DK164992B - STEERING SYSTEM FOR A GEAR CHANGE IN A MOTOR VEHICLE - Google Patents

Description

in

DK 164992B

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a gear shift control system (also called an interchange) in a motor vehicle having a manually operated gear selector for producing manual gear shift control signals, with a device operable by transducers for sensing vehicle and operating parameters. and which device may produce automatic gearshift control signals, with gear shift means for changing the transmission depending on manual or automatic gearshift control signals, with an operating mode selector operable by the driver to select the current or automatic gearshift control mode, and with an operating mode such as , when the automatic mode of operation is selected, automatically switches to neutral position in the manual mode of operation, without affecting the mode of operation and without changing the gear when certain predetermined working conditions occur.

From French Patent Specification No. 2,448,077 a control system is known having a sensor which records the speed of rotation of an input shaft and an output shaft of the exchange 20 as well as a sensor responsive to the position of the accelerator pedal. The sensor signals are applied to a control circuit which switches the exchange depending on the sensor signals. Other automatic control systems are known from US-PS 4,208,925 and French Publication No. 2,375,508. The latter letter shows a switching device for automatic or manual control.

Furthermore, a gear group selection device for motor vehicle exchanges is known with at least two groups that can be switched according to the same wiring diagram (compare DE-A-2 752 568). In these known drives, a group drive ensures that the auxiliary drive belonging to the group can only be engaged when the thus selected exchange stage results in a running speed which does not contradict the actual running speed. The device is designed so that an inappropriate group choice is excluded.

This is achieved by means of comparator devices which respond to sensor signals when a first lower threshold of the driving speed is exceeded and when a second higher threshold is reached.

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z value is exceeded. In both cases, output signals are obtained which control a selector coupling such that either one or the other selectable group is released while the other group is kept locked.

5

Finally, EP-A-60 390 containing the features specified in the preamble of claim 1 discloses an automatic coupling device for the exchange in a multi-stage vehicle drive, where it is also possible to switch the drive manually at any time. . The known device has a hand-operated gear lever for manually switching the drive, e.g. in dangerous situations or if the automatic system fails. Furthermore, the device has a calculator for automatically controlling the gear change controls. The calculator works, for example. depending on information on engine load and vehicle speed. This calculator can disable the clutch automatic depending on the driving situation and can switch it back on in case the lower speed limit is exceeded. Furthermore, the calculator may prompt the driver for manual intervention in certain operating states instead of simply disabling the automatics immediately. Thus, the driver is not surprised by an automatic switching process.

Furthermore, the known device at the manually operated gearbox has a hand-operated switch, with which the clutch automatic e.g. in overtaking maneuvers or in mountain driving can be switched off completely. An additional automatic functioning switch comes into operation with sharp braking to disable the automatic in this situation as well. In relation to this prior art, the object of the invention is to provide a control system of the kind specified in the preamble of claim 1, further developed so that the driver is easier to operate the vehicle so that he can concentrate on other tasks and thereby increasing the coupling security.

This object is achieved by the features set forth in the characterizing part of claim 1. With this design of the control system 3, it is possible to maintain fully the coupling processes in an automatic control and by a manual control. Furthermore, with this control system it becomes possible that a switch in the manual operating mode occurs automatically when certain specified disturbing operating states occur. Furthermore, the operating mode selector device has a fault-switching sensing device which determines when the gearshifts in the drive actually switch as a function of the gearshift signals. A device produces an error signal depending on a predetermined number of failed gear shift attempts for the gear change device. A further device prevents the automatic generation of additional gear change signals after the occurrence of a predetermined number of failed attempts, so that the drive can then only be manually switched. The control system is provided with a computer and an engine speed dependent control algorithm which determines the automatic control of the drive. The control algorithm automatically switches the system to the manual mode.

