JPH04203449A - Fault detecting device of step motor - Google Patents

Abstract

PURPOSE:To prevent a step out of the motor by providing a maintaining and exciting output means to output a signal to continue the excitation of coils other than a detected driving circuit to maintain a valve body to a specific position, to a flow control means, when a breaking of wire is detected. CONSTITUTION:The device consists of a valve body 1 placed in a fluid passage P and to regulate the flow rate, a step motor 2 to drive the valve body, a flow control means 3 to control the excitation of plural coils of the step motor 2, and to control the flow rate, a wire breaking detecting means 4 to detect a breaking of wire of the drive circuits provided to each coil of the step motor 2, and an abnormality deciding means 5 to decide the abnormal condition of the step motor when a breaking of wire is detected for a specific time. The fault detecting device of the step motor is composed to provide a maintaining and exciting output means 6 to output a signal to continue the excitation of the coils other than the detected drive circuit and to maintain the valve body to a specific position to the flow control means 3 when a breaking of wire is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a failure detection device for a step motor circuit that drives and controls a valve body that regulates a fluid flow rate.

(Prior art) A valve body is driven by a step motor to control the fluid flow rate. A control bag W (hereinafter referred to as ISC), an exhaust gas recirculation device (hereinafter referred to as EGR) that connects the exhaust gas passage and the intake passage and recirculates a part of the exhaust gas to the intake system, or an accelerator. Eliminating the mechanical connection between the and throttle valve,
Electronically controlled throttles, etc. that independently electrically open and close the throttle valve depending on the vehicle condition and control the amount of intake air.
Already known.

These devices employ various fail-safe mechanisms for controlling the internal combustion engine when the step motor fails. For example, when ISC detects an abnormality in the stem motor, it stops the internal combustion engine, retards the ignition timing to suppress the increase in rotation, and adjusts the fuel amount (for example, Japanese Patent Laid-Open No. 11648/1983) ). Also, EGR
In this case, when the step motor is not energized, a spring or the like is provided to bias the valve body towards the valve closing side, and when the step motor is energized, the valve is opened by the driving force, but due to wire breakage etc.
Some valves are configured to be closed by a spring when the step motor becomes abnormal (for example, Japanese Utility Model Application Publication No. 136680/1983). Even in electronically controlled throttles, valve closing control is performed using a return spring or the like when the step motor is abnormal (for example, Japanese Patent Application Laid-Open Nos. 61-23844 and 59-226244).

[Problems to be Solved by the Invention] In a control device for an internal combustion engine driven by a step motor having a fail-safe mechanism as described above, a so-called diagnosis process is used to notify the driver of the detected abnormality of the step motor and prompt repair. When detecting an abnormality for a predetermined period of time, it is determined that an abnormality has occurred, so as not to misjudge it as an abnormality (disconnected M) even when there is a possibility of normality returning, such as when there is a momentary interruption due to poor contact of the connector, etc. Therefore, it is considered that fail-safe and diagnostic processing should be performed. However, with multiple coils and sequential excitation control to control the operation of the step motor,
When one of the phases is disconnected, normal control is performed with one phase disconnected for a predetermined period of time from when the first abnormality is detected until it is determined that there is an abnormality, so there is a risk that the step motor will step out. Even if the step motor returns to normal, it may remain out of step and may not be able to be controlled normally.

For example, in a four-phase excitation type step motor as shown in FIG. 8, which consists of a stator equipped with four excitation coils around a magnetic rotor, a first phase 81, a second phase 82,
When the third phase 83 and the fourth phase 84 are energized in this order, the magnetic center rotor rotates clockwise in the figure, and vice versa. 82, 1st
When the phases 81 are energized in sequence, the rotor rotates counterclockwise. Incidentally, each phase is energized for, for example, 8 m5 sec, of which 4 sec is output so as to overlap with the energization of the next phase, and the rotation of the rotor is controlled at 45 degrees/step. At this time, for example, the second
If the phase coil is disconnected, even if the second phase is excited after the first phase is excited, the second phase will not have magnetism, the rotor will not rotate, and will easily cause vibration, and this vibration will be completely eliminated. When the next excitation signal (third phase) comes before the rotor comes to rest, if the rotor is vibrating in the opposite direction to the direction it should be driven,
When the rotor deviates from its normal rotational position, so-called step-out occurs, and the rotor does not rotate in response to the drive signal or rotates in reverse.

Therefore, an object of the present invention is to prevent step-out by controlling a step motor to maintain the valve body at a predetermined opening degree when an abnormality is first detected.

[Means to solve the problem]

In order to achieve the above object, the configuration of the present invention is characterized by having a configuration as shown in FIG.

