JPS6325338A - Intake air amount control device for engine - Google Patents

Abstract

PURPOSE:To prevent the occurrence of an engine stop and blowup, by a method wherein, when, during an acceleration state, an intake air amount is increase compared with that during an idling state, the degree of increase is increased depending upon an increase in an external load. CONSTITUTION:In addition to an intake air amount signal Sa from an airflow sensor 11, a throttle opening signal St from a throttle opening sensor 18, a number of revolutions signal SN from a number of revolutions sensor 27, and a cooling water temperature SW from a water temperature sensor 34, an external load signal SZ from an external load charge switch 33 is inputted to a control unit 100. During idle running, based on the signals, feedback control is made on a flow rate regulating valve 16 in a throttle bypass passage 15 so that the number of revolutions is adjusted to a target value. When a throttle valve 13 is fully closed and the number of revolutions exceeds a given value, an engine is decided to be in a deceleration state, increase correction is made on the flow rate regulating valve 16, but when the external load charge switch 33 is brought into an ON-state, the degree of increase is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an engine which increases the amount of intake air introduced into the engine when the engine is in a deceleration state compared to when the engine is in an idling state. The present invention relates to an intake air amount control device.

(Prior art) Conventionally, as one of the technologies related to intake air amount control in engines installed in automobiles, etc., for example, in order to maintain the engine speed at a predetermined speed (idling speed) when the engine is idling, A bypass passage is provided that communicates the upstream and downstream parts of the throttle valve in the passage, and a flow rate adjustment valve is interposed in this bypass passage, so that when the throttle valve is in a fully closed state (idling opening state), the flow rate is It is known to control the amount of intake air by changing the opening actuation amount of a regulating valve (the opening degree of the flow regulating valve, the valve opening period per unit period, etc.).

In an engine in which such intake air amount control is performed, normally, when the throttle valve is changed from a somewhat open state to a fully closed state to shift to a deceleration state, the opening operation amount of the flow rate adjustment valve becomes small. The amount of intake air decreases, and the rotational speed decreases accordingly. When the rotation speed drops below a predetermined rotation speed, engine stall is likely to occur, so in order to prevent engine stall, the amount of opening operation of the flow rate adjustment valve is increased to increase the amount of intake air, and then During the period when the throttle valve is in the substantially fully closed state, the amount of intake air is feedback-controlled so that the idling speed is maintained appropriately.

However, in such an engine, in particular,
When the engine is moved from operating at a relatively high rotational speed to a deceleration state, the rotational speed drops rapidly, resulting in a situation where the amount of intake air cannot keep up with the decrease in rotational speed, and as a result, There is a risk of engine stalling.

Therefore, in order to deal with this problem, for example, as shown in Japanese Patent Application Laid-Open No. 55-60636, when the engine is brought into a deceleration state, the engine speed is reduced compared to when it is in an idling state. In view of this, an engine intake air amount control device has been proposed that increases the amount of intake air by increasing the amount of opening operation of a flow rate regulating valve. According to such a conventionally proposed engine intake air amount control device, when the engine is in a decelerating state, the amount of intake air is increased compared to when the engine is in an idling state, thereby preventing a sudden drop in rotational speed. This will make it difficult for engine stalls to be ordered.

(Problem to be Solved by the Invention) However, in an engine to which such an intake air amount control device is applied, the degree of increase in intake air in a deceleration state compared to an idling state depends on the external load borne by the engine. It is set regardless of the size, so for example,
Air 11 operated by driving force from the engine
11 and auxiliary equipment such as the power steering pump are activated and the external load borne by the engine is large and the engine is forced to decelerate. This may result in a situation where the increase in intake air cannot keep up with the increase in intake air, and there is a risk that an engine stall may occur.

In addition, in order to eliminate this inconvenience, increasing the amount of intake air during deceleration will reduce the external load borne by the engine when the auxiliary equipment is inactive and the external load borne by the engine is reduced. When the engine is brought into a deceleration state, its rotational speed is suddenly increased, and there is a risk that an undesirable increase in rotational speed may occur.