The invention will now be described in more detail with reference to the drawing, in which: 1 shows a simplified diagram of a gear change with a control system according to the invention; FIG. 2 is a simplified block diagram of the components included in the control system of FIG. 1, FIG. 3 is a more detailed diagram of part of the control system; FIG. 4 is a circuit diagram of the order holding circuit of FIG. 3, FIG. 5 is a circuit diagram of the drive circuit of FIG. 3, 35 FIG. 6a-e flow diagrams of the main control algorithm of the control system of FIG. 1

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4 FIG. 7, 8a-c and 9a-b flow charts of subroutines in the program; 10 is a timing diagram of selected signals occurring 5 during operation of the control system of FIG. First

The vehicle exchange system 10 of FIG. 1, a hydraulically operated multistage exchange 12. An engine 14 drives the exchange 12 via a conventional clutch 16. A gear change 10 (or switching) is made by the shift valves 18, which are controlled by an interface mechanism 20, which includes a rotary valve 22, a conventional 4 -phased stepper motor 24 and a 4-bit gear encoder 26, all interconnected by gear links, which are connected to a gear bar 28 movable by the operator.

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The stepper motor 24 is driven by an exchange control unit 30 which receives input signals from the gear encoder 26 and from a magnetic sensor 32 which generates a motor speed signal by sensing the movement of the teeth on a timing gear (not shown) 20 on the motor 14.

The major electrical components of the present invention are shown in the block diagram of FIG. 2. The controller 30 includes a conventional microprocessor 40, e.g. an Intel 25 8048. An engine speed signal is applied to the microprocessor input P24 from the magnetic sensor 32 via a holding circuit (a latch) 42.

A "watch however" timer circuit 46 is coupled to the RESET input 30 of microprocessor 40 via a NOR port 61 and is coupled to an address decoder 34. The address decoder 34 is further connected to a BUS and microprocessor control lines to a command circuit circuit 50 and to holding circuits 44, 45, 51, 65 (latch).

An 8-bit counter 48 is connected to the 8-bit bus through the holding circuit 51 and is coupled to the NOR port 49 and to the microprocessor input P26. The output from NOR port 49 is coupled to a TRT input on microprocessor 40.

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5

Voltage from a battery 54 is matched by a power conditioner 53 which includes a reverse polarity diode not shown to protect the controller 30 from being incorrectly connected to the battery and a transient suppressor circuit to protect against voltage peaks above 40 volts. . The voltage supply 53 is coupled to a series auto / manual switch 56 and a neutral switch 58 and to a parallel connected parking switch 60, reverse gear 62 and gear encoder 26. The drive voltage is supplied to the stepper motor 24 via the voltage supply 53 and the switches 56 and 58. on four power circuits 52a-d supply power supply currents to the four-phase stepper motor 24 in response to control signals transmitted to the power circuits via the command circuit 50. The microprocessor input / output port 1 (5-bit) is coupled to the 15 command circuitry 50 and to the power circuits 52a. The gear wheel encoder 26 and switches 58, 60, 62 are connected to the BUS via the holding circuit 65. The holding circuits 44, 45, 51 65 are preferably Motorola MC14013 latches.

The switches 56 to 62 are preferably mounted in a suitable location in the vehicle cab. Preferably, the auto / manual switch 56 is mounted on the cover plate around the gear shaft (not shown). The neutral switch 58 is preferably mounted on the shift link in the gear lever quadrant not shown and is opened when gear lever 28 is in its neutral position. The reverse gear switch 62 is preferably mounted on the housing around the rotary valve 20, and the parking switch 60 is preferably mounted on the gear link in the gear lever quadrant. A gear display 64 preferably includes an LCD display and a serial-in / parallel-out register (not shown) which transmits data from the holding circuits 44, 45 to the LCD display. The gear display is not part of the present invention. Impulses applied to the INT input on microprocessor 40 trigger an interrupt routine, which will be described below with reference to Figures 35a · 9a and 9b.

The input / output ports P10-P13 of the microprocessor are shown in FIG. 3 connected to the command-holding circuit 50 and to each

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6 the four power circuits 52a-52d. The output ALE of microprocessor 40 outputs a 239 KHz clock signal to the command circuit 50 and to a conventional address decoder 34 for clock control of the system. The microprocessor port P17 generates signals for initiating a "command latch window" and generates a pulse width modulation interrupt signal to the NOR port 55.

