JPH0154212B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a control circuit for an automobile drive system, particularly to a control circuit for an automobile drive system.
This invention relates to a control circuit that can be applied to automobiles that have a differential mechanism that divides torque between two output shafts. BACKGROUND OF THE INVENTION Various mechanisms for controlling excess slip between the drive wheels of a motor vehicle have been considered in the automobile and truck industry. Such devices typically equalize the rotational speeds of two or more output shafts driven by a main drive or input shaft. The drive shaft is especially referred to as the output drive shaft because it is used to drive the wheels of the vehicle directly or via intermediate mechanical links. These speed differences between the axles are necessary to provide different rotational speeds to the drive shafts when turning the vehicle over bumps, potholes, or across rough terrain. Most typically, the output drive shafts are connected to the main drive shaft or propulsion shaft by a differential mechanism, which divides torque evenly between the output drive shafts to give the output drive shafts different rotational speeds. provide. In the truck industry, multi-axle tandem drive assemblies are commonly used in the truck industry using an intermediate axle to connect the main propulsion shaft from the engine to a differential on each of the two rear drive axles, hereinafter referred to as the front and rear drive axles. It is also advantageous to provide Under normal operating conditions, when the vehicle is traveling on good roads in dry weather, there will normally be no excess slip between the output drive shafts and no corrective action will be required. However, when the car is driving through mud or ice in adverse weather conditions, one wheel loses traction and begins to spin excessively, resulting in an abnormal amount of slippage, henceforth referred to as a "slip condition." call. Therefore, it is advantageous to provide a lockout mechanism or other control device to eliminate any additional differences in the rotational speed of the differential output shaft. Mechanical lockout mechanisms that couple the main drive shaft to the output shaft of a differential are used in the truck industry, examples of which are U.S. Pat.
It is disclosed in No. 3390593. Mechanical locking devices have also been used in intermediate axle differentials of tandem drive vehicles, as shown in U.S. Pat. No. 2,870,853. A ratio sensing electronic controller for a limited slip differential is disclosed in US Pat. No. 3,138,970. An electromechanical system using a selective brake controller to limit the speed difference between a pair of wheels is patented in U.S. Patent No.
Disclosed in No. 3706351. Generally, in a differential mechanism, all three axes are locked by locking two axes in a group of three axes consisting of an input drive shaft and two output drive axes, resulting in a "differential" function. is resolved. The term "lockout,""lockedcondition," or "locked condition" refers to a situation in which the differential mechanism connecting the main drive shaft to the two output shafts is deactivated, so that both output shafts rotate at the same speed and the engine The output torque is a state in which the external resistance that each output shaft receives is supplied to both required output shafts. Lockout is typically accomplished manually by the driver sensing a slip condition, or by automatic control as shown in the aforementioned U.S. Pat. No. 3,138,970. Slip control can also be achieved by means other than locking out the vehicle's differential;
The brake control system of US Pat. No. 3,706,351 provides another solution to the problem. It is thus possible to provide an electronic circuit for controlling the device which eliminates or at least reduces the amount of slip within acceptable limits. SUMMARY OF THE INVENTION Electronic controls typically provide continuous supervisory control in response to sensed input speed signals. Such a continuous monitoring system is subject to repeated cycling of the controller so long as the output shaft speeds attempt to synchronize almost immediately after lockout, the error signal disappears before the vehicle actually exits the slip condition. The electronic controller continues to monitor the output shaft speed, and if the locking device is released and the vehicle is not out of the initial slip condition, the error signal is regenerated and the control locking device is reactivated. Oscillations within drive systems typically occur at relatively high frequencies between 1 and 3 Hz. Such oscillations can have an adverse effect on the vehicle by repeatedly stressing the drive train elements and can be harmful to the driver, especially if the control system continues to recycle and the vehicle is unable to traverse the section of road that is causing the "slip" condition. Sometimes I feel hesitant. SUMMARY OF THE INVENTION It is an object of the present invention to overcome the drawbacks of the prior art by providing a slip control device that remains "locked" for a predetermined period of time without being affected by high speed cycling. That's true. Another object of the present invention is to provide a control system which is particularly useful in differential linkage systems and which provides a fixed locking time interval after an excessive difference in output speed is detected. Typical fixed locking time intervals are greater than 20 seconds and can be several minutes depending on the type of vehicle and its application. It is also an object of the present invention to provide a fail-safe indication circuit for the slip controller to ensure deactivation of the lockout controller if a true locked condition is not sensed after a predetermined time interval. By using a fail-safe circuit, the operation of the mechanical locking device and sensor function can be verified. It is also an object of the present invention to provide a slip control lockout system that includes a brake override circuit that inhibits lockout commands during braking of a motor vehicle. In accordance with the principles of the present invention, an apparatus is provided for use in a motor vehicle having a main drive shaft and first and second output shafts operative to provide drive torque to the wheels.
