Throttle control system

Abstract

A throttle control system (3) of this disclosure is provided with a motor (4) that opens and closes a throttle valve (2) of an internal combustion engine (1), and a control device (6) that controls the motor (4). When the control device (6) detects freezing of the throttle valve (2), the control device (6) performs unfreezing control for moving the throttle opening from an initial opening toward a target opening while repeatedly increasing or decreasing the throttle opening by repeatedly oscillating a drive signal of the motor (4) between an open side and a closed side.

Description

Throttle Control System

[0001] This invention relates to a throttle control system for an internal combustion engine.

[0002] In a throttle control system for an internal combustion engine, a technique is known in which, when frozen water on the throttle valve is detected, the throttle valve is opened or closed widely to remove the ice. For example, when ice is present on the closing side of the throttle valve, the throttle valve is opened wide to approximately full opening, and then quickly closed with force, causing the throttle valve to strike the ice hard and destroy it (see Patent Documents 1 and 2).

[0003] JP 2006-249952 A JP 2007-218089 A

[0004] In the above-described control, the collision between the throttle valve and ice can easily cause deformation and wear of the throttle valve and drive components, potentially impairing the quality of the throttle control system. Furthermore, because the throttle is nearly fully closed when the ice breaks, the intake volume is likely to be insufficient if the internal combustion engine is operated at the target output immediately after that. This makes it necessary to open the throttle to an opening appropriate for the target output of the internal combustion engine, which poses a problem of making it difficult to quickly achieve the target output.

[0005] One of the objects of the present invention was invented in light of the above-mentioned problems, and is to provide a throttle control system that can improve the quality of the throttle valve and drive parts, and can improve the ability of the internal combustion engine to follow the target output. However, in addition to this object, another object of the present invention is to achieve effects derived from the various configurations shown in the "Mode for Carrying Out the Invention" described below, which cannot be obtained with conventional techniques.

[0006] The disclosed throttle control system can be realized as the following disclosed aspects (application examples) and solves at least part of the above-mentioned problems. Each of the aspects from aspect 2 onwards is an aspect that can be selected as an additional aspect, and each of the aspects from aspect 2 onwards is an aspect that can be omitted. None of the aspects from aspect 2 onwards is disclosed as an aspect or configuration that is essential to the present invention.

[0007] Aspect 1. The disclosed throttle control system includes a motor that drives a throttle valve of an internal combustion engine to open and close, and a control device that controls the motor. When the control device detects that the throttle valve is frozen, the control device performs unfreezing control, which repeatedly increases and decreases the throttle opening by oscillating the drive signal of the motor between the open side and the closed side, thereby moving the throttle opening from an initial opening toward a target opening.

[0008] Aspect 2. With regard to the aspect including Aspect 1 above, it is preferable that, in the unfreezing control, the throttle opening is controlled so as not to exceed the target opening when moving from the initial opening to the target opening. Aspect 3. With regard to the aspect including Aspect 1 above, it is preferable that, in the unfreezing control, the drive signal of the motor oscillates at a predetermined cycle.

[0009] Aspect 4. In relation to aspects including Aspect 1 above, it is preferable that the target opening is on one side of the initial opening in the opening / closing direction, and that, in one cycle of the drive signal, the output time of a first signal that moves the throttle opening to one side is set longer than the output time of a second signal that moves the throttle opening to the other side.

[0010] Aspect 5. With respect to aspects including Aspect 1 above, it is preferable that the target throttle opening is closer to the closing side than the initial throttle opening, and that the unfreezing control is started before the internal combustion engine is started. Aspect 6. With respect to aspects including Aspect 1 above, it is preferable that the throttle opening is increased or decreased with an amplitude equal to or less than the difference between the initial throttle opening and the target throttle opening during the unfreezing control.

[0011] Aspect 7. In any aspect including Aspect 1 above, it is preferable that the drive signal alternately repeats an open signal that drives the throttle valve in a direction to open it to a first opening degree and a close signal that drives the throttle valve in a direction to close it to a second opening degree. It is preferable that while the open signal is being output, the close signal is output before the actual opening degree of the throttle valve reaches the first opening degree, and while the close signal is being output, the open signal is output before the actual opening degree reaches the second opening degree.

[0012] Aspect 8. In relation to the aspect including Aspect 1 described above, when the control device starts the internal combustion engine while the unfreezing control is being performed, it is preferable that the control device continues the unfreezing control until an end condition for the unfreezing control is met.

