JPH0238780B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the idling speed of an internal combustion engine.

Conventionally, a bypass passage is branched from the intake passage upstream of the throttle valve, and this bypass passage is connected to the intake passage again downstream of the throttle valve, and a negative pressure diaphragm type control valve device is provided in the bypass passage, and a negative pressure diaphragm type control valve device is provided in the bypass passage. The diaphragm negative pressure chamber of the type control valve device is connected to the intake passage downstream of the throttle valve via a negative pressure conduit, and an electromagnetic control valve for controlling the cross-sectional area of the flow passage is installed in this negative pressure conduit. By controlling the control valve according to the operating state of the engine, the negative pressure applied to the diaphragm negative pressure chamber of the negative pressure diaphragm type control valve device is controlled, thereby controlling the flow passage cross-sectional area of the bypass passage and idling the engine. An idling rotation speed control device is known that controls the amount of intake air supplied from a bypass passage during operation. However, with such conventional idling rotation speed control devices, first of all, when the vehicle is used in a cold region, the electromagnetic control valve freezes, making it impossible to control the flow passage cross-sectional area of the negative pressure conduit, and as a result, the negative pressure Since it becomes impossible to control the cross-sectional area of the bypass passage by the pressure diaphragm type control valve device, there is a problem in that the amount of intake air supplied from the bypass passage cannot be controlled. Second, because conventional idling speed control devices use a negative pressure diaphragm type control valve device, the controllable range of the flow passage cross-sectional area of the bypass passage is narrow, and therefore the negative pressure diaphragm type control valve device is fully opened. However, sufficient intake air required during fast idling operation cannot be supplied from the bypass passage. Therefore, in the conventional idling speed control device, in addition to the bypass passage, a separate second bypass passage is provided, and a bimetal operated valve is provided in this second bypass passage, and the bimetal operated valve is operated when the engine temperature is low. The valve is opened and intake air is also supplied from the second bypass passage, thereby ensuring the amount of intake air required during fast idling operation.
In this way, in the conventional idling speed control device, a second bypass passage must be provided in addition to the bypass passage, and a bimetal actuated valve must be installed in the second bypass passage, making the structure complicated. There is a problem. Furthermore, since control of the intake air during fast idling operation is based only on the expansion and contraction of the bimetal element, there is a problem in that the amount of intake air cannot be accurately controlled during fast idling operation.

An idling rotational speed control method that accurately controls the amount of air flowing through a bypass passage during fast idling operation, maintains the engine rotational speed at an optimum value during fast idling operation, and ensures a good heating effect in the passenger compartment. Our goal is to provide the following.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, 1 is an engine main body, 2 is a surge tank, 3 is an intake pipe, 4 is a throttle valve, and 5 is an air flow meter, and this air flow meter 5 is connected to the atmosphere via an air cleaner (not shown). Ru. The surge tank 2 is common to each cylinder, and is connected to the corresponding cylinder via a plurality of branch pipes 6, and a fuel injection valve 7 is attached to each of these branch pipes 6, respectively. on the other hand,
A flow control valve device 8 is attached to the surge tank 2 . As shown in FIG. 2, this flow control valve device 8 includes a motor housing 10 holding a step motor 9, a motor housing end plate 11, and a valve housing 12.
0, 12 and the end plate 11 are secured together by bolts 13. As shown in FIGS. 1 and 2, a flange 14 is integrally formed on the valve housing 12, and this flange 14 is fixed onto the outer wall surface of the surge tank 2 with bolts. Valve housing 1
A valve chamber 15 is formed in the valve housing 12, and the valve chamber 15 is connected to the intake pipe 3 upstream of the throttle valve 4 through a bypass pipe 16 fixed to the valve housing 12, as shown in FIG. . On the other hand, as shown in FIGS. 1 and 2, a cylindrical protrusion 17 that protrudes into the surge tank 2 is integrally formed at the tip of the flange 14, and a cylindrical air outlet hole 18 is provided within this protrusion 17. It is formed. An annular groove 19a is formed at the inner end of the air outlet hole 18, and the valve seat 19 is fitted into the annular groove 19a.

On the other hand, the step motor 9 connects the valve shaft 20 and the valve shaft 2
a rotor 21 disposed coaxially with the rotor 2;
1 and a pair of stators 22 and 23 fixedly arranged with a slight gap between them. As shown in FIG. 2, the end of the valve shaft 20 is supported by a hollow cylindrical bearing 24 made of sintered metal fixed to the motor housing 10, and the middle part of the valve shaft 20 is fixed to the housing end plate 11. It is supported by a sintered metal bearing 25. In addition, the valve stem 20
A first stop pin 26 that contacts the rotor 21 when the valve shaft 20 is in the maximum forward position is fixed to the valve shaft 20, and a first stop pin 26 that contacts the rotor 21 when the valve shaft 20 is in the maximum retraction position is fixed to the valve shaft 20. Two stop pins 27 are fixed. Note that the bearing 24 has a first
A slit 28 is formed into which the stop pin 26 can enter. Furthermore, motor housing 1
An external thread 29 is threaded onto the outer circumferential surface of the valve shaft 20 located inside the valve shaft 20, and this external thread 29 extends from the left end of the valve shaft 20 to the right in FIG. It terminates just beyond the point. Further, an external thread 29 is provided on the outer peripheral surface of the valve stem 20.
A flat portion 30 is formed extending to the right from near the termination position of the valve shaft 21, and as shown in FIG. 31 and a flat inner peripheral surface 32.
Therefore, the valve shaft 20 is supported by the bearing 25 so as to be non-rotatable and slidable in the axial direction. Further, as shown in FIG. 3, an outwardly projecting arm 33 is integrally formed on the outer peripheral wall surface of the bearing 25, and on the other hand, an arm 33 having a contour shape that matches the outer peripheral contour shape of the bearing 25 is formed on the housing end plate 11. A bearing fitting hole 34 is formed. Therefore, the bearing 25 is inserted into the bearing fitting hole 3 as shown in FIG.
4, the bearing 25 is non-rotatably supported on the housing end plate 11. Valve stem 20
A valve body 36 having a substantially conical outer circumferential surface 35 is secured to the tip of the valve body 36 by a nut 37.
An annular air flow passage 3 is provided between the outer peripheral surface 35 of the valve seat 19 and the valve seat 19.
8 is formed. Furthermore, a compression spring 39 is inserted into the valve chamber 15 between the valve body 36 and the housing end plate 11.

