JPS6395895A - Step-out adjustment device of step motor for internal combustion engine - Google Patents

Abstract

PURPOSE:To secure good operation of an engine, by a method wherein if a step motor is out of step during the engine operation, adjustment is immediately for the step out. CONSTITUTION:Means 100 for determining a requested step position determines the requested step position corresponding to an operation state of an engine, and controls a step position of a step motor 17 to the requested step position based on the step position stored in a memory means 101 for storing the present step position of the step motor 17. A discrimination means 102 discriminates whether or not the requested step position takes the upper limit position or the lower limit position continuously for a predetermined time or longer (step out). When the discrimination means 102 discriminates the step out, a drive control means 103 drives the step motor 17 to the maximum step position or the minimum step position so that the actual step position of the step motor 17 is made coincident with the position of the step motor 17 stored in the memory means 101.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a step-out adjustment device for a step motor in an internal combustion engine.

[Conventional technology]

In an internal combustion engine in which the amount of fuel or air supplied into the engine cylinder is controlled using a step motor, the engine speed or intake amount is normally controlled as described in Japanese Patent Laid-Open No. 61-126364. The required step position of the step motor is determined from negative pressure, etc., and the step motor is drive-controlled so that the step position of the step motor becomes the required step position. However, with such a step motor, it is difficult to directly detect the actual step position of the step motor. Therefore, as described in Japanese Unexamined Patent Publication No. 57-26238, a memory means for storing the step position of the step motor is usually provided, and the step motor is moved to the maximum step position or the minimum step every time the engine is stopped or started. the actual step position of the step motor matches the step position of the step motor stored in the storage means, and then the step motor is driven by regarding the step position stored in the storage means as the actual step position. I try to control it.

[Problem that the invention seeks to solve]

However, in reality, during engine operation, the actual step position of the step motor and the step position stored in the storage means may deviate, that is, the step motor may step out. If the step motor is driven and controlled based on the stored step position, the amount of fuel or air cannot be accurately controlled. Conventionally, as described above, step-out is adjusted every time the engine is stopped or started, but this method has a problem in that step-out that occurs during engine operation cannot be adjusted.

[Means for solving problems]

In order to solve the above problems, the present invention has a means 100 for determining a required step position according to the operating state of the engine, as shown in the block diagram of the invention in FIG. 1. Storage means 101 for storing information. In an internal combustion engine in which the step motor 17 is drive-controlled so that the step position of the step motor 17 becomes the required step position based on the step position stored in the storage means 101, the required step position is a predetermined upper limit position. Or a determining means 102 that determines whether the lower limit position has been maintained for a predetermined period of time or more.
Then, when the requested step position remains at the upper limit position or the lower limit position for a certain period of time or more, the step motor 17 is driven to the maximum step position or the minimum step position, and the actual step position of the step motor 17 is stored in the storage means 101. It is equipped with a drive control means 103 that matches the stored step position of the step motor 17.

〔Example〕

Referring to Figure 2, l is the engine body, 2 is the piston, and 3
1 is a combustion chamber, 4 is an intake valve, 5 is an intake boat, 6 is an intake manifold, 7 and 8 are intake ducts, 9 is an exhaust valve, 10 is an exhaust port, and 11 is an exhaust manifold. A venturi portion 12 is formed in the intake duct 8, and the venturi portion 1
A fuel outlet 13 opens in 2. Fuel outlet 13 is L
LPG gas regulator 1 via PG gas supply pipe 14
A flow control valve 16 is disposed within the LPG gas supply pipe 14 to control the flow rate of I and PC gases.

This flow rate control valve 16 is driven and controlled by a step motor 17. On the other hand, a throttle valve 18 is arranged in the intake duct, and a bypass pipe 19 bypassing the throttle valve 18
is attached to the intake duct 7. An idling speed control valve 20 for controlling the idling rotational speed is disposed within the bypass pipe 19, and the idling speed control valve 20 is driven and controlled by a step motor 21.

