JP7690878B2 - Throttle Control Device - Google Patents

Description

The present invention relates to a throttle control device that controls the throttle valve of an on-vehicle engine.

In low-temperature environments, the throttle valve may freeze while the engine is stopped, causing malfunction. Patent Document 1 describes a technology that prevents the throttle valve from sticking due to freezing by opening and closing the throttle valve every time a certain amount of time has elapsed since the engine was stopped.

JP 2014-156845 A

In a low-temperature environment, cold intake air is blown onto the throttle valve while the engine is running. The moisture in the intake air may freeze onto the cold surface of the throttle valve. Even in such a case, when the engine is stopped, cold intake air is no longer blown onto the throttle valve. On the other hand, after the engine is stopped, the throttle valve is warmed by the residual heat of the engine. As a result, the temperature of the throttle valve rises after the engine is stopped, and the ice on the valve surface may melt. The melted water drips down the surface of the throttle valve and accumulates in the gap between the throttle valve and the throttle body. After that, as the engine cools down over time, the temperature of the throttle valve and throttle body will drop below freezing again. The water that has accumulated in the gap may then freeze again, causing the throttle valve to become stuck.

When the throttle valve is opened and closed, water adhering to the throttle valve and its surroundings can be easily shaken off, but ice may not be completely removed. On the other hand, the time when ice melts on the throttle valve surface and the time when the melted water refreezes vary depending on the situation. For this reason, simply opening and closing the throttle valve every certain amount of time after the engine is stopped may not be enough to prevent the throttle valve from sticking.

The throttle control device that solves the above problem performs sticking suppression control by opening and closing the throttle valve after the engine is stopped, to suppress the sticking of the throttle valve due to icing. The throttle control device variably sets the timing of implementing the sticking suppression control based on the outside air temperature at the time the engine is stopped, which is the outside air temperature when the engine is stopped, and the engine coolant temperature at the time the engine is stopped.

The time when the ice on the throttle valve melts after the engine is stopped and when the melted water refreezes can be predicted from the outside air temperature and water temperature when the engine is stopped. Therefore, in the above throttle control device, the throttle valve can be opened and closed after the engine is stopped using the sticking prevention control while the ice is melted. Therefore, sticking of the throttle valve due to ice while the engine is stopped can be suppressed.

If the outside air temperature and water temperature at the time of stopping are values at which freezing of the throttle valve will not occur, it is advisable not to perform the opening and closing drive of the throttle valve in the above-mentioned sticking suppression control. Also, if the outside air temperature and water temperature at the time of stopping are values at which freezing of the throttle valve may occur and at which the ice will remain without melting even after the engine is stopped, it is advisable not to perform the opening and closing drive of the throttle valve in the above-mentioned sticking suppression control. In such a case, it becomes difficult to perform the opening and closing drive of the throttle valve for sticking suppression unnecessarily in a situation where sticking will not occur.

1 is a diagram illustrating a configuration of an embodiment of a throttle control device; 4 is a flowchart showing the procedure of an opening/closing drive time setting routine executed by a microcontroller in the throttle control device. FIG. 1 is a diagram showing the state of a throttle valve with ice on its surface. 11A and 11B are diagrams illustrating the state of the throttle valve when ice melts. 4 is a graph showing the relationship between the outside air temperature when the engine is stopped, the water temperature when the engine is stopped, and the timing of driving the throttle valve after the engine is stopped.

An embodiment of a throttle control device will be described in detail below with reference to FIGS.
<Configuration of the throttle control device>
First, the configuration of the throttle control device of this embodiment will be described with reference to Fig. 1. As shown in Fig. 1, a 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. The throttle valve 12 is driven to open and close by the throttle motor 14.

The operation control of the engine 10 is performed by an ECM (engine control module) 20. In this embodiment, the ECM 20 corresponds to a throttle control device. The ECM 20 includes a microcontroller 21. The microcontroller 21 includes a processing unit 22 that executes various arithmetic processes for controlling the operation of the engine 10, and a storage unit 23 that stores control programs and data. The ECM 20 also includes a motor drive circuit 24. The motor drive circuit 24 adjusts the drive current of the throttle motor 14 in response to commands from the microcontroller 21. The ECM 20 is connected to various sensors for checking the operating conditions of the engine 10. 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 for the engine 10.

The ECM 20 controls the operation of the engine 10 according to the detection results of various sensors. Specifically, the ECM 20 controls the operation of the engine 10 by having the processing unit 22 read and execute a program stored in the storage device 23. As part of the operation control of the engine 10, the ECM 20 controls the drive of the throttle valve 12.