That is, a valve body that is interposed in a fluid passage and regulates the flow rate, a step motor that drives the valve body, a flow rate control means that controls the flow rate by controlling the excitation of a plurality of coils of the step motor, and each coil of the step motor. a disconnection detection means for detecting a disconnection in the drive circuit provided in the drive circuit; and an abnormality determination means for determining that the step motor is abnormal when the disconnection is detected for a predetermined period of time;
In a failure detection device for a step motor, when a wire breakage is detected, a holding excitation output means outputs a signal to the flow control means to continue energizing coils other than the drive circuit in which the wire breakage has been detected to hold the valve body at a predetermined position. It is characterized by having a configuration that includes the following.

[Effect]

In the step motor failure detection device configured as described above, when a disconnection is first detected, coils other than the disconnected drive circuit are continuously energized to hold the valve body in a predetermined position.
When normality is restored within a predetermined time, normal control is resumed from the held predetermined position.

On the other hand, if a disconnection is detected for a predetermined period of time, it is determined that the step motor is abnormal.

〔Example〕

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

FIG. 2 shows a vehicle internal combustion engine (
11 is a schematic configuration diagram showing an engine 11 (hereinafter referred to as an engine) and its peripheral devices.

The present embodiment includes an engine 11 and an electronic control unit 21 including a microcomputer or the like that controls the engine 11.

A surge tank 24 is provided in the intake passage 12 of the engine 11 via a throttle valve 23 on the downstream side of an air cleaner 22 that filters intake air. An intake temperature sensor 25 that detects the intake temperature is installed near the air cleaner 22, and an idle switch 26 that detects the fully closed state of the throttle valve 23 is attached to the throttle valve 23.
is attached. In addition, the surge tank 24 has
Diaphragm pressure sensor 27 that detects intake air amount
is attached.

The bypass path 28 that bypasses the throttle valve 23 and the intake passage 12 includes an idle speed control valve (the opening degree of which is controlled by controlling the excitation current of a solenoid).
(hereinafter abbreviated as rscv) 29 is installed, and this l5
By controlling the opening degree of the CV 29, the amount of intake air to the engine 11 is controlled independently of the throttle valve 23, and the idle speed is controlled to the target speed.

A fuel injection valve 30 for injecting fuel into the combustion chamber 33 of each cylinder near the intake boat 31 is provided for each cylinder, and the exhaust port 34 is provided with the exhaust passage 13. Further, a spark plug 37 is provided to protrude into the combustion chamber 33. When the mixture of intake air and injected fuel is combusted in the combustion chamber 33 and exhausted from the exhaust port 34 due to the up and down reciprocating movement of the piston, the exhaust gas is purified of unburned components etc. by the catalyst device 36. is discharged.

The igniter 39 generates high voltage, and the distributor 40 distributes and supplies this high voltage to the spark plugs 37 of each cylinder. The rotation angle sensor 41 is connected to the distributor 4
0 shaft rotation speed is detected, and an engine rotation signal is output to the electronic control unit 21, for example, every 30° CA.

A water temperature sensor 42 is installed so as to penetrate the engine block 43 and partially protrude into the water jacket, and detects the temperature of the cooling water of the engine 11 and outputs a water temperature sensor signal. In addition, a catalyst device 3 is provided in the exhaust passage 13.
An oxygen concentration sensor (hereinafter referred to as "Oz sensor") 44 that detects the oxygen concentration in the exhaust gas before it enters the exhaust gas is attached so as to protrude through a part thereof.

Further, in the middle of the exhaust gas recirculation passage (hereinafter referred to as EGR passage) 14 that connects the exhaust passage 13 on the upstream side of the Oz sensor 44 and the intake pipe 12 on the downstream side of the throttle valve 23, recirculating exhaust gas is provided. Based on the EGR cooler 46 for lowering the gas temperature and the control signal from the electronic control device 21,
An exhaust gas recirculation valve (hereinafter referred to as EGRV) 15 that controls the amount of exhaust gas recirculated to the intake pipe 12 is provided.

FIG. 4 is a diagram showing this EGRV 15 in more detail.
1 consists of a stator 153 and a rotor 154, and a valve body 15
2 has a valve 155 and a valve 155 fixed to the tip,
It consists of a rod 156 that is movable in the vertical direction in the figure. 1
57 is an inlet port into which exhaust gas flows, and 158 is an outlet port that leads exhaust gas to the intake passage 12.

When the rotor 154 rotates due to the input of a drive signal to the step motor 151, the rotational motion is converted into linear motion by the screw 159, and the motor shaft 160 moves against the spring force of the spring 161 to move the rod 154 in the vertical direction in the figure. By pulling up, the valve 155 is moved in the direction away from the seat 162 (valve opening direction). On the other hand, when the rotation direction is in the reverse direction, the motor shaft 160 moves the rod 156 downward in the figure together with the spring force of the spring 161, and the valve 155 is moved in the direction closer to the seam 62 (valve closing direction).