[0013] According to the disclosed throttle control system, the throttle valve is repeatedly opened and closed while moving from the initial opening to the target opening, thereby suppressing sudden changes in the throttle opening and unfreezing the engine. This reduces the impact load caused by the collision between the throttle valve and ice, suppressing deformation and wear of the throttle valve and drive components and improving quality. Furthermore, because sudden changes in the throttle opening are suppressed, the intake volume can be optimized when the internal combustion engine is set to the target output after unfreezing control. This improves the internal combustion engine's ability to track the target output.

[0014] 1 is a schematic diagram of an internal combustion engine to which a throttle control system is applied. It is a graph showing an example of control by the control device, where (A) shows the change in throttle opening over time, and (B) shows the change in motor drive signal over time. It is a graph showing another example of control by the control device, where (A) shows the change in throttle opening over time, and (B) shows the change in motor drive signal over time.

[0015] [1. Configuration] A throttle control system 3 of this embodiment is applied to an internal combustion engine 1 shown in Fig. 1. This internal combustion engine 1 is, for example, a gasoline engine or a diesel engine, and can be installed in automobiles, ships, driving force generating devices, power generators, etc. An electronically controlled throttle valve 2 for adjusting the amount of intake air is installed in an intake passage of the internal combustion engine 1. Near the throttle valve 2, there are provided a motor 4 for driving the throttle valve 2 to open and close, an opening sensor 5 for detecting the opening of the throttle valve 2 (throttle opening), and a control device 6 connected to the motor 4 and the opening sensor 5.

[0016] The opening sensor 5 is one specific example of means for detecting freezing of the throttle valve 2. For example, if the motor 4 is operated in a cold environment and the throttle opening does not change by a predetermined amount within a predetermined time, it is possible that the motor 4 is malfunctioning, or that the throttle valve 2 is frozen. Therefore, the control device 6 determines whether the throttle valve 2 is frozen based on the states of the motor 4 and the opening sensor 5, etc. Note that if there is another means for detecting freezing of the throttle valve 2, the opening sensor 5 may be omitted. The throttle control system 3 of this embodiment includes at least the motor 4 and the control device 6.

[0017] The control device 6 is one of the computers (electronic control units, ECUs) that control the motor 4, and has a built-in processor (arithmetic processing unit) and memory (storage device). The contents of the control performed by the control device 6 (control program) are stored in the memory, and the contents are read into the processor and executed as appropriate. The control device 6 has a function of performing unfreezing control when it detects that the throttle valve 2 is frozen.

[0018] The unfreezing control is a control that moves the throttle opening from an initial opening toward a target opening by repeatedly increasing and decreasing the throttle opening by alternately switching the drive signal of the motor 4 between the open and closed sides. The initial opening refers to the throttle opening at the start of the unfreezing control, and the target opening refers to the throttle opening at the end of the unfreezing control, which is an opening suitable for driving the internal combustion engine 1 at a target output. In this embodiment, the unfreezing control is performed before starting the internal combustion engine 1, and the target opening refers to an opening suitable for starting the internal combustion engine 1 (e.g., an opening narrowed enough to prevent a sudden increase in speed immediately after starting the internal combustion engine 1). In this embodiment, the unfreezing control controls the operating state of the motor 4 in a relatively short cycle so that the unfreezing is achieved without abruptly changing the throttle opening. That is, the operating state of the motor 4 is controlled so that the throttle opening gradually approaches the target opening while frequently increasing and decreasing with a relatively small amplitude.

[0019] The control device 6 starts the unfreezing control when the conditions for starting the unfreezing control are met. The conditions for starting the unfreezing control include at least the control device 6 detecting that the throttle valve 2 is frozen. Specific examples of other additional conditions are as follows: The internal combustion engine 1 is stopped The internal combustion engine 1 is in a cold environment The main power of the vehicle equipped with the internal combustion engine 1 has just been turned on The time elapsed since the internal combustion engine 1 was last stopped (soak time) is equal to or longer than a predetermined time.

[0020] The unfreezing control employs a technique of finely oscillating the drive signal of the motor 4 to unfreeze the throttle valve without making a large, sudden change in throttle opening. The drive signal here refers to a signal corresponding to the drive method of the motor 4, such as a voltage signal, a current signal, or a duty signal (PWM (Pulse Width Modulation) signal). The period of the drive signal is set, for example, within a range of several milliseconds to several hundred milliseconds, and preferably on the order of 10 milliseconds. The period of the drive signal may be a constant, predetermined period or a variable period. In the former case, a waveform of one wavelength may be successive, or different waveforms of the same wavelength may be successive. In the latter case, a drive signal with a variable period may be formed by combining waveforms of multiple wavelengths.