The microcontroller 21 is connected to the battery 29 via the main relay 28. 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 power from the battery 29 is supplied to the motor drive circuit 24 and the throttle motor 14 via the microcontroller 21.

When the driver turns on the ignition switch 30, the main relay 28 is closed in conjunction with the ignition switch 30, and the microcontroller 21 is started. On the other hand, when the ignition switch 30 is turned off, the microcontroller 21 controls the engine 10 to stop. After the engine 10 is stopped, the microcontroller 21 opens the main relay 28. The microcontroller 21 stops the engine 10 with the throttle valve 12 at the opener opening. The opener opening is slightly opener than the fully closed opening where the throttle valve 12 blocks the intake passage 11.

The ECM 20 also includes a soak timer 25. Regardless of whether the main relay 28 is open or closed, the soak timer 25 is constantly supplied with power from the battery 29. The soak timer 25 includes a counter for measuring the time that has elapsed since the engine 10 was stopped. When a preset time has elapsed since the engine 10 was stopped, the soak timer 25 closes the main relay 28 and starts the microcontroller 21.

<Stiction prevention drive>
The microcontroller 21 performs sticking suppression control to suppress the throttle valve 12 from sticking due to icing while the engine 10 is stopped. The microcontroller 21 determines the timing of performing the sticking suppression control when the engine 10 is stopped.

Figure 2 shows a flowchart of the engine stop processing executed by the microcontroller 21 to determine the implementation timing of the sticking suppression control. The microcontroller 21 executes the engine stop processing as a post-processing after the engine 10 is stopped in response to the ignition switch 30 being turned off.

When this process starts, the microcontroller 21 first acquires the current outside air temperature T1 and engine water temperature T2 in step S100. The outside air temperature T1 acquired here corresponds to the outside air temperature at stop, which is the outside air temperature T1 when the engine 10 is stopped. The engine water temperature T2 acquired here corresponds to the engine stop water temperature, which is the cooling water temperature of the engine 10 when the engine 10 is stopped.

Next, in step S110, the microcontroller 21 sets the drive timing, which is the time to open and close the throttle valve 12 for the sticking suppression control, based on the outside air temperature and water temperature when the engine is stopped. The value of the drive timing set here represents the elapsed time from when the engine 10 is stopped to when the opening and closing drive is performed.

After setting the drive timing, in step S120, the microcontroller 21 transmits the drive timing value set in step S110 to the soak timer 25, and then ends the engine stop processing. After completing this processing, the microcontroller 21 opens the main relay 28 to stop its own operation.

After the engine 10 is stopped, the soak timer 25 closes the main relay 28 and starts the microcontroller 21 when the time indicated by the drive timing value transmitted from the microcontroller 21 has elapsed. The microcontroller 21, which has been started in this way, drives the throttle valve 12 to open and close, and then opens the main relay 28 to stop its own operation. The opening and closing drive here is performed by driving the throttle valve 12 to open to a preset opening, and then driving the throttle valve 12 to close to the opener opening.

Depending on the outside air temperature and water temperature when the engine is stopped, the throttle valve 12 may not be opened or closed after the engine 10 is stopped. In this case, the microcontroller 21 sets an invalid value as the drive timing value in step S120. In this case, the microcontroller 21 does not transmit the drive timing to the soak timer 25 in step S120.

<Setting the implementation timing of adhesion suppression control>
Next, the setting of the timing for driving the throttle valve 12 to open and close in the sticking suppression control, i.e., the setting of the drive timing in step S110 in Fig. 2, will be described with reference to Fig. 3 to Fig. 5. First, the sticking of the throttle valve 12 that is suppressed by the sticking suppression control will be described.

In a low-temperature environment, low-temperature intake air is blown into the engine 10 while it is operating. The low-temperature intake air can cool the throttle valve 12 below freezing while the engine 10 is operating. In such a case, moisture contained in blow-by gas, etc. can freeze onto the surface of the throttle valve 12. As shown in FIG. 4, the engine 10 can stop with ice adhering to the surface of the throttle valve 12.

When the engine 10 stops, cold intake air is no longer blown onto the throttle valve 12. However, residual heat remains in the engine 10 for a while after it has stopped. Therefore, after the engine 10 stops, the residual heat of the engine 10 warms the throttle valve 12, which can melt the ice that has adhered to its surface.

As shown in Figure 5, water that melts from the surface of the throttle valve 12 drips down the surface of the throttle valve 12 and accumulates in the gap between the throttle valve 12 and the throttle body 13. As time passes and the engine 10 cools down, the temperatures of the throttle valve 12 and the throttle body 13 also drop. If the outside air temperature is below freezing, the temperatures of the throttle valve 12 and the throttle body 13 also drop below freezing. This can cause the water that has accumulated in the gap to freeze again, causing the throttle valve 12 to become stuck.

