JPH10103084A - Throttle controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide at lower costs a throttle controller having a backup function of operating as emergency while causing no major troubles even upon a malfunction in its CPU. SOLUTION: A throttle controller includes a WDC decision circuit 5 for detecting a malfunction in a CPU 3, a backup circuit 4 constituted of hardware, and a mode changeover switch 7 for selectively choosing between output signals from the CPU 3 and the backup circuit 4. The throttle controller controls an associated throttle valve normally or in its normal mode based on a drive signal A outputted from the CPU 3, while upon a malfunction in the CPU 3 or in its backup mode based on a drive signal B outputted from the backup circuit 4 through the changeover of the mode changeover switch 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throttle control device for electronically controlling the opening and closing of a throttle having no mechanical link with an accelerator operation, and more particularly to a throttle control device for calculating a throttle drive amount. The present invention relates to a throttle control device with a backup function capable of continuing operation even when a problem occurs.

[0002]

2. Description of the Related Art Conventionally, no mechanical link is provided between an operation system such as an accelerator pedal and a throttle valve, and instead, a throttle valve is electronically controlled according to an accelerator operation amount to open and close. Throttle control is used. Engine control independent of accelerator pedal movement, such as idle speed control, rotation adjustment control during automatic shifting, and output limit control during wheel idling, is realized by opening and closing the throttle valve itself without providing a bypass valve. That's why.

As an example of the throttle control device, there is an electronic throttle control mechanism described in Japanese Patent Application Laid-Open No. 5-302541. This electronic throttle control mechanism (ECU) is generally configured as shown in FIG. That is, a motor drive circuit 95 and a clutch drive circuit 96 are provided around a main CPU 93 that receives input of accelerator opening data and engine speed data via an AD converter 91 and a buffer circuit 92, and further includes a sub CPU 94. I have.

[0004] The ECU 90 executes a main CPU 93 based on accelerator opening data and engine speed data.
To calculate the basic target step position of the throttle valve, calculate the final target step position by taking into account signals relating to the shifting operation of the automatic transmission, the wheel idling prevention control, and the like. Based on the final target step position, the motor drive circuit 95 The basic function is to perform throttle control by using. The sub CPU 94 calculates the basic target step position at a predetermined timing, and the main CPU
Compare with the value calculated by U93, and if different, C
Judge as a PU failure and perform fail-safe processing. The fail-safe processing is performed by the clutch drive circuit 96.
This is to separate the throttle valve from the control of the motor drive circuit 95. Accordingly, as a result, the throttle valve is fully closed by the bias of the return spring regardless of the accelerator opening data and the like, thereby preventing runaway.

[0005]

However, the conventional throttle control device (ECU 90) has the following problems. That is, the sub CPU 94 in the ECU 90 is basically similar to the main CPU 93, although the function is slightly simplified as compared with the main CPU 93, such as not calculating the final target step position. The cost increase factor is not small.

Further, when it is determined that a CPU failure has occurred, a fail-safe process of forcibly closing the throttle completely is performed, so that only idling can be performed even if there is no failure in the engine itself. Become. For this reason, for example, if it is determined that a CPU failure has occurred during the operation of the automobile, it must be stopped on the spot, and it is very difficult to even drive to the nearest repair shop in an emergency. In other words, despite having two CPUs, there is no backup function. Sub CP
It is conceivable to provide the U94 with the same arithmetic function as the main CPU 93 to provide a backup function. However, as described above, since both are CPUs and have basically the same structure, abnormalities are simultaneously caused by the same cause. In many cases, this is not expected to be an effective backup method. Further, even though the main CPU 93 is in a state where there is no abnormality and the operation can be continued, there is a possibility that an abnormality occurs only in the sub CPU 94 and thereby a CPU failure is determined.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a low-cost throttle control device having a backup function capable of performing an emergency operation without a major problem even if a CPU abnormality occurs. It was made as an issue to provide to.

[0008]

According to a first aspect of the present invention, there is provided a throttle control having a calculating means for calculating a throttle driving amount based on an accelerator operation amount signal and a throttle opening signal. A device,
Compare the accelerator operation amount signal with the throttle opening signal,
Hardware backup means for determining the throttle drive direction in the opening direction when the throttle opening signal is smaller than the accelerator operation amount signal, and otherwise in the closing direction, and abnormality detection for detecting an abnormality in the arithmetic means Means for selecting an output of the arithmetic means in a normal state, and selecting an output of the hardware backup means when an abnormality of the arithmetic means is detected by the abnormality detecting means. Performs throttle control based on a signal selected by the user.

