JP2007016638A - Idling speed controller drive control device and idling speed controller drive control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit temperature rise of a stepping motor driving and controlling a valve of an idling speed controller, in relation to a control device and a control method of the idling speed controller supplying intake air quantity necessary for an engine at a time of idling operation. <P>SOLUTION: This invention relates to the control device of the idling speed controller adjusting intake air quantity at a time of idling operation of the engine. The device consists of a stepping motor opening and closing the valve of the idling speed controller, a driver means driving the stepping motor at fixed current. The control means varies resistance value of a current detection resistance connected to a field coil of the stepping motor in series according to an operation condition of the engine. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an idling speed controller (ISC) that supplies an intake air amount necessary for an engine during idling operation, and more particularly to a control device and a control method for a stepping motor that drives and controls an ISC valve.

  In many cases, an ISC that supplies air necessary for a cylinder of an engine during idling operation is installed in an intake path of an engine of an automobile including a motorcycle. This ISC is provided in the intake path to the engine together with a throttle valve that provides the intake amount necessary for the engine during normal operation of the engine other than idling operation, and maintains the engine speed during idling within a certain range. Take a role. In other words, when the engine is idling, the throttle valve is fully closed if the accelerator is not operated. By supplying the necessary intake air amount to the engine via the ISC, The engine speed at is controlled to an appropriate value. The amount of intake air supplied from the ISC to the engine is adjusted by controlling the valve opening of the ISC, and the adjustment of the opening of the ISC valve is often performed by controlling the rotation of the stepping motor.

  A stepping motor that adjusts the valve opening of the ISC is output from an ECU (Electronic Control Unit, hereinafter referred to as “control device” as appropriate) that controls the engine in an integrated manner based on the throttle opening and output signals of various sensors. The rotation angle is controlled by the number of pulse signals. As a result, it is possible to adjust the amount of intake air sucked into the cylinder of the engine via the ISC, and the engine idling speed can be controlled.

  In the rotation control of the stepping motor, the closed loop control for detecting the rotation amount and feeding back the detection output to the input signal side as in the case of the DC servo motor is not necessarily required. However, a situation called out-of-step, in which the rotation angle cannot follow the pulse signal from the control device due to factors such as excessive load torque and noise, can be caused. That is, a deviation value may be generated between the step value of the stepping motor recognized by the control device and the valve opening of the ISC converted into the actual step value of the stepping motor. It is necessary to take measures for this (for example, Patent Document 1).

A stepping motor used for opening / closing driving of such an ISC valve not only increases the rotational torque in order to avoid the above-mentioned step-out, but also holds torque for maintaining a desired rotational angle constant. It was necessary to use the one with a large technical specification. Furthermore, since the stepping for adjusting the ISC and its valve opening is installed in the vicinity of the engine, its installation environment temperature is high.
JP 11-166436 A

  For this reason, since a large current always flows through the field coil constituting the stator of the stepping motor used to open / close the ISC valve, a great amount of heat is generated in combination with the high installation environment temperature. In some cases, it was difficult to keep within the operating temperature specifications.

  However, the ISC provides an intake amount necessary for the engine during idling operation of the engine, and intake air to the engine is provided from the throttle valve at times other than idling operation. For this reason, for example, when the throttle valve is open, it is not necessary to adjust the opening of the ISC. In such a case, a large load is not applied to the stepping motor that drives the opening and closing of the ISC valve. Further, even during idling operation, for example, after the engine speed during idling operation is stabilized, the intake air amount supplied from the ISC to the engine may be maintained constant, and the load torque applied to the stepping motor Does not fluctuate. In particular, since motorcycles are usually not equipped with devices that generate a large load torque such as an air conditioner that affects the engine speed during idling, the engine idle speed is stabilized. The load fluctuation of the stepping motor is extremely small.

  For this reason, the present invention suppresses the current flowing in the field coil by variably controlling the voltage applied to the stepping motor used for opening / closing the ISC valve when the engine operating state is predetermined, Accordingly, an object of the present invention is to provide a control device and a control method for a stepping motor that suppresses the temperature increase of the stepping motor.