Each step motor 17.21 has a respective electronic control unit 3.
Controlled by an output signal of 0.

i Child's side? The il unit 30 consists of a digital computer, which includes a ROM (read-on memory) 32, a RAM 8 (random access memory) 33, a CPU (microprocessor) 34, an input port 35 and an output port 36 interconnected by a bidirectional bus 31. Equipped with. Further, a backup RAM 37, which is a nonvolatile memory, is connected to the CPU 34. A negative pressure sensor 22 that generates an output voltage proportional to the negative pressure in the intake manifold 6 is attached to the intake manifold 6, and the negative pressure sensor 22 is connected to the input port 35 via an AD degree converter 38. Further, an oxygen concentration detector 23 is installed inside the exhaust manifold 11, and this oxygen concentration detector 23 is connected to the comparator 3.
9 to the input port 35. Furthermore, the input port 35 is equipped with a rotation speed sensor 4 that generates an output pulse every time the engine crankshaft rotates by a predetermined crank angle.
0 is connected. The output boat 36 is connected to the corresponding drive circuit 4
1.42 to step motors 17.21, respectively.

When the engine is operating, an amount of LPG gas proportional to the intake air amount is supplied from the fuel outlet 13 into the venturi part I2,
This LPG gas amount is corrected by a flow control valve 16 driven by a step motor 17. That is, the oxygen concentration detector 23 outputs an output voltage of about 0.1 volt when the exhaust gas is in an oxidizing atmosphere, that is, when the air-fuel ratio of the mixture made of LPG gas supplied into the engine cylinder is larger than the stoichiometric air-fuel ratio. When the exhaust gas is in a reducing atmosphere, that is, when the air-fuel ratio of the air-fuel mixture supplied into the engine cylinder is smaller than the stoichiometric air-fuel ratio, an output voltage of about 0.9 volts is generated. Therefore, based on the output signal of the oxygen concentration detector 23, the amount of LPG gas flowing out from the fuel outlet 13 can be feedback-controlled so that the air-fuel ratio becomes the stoichiometric air-fuel ratio.

FIG. 3 shows a flowchart for calculating the required step position of step motor 17.

Referring to FIG. 3, first, in step 50, it is determined whether the operating conditions are such that feedback control of the air-fuel ratio is required. If the operating state requires feedback control, the process proceeds to step 51, where the output signal of the oxygen concentration detector 23 is taken into the CPU 34, and then, in step 52, the required step position S is determined from the output signal of the oxygen concentration detector 23.
is calculated. On the other hand, if it is not the feedback condition, the process proceeds to step 53, where the output signal of the negative pressure sensor 22, the output signal of the rotational speed sensor 40, etc. are taken into the CPU 34, and then, in step 54, the required step position Is is determined from the engine rotational speed, negative pressure, etc. is calculated. The relationship between the engine speed, negative pressure, etc. and the required step position S is stored in advance in the ROM 32, so in step 54, the relationship between the ROM 32
The required step position S is determined from these relationships stored in the system.

FIG. 4 shows the change in the required step position ffs calculated in step 52 of FIG. When the step position increases, the step motor 17 operates in the direction in which the flow rate control valve 16 opens, thereby increasing the amount of LPG gas supplied. On the other hand, when the step position of the step motor 17 becomes smaller, the flow rate control valve L6 operates in the direction of closing, and therefore the amount of LPG gas supplied decreases. In the curve P of FIG. 3, the interval tI+3+t% indicates a time when an air-fuel mixture richer than the stoichiometric air-fuel ratio is supplied into the engine cylinder, and at this time the required step position S is gradually decreased. That is, the flow rate control valve 16 is moved in the valve closing direction to reduce the amount of LPG gas supplied. On the other hand, in the songs S and SP in Fig. 3, the interval tZ+4+''h indicates a time when air-fuel mixture thinner than the stoichiometric fuel ratio is supplied into the engine cylinder, and at this time, the required step position S gradually changes. In other words, the flow rate control valve 16 is moved in the opening direction to increase the amount of LPG gas supplied.