In view of the above, the present invention is designed to increase the amount of intake air when the engine is in a deceleration state compared to when the engine is in an idling state, and moreover, the amount of intake air increases as the engine decelerates. An object of the present invention is to provide an intake air amount control device for an engine that can reliably prevent engine stall or undesired rotational speed up, regardless of the magnitude of external load borne by the engine.

(Means for Solving the Problems) In order to achieve the above-mentioned object, an engine intake air amount control device according to the present invention, as shown in the basic configuration in FIG. an intake air introducing means for guiding the
An operating state detection means for detecting the operating state of the engine, an external load detection means for detecting the state of the external load borne by the engine, and combustion through the intake air introduction means based on the detection signal obtained from the operation state detection means. Intake air amount control means for increasing the amount of intake air introduced into the engine compartment when the engine is in a decelerating state compared to when the engine is in an idling state, and correcting the degree of increase in the amount of intake air brought about by the intake air amount control means. and a quantity increase degree correction means,
The amount increase degree correcting means causes the intake air amount control means to increase the degree of increase described above in accordance with the increase in the external load detected by the external load detection means.

(Function) In the engine intake air amount control device according to the present invention configured as described above, when the intake air amount control means detects a deceleration state of the engine by the operating state detection means,
Control is performed to increase the amount of intake air introduced into the combustion chamber via the intake air introduction means compared to when the engine is in an idling state.

At this time, the increase degree correction means increases the degree of increase in intake air brought about by the intake air amount control device in accordance with the increase in external load borne by the engine, which is detected by the external load detection means. It is assumed that the correction operation is performed as follows.゛In this way, when the engine is in a decelerating state, the degree of increase in intake air is changed according to the magnitude of the external load that it bears, thereby reliably avoiding engine stall or undesired speed up. That will happen.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 2 shows an example of an engine intake air amount control device according to the present invention, together with the main parts of an engine equipped with the device.

In FIG. 2, the intake passage 1 is
The flow rate of the intake air introduced into the air flow sensor 11
Detection signal S detected by and corresponding to the flow rate of intake air
a is obtained from the air flow sensor 11 and supplied to a control unit 100, which will be described later. The intake air is evacuated by a throttle valve 13 provided in an intake passage 12 and then transferred to an intake valve 17 provided in the engine body E.
is guided to the combustion chamber 19 via the The throttle valve 13 is
In response to depression of an accelerator pedal (not shown),
The degree of opening thereof can be changed. The opening of the throttle valve 13 is detected by the throttle opening sensor 18, and a detection signal St corresponding to the opening of the throttle valve 13 (hereinafter referred to as throttle opening) is sent from the throttle opening sensor 18 to the control unit 100. Supplied. Further, between the air flow sensor 11 and the throttle valve 13 in the intake passage 12, there is a saw which bypasses the throttle valve 13 and communicates with a surge tank 14 provided in the middle of the intake passage 12. It is open, and the bypass passage 15 and surge tank 14
A flow rate adjustment valve 16 is provided in the communication path. The opening time of the flow rate regulating valve 1G is changed according to the pulse width of the valve opening drive pulse signal Cp supplied from the control unit 100.

Further, a fuel injection valve 20 is installed at a predetermined position in the intake passage 12, and this fuel injection valve 20 opens at a predetermined timing according to the pulse width of the injection drive pulse signal Cq supplied from the control unit 100. The valve is activated and fuel, which is pressure-fed from a fuel supply system (not shown), is intermittently injected toward the intake port of the intake passage 12 near the combustion chamber 19 to form a mixture with intake air. This air-fuel mixture is sucked into the combustion chamber 19, ignited by the spark plug 21, and combusted, thereby operating the engine.

The air-fuel mixture combusted in the combustion chamber 19 is discharged into the exhaust passage 23 via the exhaust valve 22 as exhaust gas.

