JP3148449B2 - Step motor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention moves an object mechanically biased to a reference position such as a fully open or fully closed position, such as a throttle valve, against the biasing force. The present invention relates to a control device for a step motor used for causing the motor to operate.

[0002]

2. Description of the Related Art In a stepping motor for moving an object, if the position of a rotor or an object mechanically linked to the rotor does not change while the energization of the stepping motor is stopped, energization is resumed in the excitation phase at the time of energization stop. Thus, synchronization between the rotor and the excitation phase is obtained, and the object moves in synchronization with the switching of the excitation phase.

However, if an urging force is applied to the object, the rotor or the object may move while the power supply to the stepping motor is stopped. In such a case, even if the energization is restarted in the excitation phase when the energization is stopped, synchronization is not immediately secured. For example, as schematically shown in FIG. 2 (a), despite the fact that the energization is stopped when the object or the rotor is at the position k, while the energization is stopped, it moves as indicated by an arrow l,
When the current is moved to the position m when the energization is resumed, the object does not immediately move in synchronization with the switching of the excitation phase even if the energization is resumed in the excitation phase at the time of the energization stop. In such a case, in order to speed up the rotation of the step motor,
If the switching time interval of the excitation phase is inadvertently reduced, the stepping motor may lose synchronism.

To cope with this, Japanese Patent Publication No. 57-54
The technology described in JP-A-613 is proposed. In this technique, as schematically shown in FIG. 2 (c), the excitation phase is switched at a long time interval for a predetermined time after resumption of energization. Here, the switching time interval of the excitation phase is a time during which a sufficient torque is generated.

However, in this technique, it is difficult to accurately determine the low-speed initial energizing period, and in order to reliably prevent the stepping motor from stepping out, the low-speed initial energizing is continued for a long period with a margin. There must be. Therefore, there is a problem that the object is not moved quickly. JP 1
Japanese Patent Publication No. 259793 proposes a technique for solving this problem. In this technique, low-speed initial energization is performed during one cycle of the excitation phase. It is considered that this makes it possible to minimize the low-speed initial energization period.

[0006]

However, these techniques have two problems. (1) Synchronization may be secured early in low-speed initial energization depending on the positional relationship between the excitation phase and the rotor when energization is restarted. In extreme cases, synchronization may be ensured in the first excitation phase, or synchronization may be achieved in the second, third,... In such a case, the stepping motor can be accelerated by gradually reducing the switching time interval of the excitation phase immediately after synchronization is obtained. However, Japanese Patent Laid-Open Publication No.
According to the technique disclosed in Japanese Patent Application Laid-Open No. 3 (1993) -1995, even in such a case, the acceleration is not performed until the excitation phase makes one cycle. That is, although there is room for driving the step motor more quickly, it is not used.

(2) The object and the step motor may be mechanically linked by a gear train or the like. In such a case, the object position does not always correspond to the rotor position due to backlash of the gear train or the like. This is schematically shown in FIG. 2B, where j indicates the backlash. In such a case, the object may not move even though the synchronization between the excitation phase and the rotor is ensured during the cycle of the excitation phase. When such a situation occurs, the switching time interval of the excitation phase is gradually reduced, and the object starts to be moved in the middle of speeding up the rotation of the step motor. When the switching time interval of the excitation phase with respect to the step motor becomes short, the step motor is rotated at a high speed, but the torque becomes small. Therefore, the object starts to be moved with the torque reduced. For this reason, a situation occurs in which the stepping motor loses synchronism when the object starts to move.

When the object is urged to the reference position, it is usual that the energization is restarted in the excitation phase corresponding to the reference position. However, a phenomenon often occurs in which the reference position and the predetermined excitation phase do not correspond to each other due to aging, and the object does not move from the reference position even after the excitation phase has been cycled. SUMMARY OF THE INVENTION The present invention solves the above two problems, and does not continue the low-speed initial energization although there is room to be able to switch to the acceleration energization sooner. Is to try without getting out of sync.