  Therefore, the present invention is an ISC control device that adjusts the amount of intake air during idling of an engine, a stepping motor that opens and closes the valve of the ISC, and driver means that drives the stepping motor with a constant current And a control means for outputting a drive signal to the driver means, wherein the control means includes a current detection resistor connected in series to the field coil of the stepping motor according to the operating state of the engine. It is an object of the present invention to provide an ISC drive control device characterized by varying a resistance value.

  The control means increases the resistance value of the current detection resistor when the valve open / close state is maintained constant rather than when the valve open / close state of the ISC is varied. Thus, the present invention suppresses the temperature increase of the stepping motor by reducing the current flowing in the field coil that constitutes the stator of the stepping motor used for opening / closing the ISC valve.

  Here, the current detection resistor includes a first resistor connected to the field coil and a second resistor larger than the resistance value of the first resistor. Then, when the current flowing through the field coil constituting the stator of the stepping motor is reduced, switching control is performed so that the combined resistance value of the current detection resistor is increased.

  The resistance value of the current detection resistor is less than the lower limit value or lower limit value of the rated current of the stepping motor when the open / closed state of the valve is kept constant. Is set to be This suppresses the temperature rise of the stepping motor and reduces the possibility of stepping out of the stepping motor.

  By the way, the control means sets the resistance value of the current detection resistor at least when an intake throttle valve provided in the intake path of the engine opens more than a predetermined opening or when the engine idle rotation is stabilized. The switching to increase is performed.

  The ISC drive control circuit according to the present invention outputs a pulse signal of a predetermined number of waste feed steps to the number of steps for fully closing the ISC valve to the stepping motor immediately after the engine is stopped. The accumulation of so-called missteps between the valve opening of the ISC and the stepping motor is removed by performing the ISC initialization process.

  The present invention, as its second form, further comprises an ISC drive control method in which a stepping motor opens and closes an ISC valve that adjusts the intake air amount during idle operation of the engine. (A) Operation of the engine Detecting a state; (b) comparing whether or not the detected operating state matches a predetermined state set in advance; and (c) comparing the operation in step (b). And increasing the resistance value of a current detection resistor connected in series to the field coil of the stepping motor when the state matches the predetermined state. A control method is provided.

  Here, the predetermined state set in advance in the step (b) includes at least a state in which an intake throttle valve provided in the intake path of the engine is opened more than a predetermined opening degree, and an idle state of the engine. A current value that flows through the field coil of the stepping motor due to an increase in the resistance value of the current detection resistor in the step (c), or a lower limit value of a rated current of the stepping motor, Control is performed so as to be less than the lower limit value.

  And after the said step (c), when the said engine is stopped, it has the step which performs the initialization process of the valve opening degree of the said ISC. Here, the initialization process is performed by outputting a pulse signal having a predetermined number of waste feed steps to the number of steps for fully closing the valve of the ISC to the stepping motor.

  In the ISC drive control device and control method according to the present invention, the resistance value of the current detection resistor connected to the field coil constituting the stator of the stepping motor used for opening / closing driving of the valve of the ISC is determined based on the engine operating state being predetermined In this case, the temperature increase of the stepping motor is suppressed by increasing the value when the valve open / close state is kept constant rather than when the valve open / close state of the ISC is changed. This also suppresses power consumption during engine idling.

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

  FIG. 1 is a diagram showing a schematic configuration of an engine (here, a single-cylinder four-cycle engine for a motorcycle) having an ISC that is a control target of the present invention.

  As shown in FIG. 1, an engine 6 is an engine control device that comprehensively controls an electric fuel pump device, a fuel injection device, an ignition plug ignition device, an intake throttle, and an idle speed control device (hereinafter referred to as “ISC”). (Hereinafter referred to as “ECU: Electronic Control Unit”) 1.

  In this case, the above-described electric fuel pump device is constituted by a fuel tank (hereinafter referred to as “fuel pump” as appropriate) 2, the fuel injection device is constituted by an injector 3, and the ignition plug ignition device is an ignition coil 4 and a spark plug 5. Consists of.

