MXPA00009611A - Tracked vehicle steering system with failure detection - Google Patents

Abstract

A control system is provided for a tracked vehicle drive/steering system having an engine driven hydraulic steering pump (40) which drives a hydraulic steering motor (42). The steering pump (40) is responsive to steering control signals representing a status of an operator manipulated steering wheel (74). The steering motor (42) provides an input to a differential track drive mechanism which responds to manipulation of the steering wheel (74) and drives left and right tracks to turn the vehicle. The control system includes a control unit (70) which receives signals from an engine speed sensor (62), a steering motor rotation speed and direction sensor (80), and the steering control signals. The control unit (70), when the steering control signals indicate that the steering wheel (74) is turned in a direction opposite to a direction of rotation of the steering motor (42), generating and saving a first ratio value representing a ratio of the motor speed to the pump speed. Then, if the steering control signal is unchanged after certain time duration, the control unit (70) generates and saves a second ratio value representing a later ratio of the motor speed to the pump speed. The control unit (70) then calculates a difference value representing a difference between the first and second ratio values, and generates a fault signal if the difference value has a magnitude which is less than a predetermined magnitude. Thus, the control system generates a fault signal when the sensed signals indicate that the steering pump swashplate position is not changing as it should in response to changes in steering wheel position.

Description

DB SYSTEM DB ADDRESS ÜN VEHICLE WITH BAND8 WITH DB PALLA DETECTION Background of the Invention The present invention relates to a steering / steering system of a vehicle with bands.

Known production of belted vehicles, such as the John Deere series 8000T and 9000T tractors, includes a motor-driven variable displacement steering pump which powers a fixed displacement hydraulic steering motor. The steering motor also drives, by means of a transverse axle, and of a gear to a left planetary impeller. The steering motor also drives, through the transverse axle, a gear and a reverse gear, a right planetary direction. An address control signal is provided by a transducer which detects the rotation of a steering wheel. The speed and direction of rotation of the steering motor is normally proportional to the position of the steering wheel, and these parameters are sensed by a direction sensor and a Hall effect motor speed. Certain types of failures related to the steering pump, such as contamination in the control valve and the malfunction of the feedback joint between the steering pump oscillating plate and its secondary phase steering control valves can cause the oscillating plate of the pump to be hydraulically closed (stuck) in a certain non-zero position. This type of failure can lead to a continuous turning of the vehicle, even when the steering wheel is in an orderly position of not turning. It may be desirable to provide a method for detecting such faults, and to prevent the vehicle from returning unless the overturning is actually commanded by the operator.

Synthesis of the Invention Therefore, an object of this invention is to provide a system or method for detecting certain faults in a steering system / driving vehicle with bands.

A further object of the invention is to provide such a system which prevents the vehicle from returning unless the return is actually ordered by the operator.

These and other objects are achieved by the present invention, wherein a control system for a belt drive / drive system includes a control system of the steering system which receives signals from a pump speed sensor ( engine speed) and from a steering motor velcro sensor. The ratio of the engine speed to the pump speed represents the angle of the steering pump oscillating plate during the steering action. For a normally operating steering system, if the pump receives a control signal in a reverse direction, the angle of the pump's oscillating plate may begin to decrease. When the control unit sends a reverse directional direction command above a certain amount, it also calculates and stores the ratio of the motor speed to the pump speed. The control unit recalculates the aforementioned ratio after a certain duration of time, if the same reverse command instruction is still present. The control unit generates a fault signal if the ratio is not decreasing.

Brief Description of the Drawings Fig. 1 is a simplified schematic diagram of a belted vehicle impeller and the control system of the present invention; Y Figures 2 to 6 show a logical flow diagram of an algorithm executed by a control unit to band of a microprocessor of the control system of Figure 1. n ^ sr. iption of the Preferred Incorporation Referring to Figure 1, a motor 10 for a vehicle with belts has an output shaft 12 which drives a right angle gear 14 and a transmission 16 by means of a clutch 18. The motor 10 is controlled by a control unit of electronic motor 11. Transmission 16 drives a right or final angle drive 20, which drives a left-hand drive wheel 22 by means of the left-hand planetary drive 24, and a right-hand drive drive 26 by means of the right planetary drive 28. The planetary steering drives 24 and 28 are preferably such as those described in U.S. Patent No. 5,390,751, granted on February 21, 1995 to Puetz et al., and assigned to the assignee of this application. Additional outboard planetariums (not shown), such as those provided on John Deere 8000T tractors, are mounted between the steering planetaries and the respective drive wheels, but are not described anymore because they are not directly involved in the subject matter of this request. A parking brake 30 is coupled to the output shaft of the transmission 16, and the left and right service brakes 32 and 34 are coupled to the left and right steering wheels 22 and 26 respectively.

