CA1144624A - Control system for controlling a power transmission device - Google Patents
Control system for controlling a power transmission deviceInfo
- Publication number
- CA1144624A CA1144624A CA000396515A CA396515A CA1144624A CA 1144624 A CA1144624 A CA 1144624A CA 000396515 A CA000396515 A CA 000396515A CA 396515 A CA396515 A CA 396515A CA 1144624 A CA1144624 A CA 1144624A
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- Prior art keywords
- gear
- control means
- signal
- drive
- reversing
- Prior art date
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Abstract
The invention relates to a control system for controlling a power transmission device arranged between a driving engine and a drive axle of a vehicle and comprising a torque converter and an automatic step gearbox. The gearbox is equipped with an electric control device having a microcomputer, which device permits the operator to select, by means of a selector lever, the desired driving direction of the vehicle even if it is moving in the opposite direction to the desired direction. When a directional command signal is sent to the control device, reversing gear control means therein reverse the working direction of the gearbox so that the gearbox works in the opposite direction to the driving direction. First gear can be obtained by manually operating the selector lever to cause a forced downshift signal to be sent to drive gear control means, provided the vehicle speed is within the working range of second gear. The control system of the invention is particularly suitable for use in construction vehicles such as wheeled loaders.
Description
iZ4 This is a divisional application of Canadian application No. 354,890 filed on June 26, 1980.
The invention of the present divisional appli-cation relates to a control system for controlling a power transmission device of work vehicles such as wheeled loaders, in which the driving direction is reversed at short intervals during operation.
A vehicle operatorhas a number of tasks to per-form at the same time: steering the vehicle, shifting the vehicle gearbox, and operating the implement, e.g. lifting and tipping a bucket.
The purpose of the invention is primarily to make these tasks easier for the operator of such a vehicle by automatically controlling the operation of the gearbox.
According to the present invention, there is provided a control system for controlling a power trans-mission device arranged between a driving engine and an out-put drive axle of a vehicle and comprising a torque converter and a mechanical step gearbox, the gearbox having at least two drive gears for altering the torque transmitted to the drive axle, between which gears the shifting sequence can be controlled automatically dependent on engine parameters such as load and rotational speed, and having a reversing gear device for changing the rotational direction of the drive axle, the reversing of which gear device is controlled by a directional selector control which is manually actuated by the vehicle operator. The control system of the invention is characterized in that it comprises an electrical control device having drive gear control means and reversing gear control mean~, which ar~ joined to gear couplings and/or gear brakes operable by elec~rical control and associated with the drive gears or the reversing gear for controlling the rotational speed and the direction of the drive axle.
A sensor for the rotational speed of the drive axle or the speed of the vehicle is connected to a comparator which is operable to compare the actual speed value from the sensor with a predetermined speed limit value stored in a memory and, when the actual value is less than the limit value, to send a go-ahead signal to the drive gear control means.
A forced downshift signal sender is connected to the drive gear control means and is operable upon manual actuation by the operator to produce a forced downshift signal which, if the go-ahead signal is present, causes the drive gear con-trol means to engage the lowest drive gear. The directional selector control is connected to the control device to supply it with a directional command value signal, and when the command value signal is changed to indicate the opposite direction, a reverse signal is sent to the reversing gear control means for changing over the reversing gear and at the same time to the drive gear control means for inhibiting the forced downshift function and engaging the next lowest drive gear.
The electrical control device preferably includes a microcomputer.
The reversing gear arrangement can either comprise a separate reversing gear, with the gearbox comprising a number of drive gears which can be used independently of the driving direction, or separate sets of driving gears for forward and reverse. In the latter case, the gear ratios for reverse driving can be selected independently of the gears for driving forward.
114~
First gear is used p;imarily for bucket filling, and the filling work can be done more quickly with operator-actuated downshifting than if the gearbox must wait for an automatically controlled downshift signal. In this case, it is suitable to block actuation of the forced downshift signal sender when the vehicle sp~ed is greater than a certain maximum speed, since downshifting to first gear would then cause a powerful retardation. This maximum speed can suitably be selected so as to permit downshifting only withinthe range of second gear.
A practical arrangement for a vehicle such as a wheeled loader is to arrange the directional selector control and the forced downshift signal sender as a multi-function control next to the steering wheel, so that the operator can operate the steering wheel, directional selector control and forced downshift signal sender with one hand. The operator then has the other hand free to operate the bucket and to help with the controls to speed up the reversing if necessary.