[0009]

According to the present invention, there is provided:
As schematically shown in FIG. 1, a step motor D for moving an object C urged by a spring B or the like toward a reference position (for example, a position in contact with the stopper A) against the urging force. A control device, an object position detecting means E for detecting an actual position of the object C, an exciting phase switching means F for sequentially switching an exciting phase for energizing the step motor D, a detection value of the object position detecting means E, Synchronous movement timing detection means G for detecting the timing at which the object C starts to move in synchronization with the switching of the excitation phase from the operation timing of the excitation phase switching means F, and the operation timing of the excitation phase switching means F for the synchronous movement A time interval is set to a long time until the synchronous movement is detected by the timing detecting means G, and the time interval is gradually reduced after the synchronous movement is detected.
And a control device for the step motor having the following. Here, the long time interval means the torque required to move the rotor at the asynchronous position to a position synchronized with the excitation phase and to move the object against the load in synchronization with the switching of the excitation phase. This is the time interval at which torque greater than the value is generated in the step motor.

[0010]

According to the present invention, it is directly detected whether or not the object has started to move in synchronization with the switching of the excitation phase, and the low-speed initial energization and the acceleration energization are switched before and after that. Therefore, the low-speed initial energization is not unnecessarily continued or the switching to the acceleration energization is not performed too quickly, and the step motor is accelerated quickly without step-out.

[0011]

According to the present invention, the step motor is accelerated as quickly as possible under the condition that no step-out occurs, and the responsiveness of the movement of the object is improved. Therefore, when the present invention is used for controlling the rotation of a throttle valve, for example,
The responsiveness of the engine is improved. Moreover, since the present invention does not switch to the acceleration energization under predetermined conditions, it is necessary to cope with the secular change in the backlash or the reference position of the gear train cooperating between the step motor and the object. As a result, maximum responsiveness is ensured under the condition that no step-out occurs at all times.

[0012]

FIG. 3 shows a system configuration of an embodiment in which the present invention is applied to an engine traction control system. In the figure, reference numeral 2 denotes an engine, and a main throttle valve 8 is attached to an intake pipe 6 of the engine. The main throttle valve 8 is mechanically linked to an accelerator pedal (not shown) and rotates according to the amount of depression of the accelerator pedal. A sub-throttle valve 12 is incorporated in the intake pipe 6 for traction control of the engine 2. The sub-throttle valve 12 is biased to a fully open position by a spring (not shown). Then, when a slip occurs in the wheels, it is used to reduce the passage area of the intake passage 6 to eliminate the slip. The sub-throttle valve 12 is rotated by a step motor 10. That is, in this embodiment, the sub-throttle valve 12 is an object that is moved by the step motor 10. The throttle sensor 4 is attached to the shaft of the sub-throttle valve 12, and the opening degree of the throttle valve 12, that is, the actual position of the object moved by the step motor 10 can be detected.

A detection signal of the throttle sensor 4 can be inputted to a CPU 26 through an input interface 24. In addition, a detection signal of the sensor 14 for detecting the accelerator opening and a detection signal of the sensor 16 for detecting the wheel speed can be input to the CPU 26 via the input interface 24. The CPU 26 has a ROM 28 and a RAM 3
0 are connected to form a microcomputer system 20. In addition, a drive circuit 22 is connected to the CPU 26, and the drive motor 22 drives the step motor 10.

In this embodiment, the stepping motor 10 is of a four-phase type, which is used for 1-2-phase excitation.
That is, the excitation phase is sequentially switched for each phase of the step motor 10 according to the excitation phase pattern shown in FIG. To move the sub-throttle valve 12 from the fully open position to the closed side, the excitation phase pattern is switched in the order of 0 →... → 7 → 0 →.

In this embodiment, a program for causing the CPU 26 to execute the process shown in FIG. 5 is stored in the ROM 28.
The processing of the ROM 28 is performed when the target opening of the sub-throttle valve 12 calculated by the CPU 26 based on the values of the sensor 14 for detecting the accelerator opening and the sensor 16 for detecting the wheel speed is different from the current opening. Is executed in the interrupt,
Thereafter, it is arranged to execute the interruption every time the time set in step S7 elapses.