As shown in FIG. 2, the rotor 21 includes an inner cylinder 40 made of synthetic resin, an intermediate cylinder 41 made of metal that is fitted and fixed onto the outer peripheral surface of the inner cylinder 40, and an intermediate cylinder 41 that is bonded onto the outer peripheral surface of the intermediate cylinder 41. An outer cylinder 42 made of a permanent magnet is adhesively fixed with an adhesive, and N poles and S poles are alternately formed in the circumferential direction on the outer circumferential surface of the permanent magnet outer cylinder 42, as will be described later. As can be seen from FIG. 2, one end of the intermediate cylinder 41 is supported by an inner race 44 of a ball bearing 43 supported by the motor housing 10, while the other end of the intermediate cylinder 41 is supported by the housing end plate 11. supported ball bearing 4
It is supported by the inner race 46 of No. 5. Therefore, the rotor 21 is rotatably supported by the pair of ball bearings 43 and 45. It can also be seen that an inner thread 47 is formed in the center hole of the inner cylinder 40 to engage with the outer thread 29 of the valve shaft 20, so that when the rotor 21 rotates, the valve shaft 20 is moved in the axial direction. .

Stator 22 and stator 23 fixedly disposed within motor housing 10 have the same structure, and therefore only the structure of one stator 22 will be described with reference to FIGS. 4 to 7. Fourth
Referring to FIG. 7, the stator 22 includes a pair of stator core portions 51 and 52 and a stator coil 5.
3. The stator core portion 51 includes an annular side wall portion 54, an outer cylinder portion 55, and an annular side wall portion 5.
4, and eight magnetic pole pieces 56 extending perpendicularly to the annular side wall portion 54 from the inner peripheral edge of the magnetic pole piece 4. These magnetic pole pieces 56 have a substantially triangular shape and are arranged at equal angular intervals. On the other hand, the stator core portion 52
is composed of an annular side wall portion 57 and eight magnetic pole pieces 58 extending perpendicularly to the annular side wall portion 57 from the inner peripheral edge of the annular side wall portion 57, and these magnetic pole pieces 58 have a substantially triangular shape like the magnetic pole pieces 56. and are arranged at equal angular intervals. These stator core parts 51 and 52 are connected to each other in such a way that their magnetic pole pieces 56 and 58 are equally spaced from each other, as shown in FIGS. , 52 form the stator core. When a current flows through the stator coil 53 in the direction shown by arrow A in FIG. 7, a magnetic field shown by arrow B is generated around the stator coil 53 in FIG. 6, and as a result, the magnetic pole piece 56 has an S pole and a magnetic pole A north pole is generated in each piece 58. Therefore, it can be seen that N poles and S poles are alternately formed on the inner peripheral surface of the stator 22. On the other hand, if a current is applied to the stator coil 53 in the direction opposite to the arrow A in FIG. 7, an N pole is generated in the magnetic pole piece 56 and an S pole is generated in the magnetic pole piece 58.

FIG. 8 shows the stator 22 and stator 23 arranged in tandem as shown in FIG. In FIG. 8, the same components of the stator 23 as those of the stator 22 are indicated by the same reference numerals. As shown in FIG. 8, if the distance between the adjacent magnetic pole pieces 56 and 58 of the stator 22 is l, the magnetic pole pieces 56 of the stator 23 are
It is shifted by 1/2 with respect to the magnetic pole piece 56 of. That is,
The distance d between adjacent magnetic pole pieces 56 of the stator 22 is 1
In terms of pitch, the magnetic pole piece 56 of the stator 23 is offset from the magnetic pole piece 56 of the stator 22 by 1/4 pitch. On the other hand, as shown in FIG.
On the outer peripheral surface of the permanent magnet outer cylinder 42, N poles and S poles are formed alternately in the circumferential direction, and the distance between adjacent N and S poles is equal to the distance between adjacent magnetic pole pieces 56 and magnetic pole pieces 5.
Matches the interval of 8.

Referring again to FIG. 1, the step motor 9 is connected to an electronic control unit 61 via a step motor drive circuit 60. Furthermore, the electronic control unit 61 includes a vehicle speed sensor 62, an engine cooling water temperature sensor 63, an engine speed sensor 64, a throttle switch 65, and a neutral switch 6 of the automatic transmission.
A hydraulic switch 67 is also connected. The vehicle speed sensor 62 is composed of, for example, a rotating permanent magnet 68 installed in a speedometer and rotated by a speedometer cable, and a reed switch 69 that is turned on and off by the permanent magnet 68, and is proportional to the vehicle speed. A pulse signal is sent to the electronic control unit 61. Water temperature sensor 63
detects the engine cooling water temperature and sends a signal representing the engine cooling water temperature to the electronic control unit 61. The rotation speed sensor 64 is connected to a rotor 71 that rotates in synchronization with the crankshaft in the distributor 70.
and an electromagnetic pickup 72 disposed opposite to the serrated outer periphery of the rotor 71, and sends pulses to the electronic control unit 61 every time the starter crankshaft rotates by a certain angle. The throttle switch 65 is actuated by the rotational movement of the throttle valve 4 and is turned on when the throttle valve 4 is in a fully closed state, and sends its detection signal to the electronic control unit 61. neutral switch 66
detects whether the automatic transmission is in drive range D or neutral range N, and sends the detection signal to electronic control unit 61.

On the other hand, FIG. 11 shows an air conditioner 200. The air conditioner 200 includes an air duct 203 having an air intake 201 and an air outlet 202. Air intake port 201 is connected to outside air, and air outlet port 202 opens into vehicle cab 204 . A motor 20 is installed inside the air duct 203.
A fan 206 driven by 5 is provided,
When the fan 206 rotates, air sucked into the air duct 203 from the air intake port 201 is discharged from the air exhaust port 202. Furthermore, air duct 203
An air mix damper 208 fixed to a rotating shaft 207 is installed inside. An arm 209 is fixed to the rotation shaft 207, and the tip of the arm 209 is connected to a diaphragm 212 of a negative pressure diaphragm device 211 via a control rod 210.
Negative pressure diaphragm device 211 is diaphragm 21
Negative pressure chamber 213 and atmospheric pressure chamber 2 separated by
14, and a compression spring 215 for pressing the diaphragm is inserted into this negative pressure chamber 213. Negative pressure chamber 2
13 is connected to the atmosphere via a throttle 216 on the one hand, and a negative pressure conduit 217 and an on-off control valve 2 on the other hand.
18 into the surge tank 2 (FIG. 1). As shown in FIG. 11, this opening/closing control valve 218 is connected to an output terminal of an electronic control unit 219 for an air conditioner controller, and an air conditioner switch 73 and a room temperature setting device 221 are connected to the input terminals of the electronic control unit 219. and the room temperature sensor 222 are connected. Continuous pulses are supplied from the electronic control unit 219 to the solenoid of the on-off control valve 218, and the duty ratio of the supplied continuous pulses increases, so that the opening time of the on-off control valve 218 becomes longer. On the other hand, as shown in FIG. 11, an evaporator 223 for cooling air is installed in the air duct 203.
and a heat exchanger 224 for air heating. Refrigerant is supplied to this evaporator 223 from an engine-driven compressor (not shown) through a refrigerant inflow pipe 225, and after removing heat from the air flowing in the air duct 203, it is returned to the compressor through a refrigerant return pipe 226. Ru. On the other hand, the heat exchanger 224
Engine cooling water is supplied into the air duct 203 through a cooling water supply conduit 227, and after giving heat to the air flowing through the air duct 203, is returned to the radiator (not shown) through a cooling water return pipe 228.

