JP3241661B2 - Method and apparatus for controlling intake throttle valve of diesel engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for controlling an intake throttle valve provided in an intake passage of a diesel engine and driven to be opened and closed by a step motor.

[0002]

2. Description of the Related Art Since the output adjustment of a diesel engine is mainly performed by controlling the fuel injection amount, conventionally, the intake air amount control has not been required to have very high accuracy. However, in order to satisfy the increasing demand for emission improvement in recent years, it has become necessary to secure a large amount of EGR through an exhaust gas recirculation (hereinafter referred to as “EGR”) device, and to secure a large amount of EGR. In order to achieve this, it has become necessary to precisely control the amount of intake air to the diesel engine itself. In order to enable such fine control of the intake air amount, there has been a demand for an intake throttle valve device capable of controlling the degree of opening independently and independently of the accelerator pedal without interlocking with the accelerator pedal. .

Conventionally, in order to satisfy such demands, there has been proposed a device capable of independently controlling the opening degree of an intake throttle valve by a forward / reverse rotation motor, such as a device described in Japanese Patent Publication No. 61-20268. It has been put to practical use. In addition, a step motor-type intake throttle valve control device that realizes more accurate opening control by employing a step motor as such a forward / reverse rotation motor has been put to practical use.

[0004]

However, in such a device, if the opening of the intake throttle valve is delayed, there arises a problem that the amount of intake air introduced into the diesel engine becomes insufficient and smoke is generated. There is. Therefore, high responsiveness is required when the intake throttle valve is opened. Also,
Since the intake throttle valve is urged in the valve closing direction by the flow resistance of the air flowing in the intake passage, a higher driving torque is required when the valve is closed. Therefore, in the above-described step motor type intake throttle valve control device, a large-sized and expensive step motor having a high output is required to meet such demands.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a small-sized, low-cost stepping motor and a responsiveness and a driving torque at the time of opening an intake throttle valve. Is to provide a control method and a control device for an intake throttle valve of a diesel engine, which can appropriately secure the throttle valve.

[0006]

In order to achieve the above object, the present invention is directed to a step number control based on a predetermined step position of a step motor drivingly connected to an intake throttle valve of a diesel engine. In the intake throttle valve control method for a diesel engine that opens and closes the intake throttle valve based on the target number of steps according to the engine operating state,
The gist of the invention is that, when opening and closing the intake throttle valve for controlling the step motor, the operating speed of the step motor toward the valve opening side of the intake throttle valve is higher than the operating speed of the step motor toward the valve closing side .

[0007] The invention described in claim 2 is the first invention.
In the method of controlling an intake throttle valve of a diesel engine described in the above, the gist of the invention is that the intake throttle valve is constantly urged toward the valve opening side.

[0008] The invention described in claim 3 is the first invention.
In the method of controlling an intake throttle valve for a diesel engine according to claim 2, the drive voltage of the step motor is constantly monitored, and when the drive voltage falls below a predetermined voltage, the operation speed of the step motor is reduced by closing the intake throttle valve. The gist of the present invention is to further reduce the operating speed to the valve side.

According to a fourth aspect of the present invention, there is provided a diesel engine for opening and closing the intake throttle valve based on a step number control based on a predetermined step position of a step motor driven and connected to the intake throttle valve of the diesel engine. the intake throttle valve control apparatus for an engine, machine of the step motor
When controlling to the target number of steps according to the
Actuating speed of the step motor to the valve opening side of the intake throttle valve
Operating speed of the step motor to the closing side of the intake throttle valve
And operating speed setting means for setting higher than, and its gist that obtain Bei the operation command means allowed to operate the step motor based on operating speed of the set.

The invention described in claim 5 is the same as the invention in claim 4.
The gist is that the intake throttle valve control device for a diesel engine further includes an urging means for urging the intake throttle valve to the valve opening side.

[0011] The invention according to claim 6 is the invention according to claim 4.
Or the intake throttle valve control device for a diesel engine according to 5, further comprising monitoring means for monitoring a drive voltage of the step motor, wherein the operating speed setting means sets the monitored drive voltage to a predetermined voltage or less. The gist of the present invention is to set the operation speed of the step motor to the valve closing side of the intake throttle valve to be lower than the operation speed.

According to the method of the first aspect and the configuration of the fourth aspect, the opening speed of the intake throttle valve can be increased at the time of opening the intake throttle valve which requires high responsiveness. become able to. On the other hand, when the valve is closed, not so high responsiveness is required.Therefore, by reducing the valve closing speed and increasing the driving torque, the stepping motor of the stepping motor can be prevented while receiving the flow resistance of the air flowing in the intake passage. It can be suppressed. Therefore, it is possible to suppress the occurrence of step-out of the step motor while suitably securing the response at the time of opening the intake throttle valve, while using a small-sized and low-cost step motor.

The method according to claim 2 and the method according to claim 5
According to the configuration described in (1), at the time of valve opening that requires high responsiveness, the valve is assisted by the urging force, so that the valve opening speed can be easily increased. On the other hand, at the time of valve closing that does not require very high responsiveness, it is possible to suppress step-out of the step motor while resisting the urging force by reducing the operation speed of the step motor and increasing the driving torque. become. Therefore, the responsiveness and the driving torque at the time of opening the intake throttle valve can be more preferably ensured while using a small-sized and low-cost step motor.

Further, according to the method of the third aspect and the configuration of the sixth aspect, even if the output of the step motor decreases due to the reduction of the driving power, the operation speed of the step motor is reduced to a sufficient level. By ensuring a sufficient drive torque, the occurrence of step-out of the step motor can be suppressed.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of an intake throttle valve control device for a diesel engine according to the present invention.