In this throttle control device, normally,
The calculation means for receiving the accelerator operation amount signal and the throttle opening signal calculates the throttle drive amount based on these signals. Therefore, the signal of the throttle drive amount is selected by the switching means, and the throttle control is performed based on this signal. Done. Here, the calculation of the throttle drive amount by the calculation means does not necessarily have to be performed based only on the accelerator operation amount signal and the throttle opening signal, and other signals may be added. Examples of other signals include a signal of an engine cooling water temperature and a signal related to a shift operation of the automatic transmission. Further, a signal or the like related to wheel idling prevention control may be included. Also, throttle control is
The purpose is to drive a rotary drive means such as a step motor connected to the throttle based on a signal of the throttle drive amount to set the throttle opening to a target value.

In this throttle control device, while such throttle control is being performed, the operating state of the calculating means is constantly monitored by the abnormality detecting means. This monitoring is performed by detecting a pulse signal constantly output from the arithmetic means. That is, the pulse signal maintains a constant wave height and frequency as long as the arithmetic means is operating normally, so that when the wave height or frequency changes or the signal stops, the abnormality detecting means turns to the arithmetic means. It detects abnormalities. Then, when an abnormality is detected, selection of a signal by the switching means is switched. That is, a signal in the throttle drive direction from the hardware backup means is selected instead of the signal of the throttle drive amount from the arithmetic means. Therefore, thereafter, the throttle control is performed based on the throttle driving direction determined by the hardware backup means.

The hardware backup means receives the accelerator operation amount signal and the throttle opening signal in the same manner as the arithmetic means. However, the hardware backup means does not perform an arithmetic operation based on these signals as in the arithmetic means. The driving direction of the throttle is determined based on the magnitude relationship. That is, when the throttle opening signal is smaller than the accelerator operation amount signal, the throttle driving direction is determined to be the opening direction, and otherwise, the throttle driving direction is determined to be the closing direction. This determination itself is always made irrespective of whether or not an abnormality has occurred in the arithmetic means. However, when the abnormality detecting means has not detected an abnormality in the arithmetic means, it is not selected by the switching means. Is not done. When the abnormality detecting means detects the abnormality, the selection is made by the switching means as described above, and the throttle control is performed by the signal.

Therefore, when the throttle control is performed based on the output signal of the hardware backup means due to the occurrence of an abnormality in the arithmetic means, if the throttle opening signal is smaller than the accelerator operation amount signal, the throttle valve moves in the opening direction. Otherwise, the throttle is driven in the closing direction. That is, the control to open the throttle is performed only when the throttle opening is insufficient with respect to the accelerator operation amount, and otherwise, the control to close the throttle is performed. For this reason, even if an abnormality occurs in the calculation means and high-precision throttle control by calculation of the throttle drive amount cannot be performed, the output signal of the hardware backup means performs a large trouble-free operation following the accelerator operation amount. be able to.

The hardware backup means is not configured to perform software processing like the arithmetic means, but determines the output signal mechanically with respect to the input signal such as an operational amplifier or a comparator. It is configured in a hardware manner by combining elements that perform the operations described above. Therefore, since the structure is completely different from that of the arithmetic means, the abnormality is not always caused by the same factor as that of the arithmetic means. For this reason, it functions effectively as a backup means when an abnormality occurs in the arithmetic means.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. The present embodiment relates to a throttle control device for an automobile engine, in which a throttle valve having no mechanical link with an accelerator pedal is opened and closed by electronic control.

[Apparatus Configuration] The throttle control apparatus 1 according to the present embodiment is generally configured as shown in the block diagram of FIG. The throttle control device 1 includes a CPU 3 that calculates a throttle drive amount, and a backup circuit 4 that performs a backup function when an abnormality occurs in the CPU 3.
And a WDC determination circuit 5 for detecting the occurrence of an abnormality in the CPU 3
A mode changeover switch 7 for selecting one of an output signal of the CPU 3 and an output signal of the backup circuit 4, and a motor driver stage 9 for generating a motor drive pulse based on the signal selected by the mode changeover switch 7. Is arranged.

The connection relationship between these components in the throttle control device 1 is as follows. That is, C
The drive signal A from the PU 3 and the drive signal B from the backup circuit 4 are input to the mode changeover switch 7,
A WDC signal is input from the PU 3 to the WDC determination circuit 5,
A mode switching signal is input from the WDC determination circuit 5 to the mode switching switch 7, and the output of the mode switching switch 7 is input to the motor driver stage 9.