[0021] The control device 6 ends the unfreezing control when the termination condition for the unfreezing control is met. For example, in any of the following cases, the control device 6 determines that the termination condition for the unfreezing control is met and ends the unfreezing control: - The execution time of the unfreezing control has reached a predetermined execution time or more; - The number of oscillations of the drive signal has reached a predetermined number of oscillations or more; - The throttle opening has reached the target opening; - The actual opening of the throttle valve 2 has reached the target opening.

[0022] 2A is a graph showing the change in throttle opening from the initial opening to the target opening. FIG. 2B is a graph showing the change over time in the drive signal (duty signal) of the motor 4, which is controlled to achieve this change in throttle opening. In this example, the initial throttle opening is θ ０ and the target opening is the initial opening θ ０ θ located on the closing side (or at the same opening) １ θ ０ is, for example, the opening degree less than full opening, and θ １ is, for example, the opening degree more than fully closed. ２ is the throttle opening that satisfies the end condition of the unfreezing control (fully closed ≦ θ １ ≦θ ２ ≦θ ０ ≦Full throttle).

[0023] Time t ０When the main power supply of the vehicle is turned on (the main switch is turned on), the control device 6 has not yet detected the freezing of the throttle valve 2. Taking into consideration the possibility that the internal combustion engine 1 will start thereafter, the control device 6 sets the target opening of the throttle valve 2 to the current initial opening θ ０ to target opening θ １ The drive signal of the motor 4 is changed from 0 to -D ０ As a result, a force acts on the throttle valve 2 to move it in the closing direction.

[0024] Assuming that the motor 4 is not broken and the throttle valve 2 is not frozen, the actual opening of the throttle valve 2 is equal to the target opening θ １ On the other hand, when the throttle valve 2 is frozen, the throttle opening detected by the opening sensor 5 does not change. As shown in FIG. 2A, the throttle opening changes from the initial opening θ ０ Therefore, at time t ０ A predetermined time has elapsed since time t １ Even if the throttle opening is set to the initial opening θ ０ If the condition remains the same, it is determined that the throttle valve 2 is frozen, and unfreezing control is initiated.

[0025] In the defreezing control, the drive signal of the motor 4 is +D １ The period during which the drive signal is controlled to -D ２ The periods controlled by the +D １ The drive signal +D is an open signal that drives the throttle valve 2 in the opening direction, １ If the drive signal of -D continues to be output, the throttle opening becomes the first opening. ２ The drive signal -D is a close signal that drives the throttle valve 2 in the closing direction, ２This is an open signal that causes the throttle opening to become the second opening if the drive signal is continuously output. In this embodiment, the first opening is the fully open opening, and the second opening is the fully closed opening. The drive signal is configured as a signal that alternates between an open signal and a close signal. The magnitudes (duty ratios) of the open signal and the close signal are set appropriately. It is preferable that the drive signal is controlled so that the throttle opening does not change excessively, and the throttle opening is set to the initial opening θ ０ to target opening θ １ When moving to the target opening θ １ It is preferable that the driving signal is controlled so as not to exceed +D １ When the drive signal is output, before the throttle opening reaches the first opening, -D ２ A drive signal of -D is output. ２ When the drive signal is output, before the throttle opening reaches the second opening, +D １ It is preferable that a drive signal of the above formula be output.

[0026] While the open signal is being output, the initial opening θ ０ The absolute value of the opening increase amount based on the initial opening θ ０ and target opening θ １ Similarly, while the close signal is being output, the initial opening θ ０ The absolute value of the decrease in opening angle based on the initial opening angle θ ０ and target opening θ １ The open signal is output before the difference in opening degree between the open signal and the closed signal exceeds the time P １ and the output time of the open signal P ２ Each of these is the actual amplitude of the throttle opening relative to the initial opening θ ０ and target opening θ １ The time is set to be short enough not to exceed the difference in opening between the two valves. １ and the output time of the open signal P ２ Regarding the magnitude relationship of the close signal (-D ２ drive signal) is an open signal (+D １ The drive signal is longer than that of the