The command holding circuit 50 is coupled to each of the power circuit 10 circuits 52a-d. Each power circuit is coupled to the battery voltage + V and to the four stages I-IV of the stepper motor 24. The battery voltage is also coupled to an impulse width modulator 57 which produces an impulse width modulated signal having a duty cycle inversely proportional to the magnitude of + V to 15 maintain a constant mean current on the phase motor phase windings regardless of changes in battery voltage + V. The output of the pulse width modulator 57 is transmitted to each of the power circuits 52a-d via NOR gate 55 only when the signal from microprocessor port P17 is low.

The NOR gate 61 and the inverter 63 provide signals to the command-holding circuit 50 and to the RESET terminal of the microprocessor 40, such that the power circuits outputs 9-12 of the command-holding circuit are low, whereby the voltage circuits 25 52a-d are interrupted when a 5 volt regulator-supplied voltage is applied. is low or when the "watchdog" timer circuit 46 has run out. Low voltage reset circuit 67 includes a voltage detector 8212 (not shown) coupled to a flip-flop which is not shown which can be reset so that the flip flop holds the microprocessor reset when the control voltage is low and for a predetermined period of time after it has returned to its normal level.

In FIG. 4, the command-holding circuit 50, which includes a Motorola MC14018 connected to four holding circuits 70 in the form of a "quad latch", receives the drive commands for the step motor from the microprocessor input / output ports P10.

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7 P13. The outputs of the quadruple holding circuit 70 are coupled to the respective inputs of the power circuits 52a-d. A NOR port 72 connects a microprocessor signal Bf? and a "latch command" signal from the address decoder 34 to the clock signal input C5 at the input of a "D-latch" 74, which is preferably one half of a Motorola MC14013. The microprocessor output ALE is coupled to the clock input of a number 76 that divides by four, preferably a Motorola MC14024. The microprocessor output P17 is coupled to the clock input of another "D-latch" 78, which is also preferably 1/2 the Motorola MC14013. The command circuit 50 further includes an OR gate 80 coupled to an inverter 63, the four holding circuits 70, the numerator 76, and the D holding circuits 74, 78 as shown. Finally, the command circuit 50 includes an inverter 82 which generates a "fly-15 back sense inhibit" saving signal from the Q output of the D-holding circuit 78.

The command-holding circuit 50 operates as follows: It is assumed that commands for operating the stepper motor are present on the microprocessor inputs / outputs P10-P13. The microprocessor 40 will then send a "window command" pulse to the D circuit 78, which switches the Q output of the D-latch 78 and the D input of the D-latch 74 to high, thereby opening a "window" . When a "latch strobe" pulse is then applied to the NOR gate 72, the Q output of the D latch 74 and the L input of the quad latch 70 change to high and the 25 quad latch 70 transmits the stepper motor drive commands to the respective power circuits 52a-52d.

Each of the power circuits 52a-d, shown in FIG. 5, includes an OR gate 90 with inputs coupled to the output of the NOR-30 gate 55 and a corresponding drive output 9-12 on the command-holding circuit 50. The output of the OR gate 90 is coupled to a conventional push-pulse power amplifier 92 The output of the push-pull amplifier 92 is coupled to a conventional Darlington power limiting circuit 94. The output of the drive circuit 94 is coupled to the corresponding of the stepper motor windings I-IV or phases as indicated by 100. Each power circuit 52a-d also includes a "fly-back" sensor circuit

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8 96, which draws the microprocessor inputs / outputs P10-P16 to ground when the phase motor phase windings are driven.