First, an outline of a diesel engine provided with a valve device according to the present embodiment will be described with reference to FIG. An intake passage 2 is connected to a combustion chamber 12 of the diesel engine 1 via an intake valve (not shown). An air cleaner 3 for filtering the intake air, a pressure sensor 6 for detecting the pressure (atmospheric pressure) of the intake air, and an intake temperature sensor 78 for detecting the temperature of the intake air are provided in the intake passage 2 from the upstream side. An intake throttle valve 4 for adjusting the amount of intake air introduced into the combustion chamber 12 is provided.

The intake throttle valve 4 is opened and closed by a stepping motor 40 and a drive mechanism 5 mainly composed of a gear group for drivingly connecting the step motor 40 and the intake throttle valve 4. The drive of the step motor 40 is controlled by an electronic control unit (hereinafter referred to as “ECU”) 19 for performing various controls of the diesel engine 1. Further, the drive mechanism 5 is provided with a full-open switch 39 which is turned on when the intake throttle valve 4 is located closer to the open side than a predetermined position near the fully open position.

On the other hand, in the intake passage 2, further downstream of the intake throttle valve 4, a branch is made from an exhaust passage 7 connected to the combustion chamber 12 via an exhaust valve (not shown), and merges into the intake passage 2. EGR (exhaust gas recirculation) passage 8 is connected. The EGR passage 8 is provided with an EGR control valve 9 which is opened and closed by an actuator 10 such as a diaphragm controlled by the ECU 19. The amount of intake air is adjusted by the intake throttle valve 4 and the amount of EGR is adjusted by the EGR control valve 9 to adjust the amount of EG for the amount of intake air introduced into the combustion chamber 12.
The ratio of the R amount, that is, the EGR ratio can be freely set. That is, appropriate EGR control can be performed over the entire operation range of the diesel engine 1.

The auxiliary combustion chamber 1 of the diesel engine 1
3 is provided with an injection nozzle 11 for injecting fuel. This fuel injection nozzle 11 is connected to a fuel injection pump 14. The fuel injection pump 14 is driven based on the rotation of the output shaft 23 of the diesel engine 1 and pressurizes and supplies fuel to the injection nozzle 11. Also,
The fuel injection pump 14 includes a timer control valve 15 and a spill valve 16 for adjusting the injection timing and injection amount of the fuel injected from the injection nozzle 11. The operations of the timer control valve 15 and the spill valve 16 are also controlled by the ECU 19.

A rotor (not shown) which rotates in synchronization with the rotation of the output shaft of the diesel engine 1 is provided in the fuel injection pump 14, and a protrusion formed on the outer peripheral surface of the rotor is detected. A rotation speed sensor 17 comprising an electromagnetic pickup for outputting a pulse signal corresponding to the rotation speed is provided. This rotation speed sensor 17
Is taken into the ECU 19 as a signal contributing to the calculation of the rotational speed of the diesel engine 1.

In addition, the ECU 19 stores accelerator opening information (accelerator opening information) detected by the accelerator opening sensor 18 including atmospheric pressure information detected by the pressure sensor 6 and intake air temperature information detected by the intake air temperature sensor 78. Pedal depression information) and IG (ignition)
ON / OFF information of switch 20, starter switch 21
, The cooling water temperature information detected by the water temperature sensor 77, the output voltage information of the battery 22 that supplies power to various electric devices including the ECU 19 and the step motor 40, and the like. ing.

Next, details of the drive mechanism 5 for opening and closing the intake throttle valve 4 will be described with reference to FIGS.
2 is a side sectional structure of the intake throttle valve 4 and its driving mechanism 5, FIG. 3 is a front view of the driving mechanism 5, and FIG. 4 is a driven gear 29 provided in the driving mechanism 5 and its driven gear 29. 3 shows a partial cross-sectional structure of a peripheral portion.

As shown in FIG. 2, the intake throttle valve 4 for making the opening area of the intake passage 2 variable and adjusting the amount of intake air flowing through the passage 2 is rotatable integrally with a valve shaft 26. Fixed. The valve shaft 26 is rotatably supported by a throttle body 25 connected to the intake passage 2. One end (the upper end in FIG. 2) of the valve shaft 26 is connected to the throttle body 25 via a return spring 27. And, the valve shaft 26 and the intake throttle valve 4
Is biased in a direction to open the intake throttle valve 4 by the biasing force of the return spring 27.

On the other hand, a driven gear 29 provided in a gear box 28 mounted on the throttle body 25 is integrally rotatably attached to the other end (the lower end in FIG. 2) of the valve shaft 26. The driven gear 29 is meshed with a second intermediate gear 37 rotatably supported by a support shaft 35 provided in the gear box 28. Further, a first intermediate gear 36 that rotates integrally with the second intermediate gear 37 is attached to the support shaft 35. This first intermediate gear 3
Reference numeral 6 meshes with a drive gear 38 attached to the output shaft 41 of a step motor 40 mounted on the gear box 28 so as to be integrally rotatable. That is, the rotation of the output shaft 41 driven by the step motor 40 is transmitted to the valve shaft 26 via the driving gear 38, the first intermediate gear 36, the second intermediate gear 37, and the driven gear 29. The rotation of the valve shaft 26 drives the intake throttle valve 4 to open and close.

As shown in FIG. 3, the valve shaft 26 has a lever 3 having two arms 32a and 32b.
2 is rotatably mounted. This lever 32 is connected to the driven gear 29 via a relief spring 31. The lever 32 is connected to the relief spring 3
The driven gear 29 is urged in the counterclockwise direction in FIG. One of the arms 32b provided on the lever 32 is bent in an L-shape and extends toward the driven gear 29. The distal end of the arm 32b is engaged in a groove 30 formed in the driven gear 29, as shown in FIG. The lever 32 is relatively rotatable with respect to the driven gear 29 by the gap between the groove 30 and the tip of the arm 32b. However, usually, the tip of the arm portion 32b is
Due to the urging force of 1, the groove 30 is in contact with the side wall on the counterclockwise direction centering on the valve shaft 26. In this state, the driven gear 29 and the lever 32 are integrally rotated.