This device includes a device that detects a slip state by sensing the relative rotational speed of the first and second output shafts, and a device that is activated in response to the sensing device to eliminate an excessive slip speed difference between the output shafts. It has a control device. In one embodiment, a control device is actuated within the differential mechanism and responsive to the sensing device to lock two of said shaft groups to rotate at the same speed. The control device operates for a predetermined time after activation. The present invention includes a fork and yoke assembly that slidingly engages a clutch collar to lock the main input shaft of an intermediate axle differential and one output shaft of the intermediate axle differential, or to lock both output shafts together. It is particularly applicable to tandem drive vehicles using intermediate axle differentials. FIG. 1 is a block diagram illustrating a slip control circuit according to the present invention. A controller, generally designated 10, is connected to receive electrical signals from two sensors (not shown) that detect the rotational speed of two of the output drive shafts. Typically a first sensor may be arranged to detect the rotational speed of the main drive (input) shaft at the input to the differential, and a second sensor may be arranged to detect the rotational speed of the output shaft from the differential. It can be arranged to detect speed. The sensor itself can be of any conventional design, such as a gear fixed to the drive shaft or a magnetic sensor that provides an output pulse as it passes each tooth of a rotor. In this case, the frequency of the input signal is proportional to the rotational speed of the shaft. The sensed signals W ₁ , W ₂ are input line 1
1 and 12 to a differential circuit 14 which measures the difference between the two signal frequencies. Differential circuit 14 typically includes a comparator (COMP) that compares the difference between the absolute values of two input signals, where the absolute value is proportional to each input frequency with a reference value. The reference value can be generated by adding the two input signals and multiplying by a reference value appropriate to the type of comparator used (eg 0.05). Thus, differential circuit 14 can provide an output signal along line 15 only if the difference in rotating shaft speed is greater than a predetermined allowable slip value. Depending on the normal operating conditions of the motor vehicle, certain slips can obviously be tolerated, for example driving during turns or along rough terrain, and different tire diameters can be accommodated. The output signal along line 15 may be referred to as an error signal or DIFF signal indicative of an excessive difference in rotational speed of the shafts. The DIFF signal is supplied to two timers T1 and T3 shown at 16 and 18. Timer T1 is
The output pulses are delivered after a nominal turn-on delay on the order of 0.25 to 0.5 seconds and are delivered to minimize "false" start-ups in the presence of initial wheel slip. After this turn-on delay, the output of timer T116 is
It is fed to the setting input of RS flip-flop 19 and provides an output pulse to its Q output. The output pulses are provided via line 20 to a power amplifier 21 which drives a control device or solenoid 22. The controller 22 is used to activate a device that eliminates slip conditions detected by sensor inputs.
A solenoid employed as control device 22 is used to shift the clutch collar and place the differential in a "locked" condition. Such applications will be described in detail later. Controller 22 may be used in conjunction with a selective brake control system similar to that disclosed in U.S. Pat. No. 3,706,351, or in four-wheel drive vehicles of the type disclosed in U.S. Pat. The combination can supply drive torque to the front drive axle of such a vehicle. The drive signal from the power amplifier 21 is also supplied to a timer T2 shown at 23. Timer T2 is a basic cycle timer that provides a predetermined time interval, typically 30 to 60 seconds, during which controller 22 remains activated. At the end of this predetermined time interval T2 is
The output signal is supplied to the OR circuit 24, and the OR circuit 24
provides an output to the reset terminal of flip-flop 19. When reset, flip-flop 1
The Q output of 9 goes low, disengaging controller 22. Since the output of timer 18 is also provided to the input or OR circuit 24, the reset of flip-flop 19 also occurs after the expiration of timer T3, the fail-safe timer. Fail safe timer T3
is typically larger than the time interval T1
Set to less than 2. The purpose of the failsafe timer is to disarm controller 22 if the slip condition is not cleared after time interval T3. For example, time interval T2 can be set to 30 seconds and time interval T3 can be set to 15 seconds. 15
If the DIFF signal is still present on line 15 at the end of the second, failsafe timer T3 resets flip-flop 19 and disarms controller 22. The failsafe timer operates under the assumption that the previously sensed slip condition has resolved after time interval T3 and the DIFF signal along line 15 is no longer present. If the DIFF signal is still present, it is assumed that some kind of failure has occurred, such as a sensor failure or lockout mechanism failure. In either case, it is desirable to release the control device and provide an indication of the fail-safe condition to the operator. The time interval T3 can be set anywhere within the range defined by T1 and T2. For example, the time interval T2 can be 30.5 seconds and the timer T3 can be set to 30.0 seconds. Due to this condition, timer T
3, a very narrow window (30.0 to 30.5 seconds) is possible, and spurious noise due to severe gear vibration etc.