Further advantages and features of the invention will become apparent from the following detailed description of a preferred embodiment as illustrated by way of example in the accompanying drawings, in which:
Fig. 1 shows in block diagram form a power transmission device for a wheeled loader.
Fig. 2 shows in block diagram form a control device for the gearbox of the power transmission device.
Fig. 3 shows in block diagram form a control device equipped with a microcomputer.
Fig. 1 shows a driving engine M which drives a hydrodynamic torqueconverter C, which in turn drives a mechanical gearbox T which has four driving gears and one reversing gear, with the aid of which the drive gears can be used to drive the output axle A, and thus the vehicle, either forwards or backwards. The shifting in the gearbox is controlled electrically by means of an electrical control device 1. A driving direction control is connected to the control device 1.
Fig. 2 indicates with a dashed rectangle the electrical control device 1 for controlling the gear~ox T of the loader. For this purpose, the-control device has drive gear control means 2 wh~ch are connected, via a first output 3, with solenoids or the like for operating couplings or brakes 4 associated with the gear-box driving gears. The control device 1 also comprises reversing gear control means S which are connected, via a second output 6, to solenoids or the like for operating the couplings and brakes 7 a~sociated with the gearbox reversing gear.
A first input 8 of the control device 1 is connected to a sensor 9 for the speed of the loader. The sensor 9 can, for example, sense the r.p.m. of the output axle A (Fig. 1). A second input 10 of the control device is connected t~ a forced downshift signal sender 11, suitably made as a part of a multifunction control, for example in the fonm of a ~elector lever 12 located next tothe ~teering wheel. A third input 13 is connected to an indi-cator 14 for the desired driving direction. Thi8 indicator 14 i8 also suitable included in the multifunction control constructed as a directional selector lever 12. A fourth 1144~2i~
input 15 is connected to a sensor 16 for the driving direc-tion of the vehicle. Also sensor 16 can sense the output axle A and can possibly be combined with sensor 9. A
fifth input 17 in the control ~evice 1 is connected to a number of sensors 18 for various engine parameters such as engine r.p.m. and load.
The control device 1 contains a first-comparator 19, in which the directional command value from the 'indi-cator 14 is compared with the directional actual value from the sensor 16. When the command signal at input 13 is changed to the opposite direction to the actual value signal at input 15, the first comparator 19 sends a reverse signal on a line 20 to the driving gear control means 2. A line 21 branches off from the line 20 and leads to the reversing gear means 5.
The actual speed value from the sensor 9 at input 8 is fed over line 25 to a second comparator 26, which also has an input connected to a first memory 27 in which a predetermined blocking or limiting speed is stored, for example 25 km/h. The second comparator 26 is adapted so that when the speed value in the line 25 is less than the blocking speed value, it sends a reverse go-ahead signal via a wire 2~ to the reversing gear control means 2.
When the driving gear control means 2 receive the reverse signal on the line 20, theyactuate the down-~hifting to third gear from fourth gear, if it i~ engaged.
Otherwise, no gear shifting is actuated, i.e. the engaged gear is maintained.
When the rever~ing gear control means ~ receive -`` 11~4~;~4 the reverse signal on line 21, the means send a signal, via the output 6, to the reversing gear coupling 7 for shifting the reversing gear, provided that there is a go-ahead signal in line 2~. If this is not the case then no reversal of direction takes place. For this purpose, the reversing gear control means 5 are provided with logic circuits.
The directional command value signal at input 13 and the directional actual value signal at input 15 are also compared in a third comparator 29. When the direc-tional value is 0 and the directional command value is non-zero, it sends a start signal via line 30 to the driving gear control means 2.
An engine r.p.m. signal stemming from the sensors 18 at input 17 is ~ent to a fourth comparator 31, which also has an input connected to a second memory 32 for a predetermined r.p.m. limit value, e.g. 1000 r.p.m. The comparator compares the engine r.p.m. with the r.p.m.
limit value, and when the engine r.p.m. exceeds this limit value the comparator 31 sends a soft-start signal via line 33 to the driving gear control means 2.
