JP4252928B2 - How to prevent belt slip - Google Patents

Description

  The present invention relates to a belt slip prevention method for preventing slipping of a belt wound around a drive pulley provided in a motor and a driven pulley provided in a driven device whose load fluctuates periodically.

When transmitting the rotation of the crankshaft of the engine to the drive shaft of the compressor via a belt, the rotation speed of the crankshaft and the rotation speed of the compressor drive shaft are detected, and the difference or ratio between the two rotation speeds is a predetermined criterion. Japanese Patent Application Laid-Open No. 2004-133867 discloses that the determination criterion value is changed according to the angular acceleration of the crankshaft while determining that the belt has slipped when the value is exceeded.
No. 5-5499

  By the way, when the engine is cranked and started by the starter motor, the rotational load of the engine periodically changes, so that the rotational speed of the starter motor also changes periodically. In such a case, even if an attempt is made to determine belt slip when the difference or ratio between the rotation speed of the starter motor and the engine rotation speed exceeds a predetermined determination reference value, as in the above-mentioned Patent Document 1, the motor rotation speed is determined. Causes of erroneous detection of belt slip due to detection of a large rotational speed difference or rotational speed ratio even if the output phases of both sensors are slightly shifted due to variations in the characteristics of the sensor and engine rotational speed sensor. There was a possibility.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to reliably detect and suppress belt slip when a driven device whose load fluctuates periodically is driven with a belt by a motor. .

  To achieve the above object, according to the first aspect of the present invention, a belt slip wound around a driving pulley provided in a motor and a driven pulley provided in a driven device whose load fluctuates periodically. In the belt slip prevention method for preventing the rotation, a first step of predicting a change pattern in one cycle of the rotational speed of the motor that receives a periodic load from the driven device, and a first step of detecting the actual rotational speed of the motor A second step, a third step of comparing the predicted rotational speed change pattern with the detected rotational speed, and detecting a belt slip when the difference or ratio exceeds a predetermined threshold; and a belt slip And a fourth step of preventing slippage by reducing the torque of the motor when the motor is detected.

  According to the invention described in claim 2, in addition to the configuration of claim 1, in the fourth step, the torque command value of the motor is set until the belt slip is eliminated or until the one cycle ends. A belt slip prevention method is proposed, which is characterized by stepwise reduction at predetermined time intervals.

  According to the invention described in claim 3, in addition to the configuration of claim 2, in the fourth step, after the belt slip has been eliminated, the motor response delay is delayed from the torque reduction command. A method for preventing slipping of a belt is proposed, which is characterized by canceling excessive torque reduction that occurs.

  According to a fourth aspect of the present invention, in addition to the configuration of the first aspect, in the fourth step, after the belt slip is eliminated, a new change in the number of revolutions predicted based on the reduced torque is obtained. There is proposed a belt slip prevention method characterized by comprising a fifth step of detecting the belt slip again by comparing the pattern and the actual rotational speed.

  According to the fifth aspect of the present invention, in addition to the configuration of the fourth aspect, when no belt slip is detected in the fifth step, the motor torque command value is set to a predetermined value until the end of the one cycle. A method for preventing slipping of a belt is proposed, which is characterized by increasing stepwise at time intervals.

  The starter motor 15 of the embodiment corresponds to the motor of the present invention, the starter motor pulley 25 of the embodiment corresponds to the drive pulley of the present invention, the crank pulley 19 of the embodiment corresponds to the driven pulley of the present invention, The engine E of the embodiment corresponds to the driven device of the present invention.

  According to the configuration of claim 1, a change pattern of one cycle of the number of rotations of the motor that receives a periodic load from the driven device is predicted, the actual number of rotations of the motor is detected, and a difference or ratio obtained by comparing the two is compared. When the belt exceeds the predetermined threshold, the belt slip is detected, and when the belt slip is detected, the motor torque is reduced. Therefore, when the driven device whose load varies periodically is driven by the motor, Slip generated in the belt can be accurately detected and suppressed.

  According to the second aspect of the present invention, the motor torque command value is gradually reduced at predetermined time intervals until the belt slip is eliminated in the fourth step or until one cycle of the change in the rotational speed of the motor ends. Further, it is possible to prevent the torque from being reduced more than necessary and to minimize the influence of the belt slip on the drive of the driven device.