In operation, the stepper motor phase winding 100 will be continuously driven or pulsed depending on the pulse width modulated signal transmitted to the OR gate 90 via the NOR gate 55. When the Darlington drive circuit 94 interrupts, the inductive "fly-back" current will go through diode D1 and resistor Rj, thereby opening transistor T1 and charging capacitor C1. The voltage across Cl 10 will open the transistor T2 and thereby pull the microprocessor inputs / outputs P10-13 down onto the frame. Capacitor C1 and resistor R2 ensure that transistor T2 is continuously opened, rather than periodically opened when phase 100 of the motor receives pulses. The grounded state of the inputs / outputs P10-13 15 indicates to the microprocessor 40 that the phases of the stepper motor are applied correctly to voltage. After the motor windings gain voltage, a "fly-back sense inhibit" pulse will open the transistor T3, which cuts off transistor T2. This terminates the fly-back sensing and allows new stepper motor command signals to appear on microprocessor inputs / outputs P10-13.

The interchange control device 30 controls the interchange 12 according to a main control algorithm and subroutines performed by the microprocessor 40 illustrated by the flow charts of FIG. 6a-6e, 8a-8c and 9a and 9b.

The main algorithm 300 begins at step 304, after which all counters in step 306 are reset and the registers are started. Then, one enters a "read shift lever" subroutine 30 408, which is described in detail in connection with FIG. 7 via step 308. In this subroutine, the 8-bit and binary numbers of the BUS representing the position of the switches 56-62 are examined and the position of the gear selector bar 28 is formed. In step 310, a "non-valid" number is placed in an unregistered activation register (or arming register, "arm register") so that the shift algorithm 500 operation is prevented, unless steps 380 or 356 place valid numbers in the "arm" the registers "under certain

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9 specified conditions which will be described later. In step 312, the "watchdog timer" 46 is reset. If the loop or algorithm works properly, the "watchdog timer" 46 is always reset before it runs out. Step 314 5 passes the algorithm on to step 316 if the auto / manual switch 56 is in its manual position, otherwise the algorithm proceeds with step 320.

In step 316, the current gear stage of the exchange 10 12, as indicated by the encoder 26, is set as the top gear in a 4-speed "window" and the controller is not allowed to change the exchange 12 to a higher gear. Then, in step 318, a problem register is emptied, which will be explained in more detail below. The algorithm then returns to the previously described step 308. This portion of the algorithm comprises the algorithm steps used when the exchange 12 is under manual control due to the setting of the switch 16 in its manual position which disconnects the step motor 24 from the battery. 12th

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If the operator switches the auto / manual switch 56 to the auto position, a circuit between the battery 54 and the stepper motor 24 is terminated and the algorithm proceeds from step 314 to step 320 which will direct the algorithm back to step 308 and prevent 25 automatic gear changes if there is registered problem values in the problem register due to operations in steps 338, 374, 386 or 532, which will be described below.

Steps 308-320, along with steps 370 and 374, which will be described later, cause this control system to operate as follows: It is assumed that the control system is in its automatic mode of operation because the auto / manual switch 56 is in its auto position, and that the operator moves the gear lever 28. This movement will be detected and a "problem operation" will be set by steps 370 and 374 and the routine will enter the manual loop at step 310. The routine will remain in this manual loop for as long as auto / manual switch 56 does not change

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10, due to steps 374 and 320. To return to automatic operation, the operator must move the auto / manual switch 56 to its manual position so that step 314 directs the routine to step 318 to delete the problem operation set by step 374. When auto / manual switch 56 is returned to its auto position, steps 314 and 320 will allow the routine to exit the manual loop and return to automatic operation. This allows the operator to make a shift to a lower gear in the event of an emergency, to use the motor to brake 10 simply by moving the gear lever without colliding with the controller's automatic operation. It also prevents the control system from returning to its automatic operation unless the operator deliberately switches the auto / manual switch 56.