When the air conditioner switch 73 is turned on, the motor 225 is rotated and the opening control of the opening/closing control valve 218 is started. As the duty ratio of the connection pulse applied to the on-off control valve 218 increases, as described above, the opening time of the on-off control valve 218 becomes longer, and the negative pressure in the negative pressure chamber 213 increases. As a result, the diaphragm 212 rises against the compression spring 215, and the air mix damper 208 rotates in the direction of arrow P. When the air mix damper 208 rotates in the direction of arrow P, the amount of air passing through the heat exchanger 224 decreases, so the temperature of the air supplied into the driver's cabin 204 decreases. On the other hand, when the duty ratio of continuous pulses applied to the on-off control valve 218 becomes smaller, the opening time of the on-off control valve 218 decreases.
The negative pressure inside becomes smaller. As a result, the diaphragm 212 descends, causing the air mix damper 208
rotates in the opposite direction to the arrow P, and the amount of air passing through the heat exchanger 224 increases, so the temperature of the air supplied into the driver's compartment 204 increases.
The air mix damper 208 is a temperature setting device 221
The rotation is controlled so that the temperature set by the driver and the room temperature detected by the room temperature sensor 222 are equal.

As shown in FIG. 11, a hot max switch 74 is provided in the air duct 203, which engages with the air mix damper 208 and turns on when the air mix damper 208 is in the position shown by the solid line. When the air mix damper 208 is in the position shown by the solid line, all the air flowing through the air duct 203 passes through the heat exchanger 224, and the hot mix switch 74 is turned on by the driver via the air duct 203. This is when the air supplied into the chamber 204 is heated the most. At this time, the evaporator 223 plays the role of dehumidification. Further, the air duct 203 is provided with a cool max switch 75 that engages with the air mix damper 208 and turns on when the air mix damper 208 is in the position shown by the broken line. When the air mix damper 708 is in the position shown by the broken line, all the air flowing inside the air duct 203 is transferred to the heat exchanger 2.
Evaporator 2 without being heated by 24
It is the air duct 203 that is cooled by the air duct 203 and the cool max switch 75 is turned on.
This is when the air supplied into the driver's cabin 204 through the air is cooled the most. Furthermore, an evaporator outlet temperature sensor 76 is provided in the air duct 203 downstream of the evaporator 223 to detect the temperature of the air that has passed through the evaporator 223. As shown in FIG. 11, an air conditioner switch 73, a hot mac switch 74,
Coolmax switch 75 and evaporator outlet temperature sensor 76 are connected to electronic control unit 61.

FIG. 10 shows a step motor drive circuit 60 and an electronic control unit 61. Referring to FIG. 10, the electronic control unit 61 is composed of a digital computer, in which a microprocessor (MPU) 80 that performs various calculation processes, a random access memory (RAM) 81, control programs, calculation constants, etc. are stored in advance. A read-only memory (ROM) 82, an input port 83, and an output port 84 are interconnected via a bidirectional bus 85. Furthermore, a clock generator 86 is provided within the electronic control unit 61 for generating various clock signals. Further, the electronic control unit 61 includes a counter 87, and the vehicle speed sensor 62 is connected to the input port 83 via the counter 87. This counter 87 counts the output signal of the vehicle speed sensor 62 for a certain period of time using the clock signal of the clock generator 86, and a binary count value proportional to the vehicle speed is output to the input port 87.
3 and is read into the MPU 80 via the bus 85. Furthermore, the electronic control unit 61 has a pair of AD
Equipped with converters 88 and 89, the water temperature sensor 6
3 is connected to the input port 83 via the AD converter 88, and the evaporator outlet temperature sensor 76 is connected to the input port 83 via the AD converter 88.
It is connected to input port 83 via converter 89 .
The water temperature sensor 63 is composed of, for example, a thermistor, and therefore, the water temperature sensor 63 emits an output voltage proportional to the engine cooling water temperature. This output voltage is the AD converter 88
is converted into a binary number corresponding to the engine cooling water temperature, and this binary number is sent to the input port 83 and the bus 85.
is read into the MPU 80 via the . Similarly, the evaporator outlet temperature sensor 76 is comprised of, for example, a thermistor, and thus provides an output voltage proportional to the air temperature passing through the evaporator 223 (FIG. 11). This output voltage is applied to the evaporator 22 in the AD converter 89.
3 is converted into a binary number corresponding to the air temperature passing through the input port 83 and the bus 85.
is read into the MPU 80 via the . Cool Max Switch 75, Hot Max Switch 7
4. The output signals of the air conditioner switch 73, oil pressure switch 67, rotation speed sensor 64, throttle switch 65, and neutral switch 66 are sent via the input port 83 and bus 85.
Loaded into MPU80.

Within the MPU 80, the time interval between the output pulses of the rotation speed sensor 64 is calculated, and the engine rotation speed is determined from this time interval. Meanwhile, the output terminal of output port 84 is connected to a corresponding input terminal of latch 90, and the output terminal of latch 92 is connected to step motor drive circuit 60. Output port 84 has
Pulse motor drive data is written from the MPU 80, and this pulse motor drive data is sent to the latch 90.
The clock signal is maintained for a certain period of time by the clock signal from the clock generator 86. A power terminal of the electronic control unit 61 is connected to a power source 94 via an ignition switch 91 and a switch 93 of a relay 92 arranged in parallel. This switch 93 is controlled to open and close by a coil 95, one end of which is connected to a power source, and the other end connected to a drive circuit 96.
is connected to output port 84 via. Further, the opening/closing operation of the ignition switch 91 is read into the MPU 80 via the input port 83 and the bus 85.