The speed actual value signal at input 8 is also sent to a fifth comparator 34, which has a second input connected to a third memory 35 for a lower speed limit value, e.g. 2 km/h. The comparator 34 compares the actual speed of the vehicle with the limit value stored in the memory 35 and when the actual speed exceeds this limit value the comparator 34 sends a ~oft-start 6ignal via a line 36 to the driving gear control means 2.
The driving gear control means 2 are dispo~ed AO
13 ~4tiZ4 that when there is a start signal in the line 30, a shift signal is sent on output 3 to the drive gear couplings 4 for engaging second gear. This is always the case with a start signal in direct connection with a reverse signal.
If, h~wever, a soft-start signal occurs in line 33 or 36 silmultaneously with the start signal in line 30 and without an immediately preceding reverse signal in line 20, the drive gear control means 2 will instead send a shift signal for engaging third gear. For this purpose the drive gear control means 2 are provided with logic circuits.
The forced downshift signal at input 1~ is sent via a line 37 to the drive gear control means 2. The actual speed value signal is sent from input 8 of the control device 1 to a first input of a sixth comparator 38, while the second input of the comparator 38 is connected to a f~urth memory 39 for an upper limiting speed, which is suitably selected to be the same as the upperlimit of the range of second gear. The comparator 38 compares the vehicle speed with the upper limiting speed in the memory 39, and when the vehicle speed is less than the upper limiting speed, the comparator 38 sends a go-ahead signal on line 40 to the drive gear control means 2. When they receive both the forced downshift signal on line 37 and the go-ahead signal on line 40, they send a downshift signal on output 3 to the drive gear couplings 4 for downshifting to first gear. If there is no go-ahead signal in line 40, then no downshift signal i8 sent.
Input 17, connected tothe sensors 18 for engi'ne parameter , i~ connected via a line 41 to the drive gear 11~4t;Z4 control means 2, whereby they receive engine parameter signals for controlling the automatic up and downshifting of the gearb~x dependent on the load while driving. It ` is desirable thatthe shift point between the various driving gears be selected so that the accelerations are smooth when shifting. For this purpose, the shift point between two gears should be placed where the torque curves forthe two gears in question intersect. The torque can preferably be measured directly by comparison between the input and output r.p.m. of the torque converter C
(see sensors 18' and 18" in Fig. 1).
Th~s when driving the vehicle in a certain - direction, the drive gear control means control the shifting in the gearbox depending on the engine parameter signals in line 41. If the driver desires to change the driving direction he flips over the selector lever 12, whereby the sensor 14 sends a directional command value signal to input 13, which is opposite to the actual directional value signal to input 15.
The first comparator 19 now sends a reversing signal both to the drive gear control means 2 via line 20 and to the reversing gear control means 5 via line 21.
The drive gear control means 2 takes care of the down-shifting to third gear from fourth gear if fourth is engaged. The reversing gear control means 5 take care of the changing of the reversing gear provided a go-ahead signal is received ~rom the second comparator 26, i.e.
that the vehicle speed is less than 25 km/h. If this i~
not the case, there is fir~t a retardation in third gear without change-over of the reversing gear until the ~peed is reduced to below 25 km/h, whereafter there is a go-ahead signal in line 28 and the reversing gear control means 5 effect the reversal of the gearbox rotational direction.
Downshifting from fourth to third gear prevents prolonged retardation in fourth gear, which could result in overheating in the torque converter. Shifting of the reversing gear only below 25 km/h prevents excessive heat generation in the torque converter.
During the retardation process the reversing signal is maintained in the line 20, whereby the drive gear control means 2 maintains the driving gear engagement unchanged. ~hus if third gear or second gear were engaged when the operator gave the reverse command, third or second gear, respectively, would remain engaged during the continued retardation.
When the speed has dropped to 0, this is sensed by the third comparator 29 by the directional actual value signal also being 0. The comparator 29 sends a start signal onthe line 30 to the drive gear control means 2 which couple in the second gear for the start sequence in the new driving direction.
In an ordinary start without the reversing sequence, the drive gear control means 2 also receive a start signal on the line 30 for engaging second gear.
If, however, the engine r.p.m. exceeds 1000 r.p.m. or the speed of the vehicle exceeds 2 km/h, the drive gear control means 2 also receive a soft-start signal on line 33 or 36, respectively, whereby the start i8 effected in third gear and not in second gear.
