JPH04295138A - Throttle valve controller of engine - Google Patents

Abstract

PURPOSE:To prevent any shift of an air-fuel ratio by means of rapid operation of a throttle valve when delay of transportation of fuel is large, in an engine provided with a throttle valve which is operated in opening/closing by a throttle valve driving means. CONSTITUTION:A transportation delay detection means 31 which detects any transportation delay of fuel, and a control means 32 which controls a throttle valve driving means so as to make opening/closing operation of a throttle valve slower when the transportation delay of the fuel is large, than that when transportation delay is small in response to the detection by the transportation delay detection means.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine throttle valve control device for controlling a throttle valve provided in an intake passage and opened and closed by a throttle valve driving means.

0002

[Prior Art] Conventionally, an engine throttle valve control device has been used in which a throttle valve provided in an intake passage is driven by an electric actuator such as a motor, and the throttle valve is electrically controlled by a control unit. Various types are known. In this type of device, the accelerator operation amount is detected and the throttle opening degree is controlled accordingly, but there are also devices in which the throttle opening degree is further corrected in accordance with other factors. For example, JP-A-61-
The device disclosed in Japanese Patent No. 87938 corrects the throttle opening according to the engine temperature so that the lower the engine temperature, the larger the throttle opening. This is done in order to increase the engine output at low temperatures, when combustibility tends to deteriorate.

0003

[Problems to be Solved by the Invention] As mentioned above, there are systems in which the throttle opening is corrected in order to adjust the engine output depending on the engine temperature, etc., but the delay in fuel transportation has not been sufficiently considered in the past. It wasn't. In other words,
If the fuel has poor volatility or tends to adhere to the intake pipe, there will be a significant transport delay for the fuel supplied from the fuel injection valve etc. to reach the combustion chamber. When the opening of the throttle valve changes suddenly due to depression of the accelerator pedal during acceleration, the fuel does not follow the corresponding increase in the amount of intake air, and the air-fuel mixture sent into the combustion chamber becomes lean. There was a problem that drivability deteriorated.

[0004] The present invention solves the above problem, and aims to maintain good drivability by preventing the air-fuel ratio from shifting due to sudden throttle valve operation when there is a large delay in fuel transportation. The purpose of the present invention is to provide an engine throttle valve control device that can perform the following functions.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an engine that is equipped with a throttle valve in an intake passage and a throttle valve drive means that opens and closes the throttle valve. A transportation delay detection means detects a fuel transportation delay by detecting a parameter related to the transportation delay detection means, and according to the detection by the transportation delay detection means, when the fuel transportation delay is large, the above-mentioned and control means for controlling the throttle valve driving means so as to slow down the opening and closing operations of the throttle valve.

It is preferable that the transportation delay detection means detects a transportation delay related to the vaporization state of the fuel. For example, this transportation delay detection means detects the volatility of fuel, and detects a fuel transportation delay based on this volatility. Alternatively, detect the amount of fuel adhering to the intake pipe,
A delay in fuel transportation is detected based on the amount of fuel adhering to the intake pipe. Alternatively, a delay in fuel transportation may be detected by checking the vaporization state of the fuel based on the engine temperature.

[0007]

[Operation] According to the above configuration, when the accelerator operation amount changes due to acceleration operation etc. under a situation where there is a large fuel transport delay, the corresponding change in throttle opening becomes slower, resulting in a fuel transport delay. The increase in intake air amount becomes gradual to correspond to the above.

[0008]

[Embodiment] An embodiment of the present invention will be explained based on the drawings. FIG. 1 shows an outline of the entire device. In this figure, each cylinder of an engine body 1 has a combustion chamber 3 above a piston 2.
is formed. The combustion chamber 3 is equipped with a spark plug 4, and has an intake port communicating with an intake passage 5 and an exhaust port communicating with an exhaust passage 6. These ports are connected to an intake valve 7 and an exhaust valve 8. is opened and closed.