  The fuel tank 2 stores fuel supplied to a combustion chamber (cylinder or cylinder) 7 of the engine 6. The fuel stored in the fuel tank 2 is supplied to the injector 3 via the fuel supply pipe 8. The air filter 9 removes dust and dirt from the air supplied to the engine 6 (air in the outside air). The intake throttle 10 and the ISC 11 control the amount of air sucked into the combustion chamber 7 via the intake pipe 13 extending from the air filter 9 to the intake valve 12. The intake throttle 10 controls the amount of air during normal operation other than during idle operation, and the ISC 11 controls the amount of air during idle operation. The ISC 11 includes a stepping motor and is installed so as to form a bypass path for the intake throttle 10.

  The injector 3 injects fuel into the combustion chamber 7 at the same time that air is drawn into the combustion chamber 7. As a result, an air-fuel mixture in which fuel is injected into the air is injected into the combustion chamber 7. The injector 3 pressurizes the fuel supplied via the fuel supply pipe 8 and then injects the fuel.

  The intake valve 12 opens and closes a path from the intake pipe 13 to the combustion chamber 7 in an intake stroke to be described later. The exhaust valve 14 opens and closes a path from the combustion chamber 7 to the exhaust pipe 15 in an exhaust stroke described later. The ignition coil 4 generates a high voltage at the timing when the ignition command is received from the ECU 1. The spark plug 5 is ignited upon application of a high voltage generated in the ignition coil 4, and burns the fuel gas compressed in the combustion chamber 7. The exhaust pipe 15 guides exhaust gas generated by the explosion of the fuel gas from the engine 6 to the muffler 16. The muffler 16 discharges exhaust gas to the outside air after reducing noise such as explosion sound and exhaust sound, and a catalyst device (hereinafter referred to as “catalyst” as appropriate) 18 is installed in the muffler 16. The catalyst 18 purifies the exhaust gas before being released to the outside air.

  An engine temperature sensor 19 that measures the surface temperature of the engine 6 is installed on the surface of the engine 6. Further, the engine 6 is installed, for example, in the vicinity of the inlet in the muffler 16 for detecting an opening degree of the throttle 20 installed around the intake throttle 10 and measures the oxygen concentration in the exhaust gas. Oxygen sensors 21 and the like (these are collectively referred to as various sensors 25) are installed, and these sensors are connected to the ECU 1 as will be described later. The ECU 1 includes these sensors (which may include a switch or the like). Based on this signal, the engine 6 is optimally controlled.

  Next, the operation in each process of the single cylinder four-cycle engine having the above-described configuration will be briefly described.

  First, in the intake stroke which is the first stroke, air (air in the outside air) filtered by the air filter 9 to remove dust and dirt (air in the outside air) enters the combustion chamber 7 of the engine 6 in the combustion chamber 7. Supplied by the negative pressure generated by the downward movement of the piston. At this time, the intake valve 12 is opened.

  On the other hand, simultaneously with the supply of air to the combustion chamber 7, fuel is injected from the injection port of the injector 3. The fuel injection amount supplied from the injector 3 is adjusted by the fuel injection time of the injector 3 that performs the injection operation according to the pulse width of the fuel supply instruction pulse signal from the ECU 1.

  Next, in the compression stroke that is the second stroke, the fuel gas that is a mixture of air and fuel supplied into the combustion chamber 7 is compressed by the upward movement of the piston. At this time, the intake valve 12 and the exhaust valve 14 are closed.

  Next, in the combustion stroke that is the third stroke, the ignition coil 4 that has received the ignition command at a predetermined timing from the ECU 1 generates a high voltage. Then, by applying this high voltage to the spark plug 5 and igniting the spark plug 5, the compressed fuel gas is exploded. The piston is rapidly pushed down by this explosive force.

  Next, in the exhaust stroke which is the fourth stroke, the fuel gas burned in the combustion stroke is released into the outside air as exhaust gas. The exhaust gas is released from the combustion chamber 7 by raising the piston pushed down in the combustion stroke while the exhaust valve 14 is opened. The exhaust gas is guided into the muffler 16 through the exhaust pipe 15 and is released to the outside air after reducing noise such as explosion sound and exhaust sound.

  FIG. 2 is a block diagram illustrating a schematic configuration example of the above-described control means (ECU) 1 that comprehensively controls the operation of the engine 6.