On the other hand, in the pulse motor drive circuit 60, the stator coil 53 of the stator 22 and the stator coil 53 of the stator 23 are wound in the same direction in FIG. 8, and in FIG. 10, the winding start terminals S ₁ , At S ₂ , the winding end terminals of these stator coils 53 are indicated by E ₁ and E ₂ , respectively. Furthermore, in FIG. 10, the intermediate taps of the stator coil 53 are designated M ₁ and M ₂ , respectively. Winding start terminal S ₁ and intermediate tap in stator 22
The stator coil 53 between _M1 forms a 1-phase excitation coil, and the stator coil 53 between the winding end terminal _E1 and the intermediate tap _M1 forms a 3-phase excitation coil. Further, in the stator 23, the stator coil 53 between the winding start terminal S ₂ and the intermediate tap M ₂ forms a two-phase excitation coil, and the stator coil 53 between the winding end terminal E ₂ and the intermediate tap M ₂ forms a four-phase excitation coil. Form. As shown in FIG. 10, the pulse motor drive circuit 60 includes four transistors Tr ₁ ,
Tr ₂ , Tr ₃ , Tr ₄ , and winding start terminals S ₁ , S ₂ and winding end terminals E ₁ , E ₂ are transistors Tr ₁ , Tr ₂ ,
Connected to the collectors of Tr ₃ and Tr ₄ . Further, the intermediate taps M ₁ and M ₂ are grounded via a power source 94.
The collectors of the transistors Tr ₁ , Tr ₂ , Tr ₃ , Tr ₄ are connected to the corresponding back electromotive force absorbing diodes D ₁ , D ₂ , D ₃ ,
connected to the power supply 94 via D ₄ and the resistor R;
The emitters of each transistor Tr ₁ , Tr ₂ , Tr ₃ , Tr ₄ are grounded. In addition, each transistor Tr ₁ , Tr ₂ ,
The bases of Tr ₃ and Tr ₄ are connected to the corresponding output terminals of latch 92.

As described above, the engine rotation speed is calculated within the MPU 80 based on the output signal of the rotation speed sensor 64. On the other hand, in the ROM 82, a function representing a desirable relationship between engine cooling water temperature and engine speed, for example, is stored in advance in the form of a mathematical formula or a data table of final points. In the MPU 80, the moving direction of the step motor 9 necessary to bring the current rotation speed to a predetermined desired rotation speed is determined from this function and the current engine rotation speed, and the step motor 9 is sequentially moved in that direction. Step motor drive data for step movement is obtained and this drive data is written to the output port 84. This write operation is performed, for example, every 8 msec, and the output port 8
The step motor drive data written in step 4 is held in latch 90 for 8 msec. MPU
For example, 4-bit drive data "1000" is sent from the output port 80 to the output port 84, and the output terminals of the latch 90 connected to each transistor Tr ₁ , Tr ₂ , Tr ₃ , Tr ₄ in FIG. , then the output terminal of the latch 90, ,
, "1", "0", "0" for 8 msec, respectively.
An output signal of "0" appears. FIG. 12 shows the output signals appearing at each output terminal, . . . of latch 90. As can be seen from FIG. 12, between times _t1 and _t2 , each output terminal of the latch 90 is set to "1", "0", "0", etc., as described above.
An output signal of "0" is displayed. In this manner, when the output signal at the output terminal of the latch 90 becomes "1", the transistor _Tr1 is turned on, and the one-phase excitation coil is excited. Then at t ₂
In the MPU 80, for example, the valve body 36 (Fig. 2)
If it is determined that the step motor 9 should be moved by one step so that the valve is moved in the valve opening direction,
Drive data "1100" is read from the MPU 80 to the output port 84, and as a result, the output terminals of the latch 90 are set to " ₁ " and " ₁ ", respectively, as shown between times t2 and t3 in FIG. ”, “0”,
An output signal of "0" is generated. Therefore, at this time, the transistor Tr ₂ is also turned on, and the one-phase excitation coil and the two-phase excitation coil are thus excited.
Similarly, between times t ₃ and t ₄ in FIG. 12, each output terminal of the latch 90 has "0", "1",
Output signals of "1" and "0" appear, and therefore the two-phase excitation coil and the three-phase excitation coil are excited at this time. Furthermore, between times _t4 and _t5 in FIG. 12, the output terminals of the latch 90 are at "0" and "0",
Output signals of "0", "1", and "1" appear, and therefore the three-phase excitation coil and the four-phase excitation coil are excited at this time. Furthermore, from Fig. 12, the signals appearing at the output terminals of the latch 90, ie, the lengths of the excitation pulses of each excitation coil, . I understand that. Generating excitation pulses such that each excitation pulse overlaps each other by 1/2 as between times t ₂ and t ₅ is called a two-phase simultaneous excitation method.

FIG. 13 shows the magnetic pole piece 5 of each stator 22, 23.
6 and 58, the outer circumferential surface of the outer cylinder 42 of the rotor 21 is developed and schematically shown. Figure 13a is the 12th
The diagram shows a case where only the one-phase excitation coil is excited, as between times t ₁ and t ₂ in the figure, and at this time, the magnetic pole piece 56 of the stator 22 is the N pole, and the magnetic pole piece 58 is the S pole.
It has become a pole. On the other hand, each of the magnetic pole pieces 56 and 58 of the stator 23 has no magnetic poles. Therefore, at this time, the magnetic pole piece 56 of the stator 22 and the rotor outer cylinder 4
The two S poles face each other, and the magnetic pole piece 58 of the stator 22 and the N pole of the rotor outer cylinder 42 face each other. Next, when the two-phase excitation coil is excited between times t ₂ and t ₃ in FIG. 12, the direction of the current in the two-phase excitation coil and the current direction in the one-phase excitation coil are the same, so Stator 2 as shown in figure b
The magnetic pole piece 56 of the stator 23 becomes the north pole, and the magnetic pole piece 58 of the stator 23 becomes the south pole. Therefore, at this time, the S pole of the rotor outer cylinder 42 is located between the magnetic pole pieces 56 of the stator 22 and the magnetic pole pieces of the stator 23, while the N pole of the rotor outer cylinder 42 is located between the magnetic pole pieces 56 of the stator 22 and the magnetic pole pieces of the stator 23.
and the magnetic pole piece 58 of the stator 23 . As mentioned above, if the interval between adjacent magnetic pole pieces 56 of the stator 22 is 1 pitch, the rotor outer cylinder 42 shown in FIG. 13b is 1 pitch to the right in FIG. This means that it has moved /8 pitches.