At the tip of the other arm portion 32a provided on the lever 32, a pressing portion 33 is provided which can abut on a fully open switch 39 provided in the gear box 28. The pressing portion 33 is in contact with the full-open switch 39 at the full-open position of the intake throttle valve 4, and can turn on the full-open switch 39. Note that, in the present embodiment, the intake throttle valve 4 is rotatable further in the opening side than the fully open position. Here, the fully open position refers to the position of the intake throttle valve 4 when the opening area of the intake passage 2 is maximized. Then, when the intake throttle valve 4 is further driven in the opening direction from the fully opened position, further opening drive is eventually restricted by a stopper (not shown). Hereinafter, the position of the intake throttle valve 4 at this time is referred to as a maximum opening position.

Further, a not-shown fully closed stopper is provided on the shaft portion opposite to the gear box 28. The fully closed stopper comes into contact with the stopper at a position where the intake throttle valve 4 is in the fully closed position.
Is restricted in the closing direction. Here, the fully closed position means the position of the intake throttle valve 4 when the opening area of the intake passage 2 is minimum, that is, 0. However, at this time, the driven gear 29 can rotate further in the closing direction than the fully closed position. When the driven gear 29 further rotates in the closing direction from the position where the rotation of the lever 32 is restricted by the contact of the stopper, the driven gear 29 is urged in the opening direction by the urging force of the relief spring 31. Will be done.

Next, an electric circuit configuration showing a control system of the diesel engine 1 will be described with reference to a block diagram shown in FIG. The ECU 19 reads out various control programs for controlling the fuel injection amount, the fuel injection timing, the EGR control, the intake air amount, etc. of the diesel engine 1 and maps for calculating values corresponding to various conditions. A dedicated memory (ROM) 61 is provided. Also, ECU
Reference numeral 19 denotes a central processing unit (CPU) 60 for executing arithmetic processing based on a program stored in the ROM 61.
And a random access memory (RAM) 62 for temporarily storing the result of calculation by the CPU 60 and data input from each sensor and the like.
R to maintain the power supply even when the power supply is cut off
AM63 and the like. These CPU 60 and ROM 6
1, a RAM 62 and a backup RAM 63 are connected to a bus 6
4 and an external input circuit 6
6 and an external output circuit 67.

On the other hand, in the ECU 19, input signals from the pressure sensor 6, the accelerator opening sensor 18, the water temperature sensor 77, and the intake temperature sensor 78 are temporarily stored in a buffer 69. The input signals stored in each buffer 69 are sequentially selected by the multiplexer 68 based on the instruction of the CPU 60, converted into digital signals by the A / D converter 65, and sent to the external input circuit 66. The pulse-like input signal from the rotation speed sensor 17 is sent to the external input circuit 66 after being binarized by the waveform shaping circuit 71. Furthermore, IG switch 2
0, the state of the starter switch 21 and the state of the fully open switch 39 are also transmitted as on / off information of those switches.
The IG switch 20 is a switch for controlling start / stop of the engine, and is turned on when the engine is started and turned off when the engine is stopped. The starter switch 21 is a switch for driving a starter motor for starting the engine, and is turned on when the starter motor rotates,
It turns off when stopped.

Further, a part of the voltage supplied from the battery 22 is also supplied to the external input circuit 66 via the A / D converter 65.
It is taken in. Thus, the ECU 19 knows the voltage VB of the battery 22 supplied to the step motor 40 and the like.

On the other hand, an external output circuit 67 of the ECU 19 includes a drive circuit 72 of the step motor 40 and the EG
A drive circuit 73 of the actuator 10 for opening and closing the R control valve 9, a drive circuit 74 of the timer control valve 15 of the fuel injection pump 14, and the fuel injection pump 1
The drive circuit 75 of the spill valve 16 is connected. A command signal is sent to each of the drive circuits 72 to 75 based on the calculation result of the CPU 60. Then, each drive circuit 72
75 drive the step motor 40, the actuator 10, the timer control valve 15, and the spill valve 16 based on the command signal.

Next, the configuration of the step motor 40 and its control mode will be described with reference to FIGS. FIG. 6 shows a plan sectional structure of the step motor 40, and FIG.
2 shows a cross-sectional side structure of the motor 40. As shown in these figures, the step motor 40 is roughly composed of a rotor 42 that can rotate integrally with the output shaft 41, and two stator cups provided to surround the rotor 42, that is, A It comprises a phase stator cup 44 and a B-phase stator cup 45. A permanent magnet 43 is provided on the outer periphery of the rotor 42 so as to be integrally rotatable. This permanent magnet 4
3 shows the stepping motor 40 shown in FIGS.
As shown in the schematic cross-sectional view, N poles and S poles of magnetic poles are alternately formed at predetermined angular intervals.

On the other hand, as shown in FIGS. 6 and 7, the A-phase stator cup 44 and the B-phase stator cup 45 have a ring shape, and the rotor 42 is rotatable in a hollow portion thereof. Is housed. These stator cups 44 and 45
Inside, two sets of coils are provided, that is, an Ap phase coil 46 and an An phase coil 47, or a Bp phase coil 48 and a Bn phase coil 49. These coils 46 to 49 are wound in the same direction.