  The ECU 1 includes an arithmetic processing unit (CPU) 30, a ROM 31 that stores a program for engine combustion control including control of the ISC, constants and relational expressions used in the control program, a correspondence map, etc., an engine temperature sensor Stepping for driving a RAM (for example, nonvolatile memory “EEPROM”, etc.) 32 for temporarily storing detection values and fluctuation data detected by various sensors such as 19, engine temperature sensor 19, various sensors 25, and valves of ISC 11. An input / output interface (I / O port) 35 for transmitting / receiving signals to / from various actuators such as a motor is provided.

  Thereby, for example, the ECU 1 performs control such as controlling the intake air amount of the ISC 11 during idling based on the detection value from the engine temperature sensor 19, and thereafter terminating the idle warm-up operation of the engine. Control of various active means such as intermittent drive control of the fuel pump 2 as described above, drive control of the injector 3 (fuel injection control), drive control of the ignition coil 4 (ignition control), etc. Control.

  Next, one configuration example of the ISC 11 in which the valve opening degree is adjusted by the stepping motor that is the control target of the present invention will be briefly described.

  FIG. 3 is a diagram showing a schematic configuration of the ISC 11, (b) is a diagram showing an internal configuration, and (a) is a cross-sectional view taken along line AA in FIG.

  The ISC 11 includes a housing 50 constituting a main body, and the housing 50 is attached to the intake pipe 13 shown in FIG. A flow passage 52 is formed inside the housing 50 so as to branch the air flowing through the intake pipe 13, and an air circulation hole 52 a communicating with the intake pipe 13 is formed on the downstream side of the flow passage 52. ing. The housing 50 is provided with a valve 55 for changing the opening amount of the air circulation hole 52a. The valve 55 is provided at the tip of the screw shaft 56, and moves the axial direction of the screw shaft 56 to change the opening amount of the air circulation hole 52a to control the air circulation amount. In the drawing, the position of the valve 55 having the largest opening amount (indicated by a solid line) is indicated by reference symbol P1, and the position of the valve 55 having the smallest opening amount (indicated by a dotted line) is indicated by reference symbol P2. That is, the valve 55 is driven to reciprocate between the position P1 and the position P2 as the screw shaft 56 rotates.

  A stepping motor 60 that drives the screw shaft 56 is installed in the housing 50. As is well known, the stepping motor 60 includes a stator (including a field coil) 60 a mounted on the housing 50 and a rotor 60 b that integrally rotates the screw shaft 56. That is, the intermediate portion of the screw shaft 56 is fixed to the rotor 60b, and rotates integrally with the rotation of the rotor 60b.

  A feed screw 56 a is formed at the end of the screw shaft 56 opposite to the valve 55, and this feed screw 56 a is screwed with a female screw 65 a formed on the inner peripheral surface of the stopper 65. The stopper 65 is formed with a projecting portion 65 b that protrudes in the radial direction, and this projecting portion 65 b is engaged with a recess 62 a of a stopper detent ring 62 mounted on the inner surface of the housing 50. It has become.

  Thereby, when the rotor 60b is driven forward / reversely by the stepping motor 60, the screw shaft 56 is screwed or screwed along the axial direction to reduce the opening amount of the air circulation hole 52a, or to reduce the air circulation. The opening amount of the hole 52a is increased. That is, the driving state of the stepping motor 60 (ISC 11) is controlled by the ECU 1 as shown in FIG. 2, and as described above, when the engine is in idle operation (see FIG. 2). When the intake throttle 10 shown is fully closed), the rotation direction and drive amount of the stepping motor 60 are controlled to control the intake amount and the engine idling rotation amount.

  FIG. 4 illustrates an example of a drive circuit for the stepping motor 60 that constitutes the ISC 11.

  As is well known, the stepping motor 60 has its rotational angle displaced in proportion to the total number of command pulses output from the control device 1 (FIG. 2). The rotational displacement angle of the stepping motor 60 is normally set by the relationship between the stator provided with a plurality of field coils and the number of teeth of the rotor, and is used for each command pulse from the control device 1. The motor 60 rotates by a step angle unique to the motor 60. Thereby, the opening degree of the valve 55 of the ISC 11 can be adjusted. Further, the rotational speed of the stepping motor 60, that is, the valve opening adjustment speed of the ISC 11, is proportional to PPS (Pulse Per Second), which is the number of pulses per unit time, which is the frequency of command pulses. Further, the rotation control of the stepping motor 60 (that is, the valve opening control of the ISC 11) is an open loop, and it is not necessary to feed back the output (displacement) result to the input side. It is configurable.