In the intake passage 5, a fuel injection valve 9 is provided near the intake port on the downstream side thereof, and a throttle valve 10 is provided upstream thereof. This throttle valve 10 is driven by an electric actuator 11 such as a servo motor, and with respect to this actuator 11,
An electric throttle driver 12 is provided that controls energization according to a control signal. The above actuator 11
and the electric throttle driver 12 constitute a throttle valve driving means.

Reference numeral 15 denotes a control unit for controlling the throttle valve 10, which includes an input port 16, an output port 17, a CPU 18, a RAM 19, a ROM 20, etc., and is formed using a microcomputer or the like. The control unit 15 includes an air flow meter 21 provided in the intake passage 5 to detect the amount of intake air, a rotation speed sensor 22 to detect the engine speed, and an accelerator pedal to detect the accelerator operation amount (the amount of depression of the accelerator pedal 13). Signals are input from a sensor 23, a throttle opening sensor 24 that detects the opening of the throttle valve 10, a water temperature sensor 25 that detects the temperature of engine cooling water, a starter switch 26 that detects the operation of the starter, and the like. A signal for operating the throttle valve 10 is output from the control unit 15 to the electric throttle driver 12.

The block diagram in FIG. 2 functionally represents the configuration of the control system. In this figure, the control unit 15 has a function as a transport delay detection means 31 that detects a delay in fuel transport, and a control means 32 that changes the opening and closing operation of the throttle valve in response to the detection of this transport delay. In this embodiment, the transportation delay detection means 31 is configured to check the volatility of the fuel and detect transportation delays due to poor volatility. Specifically, as will be described in detail later, it is determined whether the fuel is a light fuel with good volatility or a heavy fuel with poor volatility by examining the fluctuations in engine speed immediately after starting. Furthermore, since even heavy fuel becomes more volatile at high temperatures and the difference from light fuel becomes smaller, water temperature is also taken into consideration, and cases where heavy fuel is used at low temperatures are identified as cases where transport delays will be large. are doing.

Furthermore, the control means 32 is designed to slow down the throttle valve opening/closing operation by changing the throttle opening characteristic with respect to the accelerator operation amount when the transportation delay becomes large due to poor fuel volatility. . In other words, the throttle valve is controlled by outputting a control signal to the throttle driver 12 to set the throttle opening according to the accelerator operation amount based on a throttle opening characteristic in which the relationship between the accelerator operation amount and the throttle opening is determined in advance. However, two types of throttle opening characteristics shown in lines A and B in FIG. 3 are preset and stored in the control unit 15. Among these, the first throttle opening characteristic shown by line A has a relatively large rate of change in throttle opening with respect to change in accelerator operation amount, and
In the second throttle opening characteristic indicated by line B, the throttle opening change rate with respect to a change in the accelerator operation amount is smaller than in the first throttle opening characteristic. When the volatility of the fuel is good, the first throttle opening characteristic is selected, whereas when the volatility of the fuel is poor, the second throttle opening characteristic is selected.

Specific examples of control by the control unit 15 are shown in the time chart of FIG. 4 and the flow charts of FIGS. 5 to 7.

FIG. 5 shows a routine for determining heavy fuel related to the function of the transport delay detection means 31, which determines whether or not the fuel is heavy fuel by examining fluctuations in engine speed immediately after starting. The outline of this process will be explained using the time chart of FIG. 4. At the time of starting, the engine speed increases once, and after starting, the engine speed decreases to some extent. In this case, if light fuel is used, the rotational speed change will be gradual after falling below the predetermined rotational speed (first reference rotational speed) N1 (dashed line 41), whereas if heavy fuel is used If the rotation speed is lower than the first reference rotation speed N1 due to deterioration of the combustion state, the rotation speed will rapidly decrease (solid line 42), and the second reference rotation speed (lower than the first set rotation speed N1) will occur within the predetermined time Ta. (rotational speed lower by a predetermined amount) to below N2. This rotational speed fluctuation is investigated using the routine shown in FIG.