If the operator wishes to engage first gear, `` 11~4~24 for example to obtain increased force to fil~ the bucket, he actuates with the selector lever 12 the forced downshift signal sender 11, whereby a forced downshift signal is sent via the line 37 to the drive gear control means 2. Providea that there is a go-ahead signal in the line 40, i.e. that the vehicle speed is within the working range of second gear, the drive gear control means 2 effect the downshifting to first gear. If the speed is too great, it must first ~e reduced to below the upper limiting speed before downshift-ing to first gear is effected. After downshifting to firstgear has ~een effected in this ~anner, a time circuit (not shown here), in the drive gear control means '2 for example, sees to it that automatic shifting up to second cannot take place within a certain predetermined time, e.g.
five seconds.
Many functions in the control device indicated within the dashed line in Fig. 2 can be performed by a microcomputer. Fig. 3 shows in simplified block diagram form a control device constructed in this manner. It contains a data bus 50, to which a microprocessor 51 is connected. The sensors 9, 16 and 18 for the actual speed, the actual direction and the engine parameters are joined via adapters 52 to an enumerator 53 connected to the data bus 50. The direction selector 12,14 is joined to a read/write memory 54 connected to the data bus. The forced downshift -~ignal sender 11 can ~e connected in a corres-ponding manner ~not shown). The electrically operated driving and reversing gear co~plings and brakes 4,7 are joined ~ia an adapter 55 to a program memory 56, connected to t~e bu~ 50 and corresponding to the drive gear control li~ 2'~
means 2 and the reversing gear control means 5 in Fig. 1.
An output signal from the memory 54 is sent via a line 57 to an input in the enumerator 53.
An additional write/read memory 58 is joined to an indicator device 59, which shows the operator desired data, e.g. which gear is engaged at that time.
The invention of the present divisional appli-cation relates to a control system for controlling a power transmission device of work vehicles such as wheeled loaders, in which the driving direction is reversed at short intervals during operation.
A vehicle operatorhas a number of tasks to per-form at the same time: steering the vehicle, shifting the vehicle gearbox, and operating the implement, e.g. lifting and tipping a bucket.
The purpose of the invention is primarily to make these tasks easier for the operator of such a vehicle by automatically controlling the operation of the gearbox.
According to the present invention, there is provided a control system for controlling a power trans-mission device arranged between a driving engine and an out-put drive axle of a vehicle and comprising a torque converter and a mechanical step gearbox, the gearbox having at least two drive gears for altering the torque transmitted to the drive axle, between which gears the shifting sequence can be controlled automatically dependent on engine parameters such as load and rotational speed, and having a reversing gear device for changing the rotational direction of the drive axle, the reversing of which gear device is controlled by a directional selector control which is manually actuated by the vehicle operator. The control system of the invention is characterized in that it comprises an electrical control device having drive gear control means and reversing gear control mean~, which ar~ joined to gear couplings and/or gear brakes operable by elec~rical control and associated with the drive gears or the reversing gear for controlling the rotational speed and the direction of the drive axle.
A sensor for the rotational speed of the drive axle or the speed of the vehicle is connected to a comparator which is operable to compare the actual speed value from the sensor with a predetermined speed limit value stored in a memory and, when the actual value is less than the limit value, to send a go-ahead signal to the drive gear control means.
A forced downshift signal sender is connected to the drive gear control means and is operable upon manual actuation by the operator to produce a forced downshift signal which, if the go-ahead signal is present, causes the drive gear con-trol means to engage the lowest drive gear. The directional selector control is connected to the control device to supply it with a directional command value signal, and when the command value signal is changed to indicate the opposite direction, a reverse signal is sent to the reversing gear control means for changing over the reversing gear and at the same time to the drive gear control means for inhibiting the forced downshift function and engaging the next lowest drive gear.
The electrical control device preferably includes a microcomputer.
The reversing gear arrangement can either comprise a separate reversing gear, with the gearbox comprising a number of drive gears which can be used independently of the driving direction, or separate sets of driving gears for forward and reverse. In the latter case, the gear ratios for reverse driving can be selected independently of the gears for driving forward.
114~
First gear is used p;imarily for bucket filling, and the filling work can be done more quickly with operator-actuated downshifting than if the gearbox must wait for an automatically controlled downshift signal. In this case, it is suitable to block actuation of the forced downshift signal sender when the vehicle sp~ed is greater than a certain maximum speed, since downshifting to first gear would then cause a powerful retardation. This maximum speed can suitably be selected so as to permit downshifting only withinthe range of second gear.
