JPS6356417B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an intake air amount control device for controlling the amount of intake air when an internal combustion engine is idling immediately after starting, and particularly relates to setting an idling target rotation speed immediately after starting. Recently, in order to improve the exhaust purification performance and fuel efficiency of automobiles, it has become necessary to precisely control the rotation speed during idling. For this purpose, the target rotation speed is determined according to engine operating conditions such as engine temperature,
A device has been developed that performs feedback control of the amount of intake air so that the actual rotation speed matches the target rotation speed. However, the standard target rotation speed is determined to suit the specific operating conditions of the vehicle, and for example, the target rotation speed for a vehicle with an automatic transmission in the neutral position and with the air conditioner turned off is determined based on the cooling water temperature at that time. It has been established for Therefore, conditions different from those mentioned above, e.g.
It is necessary to determine a target rotation speed that matches the vehicle's current conditions by changing the reference target rotation speed depending on the manual transmission, drive position, cooling device ON condition, or a combination thereof. Furthermore, in order to adapt the target rotation speed determined as described above to the environmental conditions of the place of use, it is desirable to be able to change the target rotation speed as a whole using an external terminal. Further, when the battery voltage of the vehicle decreases, it is desirable to increase the minimum value of the target rotation speed for a certain period of time in order to effectively utilize the generator performance. The present invention sets a reference target rotation speed for idling rotation at the beginning of engine startup with respect to water temperature, and when the battery voltage drops, the target rotation speed is set for a predetermined time only in the case of a real overdischarge, not a temporary drop due to load fluctuation etc. It is an object of the present invention to provide a control device that increases a rotation speed set value. In order to achieve the above object, in the present invention, when the battery voltage continues to decrease for a predetermined period of time or more and decreases below the standard value, it is determined that there is no temporary drop or disturbance due to load fluctuation, etc., and only in that case, the predetermined period of time is determined. The configuration is such that the power generation function is improved by increasing the set value. Further, according to the embodiment of the present invention, different target rotational speeds are set for each of eight different combinations of automatic or manual transmission, drive and neutral transmission, and air conditioner on/off. This makes it possible to adapt to all mutually different requirements and to avoid excessive modifications so that no additional drawbacks arise due to duplicate modification requests. Furthermore, according to another embodiment of the present invention, the reference target rotation speed can be accurately changed in units of 50 rpm using an external terminal. The present invention will be explained in detail below based on the drawings. FIG. 1 is an embodiment diagram showing the overall configuration of the present invention, and shows a case where the present invention is applied to an internal combustion engine equipped with an electronically controlled fuel injection device. In Fig. 1, reference numeral 1 denotes the internal combustion engine main body, intake air is supplied from an air cleaner 2 to each cylinder via an air flow meter 3, a throttle chamber 4, and each branch of an intake manifold 5, and fuel is supplied to each cylinder from a fuel injector 6. is injected by. Here, the flow of intake air is controlled by a throttle valve 7 in a throttle chamber 4 that is linked to an accelerator pedal.
The throttle valve 7 is almost closed during idling. The flow of air during idling passes through the bypass port 8 and is regulated by the idle adjustment screw 9 installed therein, and also passes through the bypass passage 10 that communicates the upstream and downstream sides of the throttle valve 7, and is Interposed idle control valve 1
1 ensures the appropriate amount of air. The idle control valve 11 includes a valve body 12 interposed in the bypass passage 10, a diaphragm 13 to which the valve body 12 is connected, and a negative pressure operating chamber 15 equipped with a spring 14 that biases the diaphragm 13. The amount of lift of the valve body 12 by the diaphragm 13 is changed in response to an increase or decrease in the negative pressure introduced into the negative pressure working chamber 15, and its opening degree is decreased or increased. This negative pressure working chamber 15 communicates with the intake passage downstream of the throttle valve 7 via a constant pressure valve (pressure regulator valve) 17 through a negative pressure introduction passage 16, and also communicates with the pulse solenoid valve 1 through an atmosphere introduction passage 18.