As shown in FIGS. 8A and 8B, in the stator cups 44 and 45, as shown in FIGS. The upper teeth 50 and the lower teeth 51 (A-phase stator cup 44) or the upper teeth 52 at the same predetermined angular intervals as the magnetic poles of the magnet 43.
And lower teeth 53 (B-phase stator cup 45) are formed alternately. These upper teeth 50 and 52 and lower teeth 51 and 53
Are excited when a voltage is applied to the coils 46 to 49. Note that the teeth 50 and 51 provided on the A-phase stator cup 44 and the teeth 52 and 53 provided on the B-phase stator cup 45 are shifted by half of the predetermined angle, that is, by half a tooth. Position.

Next, the electric circuit configuration of the step motor 40 and its drive circuit 72 will be described with reference to FIG.
9A and 9B, the stepping motor 40
The relationship between the outer peripheral portion of the rotor 42 and the inner peripheral portions of the stator cups 44 and 45 is schematically shown in a form developed in a plane. In FIG. 9, the electric circuit configuration is also schematically shown in a simplified manner in order to easily explain the function of the drive circuit 72.

Ap provided in the A-phase stator cup 44
A voltage is applied to the phase coil 46 and the An phase coil 47 by a DC power supply 58. The drive circuit 72 includes an Ap-phase coil switch 54 and an An-phase coil switch 5 for allowing or interrupting application of voltage to each of the coils 47 and 48.
5 are provided. By turning on each of the coil switches 54 and 55, a voltage is applied to each of the coils 47 and 48, and the upper teeth 50 and the lower teeth 51 are excited. Although the coils 47 and 48 are wound in the same direction as described above, the directions of the currents applied to the coils 47 and 48 are opposite as shown in FIGS. 9 (a) and 9 (b). It is configured so that Therefore, when the voltage is applied to the Ap-phase coil 46 and when the voltage is applied to the An-phase coil 47, the upper teeth 50 and the lower teeth 51 are excited to different poles. That is, when a voltage is applied to the Ap-phase coil 46, the upper teeth 50 are excited to the N pole and the lower teeth 51 are excited to the S pole. On the other hand, An
When a voltage is applied to the phase coil 47, the upper teeth 50
The lower teeth 51 are excited to the N pole.

A similar electric circuit configuration is employed in the B-phase stator cup 45, and the Bp-phase coil switch 56 and the Bn-phase coil switch 57 are selectively turned on and off by the respective coils 48 and 49. Is applied with a voltage. By applying a voltage to the Bp phase coil 48, the upper teeth 52 are excited to the N pole, and the lower teeth 53 are excited to the S pole.
Is excited to the S pole, and the lower teeth 53 are excited to the N pole.

Next, the operating principle of the step motor 40 driven by the drive circuit 72 will be described with reference to FIGS. The drive circuit 72 includes the CPU 6
0, and operates on one of the coils 46 and 47 of the A-phase stator cup 44 and one of the coils 48 and 49 of the B-phase stator cup 45 simultaneously or on each of the stator cups 44. , 45 to one of the coils 46 to 49. FIG. 10 shows an energization state of each of the coils 46 to 49 of the step motor 40.

The drive circuit 72 selectively switches among eight excitation phase modes 0 to 7 as shown in FIG. As apparent from FIG. 10, in the case of the odd-numbered excitation phase mode, the coils 46, 47 and 48, 4 of the stator cups 44, 45 are provided.
A voltage is applied to each of the coils 9 at a time, and in the case of an even number, a voltage is applied to only one of the coils 46 to 49.

FIG. 9A shows an embodiment of the drive circuit 72 and the step motor 40 in the excitation phase mode 1 (the value of the lower 3 bits of elstep = 1) shown in FIG. At this time, the drive circuit 72 closes the Ap-phase coil switch 54 and the Bp-phase coil switch 56, and applies a voltage to the Ap-phase coil 46 and the Bp-phase coil 48. By applying a voltage to these coils 46 and 48, the upper teeth 50 of the A-phase stator cup 44 become the N pole, the lower teeth 51 become the S pole, and similarly, the upper teeth 52 of the B phase stator cup 45 become the north pole. The lower teeth 53 are excited to the N pole and the lower teeth 53 are excited to the S pole. At this time, the S-pole of the permanent magnet 43 of the rotor 42 has the upper teeth 50 of the A-phase stator cup 44 and the upper teeth 52 of the B-phase stator cup 45 excited to the N-pole.
At the center of the upper teeth 50 and 52. Similarly, the N-pole of the permanent magnet 43 of the rotor 42 is connected to the A-phase stator cup 44 excited to the S-pole.
The lower teeth 51 and the lower teeth 53 of the B-phase stator cup 45 are attracted to the lower teeth 51 and 53, and are drawn to an intermediate position between the lower teeth 51 and 53. Thus, the rotor 42 has the S
The pole is rotated so that the pole is located at a position between the upper teeth 50 and 52 and the N pole of the permanent magnet 43 is also located at a position between the lower teeth 51 and 53.

Thereafter, when the excitation phase mode is changed from mode 1 to mode 3, as shown in FIG. 10, the driving circuit 72 switches so that a voltage is applied to the An phase coil 47 and the Bp phase coil 48. The settings are made. FIG. 9B shows an aspect of the drive circuit 72 and the step motor 40 in the excitation phase mode 3 (the value of the lower 3 bits of elstep = 3). At this time, the upper teeth 50 of the A-phase stator cup 44 are excited to the S pole, the lower teeth 51 are excited to the N pole, the upper teeth 52 of the B phase stator cup 45 are excited to the N pole, and the lower teeth 53 are excited to the S pole. Become so. Thus, the S pole of the permanent magnet 43 of the rotor 42 becomes the lower teeth 51 of the A-phase stator cup 44 excited to the N pole.
And the N-pole of the permanent magnet 43 is similarly attracted to the intermediate position between the upper teeth 52 of the B-phase stator cup 45 and the upper teeth 50 of the A-phase stator cup 44 and the B-phase stator. The suction is performed at a position intermediate the lower teeth 53 of the cup 45. Thus, the rotor 42 is rotated rightward by half a tooth in FIG. 9, and the output shaft 41 is rotated clockwise by half the predetermined angle. In the present embodiment, the output shaft 41
When the (rotor 42) rotates rightward in FIG. 9, the intake throttle valve 4 is closed, and when the rotor 42 rotates leftward, the valve 4 is opened.