Outside the throttle control device 1, an accelerator pedal 11, a depression amount sensor 12 for detecting the depression amount thereof, a throttle valve 14, a throttle position sensor 15 for detecting the opening thereof, a throttle valve 1
The throttle motor 16 for driving the motor 4 is disposed. Here, the throttle valve 14 is the accelerator pedal 1
1 is not connected by a mechanical means such as a wire, and its opening is determined only by driving the throttle motor 16. As the throttle motor 16, a step motor is used. The output values of the depression amount sensor 12 and the throttle position sensor 15 are both analog, and are equal when the accelerator pedal 11 and the throttle valve 14 are at positions corresponding to each other. In addition, a path that bypasses the throttle valve 14 is not provided in the intake system of the engine.

The AP from the depression amount sensor 12
S signal and TPS from throttle position sensor 15
Both signals are branched into two in the throttle control device 1 and input to the CPU 3 and the backup circuit 4. Although not shown in FIG. 1, these signals are inputted to the CPU 3 after being digitized. The CPU 3 also has these 2
In addition to these, various signals are input.
For example, a signal of an engine cooling water temperature, a signal relating to a shift operation of an automatic transmission, a signal relating to wheel idling prevention control (control commonly referred to as traction control, etc.)
"Other signals"). Further, an output pulse from the motor driver 9 is input to the throttle motor 16, and the throttle motor 16 is driven to open and close the throttle valve 14.

The CPU 3 of the throttle control device 1 is a well-known logic IC that performs various arithmetic processing according to an input signal.
(Including a built-in memory in which necessary programs are stored). Here, a target throttle opening is calculated in accordance with an APS signal, a TPS signal, and other signals to set the throttle valve 14 to the target opening. Of the driving signal A. Then, the WDC determination circuit 5 attached to the CPU 3 outputs the WDC (Wa
(tch Dog Counter) has the role of monitoring the signal and detecting the occurrence of an abnormality in the CPU 3. That is, the CPU 3 has a pulse-like WD as shown in FIG.
Since the pulse height and pulse rate are constant as long as the C signal is generated and the operation is normal, the WDC determination circuit 5
When a change is recognized in the C signal, the CPU 3 outputs a mode switching signal indicating that an abnormality has occurred in the CPU 3.

The backup circuit 4 is for backup when an abnormality occurs in the CPU 3, and has a role of comparing input signals and outputting a drive signal B in accordance with the magnitude relation. The backup circuit 4 includes the CPU 3
Is configured using software, and is configured as hardware, for example, as shown in FIG. 3 using an operational amplifier. That is, A
The PS signal is negatively input and the TPS signal is positively input, so that the power supply voltage V is output as the drive signal B only when the APS signal is larger than the TPS signal, otherwise, the ground voltage (0 V ) Is output as the drive signal B. The drive signal B is treated as a control signal for opening the throttle valve 14 if the power supply voltage is V in the motor driver stage 9.
If it is V, it is handled as a control signal in the closing direction.

When the mode switch signal is not output from the WDC determination circuit 5, the mode switch 7 selects the drive signal A from the CPU 3 and outputs it to the motor driver stage 9 (normal mode). Is output, the drive signal B from the backup circuit 4 is output by switching the selection (backup mode).

[Control Operation] There are two operation modes of the throttle control device 1, a normal mode and a backup mode.
There is a street. The normal mode is an operation mode in which throttle control is performed by a drive signal A from the CPU 3, and the backup mode is an operation mode in which throttle control is performed by a drive signal B from the backup circuit 4.

First, the operation in the normal mode will be described. In the normal mode, the throttle control is performed by the drive signal A obtained by the arithmetic processing by the CPU 3. Therefore, the CPU 3 always responds to the input APS signal, TPS signal, and other signals in accordance with the throttle motor 16
Is calculated (including the direction), and is output as a drive signal A. The amount to drive the throttle motor 16 is determined by the target throttle opening and the actual opening (TPS signal).
And the difference.

The target throttle opening includes a basic target throttle opening and a final target throttle opening. The basic target throttle opening is an opening directly corresponding to the depression amount of the accelerator pedal 11, and is equal to the opening when the accelerator pedal 11 and the throttle valve 14 are mechanically linked. On the other hand, the final target throttle opening is an opening obtained by correcting the basic target throttle opening in consideration of other signals. For example, a correction for idling up when the engine cooling water temperature is extremely low, a correction for adjusting the number of revolutions when a shift operation of the automatic transmission is performed, a correction of an engine output restriction request by wheel idling prevention control, and the like. It is. Drive signal A output by CPU 3
Is based on the difference between the final target throttle opening and the TPS signal. However, it takes into account not only the difference but also the time change.