It communicates with the intake passage upstream of the throttle valve 7 via the throttle valve 7 . Thus, by opening and closing the pulse solenoid valve 19, the degree of opening of the idle control valve 11 is controlled by changing the dilution ratio of the negative pressure introduced into the negative pressure working chamber 15 with the atmosphere. The pulse solenoid valve 19 is controlled by a microcomputer 20, for example. The microcomputer 20 mainly includes a microprocessor (central processing unit) 21, a memory (storage device) 22, and an interface (input/output signal processing circuit) 23. The rotational speed of the internal combustion engine 1 is detected by an electromagnetic pick-up type rotational speed sensor 24 and input to the interface 23 of the microcomputer 20 as a digital signal (actually, the unit angle obtained from the rotation of the crankshaft by the crank angle sensor) At the same time, the engine temperature of the internal combustion engine 1, for example, the cooling water temperature, is detected as an analog signal by the thermistor-type water temperature sensor 25, and is converted into a digital signal via the A/D converter 26. Input as a signal. The interface 23 also includes a throttle valve switch 27 that detects that the throttle valve 7 is in the fully closed position, a neutral switch 28 that detects that the transmission is in the neutral position, and a switch that detects when the vehicle speed is at a predetermined value, e.g. ON and OFF signals are respectively input from a vehicle speed switch 29 which detects that the vehicle speed is 8 km/h or less. In FIG. 1, the throttle valve switch 27 is an analog sensor using a variable resistor.
Although the signal is shown inputted via the A/D converter 30, the on/off signal that detects the fully closed position is
An off-type switch may also be used. Further, the memory 22 stores in advance an optimal target rotation speed N _SET (target rotation speed during idling) corresponding to engine operating conditions such as engine temperature. The microprocessor 21 determines the current operating state based on the signal from the water temperature sensor 25, etc., reads out the corresponding target rotation speed _NSET , and also determines the actual rotation speed N based on the signal given from the rotation speed sensor 24. Calculate _RPM and find the deviation △N between N _SET and N _RPM
(△N=N _RPM −N _SET ) is detected. Next, the microprocessor 21 calculates the actual rotational speed.
Control constants, that is, proportional constants and integral constants are set according to N _RPM and the deviation △N, a control value is calculated from these control constants and the deviation △N, and the pulse solenoid valve 19 is operated according to the control value. The actual rotation speed can be adjusted by changing the duty of the driving pulse signal.
Feedback control is performed on the intake air amount so that N _RPM matches the target rotation speed N _SET . Further, the microprocessor 21 determines whether or not to perform the above-mentioned feedback control according to the states of the throttle valve switch 27, neutral switch 28, vehicle speed switch 29, etc., whether or not there is a fuel cutoff, and performs the feedback control. Only when it is determined that this is the case, the duty of the pulse signal is changed to perform feedback control, and in other cases, open loop control is performed. Figure 2 is a characteristic diagram showing various relationships between cooling water temperature and target rotational speed during feedback control. The value, that is, the duty of the pulse signal is changed according to the cooling water temperature. Note that in open-loop control, feedback control is not performed to match the actual rotation speed and the target rotation speed, so even if the control value is set as described above, the actual rotation speed will not be as shown in Figure 2. It does not exactly match the characteristics. However, there is a predetermined relationship between the actual rotation speed, operating conditions (for example, cooling water temperature), and control values, and it is important to know how much control should be used to achieve a certain rotation speed in a certain operating condition. Since it is known whether the rotation speed is good or not, by setting the control amount to that value, it is possible to obtain almost the desired rotation speed. Specifically, control values corresponding to the temperature are stored in advance as a data table in the ROM (read-only memory) in the memory 22 shown in FIG. and read out the corresponding control value. By controlling in this way, even if you start driving immediately after a cold start without warming up, the control value will decrease as the engine warms up while driving.