[0027] Here, the initial opening θ of the throttle opening ０Based on the target opening θ １ The direction in which the valve is open is defined as one side, and the initial opening angle θ ０ Based on the target opening θ １ The direction in which there is no "( )" is defined as the other side. Also, in one cycle of the drive signal, a signal that moves the throttle opening to one side is defined as a first signal, and a signal that moves the throttle opening to the other side is defined as a second signal. In the example shown in FIG. 2(B), the close signal is the first signal, and the open signal is the second signal. In the unfreezing control of this embodiment, the output time P of the first signal is １ is the output time P of the second signal ２ is set longer than ２ <P １ ). The initial opening θ ０ and target opening θ １ and are the same, the output time P １ and the output time P of the second signal ２ are set to be the same.

[0028] Time t ２ is the time when the termination condition for the unfreezing control is met (when the throttle opening is θ ２ In the example of FIG. 2, the time t ２ At time t, the ice that had been causing the freezing of the throttle valve 2 is broken, and the frozen state is released. ２ After that, the throttle opening is set to the target opening θ １ The drive signal of the motor 4 is controlled so that ３ The throttle opening is set to the target opening θ １ Matches.

[0029] 3A and 3B show the target opening θ ３ is the initial opening θ ０ 8 is a graph showing the change over time in the throttle opening and drive signal when the throttle valve is positioned closer to the open position than θ ４ is the throttle opening that satisfies the end condition of the unfreezing control (fully closed ≦ θ ０ ≦θ ４ ≦θ ３ 3B, the open signal is the first signal and the close signal is the second signal. １is the output time P of the second signal ２ is set longer than ２ <P １ ).

[0030] Time t ４ is the time when the termination condition for the unfreezing control is met (when the throttle opening is θ ４ In the example of FIG. 3, the time t ４ At time t, the ice that had been causing the freezing of the throttle valve 2 is broken, and the frozen state is released. ４ After that, the throttle opening is set to the target opening θ ３ The drive signal of the motor 4 is controlled so that ５ The throttle opening is set to the target opening θ ３ Matches.

[0031] It is preferable that the unfreezing control be started before starting the internal combustion engine 1. For example, when a request to start the internal combustion engine 1 is transmitted from another ECU, it is preferable to check whether the throttle valve 2 is frozen, and if it is detected that the throttle valve 2 is frozen, to start the internal combustion engine 1 after starting the unfreezing control. More preferably, it is preferable that the internal combustion engine 1 be started after the unfreezing control has ended. If the internal combustion engine 1 is started while the unfreezing control is being performed, it is preferable that the unfreezing control be continued until the end condition for the unfreezing control is met. In other words, it is preferable that the internal combustion engine 1 be started while the unfreezing control is being continued.

[0032] [2. Actions and Effects] (1) The throttle control system 3 described above includes a motor 4 that drives the throttle valve 2 of the internal combustion engine 1 to open and close, and a control device 6 that controls the motor 4. When the control device 6 detects that the throttle valve 2 is frozen, it vibrates the drive signal of the motor 4 to repeatedly increase and decrease the throttle opening while maintaining the initial opening θ ０ to target opening θ １ , θ ３ Then, the defreezing control is performed to move the object toward the target.

[0033] In this way, the throttle opening is repeatedly increased and decreased until the initial opening θ ０ to target opening θ １ , θ ３By moving the throttle valve 2 to the position shown in FIG. 1, the ice can be broken up and the frozen state can be released without abruptly changing the throttle opening. This reduces the impact load caused by the collision between the throttle valve 2 and the ice, and reduces deformation and wear of the throttle valve 2 and drive components (motor 4, power transmission mechanism, etc.), improving quality.

[0034] In addition, sudden changes in the throttle opening are suppressed, and the overall movement of the throttle opening is controlled to the target opening θ １ , θ ３ The throttle opening can be adjusted to approach the target opening θ １ , θ ３ Therefore, regardless of the timing, such as during or after the unfreezing control, the throttle opening is kept at the target opening θ １ , θ ３ This allows the intake air amount to be adjusted to a value close to the target output, thereby achieving an intake air amount suitable for operating the internal combustion engine 1 at the target output. Therefore, the ability of the internal combustion engine 1 to follow the target output can be improved.