Can be used to eliminate detection of DIFF signals. (Embodiment) An example in which an embodiment of the present invention is used in an intermediate axle differential mechanism of a tandem drive vehicle is shown in FIGS. 2 to 5. FIG. 2 is a plan view of the truck cab 20 and carrier 22. The carrier 22 is supported by a tandem drive gear having a rear front axle 24 and a rear rear axle 26. Torque from the automobile engine is transmitted by a main drive or propulsion shaft 30 to an intermediate axle differential 32 supported within a housing 31, which transmits the torque to a rear-front differential 34 and a rear-rear differential 36. To divide. The propulsion shaft 30 is connected to an intermediate axle differential input 38 by a universal joint 40. Intermediate axle differential 32 divides the torque provided to input 38 between a first output shaft 42 and a second output shaft 44 . In FIG. 3, the output shaft 42 is the differential mechanism 3.
2, the output shaft 44 is driven by a series of "drop" gears 45-47 which in turn are driven by the right gear of the differential 32. The output shaft 44 rotates a pinion gear, which drives the ring gear of the rear-front differential mechanism 34. The output shaft 42 is connected by a universal joint 48 to the propulsion shaft 50, which in turn drives the ring gear of the rear differential 36. A collar 52 is keyed to the output shaft 42. Collar 52 is movable axially relative to shaft 42 by a fork (not shown) and is
As shown in the figure, it moves to the left and engages with the teeth 54 provided on the front side of the drop gear 45. color 52
When the drop gear 45 and the output shaft 42 engage with the teeth 54, the drop gear 45 and the output shaft 42 are mechanically locked to each other and rotate at the same speed. The differential mechanism 32 has a collar 52 with teeth 54.
It will not change from the same speed division until it is disengaged. A typical tandem axle assembly including an intermediate axle differential and lockout mechanism is disclosed in U.S. Pat.
No. 2870853 and Rotwell, published by Rotwell International, Troy, Michigan.
SFHD, STHD, SUHD parts collection SP-7646-1
No. They are shown here for reference. The two sensors 56 and 58 are held by the differential box 31. The sensor 58 senses the rotational speed of the output shaft 42 in response to the rotational movement of the teeth of the gear 45. The sensor 56 senses the rotational speed of the main drive shaft 30 in response to the rotational movement of the toothed rotor 60 held by the case of the differential mechanism 32. sensor 5
6, 58 supply output signals along lines 62, 64 to a control device controller 66 located on the housing 31 of the intermediate axle differential 32. input signal line 62,
Upon sensing the speed difference in response to a signal along line 64, controller 66 provides an output signal along line 68 to pneumatic solenoid valve 71, which operates in the normal manner to move collar 52 and displace the intermediate axle. Lock out the differential mechanism 32. When a lockout condition begins, the controller 66 provides a signal to an indicator light 72 visible to the driver of the motor vehicle. Control unit 66 is powered by the brake light circuit and includes a device for disabling the lockout mechanism upon application of the vehicle brakes. A battery indicated at 74 in FIG. 2 is connected to a stop light switch 76 which closes in response to the actuation of a foot valve 78. The interconnection between the control device 66 and the brake light circuit makes it possible to detect an open track condition.
In this case, an open brake circuit is detected by the control device 66, which deactivates the lockout operation. FIG. 4 is a block diagram showing the main elements of control device 66. Input signals from sensors 56, 58 are routed along input lines 62, 64 to respective signal shaping circuits 80, 8.