The rotation speed of the engine operating in this manner is determined by the rotation speed sensor 2 disposed in relation to the crankshaft 26 in the crank mechanism that converts the reciprocating motion of the piston 24 into rotational motion.
7, and a detection signal Sn corresponding to the engine speed is supplied to the control unit 100. The driving force of the crankshaft 26 is transmitted to the drive shaft 29 via the belt 28, and the driving force transmitted to the drive shaft 29 is
Via the electromagnetic clutch 31, it is transmitted to an external load 30, such as an air conditioner, which is operated by the driving force from the engine.

When the electromagnetic clutch 31 is supplied with a load actuation signal Sz obtained when a switch 33 operated to put the external load 30 into an actuating state or a non-actuating state is turned on, the electromagnetic clutch 31 receives the drive transmitted to the drive shaft 29. When the force is transmitted to the external load 30 and the supply of the load actuation signal Sz is stopped, the transmission of the driving force from the drive shaft 29 to the external load 30 is stopped.

Further, a water temperature sensor 34 is attached to the engine body E, and a detection signal Sw corresponding to the engine cooling water temperature is supplied from the water temperature sensor 34 to the control unit 100. In addition to the detection signals Sa, St, Sn, and Sw, the control unit 100 is also supplied with a load operation signal Sz obtained from the switch 33.

The control unit 100 has detection signals Sa and Sn.
Based on the amount of intake air and engine speed,
The pulse width of the injection drive pulse signal Cq supplied to the fuel injection valve 20 is changed, thereby controlling the fuel injection amount at the fuel injection valve 20. In addition, the detection signal St.

A control value is obtained according to Sn and SW and the load operation signal Sz, a valve opening drive pulse signal Cp having a pulse width corresponding to the control value is formed, and it is supplied to the flow rate regulating valve 16. By controlling the operation of the flow rate regulating valve 16, the intake air amount of the engine is adjusted.

Here, the control unit 100 determines the control value that determines the pulse width of the valve opening driving pulse signal Cp.
A correction value is calculated according to the operating state of the engine based on a predetermined fixed control value DA and the cooling water temperature at which the detection signal 3w occurs.

and the feedback correction value DF calculated based on the rotation speed difference between the actual engine rotation speed and the preset target idle rotation speed, and the operation of the external load 30. It is set by adding the deceleration correction value D2 calculated based on the state.

In that case, the control unit 100 detects the detection signal S
When it is detected that the throttle valve 13 is in an open state or that the engine speed is higher than a predetermined speed based on the small opening degree and the engine speed, It is determined that the engine is in a normal operating state, and the correction value and feedback correction value DF are each set to zero. Therefore, when the engine is in a normal operating state, the basic control value D7 is made equal to the fixed control value DA. In addition, the control unit 10
0 means that when it is detected that the throttle valve 13 is in a fully closed state and the engine speed is below a predetermined speed, it is determined that the engine is in an idling state, and the correction value DIl and the feedback correction value are and are set to predetermined values, respectively, based on the operating state of the engine and the difference in engine speed between the actual engine speed and a preset target idle speed. Therefore, when the engine is in an idling state, the basic control value is set to the sum of the fixed control value DA, the correction value, and the feedback correction value DF.

Furthermore, the control unit 100 controls the detection signal St
It is detected that the rate of change in the throttle opening is negative and smaller than the set value (the absolute value is greater than the absolute value of the set value), and that the engine speed is greater than the set speed. , it is determined that the engine has transitioned to a deceleration state, and a deceleration correction value D2 is set. At this time, the deceleration correction value D2 is set to the value D+ when it is detected that the switch 33 is turned off and the external load 30 is put in a non-operated state based on the load activation signal Sz, When it is detected that the external load 30 is in the ON state and is in the operating state, the value D2 is set to be larger than the value D1. After that, the deceleration correction value D2 is kept at the set value until the engine speed becomes equal to or less than the predetermined value.
Alternatively, the value D2 is maintained, and after the engine speed becomes below the predetermined value, the deceleration correction value D2 is changed to the set value or the value D! It is gradually decreased from 1 to 0 until it reaches zero.