When the routine shown in FIG. 5 starts, the control unit 15 first determines the start by checking the engine speed signal and the starter switch signal, and sets the start flag Fst to "1" if it is the start. Steps S1, S2). Next, in step S3, the engine speed Ne is read, and in step S4, it is determined whether the engine speed Ne has become lower than the first reference speed N1. If this determination is NO, the process directly returns to step S1.

If the determination in step S4 is YES, it is determined in step S5 whether or not the start flag Fst is "1". When the start flag Fst is "1", this flag Fst is set to "0" in step S6, a predetermined time Ta is set in the timer T, and the flag Fst is set to "0".
When becomes "0", the timer T is decremented in step S8 unless the timer T becomes "0" as determined in step S7. That is, when the engine speed falls below the first reference speed N1 after starting, a predetermined time Ta is set in the timer T, and then this time is counted down.

Further, in step S9, the engine rotation speed N
It is determined whether or not e is lower than the second reference rotation speed N2. While the engine rotational speed is equal to or higher than the second set rotational speed N2, the countdown of the timer T is repeated by returning from step S9 to step S1 and repeating the processing from step S1. Then, if the engine rotation speed Ne is maintained at the second reference rotation speed N2 or more until the predetermined time elapses, the determination in step S7 becomes YES,
In this case, the heavy flag Fh is set to "0" in step S10.
It is said that On the other hand, when the engine speed Ne becomes lower than the second reference speed N2 during the predetermined time, step S1
1, the heavy flag Fh is set to "1".

FIG. 6 shows a routine for auxiliary volatility determination based on water temperature. In this routine, the water temperature K is read in step S12, and the water temperature K is set to a predetermined temperature K in step S13.
Check whether it is higher than a. When the water temperature K is below the predetermined temperature Ka, the routine returns without changing the value of the heavy flag Fh determined in the routine of FIG. 5, but when the water temperature K becomes higher than the predetermined temperature Ka, the step In S14, the heavy flag Fh is set to "0".

FIG. 7 shows a throttle valve control routine based on the determination in the routines of FIGS. 5 and 6. When this routine starts, the heavy flag Fh is set in step S15.
It is determined whether or not is "1". And heavy flag Fh
is "0", in step S16, the first throttle opening characteristic is selected, and the throttle valve is controlled according to the accelerator operation amount based on this characteristic, thereby adjusting the throttle opening characteristic in response to changes in the accelerator operation amount. Increase the opening change rate. On the other hand, when the heavy flag Fh is "1",
In step S17, the second throttle opening characteristic is selected and the throttle valve is controlled according to the accelerator operation amount based on this characteristic, thereby reducing the throttle opening change rate with respect to the change in the accelerator operation amount, In other words, the operation of the throttle valve 10 is slowed down.

According to the apparatus of this embodiment as described above, by checking the degree of drop in the engine speed immediately after the engine is started in the routine shown in FIG. 5, it is possible to correctly determine whether the fuel is light fuel or heavy fuel. . Based on this determination and the temperature determination in the routine shown in Figure 6, if a light fuel with good volatility is being used, or even if heavy fuel is being used, the volatility will be poor due to the high temperature. When the
The throttle valve 10 is controlled according to the accelerator operation amount based on the throttle opening characteristic. On the other hand, when heavy fuel is used and the engine temperature is low, the volatility of the fuel is poor and transportation delays are large, the first throttle opening characteristic changes the amount of accelerator operation. The throttle valve 10 is controlled accordingly. Therefore, when volatility is poor, when the accelerator pedal is depressed, the increase in throttle opening will be gradual in response to the increase in the amount of accelerator operation, and the amount of intake air will increase to compensate for the delay in fuel transport. becomes slow. This prevents the air-fuel ratio from becoming lean.