As described above, the drive circuit 72 switches the excitation phase mode so that the output shaft 41 of the step motor 40
Specifically, by switching the excitation phase mode in descending order, the intake throttle valve 4 is opened, and by switching the excitation phase mode in ascending order, the intake throttle valve 4 is closed. The output shaft 41 is rotated.

By the way, in the control device of the present embodiment, when the step motor 40 is rotated, the two excitation methods are selectively used. That is, the excitation phase mode is changed one by one, specifically, the excitation phase mode is changed from mode 0 → mode 1 →
Mode 2... Or Mode 2 → Mode 1 → Mode 0... And a mode in which a mode in which only one coil is excited and a mode in which two coils are simultaneously excited are alternately repeated (hereinafter referred to as “1- Two-phase excitation method) and two excitation phase modes so that the excitation phase mode always has an odd number. More specifically, the excitation phase mode is changed from mode 1 to mode 3 to mode 5 or mode 5 to mode. The mode is switched from mode 3 to mode 1... And is rotated using only the mode in which two coils are simultaneously excited (hereinafter referred to as “2
Phase excitation method "). 1-
In the case of the two-phase excitation method, the rotation angle of the rotor 42 of the step motor 40 per switching of the excitation phase mode can be set finely, and the opening degree of the intake throttle valve 4 can be finely controlled. On the other hand, in the case of the two-phase excitation method, the rotation angle of the rotor 42 per switching of the excitation phase mode can be increased, and the opening and closing speed of the intake throttle valve 4 can be increased. In this way, by using the two excitation methods properly according to the situation, it is possible to achieve both improvement in accuracy and improvement in followability in controlling the opening degree of the intake throttle valve 4.

In the present embodiment, the opening angle control of the intake throttle valve 4 is performed by defining the rotation angle per excitation phase mode switching in the 1-2 phase excitation method as one step. Therefore, in the case of the two-phase excitation method, the motor is rotated by two steps each time the excitation phase mode is switched.

Next, a specific drive control mode of the step motor 40 for driving the intake throttle valve 4 to open and close according to the present embodiment will be described. In the present embodiment, the operation amount of the intake throttle valve 4 is calculated based on the number of steps at which the step motor 40 is driven, and the opening degree of the intake throttle valve 4 is controlled based on the calculated amount. However, when step-out of the step motor 40 occurs or when the power supply to the step motor 40 is cut off when the engine 1 is stopped, the opening degree of the intake throttle valve 4 is controlled based on the step position of the step motor 40. May not be able to correspond to the actual opening degree of the intake throttle valve 4. Therefore, in the present embodiment, prior to the control of the opening degree of the intake throttle valve 4, an initialization process for determining these correspondences is executed.

First, such initialization processing will be described. When the initialization process is started, the CPU 60
First, the on / off state of the full-open switch 39 is confirmed. Then, the CPU 60 drives the step motor 40 in the direction in which the fully open switch 39 is switched, and sets the step position at the time when the switch 39 is switched as the reference position. The setting of the reference step position is based on the step position of the step motor 40 at which the on / off state of the full-open switch 39 is switched and the current step elsac.
This is performed by storing the value of t as “0” and the mode value of the excitation phase mode at that time as an offset value elsof. This current step elsact is performed by the intake throttle valve 4
Is subtracted when the valve is opened, and is added when the valve is closed. Thus the current step elsact
Is increased or decreased with the opening and closing of the intake throttle valve 4, the opening degree of the intake throttle valve 4 can be grasped from this value.
In addition, the opening degree control of the intake throttle valve 4 includes an excitation phase corresponding step elst which is a sum of the current step elsact thus set and the stored offset value elsof.
ep is used. This excitation phase corresponding step elste
The value of the lower 3 bits of p (0 to 7) is
This corresponds to the excitation phase mode value of the step motor 40 at lsact (FIG. 10).

Next, the intake throttle valve 4 according to the present embodiment will be described.
The drive control mode of the step motor 40 during the opening degree control will be described in detail with reference to FIG. FIG.
5 is a flowchart showing a control procedure in a drive control routine of the step motor 40.

This routine is executed by the step motor 40
Is activated as an excitation interrupt for. This excitation interruption period corresponds to a switching period of the excitation phase, and this period itself is also set by the processing of this routine. In the following description, the period (switching cycle, driving frequency) at which the excitation phase is switched is referred to as a pulse rate. And the unit is the reciprocal of the time required for the excitation phase switching cycle, that is, the number of excitation phase switching per second (number of pulses).
Is represented by “PPS (pulse per second)”. Therefore, as the value of the pulse rate increases, the excitation phase switching cycle becomes shorter, and the opening / closing drive speed of the intake throttle valve 4 becomes faster.

On the other hand, in the present embodiment, a 1-2-phase excitation method in which the step motor 40 is driven one step at a time for each excitation phase switching and a two-phase excitation method in which the step motor 40 is driven in two steps are selectively used. ing. That is, even when the pulse rate is the same, the intake throttle valve 4 is opened and closed at twice the speed when driven by the two-phase excitation method than when driven by the 1-2-phase excitation method.

