soak timer 25 closes the main relay 28 and activates the microcontroller 21.

[0016] <Sticking prevention drive> The microcontroller 21 performs sticking prevention control to prevent the throttle valve 12 from sticking due to freezing during the stop of the engine 10. The microcontroller 21 determines the execution timing of the sticking prevention control when the engine 10 stops.

[0017] Fig. 2 shows a flowchart of the engine stop processing executed by the microcontroller 21 to determine the execution timing of the sticking prevention control. The microcontroller 21 executes the engine stop processing as post-processing after the engine 10 stops in response to the off operation of the ignition switch 30.

[0018] When this process starts, the microcontroller 21 first obtains the current outside air temperature T1 and the engine coolant temperature T2 in step S100. The outside air temperature T1 obtained here corresponds to the outside air temperature at the time of engine stop, which is the outside air temperature when the engine 10 stopped. Also, the engine coolant temperature T2 obtained here corresponds to the coolant temperature of the engine 10 at the time of engine stop, which is the coolant temperature when the engine 10 stopped.

[0019] Subsequently, the microcontroller 21 sets the drive timing, which is the timing for opening and closing the throttle valve 12 for sticking prevention control, based on the outside air temperature at the time of stop and the coolant temperature at the time of stop in step S110. The value of the drive timing set here represents the elapsed time from the stop of the engine 10 to the implementation time of the opening and closing drive.

[0020] After setting the drive timing, the microcontroller 21 transmits the value of the drive timing set in step S110 to the soak timer 25 in step S120, and then ends the engine stop time process. Note that the microcontroller 21 opens the main relay 28 after the completion of this process and stops its operation.

[0021] After the engine 10 stops, when the time indicated by the value of the drive timing transmitted from the microcontroller 21 elapses, the soak timer 25 closes the main relay 28 and starts the microcontroller 21. The microcontroller 21 thus started performs the opening and closing drive of the throttle valve 12, and then opens the main relay 28 and stops its operation. The opening and closing drive here is performed by driving the throttle valve 12 to the default opening degree and then driving the throttle valve 12 to the opener opening degree to close it.

[0022] Note that depending on the outside air temperature at the time of stop and the coolant temperature at the time of stop, the opening and closing drive of the throttle valve 12 after the engine 10 stops may not be performed. In this case, the microcontroller 21 sets an invalid value as the value of the drive timing in step S120. In this case, the microcontroller 21 does not perform the transmission of the drive timing to the soak timer 25 in step S120.

[0023] <Setting of the Execution Timing of Sticking Suppression Control> Next, with reference to FIGS. 3 to 5, the setting of the execution timing of the opening / closing drive of the throttle valve 12 in the sticking suppression control, that is, the setting of the drive timing in step S110 of FIG. 2 will be described. Here, first, the sticking of the throttle valve 12 suppressed by the sticking suppression control will be described.

[0024] In a low-temperature environment, cold intake air blows during the operation of the engine 10. Then, due to the cold intake air, the throttle valve 12 during the operation of the engine 10 may be cooled below the freezing point. In such a case, moisture contained in the blow-by gas or the like may freeze on the surface of the throttle valve 12. And, as shown in FIG. 4, the engine 10 may stop with ice adhering to the surface of the throttle valve 12.

[0025] When the engine 10 stops, cold intake air stops blowing onto the throttle valve 12. On the other hand, the engine 10 retains residual heat for some time after stopping. Therefore, after the engine 10 stops, the throttle valve 12 may be warmed by the residual heat of the engine 10, and the ice adhering to the surface may melt.

[0026] As shown in FIG. 5, the water melted from the surface of the throttle valve 12 drips along the surface of the throttle valve 12 and accumulates in the gap between the throttle valve 12 and the throttle body 13. Then, as time passes and the engine 10 cools, the temperatures of the throttle valve 12 and the throttle body 13 also drop. When the outside air temperature is lower than the freezing point, the temperatures of the throttle valve 12 and the throttle body 13 also drop below the freezing point. Therefore, the water accumulated in the gap may freeze again, and the throttle valve 12 may become stuck.

[0027] In the sticking prevention control, after the engine 10 stops, the throttle valve 12 is driven to open and close, thereby suppressing the sticking of the throttle valve 12 caused by the melting and re-icing of ice during the stop of the engine 10. In step S110 of FIG. 2, the microcontroller 21 sets the driving timing, that is, the timing of the opening and closing drive of the throttle valve 12 in the sticking prevention control, according to the outside air temperature at the time of stop and the water temperature at the time of stop in the manner shown in FIG. 3.