While the CPU 3 is performing the arithmetic processing, a WDC signal as shown in FIG. 2 is generated and input to the WDC determination circuit 5. The WDC determination circuit 5
Unless the pulse height and pulse rate of the C signal change,
That is, as long as the CPU 3 is normal, it does not output the mode switching signal.
3 is selected and output to the motor driver stage 9. For this reason, the motor driver stage 9 generates a drive pulse in accordance with the drive signal A to generate the throttle motor 1.
6 is driven. Thus, the opening control of the throttle valve 14 in the normal mode is performed. Therefore, in the normal mode, basically, the opening control of the throttle valve 14 is performed based on the other signals while following the depression amount of the accelerator pedal 11.

In this normal mode, the APS signal and the TPS signal are input to the backup circuit 4, and the drive signal B is output based on the magnitude relationship between the two signals. However, since the drive signal B is not selected by the mode changeover switch 7 as long as the CPU 3 is normal, the throttle control based on the drive signal B is not performed.

Next, the operation in the backup mode will be described. The control in the backup mode is performed immediately when an abnormality occurs in the CPU 3. That is, if an abnormality (such as a change in pulse height or rate or a stop of the signal) occurs in the WDC signal from the CPU 3, a mode switching signal is output by the WDC determination circuit 5, and the signal selected by the mode switching switch 7 is a driving signal. The drive signal is switched from A to the drive signal B, and the backup mode is entered. In the backup mode, the throttle control based on the drive signal B from the backup circuit 4 is performed.

In the backup circuit 4, the APS signal and T
The operational amplifier 40 compares the PS signal with the PS signal. If the APS signal is larger than the TPS signal, the power supply voltage V is output as the drive signal B. The drive signal B of the power supply voltage V is
When input to the motor driver stage 9 via the mode changeover switch 7, it is treated as a control signal for opening the throttle valve 14, so that the throttle motor 16 drives the throttle valve 14 in a direction to increase the opening. That is, the opening of the throttle valve 14 is
This is compensated for by the lack of the amount of depression of 1.

On the other hand, when the TPS signal is larger than the APS signal or when both are the same, the ground voltage 0 V is output as the drive signal B. This 0 V drive signal B is
When input to the motor driver stage 9 via the mode changeover switch 7, it is treated as a control signal for opening the throttle valve 14 so as to close the throttle valve 14.
Reference numeral 6 drives the throttle valve 14 in a direction in which the opening decreases. That is, the opening degree of the throttle valve 14 is either equivalent or excessive with respect to the depression amount of the accelerator pedal 11, and the opening degree is reduced.

Therefore, in the backup mode, if the opening of the throttle valve 14 is insufficient with respect to the depression amount of the accelerator pedal 11, the opening is increased, and if not, the opening is decreased. The valve 14 moves substantially following the amount of depression of the accelerator pedal 11, and is controlled as if it were mechanically linked. That is, the movement of the throttle valve 14 in the backup mode is close to the movement when the CPU 3 controls the throttle valve 14 at the basic target throttle opening. In this mode, other signals are not taken into account.Thus, although there are differences such as a large shift shock during automatic shifting and ineffective wheel anti-spin control, throttle control is performed without any particular problem as an emergency operation. .

Next, the operation of the throttle control device 1 having the above two control modes in the actual running of the vehicle will be described with reference to the flowchart of FIG.

(S1) In principle, the control of the throttle valve 14 by the throttle control device 1 is performed in the normal mode, that is, by the drive signal A from the CPU 3, and the CPU 3 normally outputs the APS signal, the TPS signal,
And the drive signal A calculated on the basis of the other signals to control the final target throttle opening.

(S2) And, as described above, the WDC determination circuit 5 always monitors whether the CPU 3 is operating normally by the WDC signal. If there is no change in the WDC signal, the operation of the CPU 3 is normal (S2:
Yes), the control in the normal mode of S1 is continued as it is. If there is a change in the WDC signal (S2: No), C
Since it means that an abnormality has occurred in PU3, the process proceeds to S3.

(S3) The mode shifts from the normal mode to the backup mode. That is, a mode switching signal is output from the WDC determination circuit 5 that has detected a change in the WDC signal, and the mode switching switch 7 receives the mode switching signal and switches the signal to be selected from the driving signal A to the driving signal B. Therefore, thereafter, the throttle control is performed by the drive signal B from the backup circuit 4.

(S4) Since the throttle control in the backup mode is performed based on the magnitude relationship between the APS signal and the TPS signal as described above, the subsequent processing is performed when the APS signal is larger than the TPS signal (S4: Yes). ) Is S
5 and S6 in other cases (S4: No).