As a result, the exhaust gas flowing into the inlet port 157 is
A flow rate corresponding to the distance (opening degree) between the valve 155 and the seam 62 is led out from the outlet port 158.

By controlling the degree of opening of the EGRV 15 in this way, the flow rate of the exhaust gas flowing in through the EGR cooler 46 is controlled, and the amount of exhaust gas recirculated to the nine-air passage 12 is thereby controlled.

The step motor 151 is controlled by a drive circuit shown in FIG. Note that the drive current from the drive circuit is constant current controlled by a well-known chopper circuit. In FIG. 5, the step motor 151 has a multi-phase excitation coil (
CI, C2, C3, C4) are controlled by a drive circuit that generates multi-phase drive signals (EGRI, EGR2, EGR3, EGR4) that sequentially energize the drive transistors (Tri, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, Tr2, . Tr3.Tr4) collector voltage monitoring circuit (EGRFI, EGRF
2. EGRF3. EGRF4) are set respectively.

This circuit (EGRFI, EGRF2゜EGRF3.EG
A disconnection of the drive circuit is detected by the output of RF4). Note that FIG. 5 only shows the circuit configuration regarding the drive circuit of the excitation coil C1, and regarding the other excitation coils,
It is omitted because it has a similar configuration.

In the step motor 151 of this embodiment, the excitation coils (C1, C2, C3, C4) of each phase are energized at a rate of 813 eC, of which 4 tasec is output so as to overlap with the energization of the next phase. Rotation of the rotor 154 is made accurate.

The electronic control unit 21 that controls the operation of each part of the above configuration is a central processing unit (hereinafter referred to as CPU
) 61, read-only memory (ROM) 62
, a random access memory (RAM) 63, and a bank-up RAM (BU-RAM) 64 as a central logic operation circuit. vessel(
(hereinafter referred to as ADC) 66.

A vehicle speed signal, a cylinder discrimination signal, an engine speed signal, a fully closed throttle signal, an air-fuel ratio signal, a starter signal, a neutral signal, an air conditioner signal, etc. are input to the input/output capotro 5. In addition, the input/output capotro 5 is EGRV 1
EGRV control signal for controlling the opening degree of 5, l5CV
29, a fuel injection signal for opening and closing the fuel injection valve 30, and an igniter 3.
The ignition signals etc. for turning on and off the E 9 are output to each drive circuit (not shown), and the drive circuit turns on and off the E
It controls the GRV 15, l5CV 29, fuel injection valve 30, igniter 39, etc., respectively. In addition, the intake air amount signal, intake air temperature signal, water temperature signal, battery signal, etc. from each sensor 27, 25, 42 are input to the ADC 66,
The DC 66 sequentially converts these analog signals into digital signals in accordance with instructions from the CPU 61.

FIG. 6 is a flowchart showing a process when detecting disconnection of a step motor as an embodiment of the present invention.

In step 61 (hereinafter referred to as S61), the nth (n=1.2, 3.4) transistor (hereinafter referred to as Trn
For example, the first transistor is Trl (
) is in the OFF state, and only when an affirmative determination is made, the process proceeds to the following flow. This means that Trn is O
This is because when it is in the N state, it is grounded and the corresponding collector voltage (hereinafter referred to as EC'RFn, for example, the first collector voltage is expressed as EGRFI) is always in the LO state. When it is determined in 361 that Trn is in the OFF state, in 362 it is determined whether EGRFn corresponding to Trn determined to be OFF in S61 is in the LO state. If it is determined to be in the Lo state, it is assumed that there is a disconnection in the corresponding n-th drive circuit, and the process at the time of disconnection detection from 363 onwards is performed.

On the other hand, if it is determined that EGRFn is in the Hi state, it is determined that there is no abnormality and this flow is ended.

In S63, the step motor is continuously energized to the one phase that was detected to be disconnected in step 362, to hold the step motor in the position at which the disconnection was detected, and the transistor of the phase in which the disconnection was detected (
Trn) is turned OFF.

Thereafter, in S64, this disconnected state remains for a predetermined period of time (for example,
1 second).

If it is determined in S64 that the disconnection state has continued for a predetermined period of time,
In S65, failsafe is executed.

In this embodiment, the step motor is driven to fully close the valve body. Thereafter, in S66, a diagnosis code corresponding to the steering motor disconnection abnormality is stored, and a predetermined lamp (for example, an engine abnormality lamp in the instrument panel) is turned on to notify the driver.

On the other hand, if normality is restored within one second (EGRFn is Hi in S62), normal control is resumed from the step position (number of steps) of the step motor held in S63.

In this embodiment, as soon as a wire breakage is detected, the step motor is held, and then an abnormality is determined.Only when it is determined that the wire has been broken for a predetermined period of time, failsafe and diagnosis processing is performed. Even when normality is restored, control of the step motor can be resumed without step-out.