  Incidentally, the rotational torque of the stepping motor 60 increases as the value of the drive current Id flowing through the field coils C1, C2, C3, and C4 of the stepping motor 60 and the magnetic flux density B of the permanent magnet of the rotor increase. Further, in order for the stepping motor 60 to keep a predetermined rotation angle constant, it is necessary to keep a constant holding current Ih flowing through the field coils C1, C2, C3, and C4.

  The drive current Id and the holding current Ih flowing through the field coils C1, C2, C3, and C4 of the stepping motor are both proportional to the value of the power supply voltage Vcc, but the drive current Id is determined by the field coils C1, C2, C3, The holding current Ih is defined by the DC resistance component and the power supply voltage Vcc in the impedances of the field coils C1, C2, C3, and C4.

  FIG. 4A shows an example of a drive circuit (driver circuit) in the case where the field coils C1, C2, C3, and C4 of the stator are configured by four-layer unipolar (single pole excitation). FIG. 4B shows an example of a drive circuit (driver circuit) when the field coils C1, C2, and C3 of the stator are configured by three-layer bipolar (bipolar excitation).

  The driving of the ISC 11 according to the present invention employs the driving circuit shown in FIG. Here, the external resistance Rx is inserted so as to improve the rotational torque during high-speed rotation and to greatly reduce the holding current required to maintain the rotational angle constant in a predetermined case. That is, in this method, the non-inductive resistance Rx having an extremely small inductance value L is inserted in series with the field coil drive circuit while the applied voltage is set high (the battery voltage can be used as it is). The current time constant is reduced to suppress a decrease in current when the rotation angle of the stepping motor 60 is rotated at a high speed, and the holding current Ih is suppressed by making the resistance value of the external resistor Rx variable as described later. Is possible.

  In FIG. 4A, the field coils C1, C2, C3, and C4 of the stepping motor 60 are individually driven by transistors T1, T2, T3, and T4, respectively. That is, when the stepping motor 60 is to be rotated by a predetermined rotation angle by exciting the field coil C1, a pulse having a predetermined width is applied from the command pulse circuit (control device 1 in FIG. 2) to the gate of the transistor T1. Output a signal.

  In FIG. 4B, the field coils C1, C2, C3 of the stepping motor 60 are driven bidirectionally by on / off control of the transistors T1 to T6. That is, when the stepping motor 60 is to be rotated by a predetermined rotation angle by exciting the pair of field coils C1 and C2 in the first direction, the transistors T1 and T2 are turned on. When the stepping motor 60 is to be rotated backward by a predetermined rotation angle by exciting the set of the field coils C1 and C2 in the second direction opposite to the first direction, the transistor T2 and the transistor T4 Is turned on. Therefore, a pulse signal having a predetermined width is selectively output from the command pulse circuit (control device 1 in FIG. 2) side to the gate circuits of the transistors T1 to T6.

  4A and 4B, in the drive control device of the ISC 11 according to the present invention, the resistance value of the external resistor Rx is set to a small resistance value for driving. As a result, the drive current Id is increased to generate a large drive torque. If the opening of the valve 55 is kept constant in the ISC 11 and the engine operating state is predetermined, the holding current Ih is decreased by increasing the resistance value of the external resistance Rx, and the stepping motor It suppresses the temperature rise of 60 and power consumption.

  In the present invention, when the stepping motor 60 is driven, that is, when the rotation angle is displaced, a large excitation current is generated in the field coil C by setting the value of the external resistance Rx small in order to generate a large driving torque. To flow. When maintaining the rotation angle of the stepping motor 60, normally, a large holding torque is applied by flowing a relatively large holding exciting current through the field coil C while keeping the value of the external resistance Rx small. maintain. However, although the rotation angle of the stepping motor 60 is maintained, when the load fluctuation does not occur in the ISC 11 or when the opening adjustment of the valve 55 of the ISC 11 does not become a problem, the resistance value of the external resistor Rx The holding current Ih is greatly reduced by increasing the voltage to suppress the temperature rise of the stepping motor 60 and the power consumption. Examples of such cases include when the valve 10 of the intake throttle 10 (FIG. 1) is opened by a predetermined opening or more, or when the idle rotation of the engine is stabilized.