  According to the third aspect of the present invention, after the belt slip is eliminated in the fourth step, the excessive torque reduction that occurs later than the torque reduction command is canceled due to the response delay of the motor. Despite the elimination, unnecessary torque reduction can be prevented, and the driven device can be driven effectively while minimizing the influence of torque reduction.

  According to the fourth aspect of the present invention, after the belt slip is eliminated in the fourth step, the new rotation speed change pattern predicted based on the reduced torque and the actual rotation number are obtained in the fifth step. In comparison, since the belt slip is detected again, it is possible to cope with the case where the slip once reappeared before the end of one cycle of the change in the rotational speed of the motor.

  According to the fifth aspect of the present invention, if no belt slip is detected in the fifth step, the torque command value of the motor is increased stepwise at predetermined time intervals until one cycle of the change in the rotation speed of the motor is completed. By reducing the slip, the torque of the motor is increased within a range in which the slip of the belt does not recur, and the driven device can be driven effectively while minimizing the influence of the torque reduction.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 to 10 show an embodiment of the present invention. FIG. 1 is a front view of an automobile engine, FIG. 2 is an explanatory diagram of the main phase angle and sub-phase angle of the engine, and FIG. 3 is cranking the engine. FIG. 4 is an explanatory diagram of a method for obtaining a predicted value of the rotational speed, FIG. 5 is an explanatory diagram of a method of detecting a belt slip, and FIG. 6 is a flowchart of a slip detection process. 7 is a graph showing the actual torque reduction rate when the torque command value is zero, FIG. 8 is a graph showing the actual torque reduction rate when the torque reduction control is performed three times, and FIG. 9 is a change of the torque command value. FIG. 10 is a flowchart of the torque control process.

  As shown in FIG. 1, an in-line four-cylinder engine E of an automobile includes an accessory bracket 12 attached to the side of an engine block 11, and an air conditioning compressor 13, a water pump 14 and a starter motor 15 are provided on the accessory bracket 12. Supported. An auto tensioner 17 is supported by a tensioner bracket 16 attached to the side surface of the engine block 11. A crank pulley 19 provided on the crankshaft 18 of the engine E, an air conditioning compressor pulley 21 provided on the rotary shaft 20 of the air conditioning compressor 13, a water pump pulley 23 provided on the rotary shaft 22 of the water pump 14, and a starter motor A belt 28 is wound around a starter motor pulley 25 provided on the 15 rotation shaft 24, an idler pulley 26 provided on the engine block 11, and a tensioner pulley 27 provided on the auto tensioner 17. The rotation directions of the crank pulley 19, the air conditioning compressor pulley 21, the water pump pulley 23, the starter motor pulley 25, the idler pulley 26, and the tensioner pulley 27 are indicated by arrows.

  The auto tensioner 17 includes a tensioner main body 29 that can be expanded and contracted, and an upper end of the auto tensioner 17 is pivotally supported by the tensioner bracket 16 via a fulcrum pin 30. An intermediate portion of the swing arm 32 is pivotally supported on the tensioner bracket 16 via a fulcrum pin 31, and one end of the swing arm 32 is pivotally supported on the lower end of the tensioner body 29 via a fulcrum pin 33. The tensioner pulley 27 is pivotally supported on the other end of the arm 32 via a rotating shaft 34.

  An ignition switch 35 for starting the engine E, a motor speed sensor 36A for detecting the motor speed of the starter motor 15, a main phase angle sensor 36B for detecting the top dead center (TDC) of the engine E, and a crank angle are detected. The electronic control unit U connected to the sub phase angle sensor 36 </ b> C controls the operation of the starter motor 15 via the motor controller 37 and the inverter 38.

  As shown in FIG. 2, during one cycle when the crankshaft 18 of the engine E rotates twice, the cylinders # 1 to # 4 are moved in order of # 1 → # 3 → # 4 → # 2 every 180 ° crank angle. The main phase angle sensor 36B outputs a main phase angle signal every 180 °. The sub phase angle sensor 36C outputs a sub phase angle signal every 30 ° of crank angle.