Now, when the process proceeds to this routine, C
First, in step S101, the PU 60 compares the current step elsact with the target step elstrg. The target step elstrg is a value set as the step position of the step motor 40 corresponding to the target opening at the time of controlling the opening of the intake throttle valve 4. The target step elstrg is determined, for example, by the intake air amount or the engine speed N.
E is set based on the operating state of the engine 1 such as E,
The water temperature sensor 77, the pressure sensor 6, and the intake air temperature sensor 78
The correction is made based on parameters such as the cooling water temperature, the atmospheric pressure, the intake air temperature, etc. The setting and correction of these target steps elstrg are performed by a regular interrupt (time synchronization) routine (not shown). The target step elstrg is set such that the step position of the step motor 40 when the intake throttle valve 4 reaches the fully open position is set as a reference step position, that is, “0” step, and the target step elstrg is increased as the motor 40 is driven in the valve closing direction. It is set as the number of steps to take a value.

If it is determined in step S101 that the target step elstrg is larger than the current step elsact, the CPU 60 determines in step S102 that the current step elsact and the excitation phase corresponding step elstep (FIG. 10) are respectively executed. 2 "
The valve opening drive flag “exopen” is turned off. On the other hand, if the current step elsact is larger, the CPU 60
Is "2" from the current step elsact and the excitation phase corresponding step elstep as processing S103.
Is subtracted, and the valve opening drive flag “exopen” is turned on.
The drive circuit 72 changes the excitation phase of the step motor 40 based on the value (0 to 7) of the lower three bits of the excitation phase corresponding step elstep changed at the time of the next excitation switching, and sets the intake throttle valve 4 at this point. The opening degree corresponds to the current step elsact changed in.

In the present embodiment, when the current step elsact and the target step elstrg match, or the driving direction of the step motor 40 is reversed, that is, the driving direction of the step motor 40 is reversed. When the target step elstrg is changed as described above, stop control for stopping the step motor 40 is performed through a process (not shown) of this routine, and the stop control flag exstop is turned on. Step motor 40
When the driving of the motor is stopped or when the driving direction is reversed, the step-out may occur due to the inertial force. Therefore, in such a case, the CPU 60
The excitation phase is fixed as it is for a predetermined time required for stabilization of the motor, thereby suppressing the occurrence of step-out.

By the way, the stepping motor 40 of the present embodiment uses two driving methods as described above. Usually, the step motor 40 is driven by the two-phase excitation method.
03 is executed as it is. However, the step motor 40
Is excited in one phase or the target step elstrg
If there is only one step difference between the step motor 4 and the current step elsact, the step motor 4
Drive 0. In this case, in the process S102 or the process S103, the current step elsact and the excitation phase corresponding step elstep (FIG. 10) are added or subtracted by "1", and the step motor 40 is driven by one step.

Now, the current step elsac
After changing t and the excitation phase corresponding step elstep,
The CPU 60 determines in step S104 that the battery voltage VB
Is higher than 12V. Note that this 12V
Is a voltage serving as a standard for sufficiently drawing out the drive performance of the intake throttle valve as the step motor 40.

In this step S104, if the battery voltage VB is higher than 12 V, that is, if a sufficient voltage is applied to the step motor 40, the CPU 60 executes the step S104.
Move to 108. In this processing S108, the CPU 6
0 determines whether or not the valve opening drive flag exopen is ON, that is, whether or not to drive the intake throttle valve 4 to the valve opening side. If the valve opening drive flag “exopen” is ON, the CPU 60 determines in step S110 whether the stop control of the step motor 40 was performed at the time of the previous excitation phase switching, that is, the previous stop control flag “exst”.
It is determined whether or not op is on. When stop control was not performed last time (previous exstop = OF
F), in step S112, the CPU 60 sets the pulse rate to 200 PPS. On the other hand, if the stop control was previously performed on the step motor 40 (the previous
(p = ON), the CPU 60 proceeds to step S111.
Set the pulse rate to 150 PPS. When driving is started from a stopped state, the step motor 40 needs a high starting torque. Therefore, in the present embodiment, even when driving in the valve opening direction is started from the stopped state (previous exstop = ON), the stepping motor 4
By increasing the drive torque by decreasing the pulse rate of 0, the occurrence of step-out is suppressed.

On the other hand, in step S108, when the valve-opening drive flag “exopen” is off, that is, when the step motor 40 is driven to the valve-closing side, the CPU 60 executes step S10.
As 9, the pulse rate is set to 150 PPS. As described above, the intake throttle valve 4 is urged toward the valve opening side by the return spring 27. Therefore, the step motor 40 can drive the intake throttle valve 4 while being assisted by the urging force of the return spring 27 when the valve is opened, but must be driven against this urging force when the valve is closed. Therefore, in the present embodiment, when the valve is closed, the excitation switching cycle is set to be slow, and the drive torque of the step motor 40 is sufficiently ensured.

Next, the case where the battery voltage VB is equal to or lower than 12 V in step S104, that is, the case where the voltage supplied to the step motor 40 becomes insufficient will be described. In this case, the CPU 60 determines whether or not the battery voltage VB is equal to or lower than 11 V in the process S105. This processing S
105, when it is determined that the battery voltage VB is higher than 11 V, that is, when the battery voltage VB is 11 to 1
If it is in the range of 2 V, the CPU 60 sets the pulse rate to 100 PPS and reduces the drive speed of the step motor 40 in step S106. On the other hand, when it is determined that the battery voltage VB is 11 V or less, the CPU
In step S107, the pulse rate is set to 50 PP.
In step S, the driving speed of the step motor 40 is further reduced. As described above, when the battery voltage VB decreases, the output of the step motor 40 also decreases. Therefore, when trying to drive at the same pulse rate as usual, the driving torque when driving the intake throttle valve 4 becomes insufficient, and step-out easily occurs. Become. Therefore, in the present embodiment, when the battery voltage VB decreases as described above, the excitation switching cycle is delayed, and the driving torque of the step motor 40 is increased.