2. Signal shaping circuits 80, 82 convert the sinusoidal input signals to square waves and provide them along lines 84, 86 to gated trigger circuits 88, 90. Gated trigger circuits 88, 90 are alternately gated by an oscillator 92 to provide pulses along output lines 94 or 96. line 94,9
6 is connected to the input of an OR circuit 98, the output of which is connected via line 102 to an up/down counter 100. The signals along line 102 represent velocity pulses from one or the other sensor, the pulse frequency being directly proportional to the rotational speed of shafts 30, 42 as measured by sensors 56, 58. Oscillator 92 provides a signal along line 104 to up-down counter 100 so that line 10
2 can be associated as coming from gated trigger circuits 88 or 90. One gated trigger circuit is used to provide an up count to up/down counter 100 and the other gated trigger circuit provides a down count. The signal along line 104 from oscillator 92 is output to counter 10 depending on which particular signal sensor is being counted.
0 operation in “up” mode or “down”
mode. Up/down counter 100 is preset to a binary value of 4, for example.
The countdown of up/down counter 100 indicates that one sensor, such as sensor 56, is providing more signal per unit time than the other sensor, such as sensor 58. The up/down counter 100 counts up indicating the opposite condition. The count up and count down time windows are generated by an oscillator 110 and a sample window generator 1.
12. A typical window time interval may be on the order of 200 mS. Up/down counter 100 is preset to a binary value of 4. When zero count is reached within the sampling time window, an output signal DIFF is provided along line 114 to the output of up/down counter 100. Similarly, if the up/down counter 100 reaches binary 8 within the sampling time window,
A DIFF signal is also generated along line 114.
DIFF output signal is lock flip-flop (F/F)1
16 and one input of a NAND circuit 118. DIFF signal is a lock flip-flop 11
6 and provides a signal along its Q output to drive circuit 120 along line 122. The output of the drive circuit 120 drives the collar 52 of the intermediate axle differential mechanism, which is supplied to the solenoid 71, to drive the collar 52 of the intermediate axle differential mechanism.
Lock out 2. Drive circuit 120 provides a visual indication to the vehicle operator by energizing indicator light 72 . The lock flip-flop 116 is connected to the counter 12.
When the preset time has elapsed in 4, the counter 1
It is reset by receiving a reset pulse from 24, and is activated when the DIFF signal is generated. The counter is thus enabled and begins counting upon receiving the count enable signal from lock flip-flop 116 along line 123. The reset signal from counter 124 is provided to lock flip-flop 116 along line 128. In the example embodiment, the reset signal along line 128 is line 1.
14 occurs 435 seconds after the DIFF signal occurs. Of course, the control circuit can be modified to provide different fixed time intervals of duration, preferably greater than approximately 20 seconds, for other embodiments of the invention. The second output of counter 124 is coupled to the second output of NAND circuit 118 along line 130.
supplied to the input. This second output corresponds to fail-safe timer T3 in FIG. Again, the count enable signal along line 126 is used to provide a count start reference for enable counter 124. The output of NAND circuit 118 is applied to line 1 at the same time as the output of counter 124 provides a signal on line 130.
The presence of the DIFF signal along line 14 is used to set failsafe flip-flop 136. This condition requires the presence of the DIFF signal at time T3 using the terminology of FIG. Setting failsafe timer 136 provides a signal along line 138 to drive circuit 140 to energize failsafe indicator 144.
The output of the failsafe F/F 136 to the up/down counter 100 along line 125 immediately shuts off the controller and the drive circuit 120 is no longer activated. 5A and 5B are circuit diagrams showing details of the block diagram of FIG. 4. signal shaping circuit 80,
82 are the same, so only one circuit will be explained. The signal shaping circuit 80 includes a voltage comparator 180,
Zener diode D1 and resistor R1, C1
5, R2, C16, and C4. Resistors R5 and R9 form a voltage divider to provide a reference voltage to one input of voltage comparator 180 and the signal from the sensor to the other input.
A conventional sensor of the variable reluctance magnetic pickup type can be used, which is fitted with a shaping circuit 80.
Supply a sine wave input to the The output of comparator 180 is a square wave and is provided to gated trigger circuit 88. For purposes of illustration, the output of voltage comparator 180 is provided directly to the input of a gated trigger circuit 88 between which three NAND circuits (elements 380, 380,
382, 384) will be explained next. Gated trigger circuit 88 includes a D flip-flop 190 that is set upon receiving the output signal from voltage comparator 180 and responsively provides a high logic signal at its output. The Q output of flip-flop 190 is supplied to one input of a 4-input AND circuit 192, and the other three inputs are supplied with counter outputs, which will be described later. Gated trigger circuit 88 further includes a buffer/inverter driver 194 and supplies a logic NAND circuit 196. The output of NAND circuit 196 is a positive pulse approximately 20 μS wide and is provided to output line 94 from gated trigger circuit 88 . A similar 20 μS pulse is provided along output line 96 of gated trigger circuit 90. Lines 94 and 96 were fed to an OR circuit 99, which was connected to an inverter 202.