  When the ignition switch 35 is turned on to start the engine E, the starter motor 15 operates to crank the crankshaft 18 via the starter motor pulley 25, the belt 28 and the crank pulley 19. At this time, the load on the cranked engine E periodically varies, so that the rotation speed of the starter motor 15 detected by the motor rotation speed sensor 36A varies periodically. The reason for this will be described with reference to FIG.

  In a period T1 with a crank angle of 180 ° from when the # 2 cylinder reaches the top dead center until the # 1 cylinder reaches the top dead center, the # 1 cylinder is in the compression stroke and the # 2 cylinder is in the expansion stroke. In a period T2 of a crank angle of 180 ° from the time when the # 1 cylinder reaches the top dead center until the # 3 cylinder reaches the top dead center, the # 3 cylinder is in the compression stroke and the # 1 cylinder is in the expansion stroke. In a period T3 of a crank angle of 180 ° from when the # 3 cylinder reaches the top dead center until the # 4 cylinder reaches the top dead center, the # 4 cylinder is in the compression stroke and the # 3 cylinder is in the expansion stroke. In a period T4 with a crank angle of 180 ° from when the # 4 cylinder reaches the top dead center until the # 2 cylinder reaches the top dead center, the # 2 cylinder is in the compression stroke and the # 4 cylinder is in the expansion stroke.

  During period T1, the positive load of the # 1 cylinder in the compression stroke (the load resisting the rotation of the starter motor 15) gradually increases, and the negative load of the # 2 cylinder in the expansion stroke (the rotation of the starter motor 15 is added). The total load increases from a negative value to a positive value. As a result, the rotation speed of the starter motor 15 increases in the first half of the period T1 in which the load is negative, and the rotation speed of the starter motor 15 decreases in the second half of the period T1 in which the load is positive. The number of rotations of the starter motor 15 increases → decreases with the period T1 as one cycle. Similarly, in the periods T2, T3, and T4, the rotation speed of the starter motor 15 increases → decreases with a crank angle of 180 ° as one cycle, and the rotation speed of the starter motor 15 is increased during one cycle in which the crankshaft 18 rotates twice. Will increase or decrease four times.

The change in the rotational speed while the starter motor 15 cranks the engine E is a combination of two components. That is, as shown in FIG. 4, the rotation speed of the starter motor 15, a component that increases substantially linearly with time from the start of cranking, the elapsed time from the start of cranking described in FIG. 3 Regardless of this, a component that increases or decreases with a crank angle of 180 ° as a cycle is added. Among them, the former component increases as the torque of the starter motor 15 increases, and the latter component decreases the torque of the starter motor 15. The amount of fluctuation increases. Therefore, based on the elapsed time since starting the starter motor 15 and the torque (duty value) of the starter motor 15, a change pattern of the number of revolutions in one cycle from the top dead center to a crank angle of 180 ° is predicted. Can do.

  Thus, when the main phase angle sensor 36B detects the top dead center, the change pattern of the rotational speed with respect to the rotational angle of the starter motor 15 is obtained by superimposing the predicted change pattern of the motor rotational speed in the next one cycle. Can be predicted. Here, the rotation angle of the starter motor 15 on the horizontal axis is obtained by converting the crank angle using the diameter ratio of the crank pulley 19 and the starter motor pulley 25.

  When the belt 28 slips with respect to the starter motor pulley 25 or the crank pulley 19, the rotational speed of the starter motor 15 increases at that moment. Therefore, in FIG. 5, the predicted value of the rotational speed change pattern in one cycle starting from the top dead center is compared with the actual value detected by the motor rotational speed sensor 26A, and the difference (or ratio) is equal to or greater than the threshold value. It is possible to detect that the belt 28 has slipped.

  Next, the effect | action of the said slip detection is demonstrated based on the flowchart of FIG.

  First, the starter motor 15 is started to start the engine E in step S1, and when the main phase angle sensor 36B detects the main phase angle (top dead center) in step S2, the motor rotation following the top dead center in step S3. A change pattern for one cycle of the number (crank angle 180 °) is predicted. In the next step S4, the actual rotational speed of the starter motor 15 is detected by the motor rotational speed sensor 36A. If the difference in the actual rotational speed with respect to the predicted rotational speed becomes greater than or equal to the threshold A% (10% in the embodiment) in step S5, the belt 28 is moved. It is determined that slip has occurred, and torque control of the starter motor 15 is executed in step S8 to suppress the slip.