Next, when the three-phase excitation coil is excited between times t ₃ and t ₄ in FIG. 12, the direction of the current in the three-phase excitation coil is opposite to the direction of the current in the one-phase excitation coil, so As shown in FIG. 13c, the magnetic pole piece 56 of the stator 22 becomes the south pole, and the magnetic pole piece of the stator 22 becomes the north pole. As a result, the 13th
The rotor outer cylinder 42 shown in FIG.
It will move 4 pitches. Next, when the four-phase excitation coil is excited between times t ₄ and t ₅ in FIG. 12, the rotor outer cylinder 4 is excited as shown in FIG. 13 d.
2 is moved 1/4 pitch to the right with respect to the rotor outer cylinder 42 in FIG. 13c. Then, at time t ₅ in Figure 12,
Between _t6 , only the four-phase excitation coil is energized, so that no magnetic poles appear on each of the pole pieces 56, 58 of the stator 22, as shown in FIG. 12e. Thus, at this time, the magnetic pole piece 56 of the stator 22 and the N pole of the rotor outer cylinder 42 face each other, and the magnetic pole piece 56 of the stator 23
The rotor outer cylinder 42 is moved by 1/8 pitch to the right in FIG. 13 with respect to the rotor outer cylinder 42 shown in FIG. Then, at time t ₆ in FIG.
Drive data “0000” is written to the output port 84 from
Since all output signals of , , become "0", excitation of all excitation coils, , , is stopped.
At this time, as shown in FIG. 13e, the magnetic pole piece 56 of the stator 23 and the N pole of the rotor outer cylinder 42 are facing each other, and the magnetic pole piece 58 of the stator 23 and the rotor outer cylinder 42 are facing each other.
The S poles of the two are facing each other. Therefore, due to the attractive force exerted by the N pole of the rotor cylinder 42 on the magnetic pole piece 56 of the stator 23 and the attractive force exerted by the S pole of the rotor outer cylinder 42 on the magnetic pole piece 58 of the stator 23, the rotor cylinder 42
is held stationary in the state shown in FIG. 13e. Note that the fact that the four-phase excitation coil was excited before the rotor cylinder 42 was held stationary is stored in the RAM 81.

Next, at time _t7 in FIG. 12, if it is determined in the MPU 80 that the step motor 9 should be moved by one step in the direction in which the valve body 36 (FIG. 2) opens, the MPU 80 is finally energized. The number of phases of the excitation coil is read from the RAM 81, and if the excitation coil that was last excited is a four-phase excitation coil, the MPU 80 writes drive data "0001" to the output port 84. Thus, as shown between times _t7 and _t8 in FIG. 12, only the four-phase excitation coil is energized. At this time, since the rotor cylinder 42 is in the position shown in FIG. 13e, the rotor cylinder 42 remains stationary. Next, when the three-phase excitation coil is excited as shown between times _t7 and _t8 in FIG. 12, each magnetic pole piece 56, 58 of each stator 22, 23 has a magnetic pole as shown in FIG. 13d. appears, and thus the rotor cylinder 42 moves 1/8 pitch to the left in FIG. 13, contrary to the previous direction, relative to the rotor cylinder 42 in FIG. 13e.

When the stator 22 is sequentially excited from the one-phase excitation coil I as between times t ₁ and t ₆ in FIG.
The rotor outer cylinder 42 moves relative to the rotor 23, thereby causing the rotor 21 to rotate in one direction. Rotor 21
When the rotor rotates, the outer thread 29 of the valve shaft 20 and the inner thread 47 of the rotor inner cylinder 40 are engaged with each other as shown in FIG. 2, so the valve shaft 20 moves to the left in FIG. As a result, the cross-sectional area of the annular air flow passage 38 formed between the valve body 36 and the valve seat 19 increases, so that the air is passed from the intake pipe 3 upstream of the throttle valve 4 to the surge tank via the bypass pipe 16 in FIG. The amount of air supplied into 2 increases. On the other hand, the first
Between times t ₇ and t ₁₀ in FIG. 2, the rotor 21 rotates in the opposite direction, so the valve shaft 20 moves to the right in FIG. The cross-sectional area of the airflow passage 38 is reduced.

Figures 14 and 15 show flowcharts when controlling the amount of air flowing through the bypass passage, and Figure 16 shows the overall movement of the step motor when controlling the amount of bypass air. There is. In FIG. 16, the vertical axis shows the step position STEP of the step motor 9, and the horizontal axis shows the time t. Note that STEP=0 on the vertical axis in FIG. 16 indicates when the valve body 36 (FIG. 2) is in the fully closed position, that is, in the right end position in FIG.
STEP=125 means that when the valve body 36 is in the fully open position,
That is, it is at the left end position in FIG.
In FIG. 14, step 100 indicates that bypass air amount control is performed at time intervals. In this embodiment, an interrupt is performed every 8 msec. First, in step 101, the opening/closing operation of the ignition switch 91 is input to the input port 83.
The information is read into the MPU 80 and it is determined whether the ignition switch 91 is on. At step 101, the ignition switch 91
If it is determined that the
In step 102, the step motor 9
Initialization processing is performed. This initialization process uses the current step position STEP of the step motor 9 stored in the RAM 81,
The difference from the step position 125 when the valve body 36 (FIG. 2) is fully opened is calculated. Next, in step 103, the step motor is rotated in the direction in which the valve body 36 opens by a number of steps corresponding to this difference. Furthermore, in the step motor initialization process in step 102, the relay 92 is activated while the step motor 9 is being rotated in step 103.
The coil 95 of the relay 92 is kept energized to keep the switch 93 in the on state, and when the rotation process of the step motor 9 in step 103 is completed, the coil 95 of the relay 92 is prevented from being energized and the switch 93 is turned off. Therefore, even if the ignition switch 91 is turned off, electric power is supplied to the electronic control unit 61 via the switch 93 of the relay 92 while the step motor 9 rotates until the valve body 36 is fully opened. Time t ₁ in FIG. 16 indicates when ignition switch 91 is turned off, and time t ₂ indicates when switch 93 of relay 92 is turned off. Therefore, between times _t1 and _t2, the step motor 9 is at the step position where the valve body 36 is fully opened.
You can see that it can be rotated up to 125.