[0035] In the techniques of Patent Document 1 (JP 2006-249952 A) and Patent Document 2 (JP 2007-218089 A), the throttle valve 2 is opened and closed widely to the full open position and to the vicinity of the full closed position in order to make the throttle valve 2 hit the ice hard, so the throttle opening degree is temporarily changed to the target opening degree θ １ , θ ３ In contrast, the throttle control system 3 described above can reduce the impact acting on the throttle valve 2 and suppress sudden changes in the throttle opening. This can improve the quality of the throttle valve 2 and drive parts, and can also improve the ability of the internal combustion engine 1 to follow the target output.

[0036] (2) In the above-described unfreezing control, the throttle opening is set to the initial opening θ ０ to target opening θ １ , θ ３ When moving to the target opening θ １ , θ ３ For example, in the example shown in FIG. 2A, the throttle opening is controlled so as not to exceed the target opening θ １The drive signal of the motor 4 is controlled so that the throttle opening does not become smaller than the target opening θ １ In the example shown in FIG. 3A, the open signal is output before the throttle opening reaches the target opening θ ３ The drive signal of the motor 4 is controlled so that the throttle opening does not exceed the target opening θ ３ A close signal is output before this occurs.

[0037] In this way, the throttle opening is set to the target opening θ １ , θ ３ By adopting a control method that does not exceed this, it is possible to more reliably optimize the output (intake air amount) of the internal combustion engine 1 immediately after the unfreezing control, and improve the ability of the internal combustion engine 1 to follow the target output. In addition, since the throttle opening is not excessively closed or opened, the quality of the throttle valve 2 and drive parts can be improved.

[0038] (3) In the above-described unfreezing control, the drive signal of the motor 4 can be controlled to oscillate at a predetermined frequency. This configuration allows repeated loads to be applied to the ice, facilitating the generation of minute internal fractures. Therefore, the ice that has frozen the throttle valve 2 can be efficiently broken down, and the frozen state can be unfrozen in a short time. Furthermore, the control configuration is simple and easy to implement.

[0039] (4) In the example shown in FIG. 2, the initial opening θ ０ Based on the target opening θ １ The side where the initial opening angle θ exists (closing side) is defined as one side of the opening / closing direction. ０ Based on the target opening θ ３ In any case, the side where the first signal is outputted during one cycle of the drive signal (the opening side) is defined as one side of the opening / closing direction. １ is the output time P of the second signal that moves the throttle opening to the other side. ２ In this way, the throttle opening is set to be longer than the target opening θ １ , θ ３ The output time P of the first signal acts to approach１ By making the time relatively long, the ice can be destroyed efficiently, and the throttle opening can be adjusted to the target opening θ １ , θ ３ can be approached as follows.

[0040] (5) In the example shown in FIG. 2, the target opening θ １ is the initial opening θ ０ The throttle opening is closer to the closed position than the throttle opening at the start of the internal combustion engine 1. Furthermore, the unfreezing control is initiated before the start of the internal combustion engine 1. In this way, by starting to move the throttle opening toward the closed position before the start of the internal combustion engine 1, the amount of intake air immediately after the start of the internal combustion engine 1 can be reduced regardless of the start timing of the internal combustion engine 1, and the internal combustion engine 1 can be prevented from racing more reliably.

[0041] (6) As shown in Figures 2 and 3, in the above-mentioned unfreezing control, the throttle opening is set to the initial opening θ ０ and target opening θ １ , θ ３ In other words, the throttle opening increases or decreases with an amplitude less than the difference in opening from the initial opening θ ０ and target opening θ １ , θ ３ The motor drive signal is controlled so that the amplitude of the opening difference between the ice and the throttle valve is increased or decreased within a range equal to or less than the difference in the opening between the ice and the throttle valve. This configuration allows for efficient destruction of ice and rapid unfreezing. The throttle valve is also prevented from being excessively closed or opened. Furthermore, because the vibration is small, the impact load between the ice and the throttle valve can be reduced, preventing deterioration in the quality of the throttle valve.

[0042] (7) The drive signals shown in Figures 2(B) and 3(B) alternate between an open signal that drives the throttle valve 2 in a direction to open it by a first opening degree and a close signal that drives the throttle valve 2 in a direction to close it by a second opening degree. While the open signal is being output, a close signal is output before the actual throttle opening degree exceeds the first opening degree. Also, while the close signal is being output, an open signal is output before the actual throttle opening degree exceeds the second opening degree.

[0043] This configuration allows the throttle opening to be more reliably and smallly vibrated, breaking up the ice efficiently and unfreezing it in a short time. In addition, because the vibration is small, the impact load between the ice and the throttle valve 2 can be reduced, preventing deterioration of the quality of the throttle valve 2.