  Therefore, in the present invention, immediately after the engine is stopped, the ISC 11 initialization process is performed by outputting a pulse signal of a predetermined number of waste feed steps to the stepping motor 60 to the number of steps for fully closing the valve 55 of the ISC 11. To correct the deviation that may occur between the step value of the stepping motor 60 recognized by the control device 1 (FIG. 2) and the opening of the valve 55 of the ISC 11 converted into the actual step value of the stepping motor 60. To take action.

  FIG. 5 shows a specific example of the external resistor Rx configured so that the resistance value described in FIG. 4 can be switched. As shown in FIGS. 5A and 5B, the external resistor Rx includes a drive current regulating resistor R1 and a holding current detection resistor R2.

  5A and 5B, the switching means S is turned on when the stepping motor 60 is driven to displace its rotation angle and when the rotation angle of the stepping motor 60 is kept constant. Thereby, a large rotational torque or a large holding torque is maintained. For example, when the valve of the intake throttle 10 (FIG. 1) is opened more than a predetermined opening or when the engine idle rotation is stabilized, the temperature rise of the stepping motor 60 and the power consumption are suppressed. S is turned off.

  In the case of the first example shown in FIG. 5A, if R1 = 1Ω and R2 = 20Ω, the current detection resistor Rx is 0.95Ω when the switching means S is on, and the current detection resistance when the switching means S is off. Rx is 20Ω. In the case of the second example shown in FIG. 5B, if R1 = 1Ω and R2 = 20Ω, the current detection resistor Rx is 1Ω when the switching means S is on, and the current detection resistance when the switching means S is off. Rx is 21Ω.

  The resistance values of the drive current regulating resistor R1 and the holding current detection resistor R2 need to be determined based on the specification values such as the rated voltage, rated current, field coil impedance, and DC resistance of the stepping motor to be used.

  FIG. 6 shows an example of a flowchart of ISC drive control according to another embodiment of the present invention.

  When the engine is started, the control device 1 first performs a predetermined initial process (S1). With respect to the present invention, this initial processing includes operation control for turning on the changeover switch S shown in FIG. 5 as an initial setting. As a result, the current flowing through the field coil C is increased by decreasing the resistance value of the current detection resistor Rx, so that the rotational torque and holding torque of the stepping motor 60 are increased.

  Next, the control device detects the operating state of the engine based on output signals from various sensors and a signal indicating the valve opening of the intake throttle 10 (FIG. 1), and performs optimal control of the engine (S2). In the detection of the engine operating state (S2), for example, when it is determined that the engine idling has been stabilized from the result of the detected value from the engine temperature sensor 19 (FIGS. 1 and 2), for example (S3). By turning off the changeover switch S, the resistance value of the current detection resistor Rx is increased to decrease the holding current Ih (S4).

  Even if the engine idling speed is not stable, if the valve of the intake throttle (FIGS. 1 and 2) 10 is opened more than a predetermined opening (S5), the changeover switch S is similarly turned off. As a result, the resistance value of the current detection resistor Rx is increased to decrease the holding current Ih (S4).

  The above control is continued until the engine stop operation is performed (S6), and when the engine stop operation is performed, the valve opening initialization process of the ISC 11 is performed (S7). This ISC initialization process is performed by outputting a pulse signal having a predetermined number of waste feed steps to the stepping motor 60 immediately after the engine is stopped to the number of steps for fully closing the valve of the ISC 11. As a result, the accumulation of the deviation value is corrected between the step value of the stepping motor 60 recognized by the control device 1 and the valve opening of the ISC 11 converted into the actual step value of the stepping motor 60.

  As described above in detail, in the ISC drive control device of the present invention, when the engine operating state is predetermined, the resistance value of the current detection resistor connected in series to the field coil C of the stepping motor 60 is variable. As a result, the temperature rise and power consumption of the stepping motor are suppressed while maintaining the rotational torque and holding torque of the stepping motor 60.