The step motor 7 can take each step position, for example, from step position 0 to step position 125, but the actual range of step positions is, for example, from step position 30 to step position 90. In other words, when the step position is, for example, 60, the step motor 7
The air-fuel ratio is set in advance so that it becomes the stoichiometric air-fuel ratio when the valve is half open, and even during the feedback control valve, the step position only moves up and down a few steps around 60, for example. Therefore, the required step position S normally moves up and down around 60, as shown by curve P in FIG. That is, normally the required step position is 3.
It will never be 0 or 90, and the required step position will be 3.
If the value is 0 or 90, it means that some kind of abnormality has occurred.

Therefore, by setting the required step position 30 as the lower limit position MIN and the required step position 90 as the upper limit position MAX, the required step position 2s is not made smaller than the lower limit position MIN, and the upper limit position M
I try not to make it larger than AX. That is, for example, when the required step position Is exceeds MAX, the required step position S is set to MAX.

On the other hand, the current step position of the step motor 17 is stored in the RAM 37 in advance, and normally the actual step position of the step motor 17 and the step position stored in the RAM 37 are equal. Therefore, if the required step position S changes from, for example, 60 to 61, the RAM 37
Step motor 17 based on the step position stored in
is rotated by one step from step position 60 to 61, following the change in the required step position S.

However, for some reason, the actual step position of the step motor 17 and the step position stored in the RAM 37 may deviate from each other.
may go out of step. For example, to take an extreme example, the actual step position of the step motor 17 and the position stored in the RAM 37 may deviate by 30 steps, causing the step motor 1
RAM37 when the actual step position of 7 is 60.
Such is the case that the step position stored within is 90. In such a case, even though the step motor 17 is actually at the step position 60, the CPU 34
Then, it is determined that the step motor 17 is at the step position 90, and if the air-fuel ratio supplied to the engine cylinder becomes lean, the CPU 34 tries to make the step position of the step motor 17 larger than 90 in order to enrich the air-fuel ratio. Activate, ie try to make the required step position greater than 90. However, as described above, the required step position 2s cannot be larger than the MAX of 90, and therefore the required step position S fluctuates around 90 as shown by the curve Q in FIG. In other words, the fact that the step position S is fluctuating around MAX indicates that the step motor 17 may be out of step. On the other hand, when the actual step position of the step motor 17 is 60 and the step position stored in the RAM 37 is 30, the required step position S is MIN of the required step position S. It will fluctuate around 30.

That is, the fact that the step motor 17 is fluctuating around the required step position 14MEN indicates that the step motor 17 may be out of step.

In particular, when LPG gas is used, the amount of LPG gas supplied to make the air-fuel ratio the stoichiometric air-fuel ratio varies depending on the composition of the LPG gas. That is, when using the standard LPG gas, even if the air-fuel ratio is set to the stoichiometric air-fuel ratio when the actual step position of the step motor 17 is 60, a different LPG gas is used.
When PG gas is used, the air-fuel ratio may become the stoichiometric air-fuel ratio when the actual step position of the step motor 17 is, for example, 80. In such a case, when feedback control is being performed, the step motor 1
The actual step position of step motor 1 will vary around 80, so in such a case, the step motor 1
7 is out of IO step, the required step position S is MA
It will fluctuate around X. Therefore, when LPG gas is used, the required step position gs has more chances to fluctuate around MAX than when gasoline, whose composition hardly changes, is used.

In this way, the present invention allows the required step position S to be MAX or M.
When it fluctuates near IN, it is determined that a step-out has occurred, and the purpose is to control the drive of the step motor 17 so as to adjust the tax adjustment. It may fluctuate around MAX. For example, the flow rate control valve 16 may change over time.
This is a case where foreign matter adheres to and accumulates in the valve port of the valve, reducing the flow area of the valve boat. In such a case, in order to obtain the required flow area, the opening amount of the flow rate control valve 16 must be increased, and therefore the required step position S becomes larger. In extreme cases, the required step level ZS will fluctuate around MAX. In such a case, even if the step-out adjustment work is performed, the required step position S will still fluctuate around the MAX. Therefore, in such a case, it is assumed that it is a change over time, and the learning coefficient is corrected as described later, thereby ensuring good feedback control thereafter.