In this way, the control unit 100 sets the basic control value Da and the deceleration correction value Dz according to the operating state of the engine, adds the set basic control value D7 and the deceleration correction value D2, and calculates the control value. A valve-opening driving pulse signal Cp having a pulse width corresponding to the control value is obtained and supplied to the flow rate regulating valve 16.

By performing control by the control unit 100, when the engine is in an idling state, the intake air amount is feedback-controlled so that the actual engine speed converges to the target idling speed, and the engine is in a deceleration state. When the engine is in an idling state, the control value is the basic control value Da plus the deceleration correction value D2, so the amount of intake air is increased compared to when the engine is idling. This alleviates the sudden drop in engine speed and prevents engine stall from occurring. Furthermore, in addition to that, the deceleration correction value D2 is larger when the external load 30 is in the operating state than when it is in the non-operating state, so that the inhalation The degree of air increase is greater when the external load 30 is activated than when it is deactivated, regardless of the magnitude of the external load borne by the engine. First, engine stall or undesired engine speed up is prevented.

The control unit 100 that performs the above-described control is configured using, for example, a microcomputer, and an example of a program executed by the microcomputer in such a case is shown in the flowcharts of FIGS. 3 to 5. Refer to and explain.

The flowchart in FIG. 3 shows a basic control value calculation routine. This routine starts, for example, when the engine is started, and after the start, in process 111, the initial correction value D8 and the feedback correction value DF are set to zero. After setting, in the subsequent process 112, the detection signals St, S
After taking in n and Sw, the process proceeds to decision 113. In decision 113, it is determined whether the throttle valve 13 is in a fully closed state based on the detection signal St taken in in process 112, and if it is determined that the throttle valve 13 is in a fully closed state, decision 114 is performed. Then, based on the detection signal Sn fetched in process 112, it is determined whether the engine rotation speed N is greater than a predetermined rotation speed Na.

As a result of such judgment, the engine rotation speed N becomes the predetermined rotation speed Na.
If it is below, it is assumed that the engine is in an idling state and the process proceeds to process 115.

In process 115, based on the detection signal Sw etc. taken in in process 112, a correction value is set according to the operating state of the engine. In the subsequent process 116, a feedback correction value DF is set based on the difference between the engine rotation speed at which the detection signal Sn taken in in the process 112 is detected and a preset target idle rotation speed, and the process proceeds to process 117. 117, the basic control value D?
, a preset fixed control value DA, and the process 115
The correction value RI set in step 116 is set by adding the feedback correction value DF set in step 116, and then the process returns to step 112.

On the other hand, if it is determined in decision 113 that the throttle valve 13 is not in the fully closed state, and if it is determined in decision 114 that the engine rotation speed N is greater than the predetermined rotation speed Na, the engine operates normally. Assuming that it is in the operating state, the process proceeds to process 118, sets the basic control value D7 to the fixed control value DA, and then returns to process 112.

The flowchart in FIG. 4 shows a deceleration correction value calculation routine. In this routine, after starting, initial setting is performed to make the deceleration correction value D2 zero in process 121, and in the subsequent process 122, the detection signal St, Sn and load operating signal Sz are taken in and the process proceeds to process 123. In process 123, the rate of change ΔTh of the throttle opening based on the detection signal St captured in process 122 is calculated, and then the process proceeds to decision 124.

In decision 124, it is determined whether the rate of change ΔTh of the throttle opening calculated in process 123 is smaller than the set value -α, and it is determined that the rate of change ΔTh of the throttle opening is greater than or equal to the set value -α. If so, the engine is not in deceleration and the process returns to process 122, while
If it is determined that the rate of change ΔTh of the throttle opening is smaller than the set value −α, it is determined that the engine is in a deceleration state, and the process proceeds to decision 125.
In step 122, it is determined whether or not the detected engine rotation speed N based on the detected signal Sn is larger than a predetermined rotation speed Nb, and it is determined that the engine rotation speed N is larger than the predetermined rotation speed Nb. If so, it is determined that the amount of intake air needs to be increased, and the process proceeds to decision 126. In decision 126, it is determined whether or not the external load 30 is in operation based on the load operation signal Sz captured in process 122, and if it is determined that the external load 30 is in the non-operation state, the process Proceed to step 127 and enter the deceleration correction value D.
2 to the value D1 and returns to process 122. Further, if it is determined in decision 126 that the external load 30 is operating, the process proceeds to process 128, in which the deceleration correction value D2 is set to a value D2 that is larger than the value D1 by the value d,
Return to process 122.