When the vehicle enters an idling state thereafter, there is no fear that the idling speed will become abnormally high. In Figure 2, the standard target rotation speed setting value is
It is a polyline marked AT, A/C, OFF, N,
This is an engine with an automatic transmission AT and a cooling system A/
The case of the neutral N range when C is turned off is shown. Since it is necessary to change the set value of the target rotation speed depending on whether the equipment of the automobile, equipment such as an air conditioner, etc. is connected, and whether the transmission is connected at that time, in the present invention, various conditions The setting value is changed according to the following. The basic idea of the present invention is as follows. Firstly, an automatic transmission with an A/T does not have a clutch, whereas a manual transmission with an M/T has a large load fluctuation when the clutch is engaged. Assuming the rotation speed is +50rpm
Set to 650rpm. Second, if the vehicle is in the DRIVE range after starting, it is determined that the neutral switch is off. At this time, if the automatic transmission is equipped with an A/T, there is a tendency for the vehicle to creep, that is, the vehicle starts to move, and to reduce this, the speed is set to 800 rpm or less regardless of the water temperature. Manual transmission M/
In the case of a T-equipped engine, the speed is set at 800 rpm or less, in order to reduce the shock at the start of running, and to prevent the rotation from dropping if the clutch is engaged while the rotation is still high, causing feedback and causing excessive rotation. In the case of neutral, the target rotation speed is set high at cold start, lowered when the engine is sufficiently warmed up, and set higher for rapid cooling when there is a tendency for overheating. Third, it determines whether the cooling system is on or off, and if it is on, it is used to stabilize operation and improve cooling capacity.
The speed should be 800rpm or more. However, in the case of a drive range with automatic transmission AT, the maximum speed is 800 rpm to prevent creep, and in the steady water temperature range it is 700 rpm. The above control criteria are summarized as shown in Table 1 below.

[Table] In the above table, drive indicates 1st, 2nd, D, and R ranges for automatic transmission AT, and 1st to 5th speeds and R for manual transmission MT. Also, neutral means N, P
Indicates range. Clutch on/off is irrelevant. Figure 2 is a table of basic water temperature and target rotation speed, that is, the lines AT, A/C, OFF, N in Figure 2.
This figure shows various characteristics obtained by making the above-mentioned modifications. FIG. 3 shows a flowchart for correcting the various target rotational speeds described above. First, P1 is the setting of the basic target rotation speed of the engine's idling rotation, and is based on the table of basic target rotation speed and water temperature, that is, the line AT・A/C・
Look up the digital value table for the OFF/N line regarding water temperature and send it to the A register. Next, check the transmission type at P2. If automatic transmission AT, bypass to P4, manual transmission
If it is MT, set the value stored in the A register to the lowest value at P3.
Correct to 650rpm. At P4, check whether the air conditioner is on or off.
If it is off, go to P9. If it is on, check the transmission type again in P5, and if it is a manual transmission MT, go to P8. When the automatic transmission is AT, check whether it is neutral in P6, in this case, check whether the neutral switch is on or off, and when in the drive range (when it is off), modify the contents of the A register in P7 and set the speed above 700 rpm. do. P8 when the neutral switch is on
, modify the A register to set it to 800 rpm or more. Here, check again if it is neutral, and if it is neutral,
Go to P11, and when in drive range, modify the A register in P10 to set it to 800 rpm or less. By the above procedure, the seven lines shown in Figure 2 are created, and when the cooling system A/C is on, the engine operation is stabilized at 700 rpm or more, and when the drive range is set, the maximum speed is 800 rpm when starting. Prevent shots. Also, as shown in Figure 3, when the A/C is off with AT, it goes from P2 and P4 to P9, and when it is neutral at P9, it goes to P11, so the target rotation speed that is not subject to any correction during this period is the A register. stored inside. The last step, P11, is the modification of the contents of the A register using an external terminal, which will be described later. Next, in order to increase the amount of power generated by the generator when the battery voltage drops, the idling speed is increased for a certain period of time. Specifically, when the battery voltage is 12V or less, the repetition timing of the flowchart in Fig. 4, for example, one rotation of the engine or a certain period of time, is determined.
If it continues 16 times in units of 0.1 seconds, the third
Target rotation speed corrected according to the flowchart shown in the figure.