The CPU 60 adjusts the substantial opening / closing drive speed of the intake throttle valve 4 by reflecting the pulse rate set as described above in the drive cycle of the next step motor 40 and thereafter.

FIG. 12 shows the relationship between the battery voltage VB, the driving direction of the step motor 40, and the pulse rate set when the motor 40 is driven. As described above, when the amount of intake air supplied to the diesel engine 1 is insufficient, problems such as generation of smoke occur. On the other hand, due to the mechanism of the diesel engine, even if the intake air amount is excessive, operation will not be hindered. Therefore, when it is necessary to increase the amount of intake air, it is necessary to quickly open the intake throttle valve 4 to quickly secure the required amount of intake air. On the other hand, when the intake throttle valve 4 is closed, there is no such requirement, so that it is not necessary to increase the valve closing speed as compared to when the valve is opened.

Therefore, in the present embodiment, as shown in FIG. 12, when the battery voltage VB is higher than 12 V and the voltage applied to the step motor 40 is sufficient, the driving of the step motor 40 is mainly performed. The pulse rate is changed based on the direction, and the driving speed is faster when the valve is open than when it is closed (200 PPS when the valve is open, 150 PPS when the valve is closed). Since the intake throttle valve 4 of the present embodiment is urged toward the valve opening side by the return spring 27, the valve can be driven to open while receiving the assistance of this urging force when the valve is opened. Therefore, the step motor 40
Even when a small output (torque) having a small output is used, the valve opening speed of the intake throttle valve 4 can be increased, and the responsiveness at the time of valve opening can be sufficiently ensured. On the other hand, when the valve is closed, the step motor 40 needs to drive the intake throttle valve 4 to close while resisting the urging force of the return spring 27. However, as described above, since it is not necessary to increase the valve closing speed at the time of closing the valve, the driving speed is reduced to increase the driving torque generated by the step motor 40.

However, even when the valve is opened, a high starting torque is required immediately after the driving is started from the stopped state, so that the driving torque needs to be increased. Therefore, in such a case, the drive speed of the step motor 40 is reduced (when the valve is opened = 150 PPS) so that a sufficient drive torque can be obtained. In the present embodiment, such control is not performed at the start of the valve closing drive. This is because the drive speed at the time of the valve closing drive has already been reduced and a sufficient drive torque has been secured, so that it is not necessary to perform such control again.

Further, even when the battery voltage VB decreases and the output of the step motor 40 decreases, the drive speed is reduced to ensure a sufficient drive torque of the step motor 40 (11 to 12 V = 100PPS, 1
1 V or less = 50 PPS).

As described above, the stepping motor 4
0, the stepping motor 40 is changed.
Therefore, even when a small-sized and low-cost device having a small output (torque) is used, the required driving torque can be secured while sufficiently securing the responsiveness at the time of the valve opening drive.

As described above, according to the present embodiment, the following effects can be obtained. (1) Since the intake throttle valve 4 is always urged toward the valve opening side by the return spring 27, even when a small-sized and low-cost step motor 40 having a small output (torque) is used, the intake throttle valve 4 is used. 4 can be quickly opened.

(2) When closing the intake throttle valve 4 which needs to be driven against the urging force of the return spring 27,
By increasing the driving torque by lowering the driving speed of the step motor 40, even when a small-sized and low-cost step motor 40 having a small output (torque) is used,
Step-out can be suppressed, and stable driving can be performed.

(3) When the battery voltage VB decreases and the output of the step motor 40 decreases, the drive speed is reduced to secure a sufficient drive torque to prevent the step motor 40 from stepping out. Thus, the opening degree control of the intake throttle valve 4 can be stably performed.

(4) Immediately after the step motor 40 is switched from the stopped state to the drive in the valve opening direction, the drive speed is reduced to secure a sufficient drive torque, thereby causing the step motor 40 to lose synchronism. , And the intake throttle valve 4 can be driven to open and close stably.

(5) Since a small-sized and low-cost step motor 40 having a small output (torque) can be used, the cost and power consumption of the entire system can be reduced.

The embodiment of the present invention may be modified as follows. The value of the pulse rate in this embodiment and the value of the battery voltage VB used as a guide for changing the pulse rate are arbitrary, and the drive speed of the step motor 40 when the battery voltage VB decreases is determined by the intake throttle valve 4. These values may be set so as to further reduce the driving speed at the time of the valve closing drive.

Also, without performing control to reduce the pulse rate when the battery voltage VB decreases, the above (1),
The effect of (2) can be obtained. Next, technical ideas other than those described in the claims that can be understood from the above-described embodiment will be described below together with their effects.

(1) In the intake throttle valve control method for a diesel engine according to claim 1 or 2, immediately after the intake throttle valve is switched to the drive to the closing side, and from the stopped state of the intake throttle valve, the valve is opened. In at least one of the steps immediately after startup to the valve side, the operation speed of the step motor is temporarily reduced to be lower than the operation speed of the step motor to the valve opening side of the intake throttle valve. Throttle valve control method.