Next, prior to describing the processing of FIG. 5, the MSPD used in the processing will be described. As shown in FIG. 6, MSPD takes a value from level 0 to level 8 with a value that determines the switching time interval of the excitation phase.
When the level is 0, the switching time interval is the longest, and the step motor 10 is driven in the minimum speed and maximum torque state. At level 8, the switching time interval is the shortest, and the step motor 10 is driven at the highest speed and the lowest torque. The time interval of the level 0 is as long as the rotor or the object can move to the position corresponding to the excitation phase, that is, unless the further movement is prohibited by the stopper that regulates the fully open position, the rotor or the object is positioned at the position corresponding to the excitation phase. The time interval is set so that the object can be moved and damping caused when the rotor or the object is started is converged. The level 1 time interval is not long enough to ensure that the damping converges, but is still a time interval at which there is a torque that can move the object or rotor at the asynchronous position to the synchronous position. Although the time interval of level 2 or more can be maintained as long as the object and the rotor are synchronized, the time interval is not so long as to synchronize the asynchronous one. These levels are levels used during acceleration energization.

When the target opening of the sub-throttle valve 12 is different from the current opening, the processing of FIG. 5 is executed first. In this case, the answer is YES in step S1, and the speed level MSPD is set to zero (step S1).
2). Next, an initial value is set in STEP for determining the excitation phase (step S3). FIG. 4 shows the lower 3 bits of this STEP.
Are determined. When the occurrence of slip is detected while the sub-throttle valve 12 is at the fully open position and the sub-throttle valve 12 is closed, the number of steps corresponding to the fully open position is set as the initial value. Therefore, if there is no backlash or the like, the rotor and the excitation phase should be synchronized if the current is supplied in the excitation phase determined by the number of steps determined by the initial value. However, this is not always the case due to aging.

After the above processing, the synchronous flag is set to "0" indicating "asynchronous" in step S4, and the current opening of the sub-throttle valve 12 detected by the throttle sensor 4 is set to TA in step S5. . Next, step S
The excitation phase determined by the lower 3 bits of the STEP input in step 3 is determined, and energization in the excitation phase is started (step S6). Thereafter, a time interval corresponding to the level of the MSPD, in this case, the “0” level, is set in the timer (step S7), and after the elapse of this time, the processing in FIG. 5 is executed again.

As a result of the above processing, one of the following phenomena occurs. First, when the excitation phase determined in step S3 is on the close side from the fully open (reference) position, the rotor or sub-throttle valve 12 is moved to a position corresponding to the excitation phase by excitation in step S6 (see FIG. 8P). ). On the other hand, if the excitation phase determined in step S3 is further open from the fully open (reference) position, the sub-throttle valve 12 will not be at a position corresponding to the excitation phase. In other words, unless it moves to the position indicated by Q in FIG. 7, it cannot move beyond the position of Q1 even though it does not synchronize with the excitation phase. Also in this case, there are two cases, one is a case where the rotor is moving to the synchronous position even if the object cannot move to the synchronous position due to the existence of the backlash or the like, and the other is whether there is no backlash. In other cases, the rotor is not synchronized either because of a shift of more than the backlash. In each case, the object does not move to the synchronous position but remains at the reference position.

After the energization is started with the MSPD set to zero at the start of re-energization of the step motor in this way, the process of FIG. 5 is executed again when a time corresponding to zero of the MSPD elapses. . In this case, step S1 is NO, and it is determined whether or not the synchronization flag is set to zero (step S8). In this case, since the value of zero was set in step S4 at the time of the previous execution, the result is yes, and step S9 is executed.

In step S9, it is determined whether or not the object (sub-throttle valve 12) has started to move in synchronization with the switching of the excitation phase of the step motor 10. Specifically, the excitation phase corresponding to the fully open position is determined. When the energization is started, it is determined whether or not the difference between the throttle opening TA stored in step S5 and the current throttle opening is equal to or greater than a predetermined value. Here, when the excitation phase for one phase is switched, the opening is set to about 1/2 of that when the sub-throttle valve 12 moves following the switching of the excitation phase. It is possible to determine whether or not they have moved synchronously.

If it is determined in step S9 that the sub-throttle valve 12 has not yet moved (this corresponds to Q2 in FIG. 7).
(Which occurs at the end of the time interval shown in (2)) is negative. At the end of the time interval indicated by W in FIG.
Even if the sub-throttle valve 12 moves, if it does not reach the predetermined value, the determination result is NO. In this case, only one STEP is updated in step S10 to switch the excitation phase, and the speed level is set to 1 in step S11. Speed level 1 is a speed at which sufficient torque is generated in the stepping motor so that step-out does not occur even if the motor is asynchronous. Thereafter, step S5 and subsequent steps are repeated. Therefore, the next excitation phase is maintained at the time interval at the speed level “1”, that is, at the long time interval.