Add 100 rpm to N _SET for 5 minutes without exceeding 800 rpm. This is called speed increase in the flowchart of FIG. The program shown in FIG. 4 is a repetition of one rotation or 0.1 seconds, and for convenience of explanation, the explanation will begin by checking whether the battery voltage of P29 on the right side is 12V or higher. If the battery is at a steady voltage in P29, the speed will not increase in P30. If the voltage is insufficient, 1 is added to the counter by P31. This counter is cleared when it reaches 16, and the speed increase start signal is sent by P32.
It is supplied to P21, and at the same time the timer of P22 starts running. If the battery voltage rises before the P31 counter reaches 16, the counter is cleared to prevent activation due to a temporary drop or false signal. When P21 receives the speed increase start signal mentioned above, the following
At P22, check whether the timer has exceeded 5 minutes, and when 5 minutes have passed, the next P23 will signal the end of speed increase at P21.
Supplied to P32. In addition, if the speed is not increasing or if the timer is within 5 minutes, it is determined in P24 whether the target rotation speed N _SET according to the water temperature at that time is 800 rpm or more,
If the speed is 800rpm or higher, there is no need to increase the speed. N _SET
If it is below 800rpm, check whether the speed has started increasing in the next P25, and if it has not started, check the battery voltage in the aforementioned P29. If it is a signal to start increasing speed, the target rotation speed N _SET is increased by 100 rpm in the next P26. Furthermore, as explained with reference to FIG. 3 above,
If the speed exceeds 800 rpm, problems such as creep and start shock will occur, so the new N _SET will be set at 800 rpm in the next P27.
If it exceeds 800rpm, use P28 to reduce it to 800rpm. By using the above program, it is possible to reliably know the drop in battery voltage, which often fluctuates temporarily, and increase the target rotation speed by 100 rpm within the range up to 800 rpm, thereby making effective use of the generator. Next, the external terminal modification described in P11 of the program in FIG. 3 will be explained. In the case of a normal engine without feedback control, the idle speed can be manually set arbitrarily, but when using feedback control, it is necessary to change the control setting value, and this is achieved in the following way in the present invention. Ru. As shown in Figures 2 and 3 above, the target idling speed is determined as a function of the water temperature, and is determined by whether the transmission is an automatic transmission AT or a manual transmission MT, and whether the transmission is in drive or neutral position. The target rotation speed setting value N _SET is determined depending on whether the cooling device A/C is on or off. This allows the control unit to control the target rotation set value N _SET .
The voltage at the ISCV terminal is varied within the range of 0 to 5 V using an adjustment resistor, and N _SET is shifted to the high rotation side over the entire range of FIG. 2. Figure 5 shows an example of the register for setting the rotation speed measurement used in the above calculation. The figure shows the equivalent rotational speed of each bit. Further, FIG. 5B is a register for the target rotation setting value _NSET , and since it is 8 bits and 1 byte, the maximum rotation speed setting value is about 3200 rpm. In addition, Figure 6A shows the ISCV for external correction mentioned above.
This is a diagram showing an IVAR register that A/D converts and stores terminal voltage. Since 1 bit is 20 mV, the maximum storage capacity is approximately 5V. In addition, the manual change of the rotation set value N _SET is shown in Figure 6B.
It is preferable to use the step-by-step settings shown in the table below. The target voltage in this case is the value shown above in Figure 6B,
0.64, 1.92, 3.20, 4.48V. However, in reality, a deviation occurs between the target voltage and the voltage actually stored in the IVAR register due to A/D conversion errors, resistance variations, and the like. However, it is desirable to change the rotation setting value N _SET accurately in units of 50 rpm, as shown in FIG. 6B, for example. Since this rotation set value N _SET serves as a reference for control, if it is not accurate, it will be impossible to judge whether the subsequent control is being performed correctly. In this embodiment, the above-mentioned rotation speed can be set accurately by the following procedure. First, the result of A/D conversion of the voltage measurement value is
Assume that the value of the IVAR register is, for example, the value shown in FIG. 71. The logical product addition of the values shown in FIG. 7 and 2 is performed on this value. As a result, the values shown in FIG. 73 are obtained, and the third and subsequent digits from the left in FIG. 71 are deleted.