FIGS. 8 to 11 show a second embodiment. In this embodiment, the amount of fuel adhering to the intake pipe is detected, and a delay in fuel transportation is determined based on this. In other words, when the amount of fuel adhering to the intake pipe is small, even if the amount of fuel is increased in response to an increase in the amount of intake air during acceleration, much of it will adhere to the intake pipe, resulting in greater transportation delays. As the amount of fuel adhering to the intake pipe is related to transportation delays, this is used as a parameter. In this embodiment as well, a device as shown in FIG. 1 is used as a hardware configuration, but in addition to controlling the throttle valve 10, the control unit 15 outputs a control signal (injection pulse) to the fuel injection valve 9. and control unit 15
calculates the amount of fuel adhering to the intake pipe while controlling the fuel injection amount according to the intake air amount and the like. As shown in FIG. 8, when the amount of fuel adhering to the intake pipe is large, a throttle opening characteristic is selected in which the rate of change in throttle opening relative to the change in accelerator operation amount is relatively large. When the amount is small, the throttle valve opening/closing operation is slowed down by selecting a throttle opening characteristic in which the rate of change in throttle opening with respect to change in accelerator operation amount is relatively small.

The method of determining the amount of fuel adhering to the intake pipe in this embodiment will be summarized with reference to FIGS. 9 to 11.

As shown in FIG. 9, the fuel injected from the fuel injection valve 9 is divided into an adhering portion F1 that adheres to the wall surface of the intake pipe and a direct amount F2 that is directly sucked into the combustion chamber 3. on the other hand,
The fuel that had adhered to the intake pipe vaporizes and enters the combustion chamber 3.
The fuel is separated into a carried away fuel portion F3 which is inhaled by the fuel, and a residual fuel portion F4 which remains without being vaporized. Therefore, the actual combustion chamber 3
The amount of fuel supplied to the engine is F2+F3, and the amount of fuel adhering to the intake pipe is F1+F4. In addition, the direct injection rate α is the proportion of the directly injected portion F2 of the fuel injected from the fuel injection valve 9, and the removal rate β is the proportion of the above-mentioned removed portion F3 of the fuel adhering to the intake pipe. is determined by the intake air flow rate, temperature, injection timing, etc. For example, when injecting during the intake stroke, Figure 1
0, the characteristics are as shown in FIG. Therefore, such characteristics are experimentally investigated in advance and stored in the control unit 15 as a map, and the above-mentioned direct entry rate α and removal rate β are determined from these maps. As shown, the amount of fuel adhering to the intake pipe is determined.

To specifically explain the calculation and control processing of this embodiment, in the fuel control and calculation routine shown in FIG. Find the filling efficiency Ce from the above, and calculate the intake flow velocity Qc at the fuel injection valve location from this filling efficiency Ce and the engine rotation speed, etc.
Calculating y Subsequently, in steps S23 and S24, the direct entry rate α and removal rate β are calculated from maps such as those shown in FIGS. 10 and 11, based on the intake air flow rate Qcy, water temperature, and the like. Subsequently, in step S25, the fuel injection amount (injection pulse width) is calculated. For this calculation, for example, the basic injection amount is determined according to the intake air amount and the engine speed, and the required injection amount is determined from this and various correction amounts. , the final injection amount is calculated so that the amount of fuel actually supplied to the combustion chamber is the required amount. Following this calculation, injection is executed in step S26.

Further, in step S27, the amount of fuel injected from the fuel injection valve 9 τe and the amount of fuel already attached to the intake pipe (value determined in the previous process) τma
The amount τm of fuel adhering to the intake pipe is determined from the above-mentioned direct injection rate α and removal rate β using the following equation.

τm = (1-α)・τe + (1-β)・τma Furthermore, in the routine for throttle valve control in FIG. 13, in step S28, the intake pipe obtained by the calculation in step S27 The amount of adhering fuel τm is read, and then in step S29, the throttle opening characteristic is set in accordance with the amount τm of the fuel adhering to the intake pipe. In this case, Figure 8
As shown in the figure, the throttle opening characteristic may be switched in two stages depending on whether the amount of fuel adhering to the intake pipe τm is large or small, or the throttle valve operation becomes slower as the amount τm of fuel adhering to the intake pipe decreases. The throttle opening characteristic may be changed in multiple stages so as to achieve the following.

In this embodiment as well, when the amount of fuel adhering to the intake pipe is small and transportation delays become large, the operation of the throttle valve in response to accelerator operation during acceleration is slowed down, thereby reducing the air-fuel ratio. Leanness is prevented.