On the other hand, if the ignition switch 91 is turned on after a while after the ignition switch 91 is turned off, electric power is supplied to the electronic control unit 61. At this time, the steps in Figure 14
At step 101, it is determined that the ignition switch 91 is on, so the process advances to step 104. At step 104, it is determined whether or not the ignition flag is set, but since the ignition flag is not set at this time, the process proceeds to step 105. In step 105, it is determined whether the engine cooling water temperature is lower than 20°C based on the output signal of the water temperature sensor 63, and in step 105, it is determined whether the engine cooling water temperature is lower than 20°C.
If it is determined that the engine speed is lower than , the process proceeds to step 106, where 800 rpm is set as the control start engine rotation speed NSTA, and then the process proceeds to step 107. Meanwhile, step 105
If it is determined that the engine cooling water temperature is not lower than 20°C, the process proceeds to step 108.
In step 108, it is determined whether the engine cooling water temperature is lower than 70°C. If it is determined in step 108 that the engine cooling water temperature is lower than 70°C, the process proceeds to step 109 and the control start engine speed NSTA is determined.
After applying 500 rpm to the engine, proceed to step 107. On the other hand, if it is determined in step 108 that the engine cooling water temperature is not lower than 70℃, the step
Proceed to 110 and control start engine speed NSTA to 250r.p.
After entering m, proceed to step 107. As described above, the engine rotation speed NE is calculated within the MPU 80 based on the output signal of the rotation speed sensor 64. In step 107, it is determined whether or not the engine speed NE is smaller than the control start engine speed NSTA.
If it is smaller than NSTA, the process advances to step 103, where the step motor 9 is rotated. However, at this time, the step motor 9 is actually held stationary. On the other hand, in step 107, the engine speed NE changes to the control start engine speed NSTA.
If it is determined that it is not smaller than
Proceed to step 111, and in step 111 check the voltage of the power supply 94.
It is determined whether V _B is not lower than 10V. If it is determined in step 111 that the voltage V _B of the power supply 94 is smaller than 10V, the process proceeds to step 103 where the step motor 103 is rotated. However, even at this time, the step motor 9 is actually held stationary. On the other hand, if it is determined in step 111 that the voltage V _B of the power supply 94 is not lower than 10V, the process proceeds to step 112;
At step 112, an ignition flag is set. Next, in step 113, a starting control execution flag is set, and then in step 114, a starting step position SSTA is calculated based on the output signal of the water temperature sensor 63. Figure 17 shows the step position SSTA and engine cooling water temperature T at startup.
(°C) is shown. As can be seen from Figure 17, when the engine cooling water temperature is -20°C or lower, the starting step position SSTA is 125, and when the engine cooling water temperature is between -20°C and 70°C, as the engine cooling water temperature becomes higher, the starting step position is 125. When the step position SSTA becomes small and the engine cooling water temperature becomes 70°C or higher, the step position SSTA at startup becomes 40. The relationship between the starting step position SSTA and the engine cooling water temperature shown in FIG. The starting step position SSTA is calculated at . Next, in step 115, the step position at the time of starting is determined.
The current step position of the step motor 9 is subtracted from SSTA, and the result of this subtraction is set as the step number STEP. Then, in step 116, the number of steps is
It is determined whether STEP is negative and the step is
If the step number STEP is not negative in step 116, the process advances to step 117 and the step motor rotation direction is determined.
Zero is placed in DIR. Next, proceed to step 118 to determine the number of steps the step motor 9 should move.
STEP and step motor rotation direction DIR are RAM8
1 predetermined address. In addition, here DIR
=0 indicates the rotational direction of the step motor 9 in which the valve body 36 (Fig. 2) moves in the valve opening direction.
DIR=1 indicates the rotational direction of the step motor 9 in which the valve body 36 moves in the valve closing direction. On the other hand, if it is determined in step 116 that the step number STEP is negative, the absolute value of the step number STEP is set as STEP, and then in step 120 the step motor rotation direction DIR is set to 1, and then the process proceeds to step 118. The number of moving steps STEP of the step motor 9 and the rotation direction of the step motor are
It is stored at a predetermined address in RAM81. Next, in step 103, the number of moving steps STEP of the step motor and the step motor rotation direction DIR stored in the RAM 81 are read out and the step motor drive data is written to the output port 84, thereby causing the step motor 9 to change to the step motor rotation direction DIR.
It starts rotating by the number of steps STEP.

In the next interrupt cycle, a determination is made based on whether or not the ignition flag is set in step 104. Since the ignition flag was set in step 112 of the previous interrupt cycle, step 104 determines whether the ignition flag is set or not. It is determined that there is, and the process proceeds to step 121. In step 121, it is determined whether or not the start control execution flag is set.Since the start control execution flag was set in step 113 of the previous interrupt cycle, the start control execution flag is set in step 121. It is determined that this is the case, and the process proceeds to step 122.
In step 122, it is determined whether or not the step motor 9 is rotating toward the starting step position SSTA. If it is determined in step 122 that the step motor 9 is rotating, the step 103 is executed.
Step motor 9 continues to rotate.
In Fig. 16, time _t3 indicates when the step motor 9 starts rotating toward the starting step position SSTA, and _t4 indicates when the step motor 9 reaches the starting step position SSTA. . Therefore, between times _t3 and _t4, it is determined in step 122 that the step motor 9 is rotating;
Proceed to step 103. Note that between times t ₃ and t ₄ , as shown in FIG.
are sequentially excited every 8 msec. On the other hand, the first
In Fig. 6, when time _t4 is reached, the step motor 9
goes to step 123 to stop and
After the starting control execution flag is lowered in step 123, the process proceeds to step 124, where a counter C is set to 3 seconds. The routine shown in Figure 14 is 8m long.
Since time interrupts occur every sec, counter C contains 3
Setting the seconds means setting the number 3 to counter C.
This means to enter seconds/8msec=375.
Next, the process advances to step 125, where it is determined whether or not the engine speed NE is zero. If it is determined in step 125 that the engine speed NE is zero, that is, the engine is in a stalled state, the process proceeds to step 126, where the same step motor initialization process as in step 102 is performed. On the other hand, if it is determined in step 125 that the engine speed NE is not zero, the process proceeds to step 127, and the process proceeds to step 125.
At step 127, it is determined whether the engine is in an unstable operating state. That is, it is determined from the engine speed NE calculated by the MPU 80 whether the engine speed NE is rising or falling, and if the engine speed NE is rising and the engine speed NE is 500 rpm or more, the engine is It is assumed that the state is unstable and the process proceeds to step 103, where the engine speed NE is decreasing and the engine speed NE is 300 r.p.
Even when the value is less than m, it is assumed that the engine is in an unstable state and the process proceeds to step 103. At this time, the step motor 9
is held stationary. On the other hand, engine speed NE
is rising and the engine speed NE is below 500r.pm, or the engine speed NE is falling and the engine speed NE is 300r.pm.
pm or higher, it is determined in step 127 that the engine is in a stable operating state, and the process proceeds to step 128.
Then, warm-up control is performed. On the other hand, in the next interrupt cycle, the starting control execution flag is cleared, so the process proceeds from step 121 to step 125, and if the engine speed NE is not zero and the engine is in a stable operating state, warm-up control is performed in step 128. will be carried out.