A practical arrangement for a vehicle such as a wheeled loader is to arrange the directional selector control and the forced downshift signal sender as a multi-function control next to the steering wheel, so that the operator can operate the steering wheel, directional selector control and forced downshift signal sender with one hand. The operator then has the other hand free to operate the bucket and to help with the controls to speed up the reversing if necessary.
Further advantages and features of the invention will become apparent from the following detailed description of a preferred embodiment as illustrated by way of example in the accompanying drawings, in which:
Fig. 1 shows in block diagram form a power transmission device for a wheeled loader.
Fig. 2 shows in block diagram form a control device for the gearbox of the power transmission device.
Fig. 3 shows in block diagram form a control device equipped with a microcomputer.
Fig. 1 shows a driving engine M which drives a hydrodynamic torqueconverter C, which in turn drives a mechanical gearbox T which has four driving gears and one reversing gear, with the aid of which the drive gears can be used to drive the output axle A, and thus the vehicle, either forwards or backwards. The shifting in the gearbox is controlled electrically by means of an electrical control device 1. A driving direction control is connected to the control device 1.
Fig. 2 indicates with a dashed rectangle the electrical control device 1 for controlling the gear~ox T of the loader. For this purpose, the-control device has drive gear control means 2 wh~ch are connected, via a first output 3, with solenoids or the like for operating couplings or brakes 4 associated with the gear-box driving gears. The control device 1 also comprises reversing gear control means S which are connected, via a second output 6, to solenoids or the like for operating the couplings and brakes 7 a~sociated with the gearbox reversing gear.
A first input 8 of the control device 1 is connected to a sensor 9 for the speed of the loader. The sensor 9 can, for example, sense the r.p.m. of the output axle A (Fig. 1). A second input 10 of the control device is connected t~ a forced downshift signal sender 11, suitably made as a part of a multifunction control, for example in the fonm of a ~elector lever 12 located next tothe ~teering wheel. A third input 13 is connected to an indi-cator 14 for the desired driving direction. Thi8 indicator 14 i8 also suitable included in the multifunction control constructed as a directional selector lever 12. A fourth 1144~2i~
input 15 is connected to a sensor 16 for the driving direc-tion of the vehicle. Also sensor 16 can sense the output axle A and can possibly be combined with sensor 9. A
fifth input 17 in the control ~evice 1 is connected to a number of sensors 18 for various engine parameters such as engine r.p.m. and load.
The control device 1 contains a first-comparator 19, in which the directional command value from the 'indi-cator 14 is compared with the directional actual value from the sensor 16. When the command signal at input 13 is changed to the opposite direction to the actual value signal at input 15, the first comparator 19 sends a reverse signal on a line 20 to the driving gear control means 2. A line 21 branches off from the line 20 and leads to the reversing gear means 5.
The actual speed value from the sensor 9 at input 8 is fed over line 25 to a second comparator 26, which also has an input connected to a first memory 27 in which a predetermined blocking or limiting speed is stored, for example 25 km/h. The second comparator 26 is adapted so that when the speed value in the line 25 is less than the blocking speed value, it sends a reverse go-ahead signal via a wire 2~ to the reversing gear control means 2.
When the driving gear control means 2 receive the reverse signal on the line 20, theyactuate the down-~hifting to third gear from fourth gear, if it i~ engaged.
Otherwise, no gear shifting is actuated, i.e. the engaged gear is maintained.
When the rever~ing gear control means ~ receive -`` 11~4~;~4 the reverse signal on line 21, the means send a signal, via the output 6, to the reversing gear coupling 7 for shifting the reversing gear, provided that there is a go-ahead signal in line 2~. If this is not the case then no reversal of direction takes place. For this purpose, the reversing gear control means 5 are provided with logic circuits.
The directional command value signal at input 13 and the directional actual value signal at input 15 are also compared in a third comparator 29. When the direc-tional value is 0 and the directional command value is non-zero, it sends a start signal via line 30 to the driving gear control means 2.
An engine r.p.m. signal stemming from the sensors 18 at input 17 is ~ent to a fourth comparator 31, which also has an input connected to a second memory 32 for a predetermined r.p.m. limit value, e.g. 1000 r.p.m. The comparator compares the engine r.p.m. with the r.p.m.
limit value, and when the engine r.p.m. exceeds this limit value the comparator 31 sends a soft-start signal via line 33 to the driving gear control means 2.