In the sticking suppression control, the throttle valve 12 is opened and closed after the engine 10 is stopped, thereby suppressing the sticking of the throttle valve 12 caused by melting and re-freezing of ice while the engine 10 is stopped. In step S110 of FIG. 2, the microcontroller 21 sets the drive timing, i.e., the timing of opening and closing the throttle valve 12 in the sticking suppression control, according to the outside air temperature and water temperature at the time of stopping in the manner shown in FIG. 3.

Region R1 in FIG. 3 is a region where the outside air temperature exceeds the freezing point when the engine 10 is stopped. When the outside air temperature exceeds the freezing point, the throttle valve 12 is not frozen when the engine 10 is stopped, and the throttle valve 12 does not stick due to melting or refreezing. Even if the outside air temperature is below freezing, if the throttle valve 12 is warmed to a temperature above the freezing point by the heat of the engine 10, ice will not adhere to the throttle valve 12 while the engine 10 is operating. Curve L1 shown in FIG. 3 indicates the boundary between the region where icing of the throttle valve 12 occurs when the engine 10 is stopped and the region where icing does not occur. In region R2 above curve L1 in the figure, like region R1, the throttle valve 12 is not frozen when the engine 10 is stopped, and it is considered that the throttle valve 12 does not stick due to melting or refreezing. Therefore, in regions R1 and R2, the microcontroller 21 sets an invalid value for the drive timing so that the throttle valve 12 is not opened or closed after the engine 10 is stopped.

On the other hand, in the region below the curve L1 in FIG. 3, the throttle valve 12 is in an icy state when the engine 10 is stopped. Even in this case, if the temperature of the throttle valve 12 is maintained below the freezing point after the engine 10 is stopped, the ice will not melt, and the throttle valve 12 will not stick due to re-freezing. The curve L2 in FIG. 3 shows the boundary between the region where the ice on the throttle valve 12 melts and the region where it does not, assuming that the outside air temperature does not change after the engine 10 is stopped. If the outside air temperature does not change significantly after the engine 10 is stopped, it is considered that the ice will not melt and the throttle valve 12 will not stick due to re-freezing in the region R3 below the curve L2. Therefore, the microcontroller 21 sets an invalid value for the drive timing even in the region R3, so as not to perform the opening and closing drive of the throttle valve 12 after the engine 10 is stopped.

In contrast, in the region below curve L1 and above curve L2 in FIG. 3, there is a possibility that the throttle valve 12 may become stuck due to melting of ice and re-freezing. In the following description, this region will be referred to as the sticking occurrence region. In this embodiment, when the outside air temperature and water temperature at the time of stopping are within the sticking occurrence region, the throttle valve 12 is opened and closed after the engine 10 is stopped using sticking suppression control.

Although the opening and closing of the throttle valve 12 can easily shake off water that has adhered to the throttle valve 12 and its surroundings, it may not be possible to completely remove the ice that has adhered to the throttle valve 12. Therefore, it is desirable to open and close the throttle valve 12 using the adhesion suppression control during the period from when the ice melts until it refreezes.

On the other hand, the time when the ice on the throttle valve surface melts and the time when the melted water refreezes vary depending on the temperature of the engine 10 and the outside air when the engine is stopped. Specifically, the lower the outside air temperature, the later the time when the ice on the throttle valve 12 melts. Also, the lower the water temperature when the engine is stopped, the later the time when the ice melts. In contrast, the lower the outside air temperature, and the lower the water temperature when the engine is stopped, the earlier the time when the melted water refreezes. Therefore, the microcontroller 21 variably sets the drive timing when opening and closing the throttle valve 12 after the engine 10 is stopped by the sticking suppression control, depending on the outside air temperature when the engine is stopped and the water temperature when the engine is stopped. Specifically, the microcontroller 21 sets the value of the drive timing so that, if the outside air temperature when the engine is stopped is the same, the time when the throttle valve 12 is opened and closed is later than when the water temperature when the engine is stopped is high. In addition, the microcontroller 21 sets the value of the drive timing so that, if the water temperature when the engine is stopped is the same, the drive timing of the throttle valve 12 is later when the outside air temperature when the engine is stopped is low than when the outside air temperature when the engine is stopped is high.