In step 322, a timer / counter not shown allows counting pulses to be counted so that the time intervals between gear changes can be measured. Then, an "old gear" value is set equal to the current gear value in step 324. In step 325, the current gear value is determined and engine speed values for ups and downs are determined for the gear in question as follows: It is assumed that the operating system is in its automatic mode of operation because the auto / manual switch 56 is in its auto position and the operator moves the gear lever 28. This movement will be detected and a "problem operation" will be set by steps 25 370 and 374 and the routine will go into the manual loop at step 310. The routine will remain in this manual loop as long as auto / manual switch 56 is not changed due to steps 374 and 320. To return to automatic operation, the operator must move Auto / manual switch 56 to its manual 30 position, so that step 314 directs the routine to step 318 to delete the problem operation set by step 374. When auto / manual switch 56 is returned to its auto position ing, steps 314 and 320 will allow the routine to exit the manual loop and return to automatic operation. This 35 allows the operator to make a shift to a lower gear in an emergency, to use the engine to brake simply by moving the gear lever without colliding with the control unit.

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11 automatic operation. It also prevents the control system from returning to its automatic operation unless the operator deliberately switches the auto / manual switch 56.

5 In step 322, a timer / counter not shown allows counting pulses to be counted so that the time intervals between gear changes can be measured. Then an "old gear" value is set equal to the current gear value in step 324. In step 325, the current gear value is determined and engine speed values for upshift and downshift are determined for that gear as follows:

For all gears, including the neutral, but with the exception of the eighth gear, the engine speed at upshift is 2206 rpm, while the downshift speed is 1896 rpm. For the eighth gear, the speed of shifting upwards is 2206 revolutions per minute, while the speed of shifting downwards is 1857 revolutions per minute. These values are given by way of example only, and it is clear that other engine speeds may be sufficient.

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The next step 326 (see Fig. 6b) directs the algorithm to step 310 if problem values are recorded in the problem register, otherwise the algorithm will proceed to step 328 where a shift timer is reset and started so that the time interval 25 between successive gear changes can be determined. In step 330, a non-valid value is placed again in the activation register just as in the previously described step 310. Thereafter, the program enters the subroutine "read gear bar" via step 332 and the position of gear bar 28 is again determined by gear encoder 26.

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Step 334 directs the algorithm to step 310 if the operator has requested manual operation via auto / manual switch 56 and otherwise the algorithm proceeds to step 340. If the reverse or parking switches 62 or 60 have changed position, step 340 will direct the algorithm to step 338 wherein the problem operation register is set to a value which will prevent automatic operation due to step 326, after which the algorithm reverses

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12 back to step 310 for manual operation. Otherwise, the algorithm will proceed to step 342 which also directs the algorithm to steps 338 and 310 if the exchange is outside a working range, which is preferably defined as gears 4-10, and otherwise the algorithm will proceed to step 344, see FIG. 6c, where the "watchdog timer" is reset as previously described in step 312. This workspace prevents the transmission during automatic operation from shifting to too high a gear.

If the old gear in step 346 is the same as the new gear, which would be the case if the gear bar 28 has not been moved or if the previous gear shift was completely completed and the signal from the gear encoder 26 has changed accordingly, then the algorithm then proceeds to step 348. Otherwise, the algorithm proceeds to step 370, which will be described later. In step 348, the current gear value is entered into the old gear register. In step 350, the shift routine is set to 40 steps per command, with 40 steps of the stepper motor being the number of steps needed to produce a change of one 20 gears by the stepper motor 24.

Then, a validity test is performed in step 354, directing the algorithm to 356 if a correct signal is generated by the magnetic motor speed sensor 32, and if the proper 25 signal is not generated, is directed to step 386 where a problem value is generated, and then returned to it. previously described step 310. This validity test can be performed by examining the count in an overflow register not shown which counts the number of times over which the engine speed counter 48 flies. In step 356, a "reinforcement code" or "password" is placed in the activation register (arm register) so that a switching subroutine can be performed, as will be described later.