It is formed from a NOR circuit 200. OR circuit 9
The output of 9 is fed to an up/down counter 100, which may be of the presettable binary type, for example. Oscillator 92 may include a sampling oscillator 210 connected to a 4-bit binary counter 212. The counter 212 has lines 214a, 214
b, 214c. Output lines 214a-214c each provide a binary code designated A, . The A,,C codes provide status code inputs to the AND circuit 192 of gated trigger circuit 88. Similarly, status code A,
B, corresponds to the gated trigger circuit 90.
Supply input to AND circuit. Different status codes are gated at a given time by trigger circuits 88,9
Ensures that only one of the zeros is triggered. Oscillator 210 may typically be a 40 KHz oscillator, and the sampling rate provided by the 4-bit counter to each gated trigger circuit 88, 90 may typically be on the order of 5 KHz. Except the sensor speed is in the range of 0-1KHz.
The sampling time is chosen longer than the fastest one. Four-bit binary counter 212 provides an output along line 104 to the up/down control input of up/down counter 100. The up/down counter 100 thus counts up or down depending on the state of the control input along line 104, which is triggered by the gated trigger circuit 8.
The state changes successively from one state to the other in synchronization with the gating of 8 and 90. Oscillator 110 and sample window generator 112 are also shown in FIG. 5A. The oscillator 110
A pulse with a period of 13.3 mS is applied to its output terminal. This pulse is provided along line 220 to sample window generator 112. Sample generator 112 has a divider circuit that divides the input signal by 16 and produces a nominal 200 mS output signal along line 222.
It is supplied to the input of the NAND circuit 224. The other input of NAND circuit 224 is adjusted by the output of NAND circuit 226. The output signal of NAND circuit 224 is provided to up/down counter 100, presetting the counter to binary 4 every 200 mS. Up/down counter 100 thus has a window in which it receives velocity pulses along line 102 for a period of 200 mS before being reset to the preset binary 4. During this 200mS window period, the up/down counter 100 is
Depending on the difference in pulse frequency from 2 and 64, it counts down to 0 value or counts up to 8 value. AND from the up/down counter 100 along line 230 when the binary 8 count is reached.
An output pulse is provided to one input of circuit 232.
When it reaches 0 count, up/down counter 1
00 output along line 234 to inverter 236
is supplied to the second input of the AND circuit 232 via. The output of AND circuit 232 is connected to NOR circuit 238, which provides an output DIFF signal along line 114. Each time the output of the up/down counter 100 reaches a binary count of 8 or a binary count of 0, the DIFF signal goes high (logic 1).
Displays a significant difference in the rotational speed of the two measuring axes.
Hereinafter, FIG. 5B will also be referred to. The high DIFF signal along line 114 is provided to lock flip-flop 116 via inverter 240. Lock flip-flop 116 is a cross-connected NAND
It has circuits 242 and 244, and a NAND circuit 242
The output of is provided to an inverter/driver 246. The output of inverter/driver 246 is on line 12
2 along transistors 150, 152, 154
The signal is supplied to a driver circuit 120 consisting of. An indicator 72 indicates that the solenoid 71 is locked.
Power is also supplied by the driver circuit 120 as well. The output of NAND circuit 242 is also supplied to the count enable terminal of counter 124. The counter 124 can be preset for a predetermined period of time, i.e., a fixed time interval of 7.27 or 435 seconds;
A clock signal is provided along lines 128 and 130, respectively, after a fixed time interval. In the preferred embodiment, counter 124 is set for a fixed time interval of 435 seconds. Line 128 contains an RC time constant of 255 approximately 1/
Provides a 2 second time delay. The signal along line 128 goes high at the end of a preset time interval of, for example, 435 seconds, during which time the lock condition is maintained. Since flip-flop 116 remains locked until reset by the delay time interval signal along line 128, it remains locked during the preset time interval regardless of the value of the DIFF signal on line 114. Therefore, the time delay device 255
The timing signal along line 128 delayed by two seconds is connected to one input of NAND circuit 256 whose output feeds the input of NAND circuit 242 .