Next, 0 is inserted from the left into the value shown in FIG. 73 and shifted to the right by 4 bits, resulting in the value shown in FIG. 74. Add this value to the N _SET register shown in Figure 5B. Since the numbers A and B are 1 or 0, if it is 0100,
50rpm, 100rpm for 1000, 150rpm for 1100
The addition result is obtained. An example of the above calculation is shown in Table 2 below. This table is an example when +100rpm is desired, that is, when the input voltage target value is 3.2V, N _SET
is 600rpm. In Example 1, the recorded value of the IVAR register is 2.8V, which is deviated from the target value, and in Example 2, it is 3.2V, which is equal to the target value.

[Table] As can be seen from Table 2 above, the result of logical product addition is independent of variations in measured values, and the result of addition in the N _SET register is exactly the required 100 rpm addition. As clarified in the above process, the voltage value range to be measured may be an intermediate value of the wide range of values shown in FIG. 6B, so that there is no influence of error. As explained above, in the present invention, when the battery voltage continues to drop for a predetermined period of time, the minimum rotation speed is increased for a predetermined period of time, so that the power generation function is maintained only in the case of a true overdischarge, which is not a temporary drop due to load fluctuations, etc. Therefore, there is no risk of the engine speed increasing unnecessarily and reducing fuel efficiency and exhaust purification performance, and when it is truly necessary, the engine speed can be charged quickly. It is possible to stably increase the rotation speed over time and reliably charge the battery. In addition, the reference target rotation speed is changed for each combination of automatic transmission or manual transmission, whether the transmission is drive or neutral, and whether the air conditioner is off or on, and further, depending on the user's preference using an external signal. to determine the overall characteristics of the target rotation speed in a predetermined unit, e.g.
Since it can be changed accurately in 50 rpm increments without being affected by fluctuations in power supply voltage, the target idling speed can be set according to the actual situation.
Can be used as a reference for other controls.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment showing the overall configuration of the present invention, Fig. 2 is a graph of an embodiment showing the relationship between target rotational speed and cooling water temperature adapted to various conditions, and Fig. 3 is a graph of an embodiment. Figure 2 is an example of a flowchart of calculations to obtain various rotational speeds, Figure 4 is a flowchart for increasing the target rotational speed when battery voltage drops, and Figure 5 is a rotational speed measurement register and rotational speed. FIG. 6 is a diagram showing the setting register, FIG. 6 is a diagram showing the IVAR register and target voltage, and FIG. 7 is a diagram showing the rotation speed changing procedure. <Explanation of symbols> 1... Internal combustion engine, 2... Air cleaner, 3... Air flow meter, 4... Throttle chamber, 5... Intake manifold, 6... Fuel injector, 7... Throttle valve, 8... Bypass port, 9... Idle adjustment screw, 10... Bypass passage, 11... Idle control valve, 12... Valve body, 1
3...Diaphragm, 14...Spring, 15
...Negative pressure working chamber, 16...Negative pressure introduction passage, 17...
... Constant pressure valve, 18 ... Atmosphere introduction passage, 19 ... Pulse solenoid valve, 20 ... Microcomputer, 21
...Microprocessor, 22...Memory, 23
...Interface, 24...Rotation speed sensor,
25...Water temperature sensor, 26...A/D converter, 2
7... Throttle valve switch, 28... Neutral switch, 29... Vehicle speed switch, 30...
A/D converter.

Claims (1)

[Claims] 1. Intake control that switches between feedback control, which controls the intake air amount of the internal combustion engine so that the actual rotation speed matches the target rotation speed, and open-loop control, which does not perform feedback, according to various operating conditions of the engine. In the air amount control device, an idling standard target rotation speed set value is determined according to the water temperature, and when the battery voltage of the vehicle continues to decrease for a predetermined time or more and decreases below the standard value, the idling reference target rotation speed setting value is determined for a second predetermined time longer than the above predetermined time. An intake air amount control device comprising means for increasing the reference target rotation speed setting value.