35 Step 358 compares the engine rpm as sensed by sensor 32 with the speed at which the current gear is to be shifted upward as set

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13 in a table also used in the previous step 325. If the engine speed is not higher than the upward shift rate set in step 325, the algorithm is routed to step 388, otherwise the algorithm continues to step 360. wherein a claim for a delay of e.g. 4 seconds at an overspeed, determined. Step 362 then directs the algorithm back to step 330, thus preventing an upward shift unless this 4 second delay period has expired. Thus, it is not possible to switch upwards, 10 unless the state of excessive speed has lasted for at least 4 seconds. Steps 364 and 366 prevent shifting upwards by allowing the algorithm to return to 328 if the current gear is the same as the top gear in the window defined in step 16, or if the current gear is outside the 15 previously described. workspace on e.g. from 4th to 10th gear. If none of these conditions are met, the algorithm will proceed to step 402 where the shift direction is set to an upward shift. After step 402, the program enters a switch routine via step 406. After the switch routine is executed, the algorithm returns to step 326. The switch routine will be described later in detail and with reference to FIG. 8a-8c. Briefly, the shift subroutine generates commands which, via the command circuit 50 and the power circuits 52, rotate the stepper motor 24 and the pilot valve 22 to cause the shift valve 18 to shift the exchange 12 to the next suitable gear.

If the old gear in step 346, FIG. 6c, not the same as the new gear, the algorithm proceeds to step 370. In step 30 370, the algorithm directs to step 372, if the new gear is the same as the gear in which the exchange was prior to the last gear change, in in which case it can be assumed that a shift has been attempted but has not been possible. Otherwise, step 370 directs the algorithm to step 374, in which case it can be assumed that gear lever 28 has been moved by the operator. In the event that a gear change has been attempted but not completed, step 372

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14, the richer algorithm for step 376, unless it is the 10th attempt to change the new gear, and then the algorithm is routed to step 374. Step 374 generates an error problem value and returns the algorithm to step 310. That is, step 370- 374 5 returns the algorithm to step 310 for manual control if the gear bar 28 has been moved by the operator, if the gear encoder 26 has failed or if a shift has been unsuccessfully attempted ten consecutive times.

20 Step 376 sets the switching routine to four step motor steps per command, so that 40 steps will be ordered by 10 reviews through this part of the algorithm. Then, in step 380, an activation code, also called "arming code" or "password", is placed in the activation register "arm register" so that the shift algorithm 500 can be executed as described later. Step 382 directs the algorithm to step 402 which sets the direction of a shift upwards , or to step 404, which sets the direction for a downward shift, and then to the shift algorithm via step 406, so that that shift up or down 20o is retried.

In step 358, see FIG. 6d, the algorithm may have been routed to step 388 because the engine speed is not higher than the relevant speed of an upward shift, as set out in a table, after which the engine speed is compared to 1500 rpm. in step 388. If the engine speed is less than 1500 rpm, as might be the case if the engine was stalling, the algorithm proceeds to step 374 where a sub-speed delay requirement is introduced of 0.5 seconds, after which the algorithm proceeds to step 396. If the engine speed is not less than the downshift speed, it is not necessary to switch and the algorithm returns to step 328. If the engine speed is lower than the speed of downward shift, the algorithm will proceed to step 392, where a sub-speed delay requirement is set to 1.0 second, and then the algorithm proceeds to step 396.

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Step 396 redirects the algorithm back to step 330 if the delay required in step 392 or 394 has not expired. Otherwise, the algorithm will proceed to step 398. Step 398 redirects the algorithm back to step 328 if the current 5 or current gear is the same as the lower gear (three gears under the top gear) in the window set in step 316. Otherwise, it continues the algorithm to step 400. Step 400 also directs the algorithm to step 328 if the running gear is the same as the lower gear in the previously described working range of the gears. Otherwise, the algorithm proceeds to step 404, where the shift direction is set to a downward shift. From step 404 as well as from step 402, the algorithm enters the switching routine via step 406, after which the algorithm returns to step 326.