A second input of NAND circuit 256 is provided with a clock signal coming from oscillator 110 along line 126. NAND circuit 256 is used to prevent lock flip-flop 116 race conditions. The output of NAND circuit 256 is pulled low when the clock pulse along line 126 and the delay time signal from line 128 occur simultaneously. The low output of NAND circuit 256 makes NAND circuit 242 high, inverter/driver 246 low, and solenoid 71 and indicator 72 turned off.
At the same time, the high output of NAND circuit 242 resets counter 124. The timing signal along line 130 is the same as the signal along line 128, but without the delay. line 130
The timing signal along
A fail-safe flip-flop 136 consisting of circuits 260 and 262 is provided. NAND circuit 260 receives a signal along line 264 from brake circuit 270, which will be described below.
The output of NAND circuit 260 provides the FS signal, a fail-safe signal, which is normally low when inactive and has a high (logic 1) state during a fail-safe mode in which the circuit is shut down. For example, when a timing signal is occurring along line 130 (line 128
1/2 second before the above delayed signal) along line 114.
If the DIFF signal is still present (high, logic 1), the output of NAND circuit 260 will be low and logic
Generates 0FS signal. At the same time, NAND circuit 262
The output of becomes low (logical 0). The FS signal from NAND circuit 260 is provided to the input of NAND circuit 226 (Figure 5A). next
NAND circuit 226 provides a signal to NAND circuit 224 to preset up/down counter 100 and disable the control circuit. The signal from gate 262 provides a low output along line 138 to inverter/driver 274. The output of inverter/driver 274 is provided to driver circuit 140 which, like driver circuit 120, includes transistors 276, 278, and 280. Failsafe indicator 144 is activated when the system is operating in failsafe mode. Another feature of what is shown in FIGS. 5A and 5B is that the apparatus of FIG.
(Figure 5A). Brake circuit 270 detects brake on and open conditions (which may occur, for example, due to filament burnout or disconnection). Line 290 is connected to the brake circuit with the vehicle battery and brake lights. Line 290 when brake is applied
The voltage above is normal and 13.6. Brake circuit 270 includes resistors R25, R36, R26, capacitor C21, and a diode. Furthermore, voltage comparators 292 and 294 and an inverter 296
AND circuits 298, 300 and NAND circuit 30
2 is provided. Resistor R7, R49, R8
forms a voltage divider that feeds one input of voltage comparator 294 and the other input is connected to line 290 through resistor R25. When the brake switch is energized, the output on line 304 of voltage comparator 294 goes high, causing inverter 296 to go low. Inverter 296 is connected to NOR circuit 306 and drives the output of line 114 low (logic 0) through NOR circuit 238. Thus, by setting DIFF low during brake switch activation, the lockout circuit cannot be activated. Lockout prevention during braking is desirable to prevent lockup of the intermediate axle differential due to asynchronous wheel rotation during braking. Brake circuit 270 further provides open brake circuit detection with voltage comparator 292, which is pulled low by an open brake circuit condition. Usually resistors R36, R25, R26
1/ of the regulated supply voltage from the bias network of
Receives voltage between 3 and 2/3. During an open brake circuit condition, the logic outputs of voltage comparators 292, 294 are provided to an AND circuit 298, which is a NAND
Supply to the circuit 302 and then the AND circuit 300
supply to. The output along line 264 is the NAND circuit 2 of fail-safe flip-flop 136.
60 and sets it to generate a high failsafe signal (logic 1). Next, as described above, the FS signal presets the up/down counter 100 via the NAND circuit 226,
Generation of the DIFF signal along line 114 is inhibited. While both brake application or closed brake switch conditions and open or floating connections to the stop light circuit are effective in preventing activation of the solenoid drive circuit 120, an open circuit condition is a fail-safe flip-flop condition. 136 and remains activated until manually reset, the brake application state is simply determined by the NOR circuit 2 along line 114.
It only temporarily suppresses generation of the DIFF signal via 38. In the latter case, once the brake light is turned off, the control circuit operates and solenoid drive circuit 1
20 is activated. Another feature of the circuit shown in FIG. 5 is a power-up self-test circuit 330 consisting of cross-connected NAND circuits 332, 334, inverters 336, 338, and NAND circuit 340. The power-up self-test circuit further includes capacitor C10,
Resistor R27 and NAND circuit 342 (5th A
Figure). The voltage regulator shown in FIG. 5A provides approximately 6 regulated output voltages.