The right angle gear 14 drives a variable displacement steering pump 40, such as a 75 cubic centimeter, 90 series pump made by Sauer-Sundstrand. The pump 40, in turn, powers a fixed hydraulic displacement steering motor 42, such as a 75 cubic centimeter, 90 series engine, also made by Sauer-Sundstrand. The steering motor 42 drives, by means of a transverse shaft 44 and a gear 46, a collar gear 47 of the left planetary impeller 24, and through the transverse shaft 44, the gear 48 and the reverse gear 50, a gear of collar 52 of the right planetary impeller 28.

The steering pump 40 has an oscillating plate (not shown), whose position is controlled by an oscillating plate control valve or by electronic shift control (EDC) 60. The electronic displacement control is preferably a two-phase device with the first phase including a flap type valve operated by a pair of solenoids 59, 61, and a second phase that includes a pulse phase to the pump, as used in the production of the tractor with John Deere 8000T series belts .

A rotational speed sensor 62, such as a commercially available magnetic pickup, mounted in the vicinity of the right angle driver 14, provides a motor speed signal to a steering system unit (SSU) 70. The solenoids 59 and 61 of the valve 60 are controlled by the pump command signals (pump_command) generated by the steering system unit 70. The steering system unit 70 is communicated with the engine control unit 11.

A steering wheel rotary position transducer 72, such as a rotary potentiometer, provides the steering system unit 70 with a steering angle signal (steering angle) which represents the position of a steering wheel controlled by operator 74. This description is related to a steering input device with a neutral spring-centered position. The present invention may also be applied to a non-centered steering input device. The steering system unit 70 also receives signals from a gear shaft lever transducer 73, such as is described in U.S. Patent No. 5,406,860, issued April 18, 1995 to Easton et al.

A driving line rotation speed sensor 76, preferably a differential Hall effect velocity sensor such as that used in the production of the John Deere 8000T tractors, is mounted in the vicinity of the final impeller 20, and provides the steering system unit 70 * a final speed, vehicle speed or wheel speed signal. A hydraulic oil temperature sensor 77, such as that used in John Deere 8000T tractors, provides the steering system unit 70 with a signal of the temperature of the hydraulic oil. A magnetic ring 78 is mounted to rotate with the motor 42, and a Hall effect transducer 80 mounted near the magnetic ring 78 provides the steering system unit 70 with a motor speed signal and a motor direction signal.

The address system unit 70 includes a commercially available microprocessor (not shown) which executes a subroutine or algorithm 100 which is illustrated by figures 2 to 6. The correct operation of this subroutine requires that the address input device 72 and the engine speed and the direction sensor 80 are functional. The signal from the address input device 72 is converted to the solenoid command values by the address system unit 70. A solenoid command 1 represents a turn to the right of the address input device when it is in the address / gear forwards or one turn to the left in one direction / gear in reverse. A solenoid command 2 represents a turn to the left of the steering input device when it is in forward direction / gear or a right turn in reverse gear / direction. If it is determined that the engine speed or steering values are not reliable, such as those caused by a detectable open circuit or a short circuit fault, then this logic / subroutine is exited. For example, when it is known that the mot speed sensor 80 has faults, then the steering system unit ab an open-circuit variable as true. This variable is used to disable the subroutine in the event of failure of the motor speed sensing.

A phase 1 of the subroutine 100 includes the steps 102 to 110. The step 102 is applied when called from a main algorithm circuit (not shown) as executed by the drive system unit of the 8000T tractor production. . Step 104 calculates a motor speed value from the speed sensor 80. Step 106 checks the motor speed sensor for faults. Step 10 checks motor 42 for the conditions of May speed. In step 110 a motor speed threshold, T, e placed, which is a minimum value of the motorcycle speed required by the system to be able to detect the engine speed and the unadjusted steering.