The speed actual value signal at input 8 is also sent to a fifth comparator 34, which has a second input connected to a third memory 35 for a lower speed limit value, e.g. 2 km/h. The comparator 34 compares the actual speed of the vehicle with the limit value stored in the memory 35 and when the actual speed exceeds this limit value the comparator 34 sends a ~oft-start 6ignal via a line 36 to the driving gear control means 2.
The driving gear control means 2 are dispo~ed AO
13 ~4tiZ4 that when there is a start signal in the line 30, a shift signal is sent on output 3 to the drive gear couplings 4 for engaging second gear. This is always the case with a start signal in direct connection with a reverse signal.
If, h~wever, a soft-start signal occurs in line 33 or 36 silmultaneously with the start signal in line 30 and without an immediately preceding reverse signal in line 20, the drive gear control means 2 will instead send a shift signal for engaging third gear. For this purpose the drive gear control means 2 are provided with logic circuits.
The forced downshift signal at input 1~ is sent via a line 37 to the drive gear control means 2. The actual speed value signal is sent from input 8 of the control device 1 to a first input of a sixth comparator 38, while the second input of the comparator 38 is connected to a f~urth memory 39 for an upper limiting speed, which is suitably selected to be the same as the upperlimit of the range of second gear. The comparator 38 compares the vehicle speed with the upper limiting speed in the memory 39, and when the vehicle speed is less than the upper limiting speed, the comparator 38 sends a go-ahead signal on line 40 to the drive gear control means 2. When they receive both the forced downshift signal on line 37 and the go-ahead signal on line 40, they send a downshift signal on output 3 to the drive gear couplings 4 for downshifting to first gear. If there is no go-ahead signal in line 40, then no downshift signal i8 sent.
Input 17, connected tothe sensors 18 for engi'ne parameter , i~ connected via a line 41 to the drive gear 11~4t;Z4 control means 2, whereby they receive engine parameter signals for controlling the automatic up and downshifting of the gearb~x dependent on the load while driving. It ` is desirable thatthe shift point between the various driving gears be selected so that the accelerations are smooth when shifting. For this purpose, the shift point between two gears should be placed where the torque curves forthe two gears in question intersect. The torque can preferably be measured directly by comparison between the input and output r.p.m. of the torque converter C
(see sensors 18' and 18" in Fig. 1).
Th~s when driving the vehicle in a certain - direction, the drive gear control means control the shifting in the gearbox depending on the engine parameter signals in line 41. If the driver desires to change the driving direction he flips over the selector lever 12, whereby the sensor 14 sends a directional command value signal to input 13, which is opposite to the actual directional value signal to input 15.
The first comparator 19 now sends a reversing signal both to the drive gear control means 2 via line 20 and to the reversing gear control means 5 via line 21.
The drive gear control means 2 takes care of the down-shifting to third gear from fourth gear if fourth is engaged. The reversing gear control means 5 take care of the changing of the reversing gear provided a go-ahead signal is received ~rom the second comparator 26, i.e.
that the vehicle speed is less than 25 km/h. If this i~
not the case, there is fir~t a retardation in third gear without change-over of the reversing gear until the ~peed is reduced to below 25 km/h, whereafter there is a go-ahead signal in line 28 and the reversing gear control means 5 effect the reversal of the gearbox rotational direction.
Downshifting from fourth to third gear prevents prolonged retardation in fourth gear, which could result in overheating in the torque converter. Shifting of the reversing gear only below 25 km/h prevents excessive heat generation in the torque converter.
During the retardation process the reversing signal is maintained in the line 20, whereby the drive gear control means 2 maintains the driving gear engagement unchanged. ~hus if third gear or second gear were engaged when the operator gave the reverse command, third or second gear, respectively, would remain engaged during the continued retardation.
When the speed has dropped to 0, this is sensed by the third comparator 29 by the directional actual value signal also being 0. The comparator 29 sends a start signal onthe line 30 to the drive gear control means 2 which couple in the second gear for the start sequence in the new driving direction.
In an ordinary start without the reversing sequence, the drive gear control means 2 also receive a start signal on the line 30 for engaging second gear.