[0028] Region R1 in FIG. 3 is a region where the outside air temperature at the time of stop exceeds the freezing point. When the outside air temperature exceeds the freezing point, the throttle valve 12 at the time of stopping the engine 10 is not in a state of icing, and the sticking of the throttle valve 12 due to the melting and re-icing of ice does not occur. Also, even if the outside air temperature is below the freezing point, if the throttle valve 12 is warmed to a temperature exceeding the freezing point by the heat of the engine 10, ice will not adhere to the throttle valve 12 during the operation of the engine 10. Curve L1 shown in FIG. 3 indicates the boundary line between the region where icing of the throttle valve 12 occurs and the region where it does not occur at the time of stopping the engine 10. In region R2 above curve L1 in the figure, similar to region R1, the throttle valve 12 at the time of stopping the engine 10 is not in a state of icing, and it is considered that the sticking of the throttle valve 12 due to the melting and re-icing of ice does not occur. Therefore, in regions R1 and R2, the microcontroller 21 sets invalid values for the driving timing so as not to perform the opening and closing drive of the throttle valve 12 after the engine 10 stops.

[0029] On the other hand, in the region below the curve L1 in FIG. 3 in the lower side in the figure, when the engine 10 stops, the throttle valve 12 is in a state of icing. Also in this case, if the temperature of the throttle valve 12 is maintained below the freezing point after the engine 10 stops, the icing will not melt, so the throttle valve 12 will not become stuck due to re-icing. The curve L2 in FIG. 3 shows the boundary line between the region where the icing of the throttle valve 12 melts and the region where it does not melt when the outside air temperature does not change after the engine 10 stops. If the outside air temperature does not change significantly after the engine 10 stops, it is considered that the icing of the throttle valve 12 will not melt and the throttle valve 12 will not become stuck due to re-icing in the region R3 below the curve L2 in the lower side in the figure. Therefore, the microcontroller 21 also sets invalid values for the driving timing in the region R3 and does not perform the opening and closing drive of the throttle valve 12 after the engine 10 stops.

[0030] On the other hand, in the region below the curve L1 in FIG. 3 in the lower side in the figure and above the curve L2 in the upper side in the figure, there is a possibility that the throttle valve 12 will become stuck due to the melting and re-icing of the icing. In the following description, this region is referred to as the sticking occurrence region. In the present embodiment, when the outside air temperature at stop and the water temperature at stop are within the sticking occurrence region, the opening and closing drive of the throttle valve 12 after the engine 10 stops is performed by sticking suppression control.

[0031] In the opening and closing drive of the throttle valve 12, although the water attached to the throttle valve 12 and its surroundings can be easily shaken off, there are cases where the attached ice cannot be completely removed. Therefore, it is desirable to perform the opening and closing drive of the throttle valve 12 in the sticking suppression control during the period from when the icing melts until it re-ices.

[0032] On the one hand, the timing of ice melting on the throttle valve surface and the timing of refreezing of the melted water vary depending on the temperature of the engine 10 at the time of stoppage and the outside air temperature. Specifically, the lower the outside air temperature, the later the timing when the ice adhering to the throttle valve 12 melts. Also, the lower the water temperature at the time of stoppage, the later the melting timing. On the other hand, the timing when the melted water refreezes becomes earlier as the outside air temperature is lower and earlier as the water temperature at the time of stoppage is lower. Therefore, the microcontroller 21 variably sets the driving timing when performing the opening and closing drive of the throttle valve 12 after the stoppage of the engine 10 by sticking prevention control according to the outside air temperature at the time of stoppage and the water temperature at the time of stoppage. Specifically, when the outside air temperature at the time of stoppage is the same, the microcontroller 21 sets the value of the driving timing so that the timing of the opening and closing drive of the throttle valve 12 is later when the water temperature at the time of stoppage is lower than when it is higher. Also, when the water temperature at the time of stoppage is the same, the microcontroller 21 sets the value of the driving timing so that the driving timing of the throttle valve 12 is later when the outside air temperature at the time of stoppage is lower than when it is higher.

[0033] <Operation and Effect of Embodiment> The operation and effect of this embodiment will be described. As described above, in order to suppress the sticking of the throttle valve 12 during the stoppage of the engine 10, it is desirable to open and close the throttle valve 12 during the period from ice melting to refreezing. The timing of ice melting and the timing of refreezing can be predicted from the outside air temperature at the time of stoppage and the water temperature at the time of stoppage. In contrast, in this embodiment, the driving timing is variably set based on the outside air temperature at the time of stoppage and the water temperature at the time of stoppage so as to open and close the throttle valve 12 during the period when the ice has melted. Therefore, the sticking of the throttle valve 12 during the stoppage of the engine 10 due to ice melting and refreezing can be effectively suppressed. Also, thereby, the opening and closing drive of the throttle valve 12 can be performed at a timing capable of effectively suppressing the occurrence of sticking. Thus, even if the opening and closing drive during the stoppage of the engine 10 is not performed many times, it is possible to suppress the sticking of the throttle valve 12.