(S5) The APS signal is larger than the TPS signal, which means that the opening of the throttle valve 14 is insufficient with respect to the amount of depression of the accelerator pedal 11, so that the opening increases. Throttle motor 1
6, the throttle valve 14 is driven.

(S6) The APS signal is smaller than or equal to the TPS signal, which means that the opening of the throttle valve 14 is excessive or appropriate for the amount of depression of the accelerator pedal 11. In this case, the throttle valve 14 is driven by the throttle motor 16 in the direction in which the opening decreases.

The backup circuit 4 receives the input APS.
When there is a change in the magnitude relationship between the signal and the TPS signal, the output drive signal B is immediately changed.
Or, the throttle valve 14 is driven as in S6,
The change in the opening follows the change in the depression amount of the accelerator pedal 11. Therefore, in this mode, the throttle control is performed without any serious problem as an emergency operation, and the self-propelled operation to the repair shop is sufficiently possible.

When the APS signal and the TPS signal are equal to each other, the control on the closing side (S6) is performed because the output of the backup circuit 4 is not two levels but two levels while avoiding a complicated structure. This is for performing the process on the fail safe side, and there is no particular inconvenience in this case. When the APS signal is actually equal to the TPS signal (S4: N
This is because if the processing in the direction of closing the throttle valve 14 is performed in o) (S6), the APS signal immediately becomes larger than the TPS signal (S4: Yes), and the opening is restored (S5). In an actual driving situation, the accelerator pedal 1
This is because the amount of depression of 1 is not constant for a long time.

[Effects] As described above in detail, according to the throttle control device 1 of the present embodiment, the CPU
WDC determination circuit 5 for detecting occurrence of abnormality
Is provided with a backup circuit 4 for backing up
Normally, the throttle control in the normal mode is performed by the drive signal A from the CPU 3, and when an abnormality occurs in the CPU 3, the throttle control in the backup mode is performed by the drive signal B from the backup circuit 4 to continue the operation.

Then, as the backup circuit 4, the CP
Since a hardware configuration is used instead of a software configuration such as U3, the cost is significantly reduced as compared with using two CPUs, and the backup mode is slightly rougher than the normal mode. However, there is no major problem, and sufficient throttle control can be performed for emergency operation. Further, since the configuration of the backup circuit 4 is completely different from that of the CPU 3, the backup circuit 4 is strongly resistant to noise and the like, and is not unlikely to cause an abnormality.
It is extremely unlikely that an abnormality will occur at the same time as U3. Therefore, it can be an effective backup for the occurrence of an abnormality in the CPU 3.

[Supplement] It should be noted that the present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, the drive signal B from the backup circuit 4 is converted into a pulse by the motor driver stage 9 to drive the throttle motor 16, but depending on the type of the throttle motor 16, the drive signal B is directly transmitted by the drive signal B. Can also be driven. Further, the throttle motor 16 is actively driven by the throttle motor 16 when performing processing in the direction of closing the throttle valve 14, but the movement on the closing side may be performed by urging a return spring. Furthermore, when an abnormality of the CPU 3 is detected and control is performed in the backup mode, an abnormality display may be displayed to the driver to call attention.

[0043]

As is apparent from the above description, according to the present invention, a throttle control device having a backup function capable of performing an emergency operation without major trouble even if an abnormality occurs in the CPU is provided at low cost. can do.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a throttle control device according to an embodiment.

FIG. 2 is a diagram illustrating an example of a WDC signal output from a CPU.

FIG. 3 is a diagram illustrating a configuration example of a backup circuit.

FIG. 4 is a flowchart of throttle control.

FIG. 5 is a diagram illustrating an example of a conventional throttle control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Throttle control device 3 CPU 4 Backup circuit 5 WDC determination circuit 7 Mode switch

Claims (1)

[Claims] 1. A throttle control device having a calculating means for calculating a throttle drive amount based on an accelerator operation amount signal and a throttle opening signal, comprising: comparing an accelerator operation amount signal with a throttle opening signal;
Hardware backup means for determining the throttle drive direction in the opening direction when the throttle opening signal is smaller than the accelerator operation amount signal, and in the closing direction otherwise, an abnormality detection for detecting an abnormality in the arithmetic means And switching means for selecting an output of the arithmetic means at normal times and selecting an output of the hardware backup means when an abnormality of the arithmetic means is detected by the abnormality detecting means. A throttle control device that performs throttle control based on a signal selected by the throttle control device.