On the other hand, if it is determined in decision 125 that the engine rotation speed N is equal to or lower than the predetermined rotation speed Nb, the process proceeds to decision 130, where the detection signal Sn fetched in the previous process 122 is detected.
is larger than the predetermined number of revolutions Nb, that is, whether the engine number of revolutions N has decreased from the state of being larger than the predetermined number of revolutions Nb to the predetermined number of revolutions Nb or less. If it is determined that the engine rotational speed N at which the captured detection signal Sn is detected is greater than the predetermined rotational speed Nb, the process proceeds to process 131.
Now, load the time Tx into the built-in timer and start it, start measuring the elapsed time from the time when the engine speed N drops below the predetermined speed Nb, and start process 12.
Return to 2.

As a result, the time Tx loaded into the timer gradually decreases to zero as time passes.

Further, if it is determined in decision 130 that the detection signal Sn fetched in the previous process 122 indicates that the engine rotational speed N is equal to or lower than the predetermined rotational speed Nb, the process proceeds to decision 132; Then, it is determined whether or not the deceleration correction value D2 is zero, and if it is determined that the deceleration correction value D2 is zero, the process returns to process 122, and if it is determined that the deceleration correction value D2 is not zero. If so, proceed to decision 133.

In decision 133, it is determined whether or not the time Tx loaded in the timer is zero, that is, whether or not more than the time Tx has elapsed since the time when the engine speed N fell below the predetermined speed Nb, and the time If it is determined that the time TX or more has not elapsed, the process returns to process 122, and if it is determined that the time Tx or more has elapsed, the process proceeds to process 134. In process 134, process 127 or 12
At step 8, the predetermined value e is subtracted from the deceleration correction value D2 set to D+ or +, and the value is set as a new deceleration correction value D2, after which the process returns to process 122. As a result, the deceleration correction value D2 is maintained at the value D1 or the value D2 until the engine speed N falls below the predetermined speed Nb, and the deceleration correction value D2 is maintained at the value D1 or D2 until the engine speed N falls below the predetermined speed Nb and the predetermined time TX After , the deceleration correction value D2 will gradually decrease.

FIG. 5 shows a supply control routine of the valve opening drive pulse signal Cp to the flow rate regulating valve 16. In this routine, after starting, in process 141, the basic control value Da set in the basic control value calculation routine described above is calculated. In the following process 142, the deceleration correction value D2 set in the deceleration correction value calculation routine described above is taken in. Then, in process 143, the control value is
It is set by adding the basic control value Da taken in step 1 and the deceleration correction value D2 taken in process 142, and in the subsequent process 144, it has a width corresponding to the control value set in process 143. Valve opening drive pulse signal C
p, and sends it to the flow rate regulating valve 16 and returns to the original state.

When the intake air amount is controlled by the control unit 100 according to the program as described above, the deceleration correction value Dz is different when the external load 30 is in an operating state than when it is in an inactive state. It is said to be a big deal, but
The change in the deceleration correction value D2 and the accompanying change in the engine speed N will be explained below.