<Effects of the embodiment>
The operation and effects of this embodiment will be described.
As described above, in order to suppress the sticking of the throttle valve 12 while the engine 10 is stopped, it is desirable to drive the throttle valve 12 to open and close during the period from when the ice melts to when the ice refreezes. The time when the ice melts and the time when the ice refreezes can be predicted from the outside air temperature and the water temperature when the engine is stopped. In contrast, in this embodiment, the drive timing is variably set based on the outside air temperature and the water temperature when the engine is stopped so that the throttle valve 12 is driven to open and close during the period when the ice is melted. Therefore, the sticking of the throttle valve 12 while the engine 10 is stopped due to the melting of the ice and the refreezing can be effectively suppressed. In addition, this allows the throttle valve 12 to be driven to open and close at a time when the occurrence of sticking can be effectively suppressed. Therefore, it is possible to suppress the sticking of the throttle valve 12 without performing the opening and closing drives many times while the engine 10 is stopped.

In addition, if the outside air temperature or water temperature when the engine is stopped is high and it is considered that the throttle valve 12 is not iced when the engine 10 is stopped, the throttle valve 12 is not opened or closed while the engine 10 is stopped. In addition, if the outside air temperature or water temperature when the engine is stopped is low and it is considered that the ice on the throttle valve 12 will not melt after the engine 10 is stopped, the throttle valve 12 is not opened or closed while the engine 10 is stopped. Therefore, the throttle valve 12 is not opened or closed unnecessarily to suppress sticking when sticking does not occur.

According to the throttle control device of the present embodiment described above, the following effects can be achieved.
(1) The timing of the sticking prevention control for driving the throttle valve 12 to open and close after the engine 10 is stopped is variably set according to the outside air temperature and the water temperature when the engine is stopped. Therefore, by driving the throttle valve 12 to open and close when the ice is melted, it is possible to effectively prevent the throttle valve 12 from sticking due to refreezing of the melted water.

(2) In this embodiment, the throttle valve 12 is not opened or closed after the engine 10 is stopped in the following two cases. One is when the outside air temperature and water temperature at the time of stopping are values at which the throttle valve 12 will not freeze. The other is when the outside air temperature and water temperature at the time of stopping are values at which the throttle valve 12 may freeze, and at which the ice will remain frozen even after the engine 10 is stopped without melting. Therefore, it becomes difficult to unnecessarily open and close the throttle valve 12 to suppress sticking in a situation where sticking will not occur.

<Other embodiments>
This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

<How to deal with changes in outside temperature after the engine is turned off>
Due to the difference in temperature between day and night, the outside air temperature may change significantly after the engine 10 is stopped. Furthermore, if the vehicle is parked in a heated garage, the outside air temperature may change significantly after the engine 10 is stopped due to the heating. Therefore, even if it is predicted that sticking will not occur based on the outside air temperature and water temperature when the engine 10 is stopped, the change in outside air temperature after the engine 10 is stopped may cause the ice to melt and refreeze, resulting in sticking of the throttle valve 12. Sticking due to such changes in outside air temperature can also be suppressed by driving the throttle valve 12 to open and close after the engine 10 is stopped.

However, when the engine 10 is stopped, it is not possible to predict the change in outside air temperature after the engine 10 is stopped. Therefore, in order to prevent the throttle valve 12 from sticking due to changes in outside air temperature, it is advisable to open and close the throttle valve 12 after the engine 10 is stopped at a pre-fixed time or cycle, separate from the sticking suppression control.

Furthermore, the above embodiment may be modified as follows.
The throttle valve 12 may be opened and closed a plurality of times after the engine 10 is stopped by the sticking suppression control. The number of times the throttle valve 12 is opened and closed may be changed depending on the outside air temperature and the water temperature when the engine 10 is stopped.

-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 determine the outside air temperature when the engine is stopped.

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: Soak timer 26: Outside air temperature sensor 27: Water temperature sensor 28: Main relay 29: Battery 30: Ignition switch

Claims (2)

A throttle control device that performs a sticking suppression control for suppressing sticking of the throttle valve due to icing by opening and closing the throttle valve after an engine is stopped,
The timing of executing the sticking suppression control is variably set based on an outside air temperature at the time when the engine is stopped, which is an outside air temperature at the time when the engine is stopped, and a water temperature at the time when the engine is stopped, which is a cooling water temperature of the engine at the time when the engine is stopped ;
When the outside air temperature and the water temperature at the time of stop are values at which freezing of the throttle valve may occur during the operation of the engine and at which the freezing is maintained without melting even after the engine is stopped, the opening and closing drive is not performed.
Throttle control device. The throttle control device according to claim 1, wherein the opening and closing drive is not performed when the outside air temperature and the water temperature at the time of stopping are values at which freezing of the throttle valve does not occur.

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