The subroutine 408 called "read shift level" which is entered via steps 308 and 332 of the main algorithm 300 will be further described with reference to FIG. 7. This subroutine 408 is entered at step 410, after which the 8 bits of the BUS port of the computer 40 are read in step 412. This includes the 4-bit 20 code signals (a so-called gray code) representing the state of the gear encoder 26 Then, step 414 directs the subroutine back to step 412, unless there has been no change in the last five readings of the gear encoder 26. In step 416, the gray code number representing the position of gear in the encoder 26 is converted to a binary number. Step 418 terminates the subroutine and returns to the main algorithm 300 for performing steps 310 or 334. In this way, the status of the gear encoder 26 will be re-examined prior to any manual or automatic shift, and each time the main algorithm 300 is executed.

The switching subroutine 500, which is entered via step 406 from the main algorithm 300, will be described below with reference to FIG. 8a-8c. First, step 508 triggers a "fly-back" count, so that the controller can count the number of consecutive times that a stepper motor drive circuit has been activated, without an indication from the fly-back sensing

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16 circuit 96 that it has been turned on. A loop counter also contains a value representing the number of stepper motor stages established either at step 350 or 372 in the main algorithm 300.

5 In step 510, a register is set to an appropriate initial value so that the stepper motor 24 will be supplied with voltage in a conventional two-phase manner. In addition, an "ignore machine register" is created so that the controller will ignore fly-back signals from the last energy-supplied step motor drive circuits.

Then, in step 512, the interrupt inputs will be blocked to prevent unwanted interruptions in the switch subroutine due to the interrupt routine as described later.

In step 514, the window strobe signal appearing on a port P17 of the microcomputer 40 and applied to pins 17 on the command circuit circuit 50 switches to the logic value 1 as indicated at 650 in the signal diagram of FIG. 10. This causes the Q output 20 of the D-latch 78 to be high, see 652, thereby opening a time window in which signals can be passed through the four-fold latch circuit 70 to the driving circuits 52a-d. .

Step 516 asks if the switching routine has been activated or not activated at steps 310, 330, 356 or 380 in the main loop. If it has not been activated, step 516 will repeatedly cause a receding loop, and optionally the watch-dog timer will run out and the algorithm will be switched back by the hardwa to the beginning of the main loop 300.

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If the switching routine has been activated, the routine will proceed to step 518, after which a "latch strobe" pulse is produced as shown at 654 in FIG. 10, and the impulse is applied to the latch strobe input pin 5 of the command-holding circuit 50. This causes the quadruple latch 70 of the command-holding circuit 50 to receive and transmit drive command signals from the micro-ports P10-13 to the stepper motor circuits 52a-d. During

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During this time, the window strobe signal remains a logic 1, so that the selected drive circuit 52a-d will supply in a constant unmodulated manner sufficient drive current to change the position of the stepper motor 24.

5

After 518, the program enters a pause subroutine at step 520. The pause subroutine causes the window strobe signal to return to a logical 0 at 656 in FIG. 10, which may occur at a given time, e.g. 3.18 milliseconds, after generating the latch strobe signal. When the window strap signal becomes low, the output of the NOR gate 55 is modulated as shown at 658 in FIG. 10 of the pulse width modulator 57. The current driving the stepper motor 24 is thus modulated to reduce power consumption. The pause subroutine continues for another 2.4 milliseconds and then returns to step 522, after which the signal on the fly-back sensor line 18 in the power circuit 52-d; 5, examined. If fly-back is present, transistor T2 will draw current and a logic 0 will be present on the fly-back sensor line. If no fly-back 20 is present, this is an indication that an error has occurred, such as an open or short circuit in the stepper motor, or in the wiring to the power circuits. An error condition is also indicated when the drive circuits are disconnected but fly-back is present. In this case, the routine proceeds to step 526, which returns the routine to 512, unless it is the 30th fly-back observed in step 522. Otherwise, the crude continues to step 532 which gives an indication of a problem state and then goes to 536.

If a fly-back error 1 is not present, the routine will proceed from step 522 to steps 524-530 which rotate the stepper motor through its operating pattern depending on whether a shift or downshift is to be made. Step 534 directs the routine back to step 512 if the stepper motor 24 has stepped sufficiently (4-40 times) to complete a gear change. Otherwise, the routine proceeds to step 536, where the interrupts are again blocked as in the previously described step 512.