In phase 2, in steps 112 to 120 the subroutine reviews and continues to work only if the following conditions are true: a) the solenoid 1 command is more than 2 mA, or the solenoid 2 command is more than 25 mA. (A command greater than approximately 25 mA corresponds to a motor speed greater than 100 revolutions per minute). This minimum threshold is set to avoid false warnings in the case of a steering load on run, such as when the driving motor 42 is driven by an external power; Y b) the motor speed is not zero; Y c) the flag indicates that the stuck plate is false, and d) the temperature of the hydraulic oil is more than 20 degrees Celsius. The low oil temperature may cause excessive delay of the pump response in a normal pump. To avoid the resulting problems and to avoid generating false warnings, the subroutine is deactivated when the oil temperature is below a specific oil temperature.

Therefore, the steps 112 and 114 operate so that this subroutine remains active if the position transducer of the steering wheel 72 is operational and only if the vehicle is making a right turn to the one or a turn to the left.

Step 116 leaves the subroutine if the motor speed is not greater than 0. Step 118 transfers control to step 140 if a stuck flag value is not set that is false. Step 120 transfers control to step 140 if the hydraulic oil temperature is not greater than 20 degrees Celsius.

Phase 3 includes steps 121 to 132. Step 121 transfers control to step 140 if the calibration is in progress. Step 122 transfers control to step 140 if the current mode of operation is open circuit. Therefore, as a result of step 122, this logic and the subroutine are active only when the steering system is activated in a closed circuit mode (that is, the engine and steering speed sensor is working properly, without any known flaws that can be detected).

Step 124 directs control to step 126 if solenoid 1 is on, otherwise to step 130. Step 126 directs control to step 134 if the motor speed is less than a negative threshold, -T, otherwise to step 130. Step 130 directs control to step 132 if solenoid 2 is on, otherwise to step 140. Step 132 directs control to step 134 if the motor speed is greater than threshold T, otherwise way to step 140.

Therefore, in phase 3, as a result of steps 122 to 132, another placement of conditions must be satisfied for the subroutine to work. The steering system must not be active in an open circuit mode (eg it is active in the closed circuit mode), such as when the speed motor / steering 80 sensor is working properly. Also, with the solenoid 1 on, the motor speed must be less than the negative value of the motor speed threshold, with the solenoid 2 on, the motor speed must be greater than the positive value of the speed threshold of the motor. motor.

As a result of phases 2 and 3 (steps 112 to 120 and 122 to 132), the logic ensures that the pump control command is greater than 25 mA in the opposite direction to that of the motor rotation, for example , the operator must be rotating the steering wheel 74 opposite to the current vehicle turning direction. Steps 126 and 132 operate so that the subroutine is operative only when the motor speed is greater than 100 revolutions per minute. This avoids the false generation of fault signals in case the motor speed is driven by the external power (the overdrive direction load).

In phase 4, if these conditions are satisfied then step 134 assigns the solenoid command value 1 to a previous command variable if the solenoid (59) is on, and assigns the command value of solenoid 2 to the command value previous yes the solenoid 2 (61) is on. Then step 136 sets a stuck flag value as true, and places a stuck timer (delay timer) with a value stored as an end-of-line timer (EOL). Step 138 then calculates the ratio value of temperature 1 as the ratio of engine speed to engine speed and multiplies this by 64 (to increase its resolution).

Phase 5 includes steps 140 to 148 and operates to ensure that the vehicle is still on the same lap as the one it started. If this is the case, then the subroutine starts to reduce the value of the stopwatch to zero, otherwise (if the lap has changed), the stuck flag is set back to false. More particularly, step 140 directs the control to step 142 if the jammed stopwatch is less than or equal to the delay value, otherwise to step 150. Step 142 directs control to step 144 if the jammed stopwatch is greater than or equal to , otherwise to "step 150. Step 144 directs the center to step 148 if the previous command and the sun command variables match, otherwise to step 146 which sets the jammed flag to false, then to step 150. The country decreases the value of the jammed stopwatch.

Phase 6 includes steps 150 to 154. The c calculates the ratio of temperature 2 as the ratio of engine speed to engine speed and multiplies it (again to increase its resolution), if the jammed flag is true and the stopwatch of clogging has decreased to zero, and calculates a difference of the proportion value by subtracting the temperature ratio the temperature ratio 1. More particularly, the country directs control to step 152 if the true clog flag, otherwise ^ step 168. Step 152 will control step 154 if the jammed stopwatch is otherwise identical to step 168. Step 154 places the ratio 2 temperature equal to the motor speed / mo rate places an equal difference rate value at temperature 1-temperature 2.