The same processing is repeated until step S9 becomes yes. In this way, the excitation phase is switched from Q to R to S to T in FIG. During this time, the excitation phase switching time interval is maintained at a long time interval.

Next, at the end of the time interval T in FIG. 7 or at the end of the time interval W in FIG. 8 (when the amount of movement of the sub-throttle valve is less than a predetermined value at the end of the time interval W, the end of the time interval X When the sub-throttle valve 12 starts to move in synchronization with the switching of the excitation phase as shown in FIG.
9 is yes. When this happens, the synchronization flag is set to “1” next.
Is set (step S12) to correspond to the fact that the sub-throttle valve 12 has started to move in synchronization with the switching of the excitation phase. Next, in step S13, the excitation phase pattern is switched to the next pattern, and the MSPD is calculated (step S14). Here, the MSPD is calculated based on the difference between the target step number and the current step number. When the difference is large, the MSPD accelerates in the order of 2 → 3 → 4 → 5 → 6 → 7 → 8.

FIGS. 7 and 8 show the switching of the excitation phase according to the present invention in comparison with the prior art, where the solid line indicates the present embodiment and the broken line indicates the prior art. According to the prior art, the low-speed initial energization (that is, equivalent to MSPD = 1) is continued uniformly until the excitation phase makes one cycle. On the other hand, in the present invention, immediately after the object (in this case, the sub-throttle valve 12) starts rotating in synchronization with the switching of the excitation phase, the current is switched to the acceleration energization, and the object is rapidly accelerated.

Although not shown in FIGS. 7 and 8,
If the reference position of the sub-throttle valve 12 (corresponding to Q1 in FIG. 7) and the first excitation phase (corresponding to Q in FIG. 7) are greatly shifted due to aging, even if the excitation phase is cycled, In some cases, the sub-throttle valve 12 does not start moving. In this embodiment, even in such a case, the state of MSPD = 1, that is, the state of switching the excitation phase at long time intervals, is maintained until the sub-throttle valve 12 starts rotating in synchronization with the switching of the excitation phase. Therefore, the step motor 10 does not lose synchronism when the sub-throttle valve 12 starts moving. Then, as the anxiety disappears, the vehicle is accelerated, so that the maximum following ability is ensured within the possible range.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing the concept of the present invention.

FIG. 2 is a diagram schematically showing a conventional technique.

FIG. 3 is a diagram illustrating a system configuration according to an embodiment;

FIG. 4 is a diagram showing an excitation phase pattern;

FIG. 5 is a diagram showing a processing procedure.

FIG. 6 is a diagram showing a speed level.

FIG. 7 is a diagram illustrating an example of a processing result;

FIG. 8 is a diagram showing another example of a processing result.

[Explanation of symbols]

 D: Step motor E: Object position detecting means F: Excitation phase switching means G: Synchronous movement timing detecting means H: Time interval adjusting means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-259793 (JP, A) JP-A-56-22598 (JP, A) JP-A-56-83295 (JP, A) JP-A-59-1983 172998 (JP, A) JP-A-3-40799 (JP, A) JP-A-3-145996 (JP, A) JP-A-6-225592 (JP, A) JP-A-6-225596 (JP, A) JP-A-6-233594 (JP, A) JP-B-57-54613 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 8/00-8/42 F02D 9/00 -9/18 F02D 11/00-11/10

Claims (1)

(57) [Claims] 1. A step motor control device for moving an object urged toward a reference position side against an urging force, comprising: object position detecting means for detecting an actual position of the object; Excitation phase switching means for sequentially switching the excitation phase to be energized, detecting a timing at which the object starts to move in synchronization with the switching of the excitation phase from a detection value of the object position detection means and an operation timing of the excitation phase switching means. Synchronous movement timing detecting means, the operation timing of the excitation phase switching means, a long time interval until the synchronous movement is detected by the synchronous movement timing detecting means, and a time interval after the synchronous movement is detected. And a time interval adjusting means for gradually decreasing the time interval.