  On the other hand, if the difference in the rotational speed is less than the threshold value A% in step S5 and the actual rotational speed of the starter motor 15 is 1100 rpm or less in step S6, the main phase angle sensor 36B detects the main phase angle (upper Steps S4 to S6 are repeated until a dead center) is detected, and if the main phase angle sensor 36B detects a main phase angle (top dead center) in step S7, steps S3 to S6 are repeated. If the actual rotational speed of the starter motor 15 exceeds 1100 rpm in step S6, it is determined that the engine E has entered a complete explosion state and the start-up has been completed, and the slip detection is terminated in step S9.

  Thus, the change pattern of one cycle of the predicted motor rotation speed is compared with the actual motor rotation speed detected by the motor rotation speed sensor 36A, and when the difference between both exceeds a predetermined threshold A%, the belt 28 is changed. Therefore, the slip generated in the belt 28 when the driven device whose load fluctuates periodically like the engine E is driven by the starter motor 15 can be accurately detected.

  Next, the content of the torque control of the starter motor 15 in step S8 in the flowchart of FIG. 6 will be described based on FIGS.

  If the slip of the belt 28 occurs when the engine E is started, control is performed to reduce the torque of the starter motor 15 in order to prevent the slip from becoming more intense. At this time, if the amount of torque reduction is excessive, the engine E cannot be cranked at a sufficient speed, so that the amount of torque reduction needs to be minimized.

  As shown in FIG. 7, when the duty ratio for driving the starter motor 15 is decreased from 100% to 0%, the torque does not decrease immediately, but slowly decreases according to the time constant inherent to the starter motor 15. To do. Specifically, when 10 msec elapses from when the duty ratio is set to 0%, the torque decreases 63.2%, and when 55 msec elapses, the torque decreases 100% and becomes zero. Thus, even if the duty ratio of the starter motor 15 is decreased, the torque does not decrease immediately. Therefore, it is necessary to control the torque of the starter motor 15 in consideration of this time delay.

In the flowchart of FIG. 10, when an excessive slip of the belt 28 is detected in step S11, the torque command value of the starter motor 15 is decreased by a predetermined amount (10% in the embodiment) in step S12, and the main phase angle ( If (top dead center) is not detected, it waits for 10 msec to pass in step S14. And if not negative acceleration of the motor speed in step S15, that is, if the slip progresses there still increasing state motor speed, by repeating the step S 12 ~S14, 10msec torque command value Decrease by 10% every time. As a result, if the acceleration of the motor rotation speed becomes negative and the slip is converged in step S15, the torque command value is corrected in the increasing direction by the response delay of the starter motor 15 in step S16.

  The broken line in FIG. 8 indicates the total torque reduction characteristic of the starter motor 15 when the control for decreasing the torque command value by 10% every 10 msec is performed three times in succession. Even when 30 msec elapses from the start of torque reduction control and the slip is resolved, the torque reduction further progresses due to the response delay of the starter motor 15, so an unnecessary increase in torque reduction after 30 msec elapses ( By canceling the shaded area, excessive torque reduction is prevented.

  As described above, the torque command value of the starter motor 15 is gradually reduced at 10 msec intervals until the slip of the belt 28 is eliminated (or until one cycle of the change in the rotation speed of the starter motor 15 is completed). Reduction can be prevented and the influence of the slip of the belt 28 on the cranking of the engine E can be minimized. Moreover, since the excessive torque reduction that occurs later than the torque reduction command is canceled due to the response delay of the starter motor 15, unnecessary torque reduction is performed even though the slip of the belt 28 is eliminated. Therefore, the engine E can be effectively cranked while minimizing the influence of torque reduction.