Phase 7 includes steps 156 to 166, c to operate a fault of the stuck oscillating plate and put a pump failure, if the previous command is 1 solenoid 1 is on and the difference of the proportion greater than or equal to 5, or if the previous command is 2 and the solenoid is on and the difference of the ratio is less than or equal to +5, otherwise, the stuck flag is set as false in step 163. Therefore, when A pump fault is placed by the steering system unit 70, then the steering system unit 70 sends a signal to the motor controller 11 to shut off the engine 10 by means of a message on a CCD bus (not shown). More particularly, step 156 directs control to step 158 if the previous command and solenoid command 1 are coupled, otherwise to step 160. Step 158 directs control to step 166 if the difference ratio is not less than -5, otherwise to step 160. Step 160 directs control to step 162 if the previous command and the solenoid command 2 are coupled, otherwise to step 163. Step 162 directs the control to step 164 if the Difference rate is not greater than 5, otherwise to step 163. Step 163 places a false stuck warning value and directs the subroutine to step 168. Step 164 places a stuck oscillating plate flag and a power failure fault. motor. Step 166 places a stuck oscillating plate flag and an engine shutdown failure flag.

Phase 8 includes steps 168 through 170, which operate to clear the stuck oscillating plate fault, clear the pump fault and place the jammed stopwatch as the stopwatch value plus 0.10 seconds, if the stuck flag is false More particularly, step 168 directs the control to step 170 if the stuck flag is false, otherwise it leaves the subroutine. Step 170 clears the stuck swing plate flag and clears the engine shutdown failure flag and exits the subroutine.

Therefore, steps 154 to 166 operate to compare changes or differences in engine speed / engine speed rate to changes in the command of signals which are supposed to determine the angle of the oscillating plate (not shown). ) of the pump 40. If the changes in the value of the ratio match the changes in the signal command, then this is an indication that the system is functioning properly. If the changes in the value of the ratio do not match the changes in the signal command, then this is an indication that the system is not functioning properly and the system of the present invention generates a fault signal which can be used to trigger an engine shutdown.

Normally, when the steering wheel 74 is changed from a position that commands a turn in one direction, through a central position to a position that commands a turn in the opposite direction, the command signal supplied to the steering pump 40 it may be reversed and may cause the steering pump oscillating plate to similarly reverse its position and, therefore, that the ratio of the steering engine speed to the pump speed may vary rapidly in a similar manner. If this ratio does not vary in a manner similar to the variation of the position of the steering wheel, this is an indication that a fault of some kind has occurred and that the steering pump 40 no longer responds to the command signal of the steering wheel. pump control produced by the steering wheel 74.

This subroutine is executed continuously by the address system unit 70 during the address operation so that if the address system unit 70 detects a prolonged violation of the relationship, a fault code may be generated and stored, and a command of Engine shutdown may be sent to motor controller 11 to stop the operation of the vehicle immediately.

The following is a program listing of the computer program which implements the subroutine illustrated by the flow chart of Figures 2 through 6.

List of Logical Detection Program of the Jammed Oscillating Plate.