[0034] Also, when it is considered that the outside air temperature and the water temperature at the time of engine stop are high and the throttle valve 12 is not frozen at the time of engine 10 stop, the opening and closing drive of the throttle valve 12 during engine 10 stop is not performed. Further, when it is considered that the outside air temperature and the water temperature at the time of stop are low and the ice adhesion of the throttle valve 12 will not melt after the engine 10 stops, the opening and closing drive of the throttle valve 12 during engine 10 stop is not performed. Therefore, the opening and closing drive of the throttle valve 12 for suppressing sticking is not unnecessarily performed in a situation where sticking does not occur.

[0035] According to the throttle control device of the present embodiment described above, the following effects can be obtained. (1) The execution timing of the sticking prevention control for opening and closing the throttle valve 12 after the engine 10 stops is variably set according to the outside air temperature at the time of stop and the water temperature at the time of stop. Therefore, the throttle valve 12 can be effectively driven to open and close at a time when the ice has melted, and the sticking of the throttle valve 12 due to the re-freezing of the melted water can be effectively suppressed.

[0036] (2) In the present embodiment, in the following two cases, the opening and closing drive of the throttle valve 12 after the engine 10 stops is not performed. One case is when the outside air temperature and the water temperature at the time of stop are values at which ice formation of the throttle valve 12 does not occur. The other case is when the outside air temperature and the water temperature at the time of stop are values at which ice formation of the throttle valve 12 can occur, and the ice formation is maintained without melting even after the engine 10 stops. Therefore, it becomes difficult for the opening and closing drive of the throttle valve 12 for suppressing sticking to be unnecessarily performed in a situation where sticking does not occur.

[0037] <Other Embodiments> This embodiment can be implemented with the following modifications. This embodiment and the following modification examples can be implemented in combination with each other within a technically non-conflicting range.

[0038] <Response to Changes in Outside Air Temperature after Engine Stop> Due to the temperature difference between day and night, the outside air temperature may change significantly after the engine 10 stops. Also, when the vehicle is parked in a heated garage, the outside air temperature may change significantly after the engine 10 stops due to the heating. Therefore, even when it is predicted that sticking will not occur based on the outside air temperature at stop and the water temperature at stop, sticking of the throttle valve 12 due to melting and re-freezing of ice may occur due to such a change in the outside air temperature after the engine 10 stops. Such sticking due to a change in the outside air temperature can also be suppressed by opening and closing the throttle valve 12 after the engine 10 stops.

[0039] However, at the time of stopping the engine 10, the change in the outside air temperature after stopping cannot be predicted. Therefore, in order to suppress sticking due to a change in the outside air temperature, apart from the sticking suppression control, it is advisable to perform the opening and closing drive of the throttle valve 12 after the engine 10 stops at a fixed time or cycle in advance.

[0040] Furthermore, the above embodiment may be modified as follows. · The opening and closing drive of the throttle valve 12 after the engine 10 stops by the sticking suppression control may be performed multiple times. Also, the number of opening and closing drives may be changed according to the outside air temperature at stop and the water temperature at stop.

[0041] · Instead of the outside air temperature sensor 26, an intake air temperature sensor that detects the temperature of the intake air flowing through the intake passage 11 may be used to obtain the outside air temperature at stop.

Explanation of Reference Numerals

[0042] 10…Engine 11…Intake Passage 12…Throttle Valve 13…Throttle Body 14…Throttle Motor 20…ECM (Engine Control Module) 21…Microcontroller 22…Processing Device 23…Storage Device 24…Motor Drive Circuit 25…Sock Timer 26…Outside Air Temperature Sensor 27…Water Temperature Sensor 28…Main Relay 29…Battery 30…Ignition Switch

Claims

1. A throttle control device that performs sticking prevention control to suppress sticking of the throttle valve due to freezing by driving the throttle valve to open and close after the engine stops, wherein the execution timing of the sticking prevention control is variably set based on the outside air temperature at the time of engine stop, which is the outside air temperature at the time of engine stop, and the cooling water temperature of the engine at the time of engine stop, which is the water temperature at the time of stop, and when the outside air temperature at the time of stop and the water temperature at the time of stop are values at which freezing of the throttle valve can occur during operation of the engine and the freezing is maintained without melting even after the engine stops, the opening and closing drive is not performed Throttle control device.

2. The throttle control device according to claim 1, wherein when the outside air temperature at the time of stop and the water temperature at the time of stop are values at which freezing of the throttle valve does not occur, the opening and closing drive is not performed.

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