In step S17, the sub phase angle sensor 36C after key catcher Nseru surplus torque reduction to output a first auxiliary phase angle signal (signal to be output to the crank angle, every 30 °), based on the torque after reduction A new change pattern of the motor rotation speed is predicted, and the change pattern is connected to the first sub-phase angle signal in time. If 10 msec elapses in step S18 and the main phase angle (top dead center) is not detected in step S19, the difference between the actual rotational speed of the starter motor 15 and the new change pattern is compared with a threshold value in step S20. To do. As a result, if the difference in the actual rotational speed with respect to the change pattern is equal to or greater than the threshold value B% (10% in the embodiment), that is, if the slip of the belt 28 is still large, steps S12 to S19 are repeated. If the difference in the actual rotational speed with respect to the change pattern is equal to or less than the threshold value C% (3% in the embodiment), that is, if the slip of the belt 28 is sufficiently small, the torque command value is set to a predetermined amount (implemented in step S21 In the example, it is increased by 10%) and the process proceeds to step S18. If the difference in the actual rotational speed with respect to the change pattern is between the threshold value B% and the threshold value C%, that is, if the slip of the belt 28 is medium, steps S18 and S19 are repeated.

  When the main phase angle (top dead center) is detected in step S13 or step S19, the torque command value is returned to 100% in step S22, and the process proceeds to the slip detection process in the flowchart of FIG. 6 in step S23.

  In this way, after the slip of the belt 28 is once eliminated, the slip of the belt 28 is detected again by comparing the new rotational speed change pattern predicted based on the reduced torque with the actual rotational speed. It is also possible to cope with the case where the canceled slip recurs before the end of one cycle of the motor speed change.

  If the slip of the belt 28 is not detected again, the torque command value of the starter motor 15 motor is increased step by step at intervals of 10 msec until one cycle of the change in the motor rotation speed is completed. The engine E can be effectively cranked by increasing the torque of the starter motor 15 within a range in which the 28 slip does not recur and minimizing the influence of torque reduction.

  Although the embodiments of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.

  For example, although the engine E is illustrated as the driven device in the embodiment, the present invention can be applied to the prevention of slipping of a belt that drives any driven device other than the engine E whose load varies periodically.

Front view of car engine Illustration of engine main phase angle and sub phase angle Explanatory diagram of load fluctuation that occurs when cranking the engine Explanatory drawing of the method for obtaining the predicted value of the starter motor speed Explanatory diagram of the method for detecting belt slip Flow chart of slip detection process Graph showing the actual torque reduction rate when the torque command value is set to zero Graph showing actual torque reduction rate when torque reduction control is performed three times Explanatory drawing of the method to change the torque command value Torque control process flowchart

Explanation of symbols

15 Starter motor (motor)
19 Crank pulley (driven pulley)
25 Starter motor pulley (drive pulley)
28 Belt E Engine (driven equipment)

Claims (5)

For preventing slippage of the belt (28) wound around the driving pulley (25) provided in the motor (15) and the driven pulley (19) provided in the driven device (E) whose load fluctuates periodically. In the belt slip prevention method,
A first step of predicting a one-cycle change pattern of the rotational speed of the motor (15) that receives a periodic load from the driven device (E);
A second step of detecting the actual rotational speed of the motor (15);
A third step of comparing the predicted change pattern of the rotational speed with the detected rotational speed, and detecting a slip of the belt (28) when a difference or ratio between the two exceeds a predetermined threshold;
A fourth step of preventing slippage by reducing the torque of the motor (15) when slippage of the belt (28) is detected;
A method for preventing belt slipping.   In the fourth step, the torque command value of the motor (15) is gradually reduced at predetermined time intervals until the slip of the belt (28) is eliminated or until the one cycle is completed. Item 2. A method for preventing slipping of a belt according to Item 1.   In the fourth step, after the slip of the belt (28) is eliminated, excessive torque reduction that occurs later than the torque reduction command due to response delay of the motor (15) is canceled. Item 3. The belt slip prevention method according to Item 2.   In the fourth step, after the slip of the belt (28) is eliminated, the new rotational speed change pattern predicted based on the reduced torque is compared with the actual rotational speed, and the slip of the belt (28) is again performed. The belt slip prevention method according to claim 1, further comprising a fifth step of detecting. 6. The torque command value of the motor (15) is increased stepwise at predetermined time intervals until the end of the one cycle when the slip of the belt (28) is not detected in the fifth step. 4. A method for preventing slipping of a belt according to 4.

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