  The present invention relates to an ISC control device and control method for supplying an intake air amount necessary for an engine during idling operation, and in particular, suppresses a temperature rise of a stepping motor that drives and controls an ISC valve. Has availability.

It is a figure which shows schematic structure of the engine (here single-cylinder four-cycle engine for two-wheeled vehicles) provided with ISC which is the control object of this invention. FIG. 2 is a block diagram showing a schematic configuration example of the above-described control means (ECU) 1 that comprehensively controls the operation of the engine. It is a figure which shows schematic structure of ISC, (b) is a figure which shows an internal structure, (a) is sectional drawing along the AA of FIG. (B). It is a figure explaining the example of the drive circuit of the stepping motor which comprises ISC. The specific example of the external resistance Rx comprised so that the resistance value described in FIG. 4 can be switched is shown. The example of the flowchart of the drive control of ISC which is the other form of this invention is shown.

Explanation of symbols

1: Control unit (ECU)
10: Intake throttle 11: ISC
19: Engine temperature sensor S: Changeover switch C: Field coil Rx of stepping motor: Current detection resistance (external resistance)
R1: Driving current regulating resistor R2: Holding current detecting resistor

Claims (11)

A control device for an idle speed controller (hereinafter referred to as “ISC”) that adjusts the amount of intake air when the engine is idling.
A stepping motor that opens and closes the ISC valve;
Driver means for driving the stepping motor with a constant current;
Control means for outputting a drive signal to the driver means,
The control means varies the resistance value of a current detection resistor connected in series with the field coil of the stepping motor in accordance with the operating state of the engine.   2. The control unit according to claim 1, wherein the control means increases the resistance value of the current detection resistor when maintaining the valve open / close state constant rather than when changing the valve open / close state of the ISC. ISC drive controller.   The said current detection resistance was comprised by the 1st resistance connected to the said field coil, and the 2nd resistance larger than the resistance value of the said 1st resistance, The Claim 2 characterized by the above-mentioned. ISC drive control device.   When the open / close state of the valve is kept constant, the resistance value of the current detection resistor causes the current value flowing through the field coil of the stepping motor to be less than the lower limit value or lower limit value of the rated current of the stepping motor. The ISC drive control device according to claim 2 or 3 set up as follows.   The control means performs switching to increase the resistance value of the current detection resistor when an intake throttle valve provided in the intake path of the engine opens more than a predetermined opening or when the engine idle rotation is stabilized. The ISC drive control circuit according to claim 3, wherein the ISC drive control circuit is performed.   The control means outputs the pulse signal of a predetermined number of waste feed steps to the stepping motor to fully close the ISC valve immediately after the engine stops, thereby performing the ISC initialization process. The ISC drive control circuit according to claim 1, wherein the ISC drive control circuit is performed. An ISC drive control method that uses a stepping motor to open and close a valve of an idle speed controller (hereinafter referred to as “ISC”) that adjusts the amount of intake air when the engine is idling.
(A) detecting an operating state of the engine;
(B) comparing whether the detected operating state matches a predetermined state set in advance;
(C) when the operation state in step (b) coincides with the predetermined state, increasing a resistance value of a current detection resistor connected in series to the field coil of the stepping motor;
An ISC drive control method comprising the steps of: The predetermined state set in advance in step (b) is at least:
A state in which the valve of the intake throttle provided in the intake path of the engine is opened more than a predetermined opening;
A state in which the engine idle rotation is stable;
The ISC drive control method according to claim 7, comprising:   By increasing the resistance value of the current detection resistor in step (c), the current value flowing through the field coil of the stepping motor becomes less than the lower limit value or lower limit value of the rated current of the stepping motor. The ISC drive control method according to claim 7 or 8.   The ISC according to any one of claims 7 to 9, further comprising a step of initializing the valve opening of the ISC immediately after the engine is stopped after the step (c). Drive control method.   11. The ISC drive according to claim 10, wherein the initialization process is a step of outputting a pulse signal having a predetermined number of waste feed steps to the number of steps for fully closing the valve of the ISC with respect to the stepping motor. Control method.

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