A flowchart of another embodiment according to the present invention is shown in FIG. Since 371 and 372 are the same as S61 and 362 in FIG. 6, their explanation will be omitted. S73 is a fail-safe process that is performed as soon as a disconnection is detected in S72. Specifically, similar to 365 in FIG. 6, the step motor is driven to fully close the valve body, and in S74, the disconnection is detected in S72. The step motor is held in a fully closed state by continuously energizing one phase that is detected as being open. After that, in 375, the transistor (Trn) of the phase in which the disconnection was detected is turned off, and in S76,
In S77, abnormality determination is performed.

In S77, E corresponding to Trn turned OFF in 374
It is determined whether the LO state of GRFn continues for a predetermined period of time (for example, 1 second), and until the predetermined period of time has elapsed, S7
5, and after a predetermined time elapses, that is, EC;
When the Lo state of RFn continues for a predetermined time, a diagnosis code corresponding to step motor disconnection abnormality is stored in 37B, a predetermined lamp is turned on, and the driver is notified.

On the other hand, if it returns to normal during the determination that the predetermined time has elapsed in S77, that is, if it is determined that ERGFn is Hi in S76, this flow is terminated, and the step motor position held in S74 (fully closed position) is determined. From then on, normal control resumes.

In this embodiment, as soon as a wire breakage is detected, a failsafe is performed, and then a determination is made as to whether or not it is really a wire breakage. ), so even if the control returns to normal within a predetermined period of time, normal control can be performed from the held position without step-out.

In the above two embodiments, a method of continuously energizing only one phase was shown in order to maintain and control the rotation of the rotor. , the rotation of the rotor may be maintained and controlled. Also,
Coil energization control is performed by two-phase excitation control in which two coils overlap, but in 1-phase excitation control in which only one phase is energized at all times, or in 1-2 phase excitation control in which 1-phase excitation and 2-phase excitation are repeated. It is also possible to apply the present invention.

In the above two embodiments, 152 in FIG. 4 is the valve body of the present invention, and 151 in the same figure is the step motor of the present invention.
The drive signals (EGRI to EGR4) in FIG. 5 are used as the flow rate control means of the present invention, and the collector voltage monitoring circuit (EGRFI-EGRF4) in the same figure is used as the disconnection detection means, and 363 and 363 in FIG. 374 in FIG. 7 corresponds to the holding excitation output means of the present invention, and 364 in the same figure and 377 in FIG. 7 correspond to the abnormality determination means of the present invention.

The present embodiments all show control when detecting a break in a step motor that controls the amount of EGR, but the control is not limited to EGR, but can also be applied to control when detecting a break in a step motor used for 15CVO opening control, for example. This can be applied by setting the failsafe to the valve open side.

〔Effect of the invention〕

In the step motor disconnection detection device according to the present invention, since the valve body is held in a predetermined position at the same time as abnormality is detected, even when the valve body returns to normal during abnormality determination.

Normal control is possible from the predetermined opening degree, and step-out can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of the present invention. FIG. 2 is a schematic configuration diagram showing an internal combustion engine for a vehicle equipped with an exhaust gas recirculation device according to the present invention and its peripheral equipment. is a diagram showing the configuration of the electronic control device of the embodiment of FIG. 2, FIG. 4 is a diagram showing the configuration of the EGRV of FIG. 2 in detail, and FIG. 5 is a circuit for detecting disconnection of the present embodiment. 6 is a flowchart showing the processing when detecting a wire breakage in one embodiment according to the present invention. FIG. 7 is a flowchart showing the processing when detecting a wire breakage in another embodiment according to the invention. 1 is a schematic configuration diagram of a four-phase excitation type step motor. Explanation of symbols 11...Engine 12...Intake passage 13...Exhaust passage 14...EGR passage 15...ECRV 151...Step motor 152...Valve body 21...Electronic control unit Applicant Toyota Motor Corporation Figure 1 Figure 2 Figure 3 159 Screw 160 1540-ta Figure 7 Figure 8

Claims (1)

[Scope of Claims] A valve body interposed in a fluid passage to regulate the flow rate, a step motor that drives the valve body, a flow rate control means that controls the flow rate by controlling the excitation of a plurality of coils of the step motor, and a step. A failure detection device for a step motor, which includes a wire breakage detection means for detecting a wire breakage in a drive circuit provided in each coil of the motor, and an abnormality determination means for determining that the step motor is abnormal when a wire breakage is detected for a predetermined period of time. A step motor characterized in that the step motor is equipped with a holding excitation output means for outputting a signal to the flow rate control means to keep the valve body in a predetermined position by continuously energizing coils other than the drive circuit in which the disconnection is detected. Fault detection device.