As can be seen from FIG. 14, the process proceeds to step 118 to store the rotational speed of the step motor 9 at a predetermined address in the RAM 81, and then, in step 103, the rotation of the step motor 9 is started at step 107.
The engine speed NE is the engine speed at which control starts.
This is when the voltage V _B of the power supply 84 is not smaller than 10V. Furthermore, as can be seen from steps 105, 106, 108, 109, and 110, as the engine cooling water temperature decreases, the control start engine rotation speed NSTA increases. Next, the reason for this will be explained with reference to FIG. In FIG. 18, the vertical axis shows the voltage V required to start the step motor 9, and the horizontal axis shows the temperature Ta around the step motor 9. As can be seen from FIG. 18, the starting voltage V of the step motor 9 is
It increases as the surrounding temperature Ta decreases.
Therefore, when the step motor 9 is started when the ambient temperature Ta of the step motor 9 is low, for example when the ambient temperature is 0° C. or less, the starting voltage V is high as shown in _FIG. will decrease. In order to prevent such a drop in the power supply voltage _VB , it is necessary to increase the engine speed when starting the step motor and to cause a large charging current to flow through the power supply 94. The ambient temperature of the step motor 9 increases as the engine cooling water temperature increases. Therefore, when the engine cooling water temperature is low, the control start engine speed NSTA is increased to prevent the power supply voltage _VB from decreasing.

As mentioned above, when the step position of the step motor 9 reaches the starting step position SSTA, the 14th
Warm-up control is started at step 128 in the figure.
Next, warm-up control will be explained with reference to FIG. 15. First, in step 150, it is determined whether the counter C is zero. This counter C is set to 3 seconds at step 124 in FIG.
Proceeding to step 151 in the figure, C-1 is entered into counter C, that is, counter C is decremented by 1. The process then proceeds to step 103 in FIG. 14, at which time the step motor 9 is held stationary. Step 3 seconds after the start of warm-up control
The program proceeds to step 152 to set the counter C to 3 seconds, and then, in step 153, it is determined from the output signal of the air conditioner switch 73 whether or not the air conditioner switch 73 is on. At step 153, turn on the air conditioner switch 7.
If it is determined that 3 is not on, step
Proceed to step 154 to set the step position of the step motor 9 during warm-up operation, that is, the warm-up step position ST.
ST1 is entered and then the process proceeds to step 155. On the other hand, if it is determined in step 153 that the air conditioner switch 73 is on, the process proceeds to step 156 where ST2 is placed in the warm-up step position ST, and then the process proceeds to step 157. step 157
In step 157, it is determined whether or not the hot-mux switch 74 is on based on the output signal of the hot-mux switch 74. When it is determined in step 157 that the hot-mux switch 74 is on, the process advances to step 155. On the other hand, if it is determined in step 157 that the hot max switch 74 is not on, the process proceeds to step 158 where ST3 is placed in the warm-up step position ST, and then the process proceeds to step 159. In step 159, it is determined whether or not the cool max switch 75 is on based on the output signal of the cool max switch 75.
If the cool max switch 75 is on, the process advances to step 155. On the other hand, if it is determined in step 159 that the cool max switch 75 is not on, then in step 154 ST1 is placed in the warm-up step position ST, and then the process proceeds to step 155. Therefore, when the air conditioner switch 73 is not on, or when the air conditioner switch 73 is on but neither the hot max switch 74 nor the cool max switch 75 are on, the warm-up step position ST is reached.
ST1 can be inserted. Furthermore, if the air conditioner switch 73 is on and the hot pack switch 74 is on, the warm-up step position ST
ST2 is put in. Also, if the air conditioner switch 73 is on and the cool max switch 75 is on, the warm-up step position is
ST3 is inserted into ST. FIG. 19 shows the relationship between the warm-up step positions ST1, ST2, and ST3 and the engine cooling water temperature. As shown in Fig. 19, the warm-up step position ST1 is around 90 when the engine cooling water temperature T is -40°C, and gradually decreases as the engine cooling water temperature T rises until the engine cooling water temperature T reaches 70°C. It will be around 40. On the other hand, the warm-up step position ST2 is much larger than ST1 when the engine cooling water temperature T is between -40°C and 40°C, and gradually approaches ST1 when the engine cooling water temperature T is between 40°C and 70°C. On the other hand, at warm-up step position ST3, the engine cooling water temperature T starts from -40℃.
It gradually becomes larger than ST1 between 40°C and becomes slightly larger than ST1 when the engine cooling water temperature T is 40°C or higher. These ST1, ST2
As shown in FIG. 19, ST3 is previously stored in the ROM 82 in the form of a function of the engine cooling water temperature T or in the form of a data table of completion points. Read ST1, ST2, and ST3 from ROM82 and put them into ST.