[0044] (8) When starting the internal combustion engine 1 while unfreezing control is being performed, the control device 6 can continue the unfreezing control until the termination condition for the unfreezing control is met. In other words, the control device 6 can execute control to start the internal combustion engine 1 while oscillating the drive signal of the motor 4. Here, if the throttle opening is measured for each oscillation period of the drive signal, the throttle opening during the unfreezing control continues to approach the target opening over time and continues to change in a direction that improves the starting stability of the internal combustion engine 1. Therefore, even if the internal combustion engine 1 is started during unfreezing control, the starting stability of the internal combustion engine 1 is not impaired, and the internal combustion engine 1 can be started quickly.

[0045] [3. Other] The above-described embodiments are merely illustrative and are not intended to exclude various modifications or applications of techniques not explicitly described in the present embodiments. Each configuration of the present embodiments can be modified in various ways without departing from the spirit of the present embodiments. Each configuration of the present embodiments can be selected or combined as needed.

[0046] For example, the internal combustion engine 1 to which the throttle control system 3 is applied may be a gasoline engine or a diesel engine. The internal combustion engine 1 may be installed not only in automobiles but also in ships, driving force generating devices, power generating devices, etc. When the internal combustion engine 1 is installed in an automobile, the automobile may be an internal combustion vehicle or a hybrid vehicle.

[0047] Furthermore, although the present embodiment describes control for unfreezing the throttle valve 2, it may also be used as control for unfreezing foreign matter trapped in the throttle valve 2. In other words, the term "frozen" in this specification refers to a state in which the throttle valve 2 cannot move in at least one direction in the opening / closing direction due to a factor other than a malfunction of the throttle valve 2 (foreign matter such as ice trapped in the throttle valve 2).

[0048] The present invention can be used in the manufacturing industry of throttle control systems 3 applied to internal combustion engines 1, and in the manufacturing industry of internal combustion engines 1 to which throttle control systems 3 are applied. It can also be used in the manufacturing industry of automobiles, ships, driving force generating devices, power generating devices, etc., to which internal combustion engines 1 to which throttle control systems 3 are applied are mounted.

[0049] 1 Internal combustion engine 2 Throttle valve 3 Throttle control system 4 Motor 5 Opening sensor 6 Control device θ ０ Initial opening θ １ , θ ３ Target opening P １ First signal output time P ２ Second signal output time

Claims

1. A motor that drives the opening and closing of the throttle valve of an internal combustion engine, The motor is controlled by a control device, When the control device detects freezing of the throttle valve, it performs a freeze-release control that repeatedly increases and decreases the throttle opening by vibrating the motor drive signal between open and closed positions, thereby moving the throttle opening from the initial opening to the target opening. In the defreezing control described above, as the throttle opening is repeatedly increased or decreased, the throttle opening approaches the target opening. A throttle control system characterized by the following.

2. In the defreezing control described above, when the throttle opening moves from the initial opening to the target opening, it is controlled so as not to exceed the target opening. The throttle control system according to claim 1, characterized in that...

3. In the aforementioned defreezing control, the motor drive signal oscillates at a predetermined period. The throttle control system according to claim 1, characterized in that...

4. The target opening is located on one side of the opening / closing direction compared to the initial opening. In one cycle of the drive signal, the output time of the first signal that moves the throttle opening to one side is set to be longer than the output time of the second signal that moves the throttle opening to the other side. The throttle control system according to claim 1, characterized in that...

5. The target opening is closer to the closed position than the initial opening. The defreezing control is initiated before the start of the internal combustion engine. The throttle control system according to claim 1, characterized in that...

6. In the defreezing control described above, the throttle opening increases or decreases with an amplitude less than or equal to the difference in opening between the initial opening and the target opening. The throttle control system according to claim 1, characterized in that...

7. The drive signal consists of alternating signals: an open signal that drives the throttle valve to open to a first opening and a close signal that drives the throttle valve to close to a second opening. During the output of the open signal, the closed signal is output before the actual opening degree of the throttle valve reaches the first opening degree. During the output of the closed signal, the open signal is output before the actual opening degree of the throttle valve reaches the second opening degree. The throttle control system according to claim 1, characterized in that...

8. If the control device starts the internal combustion engine while the defreezing control is being performed, the defreezing control will continue until the termination condition for the defreezing control is met. The throttle control system according to claim 1, characterized in that...