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18 In steps 538-540, the procedure for steps 514 and 518 is repeated, but with drive commands for the micro output ports P10-P13, so that all drive circuits 52a-d are interrupted. In step 542, interrupts are enabled again.

5 In steps 544-548, the old gear value decreases or increases depending on whether the shift direction is down or up. When the switch routine is disabled in step 550 and step 552, it returns to the main algorithm 300.

i n i u

The main algorithm shown in FIG. 6a-6e can be interrupted and an interrupt routine 600 shown in Figs. 9a-9b is executed whenever an interrupt signal is applied to interrupt port INT on microprocessor 40. Interrupt routine 600 is initiated at step 601 whenever a pulse from the magnetic machine speed sensor 32 or at any time an overflow impulse from counter 48 is received by NOR gate 900. Step 602 then redirects the algorithm to step 604 unless all interrupts have been deleted, then step 624 causes a return 20 to the main loop to the point where it was interrupted.

If the "interrupt" was due to an impulse from the magnetic speed sensor 32, step 604 redirects the algorithm to steps 612-613, where counter 48 is stopped and read, interrupt register and counter 48 are deleted, and counter 48 is restarted. If counter 48 overflows, step 618 will direct the algorithm to step 622. If counter 48 does not overflow, a new count value is calculated as a weighted average of the new and old counter value with a weight ratio of 1-7 (new to 30 old). In step 622, the register which counts overflow in counter 48 is deleted and the algorithm returns to step 602.

If the magnetic pick-up 32 was not the source of the interrupt, step 604 directs the algorithm to step 606. Step 35 606 directs the algorithm to step 610 if the counter 48 is not stopped, otherwise the algorithm will continue to 608 where it is examined. , whether there is overflow in the counter 48. If there is not

Claims (3)

1. A gear shift control system (also called an exchange) in a motor vehicle with a manually operated gear selector (28) for producing manual gear shift control signals, with a device (30, 34) operable by transducers (32) to 30 sensors of vehicle and operating parameters, and which device can produce automatic gearshift control signals, with gearshift means (18, 22) for changing the gearing depending on manual or automatic gearshift control signals, with a driver-selectable mode of operation for selection 35 of the manual or automatic steering mode of the gearshift, and with an operating mode circuit which, when the automatic mode of operation is selected, automatically switches to neutral position in the manual mode of operation, without affecting the operating mode selector (56) and without changing the gearbox when certain predetermined working conditions occur, characterized in that the operating mode circuit comprises a sensor Device for fault clutches which monitor the changes of the gear change means (18, 22) for the gear shift (12) depending on the gear shift control signals, and which produce an error signal (step 372) depending on a predetermined number of failed attempts (failure attempts) of the gearshift means 10 depending on the gearshift control signals which trigger the automatic switching to manual mode of operation as well as a device which (steps 320-320) prevents the automatic generation of additional gearshift control signals after the occurrence of the predetermined number of failure attempts, in such a way that gearshifts -15 (12) can then only be changed manually. Control system according to claim 1, characterized in that the sensor coupling device comprises an exchange ratio sensor (26) for sensing the exchange step and for generating a corresponding exchange step signal, and a device for storing a first exchange step signal corresponding to it. in fact, the exchange ratio of the exchange measured before the generation of a gear change signal via the control circuit, a device for storing another exchange step signal corresponding to the actual measured ratio of the exchange after the generation of the gear shift signal via the control circuit, as a device (370) for comparing both exchange signals and for generating an error signal (374) when the second exchange step signal is the same as the first exchange step signal, even after generating a predetermined number of shift signals. Control system according to claim 1 or 2, characterized in that the device (30, 34) for generating automatic gear shift test steering signals comprises a device (358, 390) for comparing the motor speed determined by the transducer (32). ) with predetermined engine speed values which trigger a gear shift either up or down and a device (403, 404) is provided which generates automatic gear shift control signals which cause the gear shift means (18, 20) to switch the gear to hold the engine speed within a certain range. 10 15 20 25 30 35