At step 155, 1 is entered in the step number of the step motor 9, and the step motor rotation direction DIR is set.
A zero is inserted into the . As mentioned above, the step motor rotation direction DIR=0 indicates the rotation direction in which the valve body 36 (Fig. 2) moves in the valve opening direction, and the step motor DIR=1 indicates the rotation direction in which the valve body 36 moves in the valve closing direction. Indicates the direction of rotation. Next, in step 160, it is determined whether the warm-up step position ST is larger than the start-up step position SSTA shown in FIG. If it is determined in step 160 that the warm-up step position ST is larger than the starting step position SSTA, then in step 161 the warm-up step position ST is set to SSTA.
+1 can be entered. Therefore, at this time, SSTA is no longer the starting step position shown in FIG. 17, but is indicating the movement step position due to warm-up control. Next, in step 162, the number of moving steps of the step motor 9 (1) and the rotation direction of the step motor are determined.
DIR=0 is stored at a predetermined address in RAM81.
On the other hand, at step 160, the warm-up step position ST
If it is determined that the warm-up step position ST is not larger than the movement step position SSTA due to warm-up control, the process proceeds to step 163, and in step 163 it is determined whether or not the warm-up step position ST is equal to the movement step position SSTA due to warm-up control. . If it is determined in step 163 that the warm-up step position ST is not equal to the moving step position SSTA, the process proceeds to step 164, where SSTA-1 is entered into the moving step number SSTA and 1 is entered into the step motor rotation direction DIR. . Next, in step 162, the step number 1 of the step motor 9 and the step motor rotation direction DIR=1 are stored at a predetermined address in the RAM 81. Then, in step 103 of FIG.
The step motor 9 is rotated in the step number and rotation direction stored in the RAM 81. On the other hand, if it is determined in step 163 that the warm-up step position ST is equal to the moving step position SSTA under warm-up control, the process proceeds to step 103 in FIG. 14, but at this time the step motor 9 is held stationary. Therefore, the movement step position due to warm-up control
When SSTA reaches the warm-up step position ST, the step motor 9 is held stationary. As mentioned above, time _t4 indicates the time when the step position of the step motor 9 reaches the starting step position SSTA, and from this time the warm-up control is started. When the warm-up control is started, the step motor 9 is moved one step every three seconds, and when the step position reaches the warm-up step position ST, the step motor 9 is stopped. This time is time t ₅ in Figure 16.
It is indicated by. After this time t ₅ , the engine cooling water temperature T
(FIG. 19), when the warm-up step position ST changes, the step motor 9 is moved by one step. For example, if ST1 is set in the warm-up step number ST after time _t5 in FIG.
4 is turned on, the number of warm-up steps ST becomes ST2, so the step motor 9 moves one step every three seconds from ST1 to ST2.

As shown in FIG. 11, the hot max switch 74 is turned on when all the air flowing through the air duct 203 is forced to flow through the heat exchanger 224. Therefore, if the air temperature is high, it is necessary to raise it. There was a time when Furthermore, the cool max switch 75 is turned on in the air duct 2.
This is when the air flowing through 03 is completely blocked from passing through the heat exchanger 224, and therefore the air temperature needs to be lowered. Therefore, when the hot max switch 74 is turned on, the warm-up step position ST is increased as shown in ST2 in FIG. 19, thereby increasing the engine speed and increasing the engine cooling water temperature. Exchanger 2
The temperature of the air heated by 24 is increased. On the other hand, Cool Max Switch 75
Similarly, when the engine is turned on, the warm-up step position ST is increased as shown in ST3 in FIG.
3 to lower the temperature of the air cooled. Furthermore, during warm-up operation, as the engine cooling water temperature rises, the frictional force at each part of the engine decreases, so if the step motor 9 is stopped, the engine speed gradually increases. Therefore, in the present invention, as shown in FIG. 16 between times _t4 and _t5 , as the engine cooling water temperature rises, the step motor 9
The engine rotation speed is maintained at a nearly constant value by moving one step every three seconds. Furthermore, if the step motor 9 is immediately raised from the warm-up step position ST1 to ST2 when the hot max switch 74 is turned on during warm-up operation, the engine speed will instantaneously increase, causing a sense of uneasiness to the driver. give. Therefore, in the present invention, for example, the step motor 9 is switched from the warm-up step position ST1 to ST2 every 3 seconds.
The engine speed is moved step by step to prevent the engine speed from increasing instantaneously.

As described above, in the present invention, by using a step motor to control the amount of bypass air, the amount of bypass air can be controlled with high accuracy.
Furthermore, when the hot-box switch is turned on, the engine speed is increased, which causes the engine cooling water temperature to rise rapidly, thereby rapidly raising the temperature in the vehicle cab to the set temperature. can. Furthermore, in one embodiment of the present invention, when the cool max switch is turned on, the engine speed is also increased, so the speed of the cooling compressor is increased, thereby setting the temperature in the vehicle cabin. The temperature can be rapidly lowered to the desired temperature.

[Brief explanation of drawings]

FIG. 1 is an overall view of the idling speed control device according to the present invention, showing a part of the engine intake system in cross section, FIG. 2 is a side sectional view of the flow control valve device, and FIG.
The figure is a sectional view taken along the - line in Figure 2.
Figure 5 is a perspective view of the stator core part, Figure 6 is a sectional view of the stator, Figure 7 is a side sectional view taken along the - line in Figure 6, and Figure 8 is a perspective view of the stator core part. 2 is a sectional plan view of the stator, FIG. 9 is a schematic side sectional view taken along the - line in FIG. 8, and FIG. 10 is a circuit diagram of the step motor drive circuit and electronic control unit in FIG. 1. ,
Figure 11 is an overall view of the air conditioner, Figure 12
13 is a diagram showing excitation pulses of the step motor, FIG. 13 is an explanatory diagram schematically showing the step motor and rotor, and FIG. 14 is a flowchart for explaining the operation of idling rotational speed control according to the present invention. , FIG. 15 is a flowchart of the warm-up control shown in FIG. 14, FIG. 16 is a diagram showing changes in step position of the step motor, and FIG. 17 is a graph showing the relationship between engine cooling water temperature and step position at startup. 1st
FIG. 8 is a graph showing the relationship between the step motor starting voltage and the ambient temperature of the step motor, and FIG. 19 is a graph showing the relationship between the engine cooling water temperature and the warm-up step position. 3... Intake pipe, 4... Throttle valve, 8... Flow rate control valve device, 9... Step motor, 16...
Bypass pipe, 20... Valve stem, 21... Rotor, 3
6... Valve body, 53... Stator coil, 60...
Step motor drive circuit, 61...electronic control unit.

Claims (1)

[Scope of Claims] 1. The engine idling speed during engine idling operation is detected, and an intake passage upstream of the throttle valve and an intake passage downstream of the throttle valve are connected so that the idling speed becomes a predetermined speed. In an idling rotation speed control method that controls the amount of air flowing through a bypass passage connecting two engines, the step position of a flow rate control step motor provided in the bypass passage is determined by the engine cooling water temperature during engine warm-up operation. The step motor is controlled according to the first step position, and when the air mix damper provided in the air duct of the air conditioner reaches the maximum heating position after the air conditioner is activated, the step motor A method for controlling an idling rotational speed of an internal combustion engine, wherein follow-up control is performed along a second step position where the cross-sectional area of the bypass passage is larger than the first step position. 2. In the method for controlling the idling speed of an internal combustion engine according to claim 1, when the air mix damper reaches the maximum cooling position after the air conditioner is activated, the step of the step motor is A method for controlling an idling rotational speed of an internal combustion engine, wherein follow-up control is performed along a third step position where the cross-sectional area of the bypass passage is larger than the first step position.