Next, a step motor drive control method according to the present invention will be explained with reference to FIG.

Referring to FIG. 5, first, the required step position S obtained in the routine of FIG. 3 is multiplied by a learning coefficient k to obtain the required step position A. This learning coefficient is corrected due to changes over time, and can usually be considered to be equal to l.

Therefore, normally the required step position A is the required step position S.
matches. Next, in step 61, it is determined whether the requested step position A is M A X shown in FIG.
If it is not MAX, proceed to step 62. In step 62, it is determined whether or not the requested step position A is MIN shown in FIG. 4. If it is not old N, the process proceeds to step 63, where counters C and D are cleared. Since the required step position 1iA is usually not MAX or MIN, the process proceeds from step 62 to step 63 in most cases. Then step 6
In step 4, the step motor 17 is drive-controlled so that the step position of the step motor 17 becomes the required step position 1iA. At this time, if the feedback control is in progress, the requested steering knob position A changes as shown by the curve P in FIG. Based on the position S, the step position of the step motor 17 is controlled to be the required step position A.

When the required step position A is MAX or MIN, the process proceeds from steps 61 and 62 to step 65, where the counter C starts counting. Requested step position A
If continues to be MAX or MIN, the count value of counter C gradually increases, and when the counter value of counter C exceeds a certain value Co, that is, a certain period of time has elapsed since the required step position A reached MAX or MIN. Then step 6
Step 6 then proceeds to step 67, where the counter D is incremented by one. Next, in step 68, it is determined whether the count value of the counter D is larger than a constant value Do. If the count value of the counter D is smaller than Do, the process proceeds to step 69, where the step motor 17 is initialized. Initialization of the step motor 17 is a predetermined number of steps, for example, 15 steps required to rotate the step motor 17 to the maximum step position 125.
This is to issue a command to add steps and rotate the step motor 17 by the number of initialized steps. When this command is issued, the step motor 17 moves to step 64.
The rotational drive is performed by the number of initialization steps. Such initialization processing is repeated several times until the count value reaches Do. This initialization process may be performed only once.As mentioned above, in the initialization process, the step motor 17 is rotated for more than the number of steps required to rotate to the maximum step position 125, so the initialization process is performed only once. When the conversion process is completed, the step motor 17 is at the maximum step position, and at the same time the R
The step position stored in AM37 is also 125.

Therefore, when the initialization is completed, the actual step position of the step motor 17 and the step position stored in the RAM 37 will match. In addition, in the above-mentioned initialization process, the step motor 17 is rotated by more than the number of steps required to rotate the step motor 17 to the maximum step position 125, but the number of steps required to rotate the step motor 17 to the minimum step position O is Initialization processing can also be performed by rotating more than one number of rotations.

When the initialization process is completed, the step motor 17 is controlled in step 64 so that the position of the step motor 17 is at the required step position HA. Due to step motor 17 stepping out, the required step position A7! When it is fluctuating around l<MAX or MIN, initialization processing is performed to adjust the step-out, so that the required step position A changes as shown by the song IP in FIG. 4. Therefore, the routine then proceeds to step 63 via steps 61 and 62.

On the other hand, due to changes over time, the required step position A may be changed to, for example, M
When it continues to be AX, the required step position A continues to be MAX even after the initialization processing, and therefore, in this case, the process proceeds from step 68 to step 70, where correction processing is performed on the learning coefficient.