/ * We are assuming that The address input device is functional. The motor address is also functional in order to detect this condition. * / speed_limit l_motor - threshold / 2_minute_speed; yes (((Solenoidel> 250) ¡(Solenoid2> 250)) & (speed! _motor = 0) & (stuck_flag == FALSE) & (hydraulic_oil_temperature &84)) . { if ((open_circuit_l) & &(((Solenoid) & (speedljnotor < u m b r a l v e l a l d l a m d t)) Ti ((Solenoid2) & (veloc_motor > velocity_limit_motor)))). { yes (Solenoidel) previous command = 1; otherwise if (Solenoid2) previous_command = 2; stuck_advisor = TRUE stuck_crownometer = End of Line Stopwatch [0]; temp_value = (long) velocity_speed * 64 / motor_motor; } } yes ((stuck_time_clock <= End of Line Stopwatch [0]) & (stopwatch! _ stuck = 0)). { yes (((command_previous == 1) & (Solenoidel)) ¡((command_previous == 2) && amp; (Solenoid2))). { stopwatch_; } otherwise . { stuck_flag = FALSE; } } if ((stuck_flag == TRUE) &&(stuck_time == 0)). { p r o p e c t i n t t m p e r t u r 2 = (l a r g o) velocity_speed * 64 / engine_motor; proportion_difference = rate_temper atura l proporcidn_temperatura2; if (((previous_command == 1) & & (Solenoid) & & amp; (proportion_difference > = -5)) ¡((previous_command »» 2) & & (Solenoid2) & proportion_difference < = 5))). { st motor speed control ¡»ßfmask; / * Position steering system unit 153 Size * / control failure_bomb »sfmaßk; / • Place drive system unit 2? S fails * / > otherwise . { stuck_flag = FALSE; } yes (jammed_flag == FALSE). { ßt_control engine speed & = ßfmask_circular; / * Clarify drive system unit 153 fails * / control_fallal_pump & = sfmask_circular; / • Clarify address system unit 235 fails * / stuck_time_clock = End of Line timer [0] + second_end; } End of Oscillating Plate Detection Logic Jammed A *********************************** ******************* / A portion of the disclosure of this patent document contains material which is subject to the claim of copyright protection. The owner of the copyright has no objection to facsimile reproduction in any patent document or patent disclosure, as it appears in the patent files of the Patent and Trademark Office or in the registers, but in another way all4 other rights are reserved.

Although the present invention has been described in conjunction with a specific embodiment, it is to be understood that many alternatives, modifications and variations may be apparent to those skilled in the art in light of the description described above. Therefore, this invention is intended to encompass all such alternatives, modifications and variations which fall within the spirit and scope of the appended claims.

Claims (6)

1. A control system for a belted vehicle steering / driving system having a hydraulic driven engine driven pump, the steering pump responds to the steering control signals representing a condition of a steering wheel driven by a operator, the steering motor provides an input to a differential band steering mechanism which responds to the direction of the steering wheel and turns the vehicle and drives the left and right bands, the control system comprises; an engine speed sensor; a direction sensor and a rotation speed of the steering motor; Y a control unit that receives the steering control signals and is coupled to the engine speed sensor and the speed sensor of the steering engine, the control unit, when the steering control signals indicate that the steering wheel is Turned in a direction opposite to a direction of rotation of the steering motor, it generates and stores a first ratio value representing a ratio of the motor speed to the pump speed, then, if the steering control signal it does not change after a certain length of time, it generates and stores a second proportion value representing a later proportion of the engine speed at the pump speed, and the control unit calculates a difference value representing a difference between the first and second ratio values, and the control unit generates a fault signal if the difference value has a magnitude which is less than a predetermined magnitude.

2. The control system as claimed in clause 1, characterized in that the control unit generates the fault signal when the value of the difference is not less than the threshold value.

3. The control system as claimed in clause 1, characterized in that the control unit compares the steering control signals to a reference value to determine whether or not the vehicle has been ordered to turn.

4. The control system as claimed in clause 3, characterized in that the control unit determines that the vehicle has been ordered to return when the direction control signal is greater than the reference value.

5. The control system as claimed in clause 1, characterized in that the control unit prevents generation of the fault signal when the engine speed is low.

6. The control system as claimed in clause 1, characterized in that the control unit prevents generation of the fault signal when a hydraulic fluid temperature of the pump and the engine are below a certain temperature. RE8UMEN A control system for a belt drive / drive system is provided having a motor-driven hydraulic steering pump which drives a hydraulic steering motor. The steering pump responds to steering control signals that represent a condition of a steering wheel driven by an operator. The steering motor provides an input to a differential band drive which responds to the direction of the steering wheel and drives the left and right belts to turn the vehicle. The control system includes a control unit which receives the signals from a motor speed sensor, a direction and rotation speed sensor of the steering motor, and the steering control signals. The control unit, when the steering control signals indicate that the steering wheel is flipped in a direction opposite to a direction of rotation of the steering motor, generates and stores a first ratio value representing a proportion of the speed of the steering. motor at the speed of the pump. So, if the direction control signal has not changed after a certain length of time, the control unit generates and stores a second proportion value representing a later ratio of the engine speed to the pump speed. The control unit then calculates a difference value that represents a difference between the first and second proportion values, and generates a fault signal if the difference value has a magnitude which is less than that of a predetermined magnitude. Therefore, the control system generates a fault signal when the perceived signals indicate that the position of the steering pump oscillating plate is not changing as it should in response to changes in steering wheel position. »*