In addition to the above-mentioned embodiments, the control for slowing down the throttle valve opening and closing operation when the transportation delay is large based on the detection of parameters related to the fuel transportation delay is as shown in FIG. , the throttle opening characteristic may be changed depending on the engine temperature. In other words, in this example, the engine temperature is checked using a water temperature sensor, etc., without determining the weight of the fuel, and since the transportation delay becomes large when the engine temperature is low, the throttle opening is not performed when the engine temperature is low. Compared to the throttle opening characteristic when the engine temperature is high, the throttle opening characteristic has a smaller rate of change in the throttle opening with respect to the accelerator operation amount.

[0029]

[Effects of the Invention] As explained above, according to the present invention,
Delays in fuel transportation are detected by detecting parameters related to delays in fuel transportation, and when the transportation delay is large, the throttle valve drive means is configured to make the opening and closing operations of the throttle valve slower than when the transportation delay is small. Because of this control, when there is a large fuel transport delay, even if the amount of accelerator operation changes suddenly during acceleration, etc., the change in intake air amount will be gradual to compensate for the fuel transport delay. ,
Deterioration of drivability due to leaner driving can be prevented.

Furthermore, if a transport delay related to the vaporization state is detected by, for example, detecting the volatility of the fuel, checking the amount of fuel adhering to the intake pipe, or checking the engine temperature, these vaporization states can be detected. By properly detecting transport delays using parameters related to the above and controlling the throttle valve accordingly, it is possible to appropriately prevent a lean shift in response to transport delays due to deterioration of the vaporization state.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of the overall structure of the device of the present invention.

FIG. 2 is a functional block diagram of a control system.

FIG. 3 is a diagram showing the relationship between throttle opening characteristics.

FIG. 4 is a time chart showing fluctuations in engine speed immediately after engine startup.

FIG. 5 is a flowchart showing a routine for determining heavy fuel.

FIG. 6 is a flowchart showing a routine for determining volatility based on water temperature.

FIG. 7 is a flowchart showing a throttle valve control routine.

FIG. 8 is a diagram showing throttle opening characteristics that can be changed depending on the amount of fuel adhering to the intake pipe according to the second embodiment.

FIG. 9 is an explanatory diagram showing the state of fuel in the intake passage.

FIG. 10 is a diagram showing the direct fuel injection rate.

FIG. 11 is a diagram showing the fuel removal rate.

FIG. 12 is a flowchart showing a fuel control and calculation routine according to the second embodiment.

FIG. 13 is a flowchart showing a throttle valve control routine according to the second embodiment.

FIG. 14 is a diagram showing throttle opening characteristics that can be changed depending on engine temperature in the third embodiment.

[Explanation of symbols]

5 Intake passage 9 Fuel injection valve 10 Throttle valve 11 Actuator 12 Electric throttle driver 15 Control unit 31 Transport delay detection means 32 Control means

Claims (5)

[Claims] 1. In an engine equipped with a throttle valve in an intake passage and a throttle valve drive means for opening and closing the throttle valve, a delay in fuel transport is detected by detecting a parameter related to the delay in fuel transport. and a throttle valve driving means so as to make the opening/closing operation of the throttle valve slower when the fuel transportation delay is large compared to when the transportation delay is small, according to the detection by the transportation delay detection means. 1. A throttle valve control device for an engine, comprising a control means for controlling the throttle valve. 2. The engine throttle valve control device according to claim 1, wherein the transportation delay detection means detects a transportation delay related to the vaporization state of the fuel. 3. The engine throttle valve control according to claim 2, wherein the transportation delay detection means detects the volatility of the fuel, and detects the fuel transportation delay based on this volatility. Device. 4. The transportation delay detection means detects the amount of fuel adhering to the intake pipe, and detects the delay in transporting the fuel based on the amount of fuel adhering to the intake pipe. engine throttle valve control device. 5. The engine throttle valve control device according to claim 2, wherein the transportation delay detection means detects a fuel transportation delay by checking the vaporization state of the fuel based on the engine temperature.