FIG. 6 shows correction processing for learning coefficients. Referring to FIG. 6, the average step position S0 is first read into the CPU 34 in step 8o. This calculation of the average step position S0 is performed in a separate routine shown in FIG. Referring to FIG. 7, first, in step 90, it is determined whether or not feedback control is being performed.
If feedback control is not in progress, the processing routine is completed. On the other hand, if the feedback control is being performed, the process proceeds to step 91, where the average step position S0 over a long period of time of the requested step position S during the feedback control is calculated.
Then, in step 92, the average step position S0 is set to R.
It is stored at a predetermined address in AM37. During feedback control, the required step position S normally moves up and down around 60 as shown by the curve P in Figure 4, so the average step position S
0 is almost 60. Thereafter, for example, as the required step position S begins to move up and down around 70 due to changes over time, the average step position S0 gradually approaches 70 until it reaches approximately 70.

This average step position S0 represents the step knob position of the step motor 17 where the air-fuel ratio becomes the stoichiometric air-fuel ratio,
Therefore, in the above case, when the step position of the step motor 17 reaches 70, the air-fuel ratio becomes the stoichiometric air-fuel ratio.

However, when feedback control is not in progress, the required step position S is R as shown in step 54 of FIG.
A value stored in the OM 32 is used, and this value is determined on the premise that the air-fuel ratio becomes the stoichiometric air-fuel ratio when the required step position Hs is 60, for example. Therefore, even if the required step position S is set to 60 in order to make the air-fuel ratio the stoichiometric air-fuel ratio when feedback control is not in progress, when the average step position S0 is 70, the air-fuel ratio no longer becomes the stoichiometric air-fuel ratio. Even in such a case, the learning coefficient is corrected so that the required step position 2s is set to 60 so that the air-fuel ratio becomes the stoichiometric air-fuel ratio. That is, as shown in step 81 in FIG. 6, the learning coefficient is obtained from the average step position So/60, and the learning coefficient
It is used in step 60 of the figure. That is, when the required step position S is set to 60 in order to make the air-fuel ratio the stoichiometric air-fuel ratio when feedback control is not in progress, the fifth
Step 60 in the figure is represented as A=k.60. Now, assuming that the average step position TIS o is 70, it becomes k -70/60 from step 81 in Fig. 6, and therefore the required step position A is A = k 60 = (70/60).
・60=70, and the air-fuel ratio becomes the stoichiometric air-fuel ratio. In this way, the learning coefficient is provided so that even if the flow rate characteristics of the flow rate control valve 16 change due to changes over time, the air-fuel ratio can be obtained in advance based on the required step position S stored in the ROM 32.

When the learning coefficient k is corrected to a new learning coefficient k in step 70 of FIG.
, D are reset, and then in step 64 the step motor 17 is driven and controlled so that the step position becomes the required step position A.

〔Effect of the invention〕

As described above, according to the present invention, when the step motor loses synchronization during engine operation, the synchronization is immediately corrected, so that good engine operation can be ensured.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the invention, Figure 2 is an overall diagram of the internal combustion engine, Figure 3 is a flowchart for calculating the required step position, Figure 4 is a diagram showing changes in the required step position, and Figure 5 is a diagram showing changes in the required step position.
FIG. 6 is a flowchart for controlling the drive of the step motor, FIG. 6 is a flowchart for correcting the learning coefficient k, and FIG. 7 is a flowchart for calculating the average step position. 14...Fuel outlet, 14...LPG gas supply pipe, 16...Flow control valve, 17.21...Step motor, 19...Bypass pipe, 20...Idling speed control valve. 1B--, Throttle valve fj2 Figure 3 Figure 4 Figure 5 Figure 7

Claims (1)

[Claims] It comprises means for determining a required step position according to the operating state of the engine, and a storage means for storing the current step position of the step motor, and the step position of the step motor is determined based on the step position stored in the storage means. In an internal combustion engine in which a step motor is drive-controlled so as to reach a required step position, it is determined whether the required step position has been at a predetermined upper limit position or lower limit position for a predetermined period of time or more. a determining means for driving the step motor to the maximum step position or the minimum step position when the requested step position is at the upper limit position or the lower limit position for a certain period of time or more; A step-out adjustment device for an internal combustion engine step motor, comprising drive control means for matching a stored step position of the step motor.