6 pulses during startup are resistor R27 and capacitor C
held for approximately 2 seconds with an RC time constant of 10
Supply PUP (power up signal). The power up signal ensures a logic 0 signal at the output of NAND circuit 342, which is provided via line 344 to NAND circuit 332 (FIG. 5B). This signal is connected to TEST and
Apparatus is provided to test the circuit by providing a TEST signal, and the sensor input is simulated by providing a pseudo count using NAND circuits 380, 382 (FIG. 5A). A D-coded signal is also supplied by the 4-bit binary counter 212.
It is supplied to one input of the NAND circuit 380. Therefore, when the vehicle ignition is turned on and the voltage regulator stabilizes, a pulse is provided at the output of NAND circuit 384 and fed to D flip-flop 190 to generate a pseudo count, which is sampled by sampling oscillator 210 and binary counter 212. Ru.
However, gated trigger circuit 90 does not receive the pseudo count and a DIFF signal is generated along line 114. DIFF signal together with TEST signal
It is applied to NAND circuit 340, which resets power-up self-test flip-flop 330 (set by the PWR RST signal), which likewise resets fail-safe flip-flop 136. Failsafe indicator 144 is nevertheless energized for approximately two seconds, which is the time frame in which the power resume (PWR RST) signal is preset. When the PWR RST signal goes to 0, the failsafe indicator will not be energized unless a fault is detected in the circuit. The output of the NAND circuit 342 also works as a power reset (PWR RST),
NAND circuits 210, 242, 3 along with PUP signal
These are used as signals to 32,300
Resets the counter and flip-flop associated with the NAND circuit. Thus, the power up sequence not only powers up the system, but also indicates that the fault indicators and control circuit electronics are operating properly. Examples of integrated circuit elements that can be used in the circuits shown in FIGS. 5A and 5B are shown in the following table.

[Table] Typical values of the circuit elements used in FIGS. 5A and 5B are shown in the following table as an example.

【table】

【table】

【table】

TABLE The invention may be embodied in other forms within the spirit and essential characteristics of the invention. Accordingly, the foregoing description is intended to be illustrative only and not limiting; the scope of the invention is defined by the following claims, and all changes that come within the meaning of the claims are intended to be interpreted as such: shall be included in the scope.

[Brief explanation of drawings]

1 is a principle diagram of an electronic control circuit according to the present invention, FIG. 2 is a plan view of a truck cab and carrier using an intermediate axle differential mechanism according to the principles of the present invention, and FIG. 3 is a diagram of the principle of an electronic control circuit according to the present invention. FIG. 4 is a block diagram of an embodiment of a control circuit according to the principles of the present invention; FIGS. 5A to 5D are circuit diagrams showing details of the embodiment of FIG. 4; FIG. It is. Explanation of reference symbols 10...control device, 14...differential circuit, 20...truck cab, 22...carrier,
24... Front and rear axle, 26... Rear axle, 30... Propulsion shaft, 31... Box, 32... Intermediate axle differential mechanism, 34
... Front-rear differential mechanism, 36... Rear-rear differential mechanism, 40... Universal joint, 42... First output shaft, 44
...Second output shaft, 45-47...Drop gear, 52
... Collar, 56, 58 ... Sensor, 60 ... Toothed rotor, 66 ... Controller, 70 ... Air solenoid valve, 7
2... Indicator light, 74... Battery, 76... Stop light switch, 78... Foot valve.