(2) In the intake throttle valve control device for a diesel engine according to the third or fourth aspect, immediately after the drive of the intake throttle valve is switched from the drive to the valve-opening side to the valve-opening side, and to the same intake valve. State detection means for detecting at least one state immediately after the stop of the throttle valve from the stop state to the valve opening side,
Temporary deceleration means for temporarily reducing the operation speed of the step motor based on the detection of the state by the state detection means than the operation speed of the step motor toward the valve opening side of the intake throttle valve. An intake throttle valve control device for a diesel engine, comprising:

Immediately after the driving direction of the step motor is switched or immediately after the driving is started from the stopped state,
The step motor is likely to lose synchronism because inertia force does not act and the drag such as static friction force is large. According to the method described in the above (1) and the configuration described in the above (2), in such a case, In this case, the drive speed of the step motor is reduced to increase the drive torque, whereby the step out of the step motor can be suppressed.

[0074]

According to the first and fourth aspects of the present invention, the operating speed at the time of opening the valve is higher than that at the time of closing the valve.
It is possible to suppress the occurrence of step-out of the step motor while appropriately ensuring the response at the time of opening the intake throttle valve.

According to the second and fifth aspects of the present invention, the intake throttle valve is urged toward the valve opening side so that a small-sized and low-cost step motor can be used. Responsiveness and driving torque at the time of valve opening can be more appropriately secured.

According to the third and sixth aspects of the present invention, the operation speed of the stepping motor is reduced to secure a sufficient driving torque. Tone generation can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of a diesel engine to which a step motor type valve device according to an embodiment of the present invention is applied.

FIG. 2 is a sectional view showing a side sectional structure of an intake throttle valve and a drive mechanism thereof.

FIG. 3 is a front view showing a front structure of a drive mechanism of the intake throttle valve.

FIG. 4 is a partial sectional view of a drive mechanism of the intake throttle valve.

FIG. 5 is a block diagram showing an electrical configuration of the valve device of the embodiment.

FIG. 6 is a sectional view showing a planar sectional structure of a step motor.

FIG. 7 is a sectional view showing a side sectional structure of the step motor.

FIG. 8 is a schematic diagram showing a schematic structure of the step motor.

FIG. 9 is a schematic view showing the operation principle of the step motor.

FIG. 10 is a diagram showing a state of energizing each coil of the step motor.

FIG. 11 is a flowchart showing a control procedure of a drive control routine of a step motor.

FIG. 12 is a diagram showing a relationship between a pulse rate and a driving voltage of a step voltage and a battery voltage.

[Explanation of symbols]

1 ... diesel engine, 2 ... intake passage, 4 ... intake throttle valve,
Reference numeral 5: intake throttle valve driving mechanism, 6: pressure sensor, 7: exhaust passage, 8: EGR passage, 9: EGR control valve, 19: electronic control unit (ECU), 20: ignition switch, 21
... Starter switch, 22 ... Battery, 26 ... Valve shaft, 2
9: driven gear, 32: lever, 33: pressing portion, 35: support shaft, 36: first intermediate gear, 37: second intermediate gear, 38 ...
Drive gear, 39 ... Fully open switch, 40 ... Step motor, 41 ... Output shaft, 42 ... Rotor, 43 ... Permanent magnet, 4
4 ... A phase stator cup, 45 ... B phase stator cup, 46
... Ap-phase coil, 47 ... An-phase coil, 48 ... Bp-phase coil, 49 ... Bn-phase coil, 60 ... CPU, 72 ... Drive circuit, 77 ... Water temperature sensor, 78 ... Atmospheric temperature sensor.

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI H02P 8/14 H02P 8/00 R 8/38 304A (56) References JP-A-60-252137 (JP, A) 4-19340 (JP, A) JP-A-4-17744 (JP, A) JP-A-9-317501 (JP, A) JP-A-59-38238 (JP, A) JP-A-10-89093 (JP, A) A) Hikaru 3-97546 (JP, U)

Claims (6)

(57) [Claims] 1. A method for controlling an intake throttle valve of a diesel engine, wherein said intake throttle valve is opened and closed based on a step number control based on a predetermined step position of a step motor driven and connected to the intake throttle valve of the diesel engine. The step mode is set to the target number of steps according to the operating conditions.
The opening and closing operation of the intake throttle valve for controlling the operation of the intake throttle valve, the operating speed of the step motor for opening the intake throttle valve is higher than the operating speed of the step motor for closing the intake throttle valve. Intake throttle valve control method. 2. The intake throttle valve control method for a diesel engine according to claim 1, wherein the intake throttle valve is constantly energized toward a valve opening side. Method. 3. The method of controlling an intake throttle valve for a diesel engine according to claim 1, wherein the drive voltage of the step motor is constantly monitored, and when the drive voltage becomes equal to or lower than a predetermined voltage, the operation of the step motor is performed. A method for controlling an intake throttle valve of a diesel engine, wherein the speed is further reduced than the operating speed of the intake throttle valve to the valve closing side. 4. An intake throttle valve control device for a diesel engine for opening and closing said intake throttle valve based on a step number control based on a predetermined step position of a step motor drivingly connected to the intake throttle valve of the diesel engine. Set the target step according to the engine operating state of the step motor.
When controlling the number of valves, the intake throttle valve is moved toward the valve opening side.
Move the operating speed of the step motor toward the valve closing side of the intake throttle valve.
And operating speed setting means for setting higher than the operating speed of the Teppumota, intake throttle valve control apparatus for a diesel engine, characterized in that Ru and an operation command unit allowed to operate the step motor based on operating speed of the set. 5. The intake throttle valve control device for a diesel engine according to claim 4, further comprising: biasing means for biasing the intake throttle valve to a valve opening side. Control device. 6. The intake throttle valve control device for a diesel engine according to claim 4, further comprising monitoring means for monitoring a drive voltage of said step motor, wherein said operating speed setting means includes a drive voltage to be monitored. When the pressure becomes equal to or lower than a predetermined voltage, the operation speed is set to be lower than the operation speed of the stepping motor for closing the intake throttle valve to the valve closing side.