For example, as shown in FIGS. 6A and 6, the throttle valve 13 is rapidly returned to the closed direction from the somewhat open state at time t1, and the rate of change ΔTh of the throttle opening Th is set to the set value. -α, and then, at time t6, it is again opened to a certain extent, and then, at time t7, it is rapidly returned from the somewhat open state to the closed direction, so that the rate of change ΔTh of the throttle opening Th is made smaller than the set value -α, and at time t, immediately before time 1, Fig. 6C
As shown in FIG. 6, when the switch 33 is turned on and the external load 30 is activated, the deceleration correction value D2 is calculated as shown in FIG. As shown in Figure 1, at time 1. and time t
, on the condition that the rotation speed is higher than the predetermined rotation speed Nb,
At time t1, when the engine is caused to shift to a deceleration state with the external load 30 in an inactive state, the value is set to , and the engine is caused to shift into a deceleration state with the external load 30 in an active state. At time t, the value D2 is set to be greater than the value d by the value d.

Then, the deceleration correction value D2 is set at time t.
is at time 1. From then on, the engine rotation speed N becomes the predetermined rotation speed Nb.
After passing the time t2 where it descends below, the time t! From then on, the value D1 is maintained at the value D1 until time t3 when a predetermined time Tx has elapsed, and after time t3, it is gradually decreased and becomes zero at time t4. As a result, for a predetermined period after the engine shifts to the deceleration state, the control value that determines the width of the valve opening drive pulse signal Cp is changed to the basic control value Dr and the deceleration correction value D.
2 is an added value, and the change in engine speed N becomes as shown by the dashed line in FIG. 6E. The amount of air is increased by an amount corresponding to the deceleration correction value Dz, thereby alleviating the drop in engine speed and preventing the occurrence of engine stall.
a indicates the target idle rotation speed.

Further, the deceleration correction value D2, which is set to a value Dz that is larger than the value Dl by the value d at time t, is changed from time t to time t when the engine rotation speed N drops below the predetermined rotation speed Nb. The value D2 is maintained at the value D2 during the period from the time t8 until the time t when a predetermined time TX has elapsed, and after the time t9, the value is gradually decreased to the time t. It is considered to be zero. In this way, when the external load 30 is in the operating state, the control value that determines the pulse width of the valve opening drive pulse signal cp is a value d compared to when the external load 30 is in the non-operating state. is assumed to be large, and the change in engine speed N is the sixth
Compared to the case where the deceleration correction value D2 is set to the value d, as shown by the two-point vA line in Figure E, the intake air is increased by the amount corresponding to the value d, and as a result, the engine speed The drop in engine speed is alleviated, and the occurrence of engine stall is reliably prevented.

(Effects of the Invention) As is clear from the above explanation, according to the engine intake air amount control device according to the present invention, when the engine is in a deceleration state, the amount of intake air is increased compared to when the engine is in an idling state. Moreover, the degree of increase in intake air is increased in accordance with the increase in external load borne by the engine, so that when the intake air is increased due to engine deceleration, the engine Regardless of the magnitude of the external load borne by the engine, the drop in engine speed can be appropriately alleviated, and the occurrence of engine stall or undesired engine speed can be reliably avoided.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram showing an engine intake air amount control device according to the present invention in accordance with the claims, and FIG. 2 shows an example of the engine intake air amount control device according to the present invention to which it is applied. Figures 3, 4, and 5 are schematic configuration diagrams showing the main parts of the engine, and the programs executed by the microcomputer in the case where a microcomputer is used in the control unit in the example shown in Figure 2. FIG. 6 is a time chart for explaining the operation of the example shown in FIG. In the figure, 13 is a throttle valve, 15 is a bypass passage, 16 is a
is a flow rate adjustment valve, 27 is a rotation speed sensor, 30 is an external load,
33 is a switch, and 100 is a control unit. Figure 2 116

Claims (1)

[Claims] an intake introduction means for introducing intake air into a combustion chamber of the engine;
An operating state detecting means for detecting the operating state of the engine, an external load detecting means for detecting the state of an external load borne by the engine, and the intake air introducing means based on a detection signal obtained from the operating state detecting means. intake air amount control means for controlling the amount of intake air introduced into the combustion chamber through the engine to be increased when the engine is in a deceleration state compared to when the engine is in an idling state; An intake air amount control device for an engine, comprising an increase degree correcting means for correcting the degree of increase in the amount of intake air to be increased in accordance with an increase in external load detected by the external load detecting means.