Claims (1)

[Scope of Claims] 1. A main drive shaft that operates to supply drive torque to the wheels of an automobile, first and second output shafts, and a device for coupling the main drive shaft to the first and second output shafts. A vehicle drive control device comprising: (a) a device for sensing relative rotational speeds of the first and second output shafts; and (b) detecting a slip condition in response to the sensing device and eliminating the slip condition. (c) activating means for activating the means for eliminating the slip state and supplying a control signal; (d) means for operating the activating means for a predetermined period of time after activation; e) fail-safe timing means for stopping the operation of the control means if the control signal is still present a certain time before the end of the predetermined time. 2. In the device according to claim 1,
The device for coupling the main drive shaft to the first and second output shafts is a differential device, and the activation device is activated to couple two of the main drive shaft and the first and second output shafts. A device characterized by differential locking. 3. In the device according to claim 1,
The apparatus wherein the first output shaft is normally driven by the main drive shaft and the means for eliminating the slip condition includes a clutch connecting the main drive shaft to the second output shaft. 4. In the device according to claim 1,
An apparatus characterized in that the wheels of the automobile are provided with brakes, and the means for eliminating the slip condition selectively controls the action of the brakes. 5. In the device according to claim 1,
A device characterized in that the fail-safe timing device operates for a short period of time. 6. In the device according to claim 5,
The device characterized in that the certain period of time is not longer than 1 minute. 7. In the device according to claim 1,
An apparatus characterized in that the certain period of time is the same as the predetermined period of time. 8. The device of claim 1, wherein the vehicle has a brake, and the device further comprises: (a) a device for generating a brake signal in response to action of the vehicle brake; and (b) a device for generating a brake signal in response to action of the vehicle brake. and a device for receiving a signal to deactivate the control means, wherein the control means is not activated to eliminate the slip condition when the vehicle brake is applied. 9. In the device according to claim 8,
An apparatus characterized in that the motor vehicle has a brake light circuit and a brake light that is activated upon application of the brakes, and the device responsive to application of the motor vehicle brake has a device connected to the brake light circuit. 10. The device according to claim 1, further comprising a device connected to the brake light circuit for detecting an open circuit condition, and a device for deactivating the control means when detecting the open circuit condition. An apparatus characterized in that the control means starts and stops when an open state of the brake light circuit is detected. 11 A vehicle drive control device having a main drive shaft that operates to supply drive torque to the wheels of a vehicle, first and second output shafts, and a device that couples the main drive shaft to the first and second output shafts. (a) a sensor positioned adjacent to each independently rotating axle for generating a signal having a frequency proportional to the rotational speed of the axle; and (b) receiving the signal from each of the sensors; gating circuit means operable to gate said signal; (c) a count for counting said signal from said gating circuit means and generating a difference signal when a predetermined difference occurs in said count; (d) timing means for receiving said difference signal and generating a control signal for a predetermined period of time; and (e) drive means responsive to said control signal for eliminating said slip condition. Featured device. 12. The device according to claim 11, wherein the counting device is configured to count up in response to a signal from the one sensor and count down in response to a signal from the other sensor. /A device comprising a down counter, wherein said gating circuit device alternately gates signals from said sensor to said counting device. 13. The apparatus of claim 12, wherein said up/down counter is presettable and said control means further includes means for resetting said up/down counter at regular time intervals. 14. The apparatus of claim 13, wherein said constant up count is preset equal to said down count, and said presettable up/down counter adjusts said difference signal when either of said preset counts is exceeded. A device that generates 15. The device according to claim 11, further comprising a fail-safe timing device that generates a fail-safe signal when the difference signal is present a certain time before the predetermined time expires. , wherein the fail-safe signal is connected to the counting device to prevent the difference signal from being generated subsequently. 16. The apparatus of claim 15, wherein the vehicle has a brake, and the apparatus further inhibits transmission of the difference signal to the timing device in response to application of the brake. Device. 17. The apparatus of claim 15, wherein the vehicle has a brake light circuit, and the apparatus is further connected to the brake light circuit to sense an open circuit condition and prevent generation of the difference signal. Featured device. 18. The device according to claim 14, wherein the device connects the main drive shaft to the first and second shafts.
An apparatus comprising a differential device connected to an output shaft, wherein the control means differentially locks the main drive shaft and any two of the first and second output shaft groups with respect to each other. 19. The apparatus of claim 18, wherein the motor vehicle includes a clutch collar, a cooperating fork, and a yoke assembly for differentially locking the main shaft to one of the output shafts, and wherein the drive system includes a clutch collar, a cooperating fork, and a yoke assembly for differentially locking the main shaft to one of the output shafts. A device characterized by having a solenoid that differentially operates a collar. 20 Slip correction for a motor vehicle having a main drive shaft that operates to supply drive torque to the wheels of the motor vehicle, first and second output shafts, and a device for coupling the main drive shaft to the first and second output shafts. In the improved method, the method includes: (a) two of the main drive shaft and the first and second output shaft groups;
(b) locking the connecting device to eliminate the slip condition; (c) maintaining the locked condition for a predetermined time; (d) ) unlocking the coupling device if the slip condition is detected again before the end of the predetermined time period. 21. The method of claim 20, wherein the motor vehicle has brakes, and the method further includes sensing the application of the motor vehicle brakes and locking the coupling device in response to the application of the motor vehicle brakes. and the step of inhibiting. 22. The method of claim 20, wherein the motor vehicle has a brake light circuit, and the method includes the steps of: sensing an open circuit condition of the brake light circuit; and responding to the open circuit condition of the brake light circuit. and terminating the method.