If, however, the engine r.p.m. exceeds 1000 r.p.m. or the speed of the vehicle exceeds 2 km/h, the drive gear control means 2 also receive a soft-start signal on line 33 or 36, respectively, whereby the start i8 effected in third gear and not in second gear.
If the operator wishes to engage first gear, `` 11~4~24 for example to obtain increased force to fil~ the bucket, he actuates with the selector lever 12 the forced downshift signal sender 11, whereby a forced downshift signal is sent via the line 37 to the drive gear control means 2. Providea that there is a go-ahead signal in the line 40, i.e. that the vehicle speed is within the working range of second gear, the drive gear control means 2 effect the downshifting to first gear. If the speed is too great, it must first ~e reduced to below the upper limiting speed before downshift-ing to first gear is effected. After downshifting to firstgear has ~een effected in this ~anner, a time circuit (not shown here), in the drive gear control means '2 for example, sees to it that automatic shifting up to second cannot take place within a certain predetermined time, e.g.
five seconds.
Many functions in the control device indicated within the dashed line in Fig. 2 can be performed by a microcomputer. Fig. 3 shows in simplified block diagram form a control device constructed in this manner. It contains a data bus 50, to which a microprocessor 51 is connected. The sensors 9, 16 and 18 for the actual speed, the actual direction and the engine parameters are joined via adapters 52 to an enumerator 53 connected to the data bus 50. The direction selector 12,14 is joined to a read/write memory 54 connected to the data bus. The forced downshift -~ignal sender 11 can ~e connected in a corres-ponding manner ~not shown). The electrically operated driving and reversing gear co~plings and brakes 4,7 are joined ~ia an adapter 55 to a program memory 56, connected to t~e bu~ 50 and corresponding to the drive gear control li~ 2'~
means 2 and the reversing gear control means 5 in Fig. 1.
An output signal from the memory 54 is sent via a line 57 to an input in the enumerator 53.
An additional write/read memory 58 is joined to an indicator device 59, which shows the operator desired data, e.g. which gear is engaged at that time.
Claims (3)
1. A control system for controlling a power trans-mission device arranged between a driving engine and an output drive axle of a vehicle and comprising a torque converter and a mechanical step gearbox, said gearbox having at least two drive gears for altering the torque transmitted to the drive axle, between which gears the shifting se-quence can be controlled automatically dependent on engine parameters, and having a reversing gear device for changing the rotational direction of the drive axle, the reversing of said gear device being controlled by a manually actuated directional selector control, characterized in that it comprises an electrical control device having drive gear control means and reversing gear control means, which are joined to gear couplings and/or gear brakes operable by electrical control and associated with the drive gears or the reversing gear for controlling the rotational speed and the direction of the drive axle, a sensor for the rota-tional speed of the drive axle or the speed of the vehicle, said sensor being connected to a comparator which is operable to compare the actual speed value from said sensor with a predetermined speed limit value stored in a memory and, when the actual value is less than said limit value, to send a go-ahead signal to said drive gear control means, and a forced downshift signal sender connected to said drive gear control means and operable upon manual actuation to produce a forced downshift signal which, if said go-ahead signal is present, causes said drive gear control means to engage the lowest drive gear, said directional selector control being connected to said control device to supply it with a directional command value signal, and when said command value signal is changed to indicate the opposite direction, a reverse signal is sent to said reversing gear control means for changing over the reversing gear and at the same time to said drive gear control means for inhibiting said forced downshift function and engaging the next lowest drive gear.
2. A control system according to claim 1, charac-terized in that said electrical control device includes a microcomputer.
3. A control system according to claims 1 or 2, characterized in that said directional selector control and said forced downshift signal sender are in the form of a multi-function control means for location adjacent a steering wheel of the vehicle.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000396515A CA1144624A (en) | 1979-06-28 | 1982-02-17 | Control system for controlling a power transmission device |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE7905695A SE417413B (en) | 1979-06-28 | 1979-06-28 | SET TO CONTROL A POWER TRANSMISSION DEVICE AND DEVICE FOR EXECUTING THE SET |
| SE7905695-8 | 1979-06-28 | ||
| CA000354890A CA1154122A (en) | 1979-06-28 | 1980-06-26 | Method and control system for controlling a power transmission device |
| CA000396515A CA1144624A (en) | 1979-06-28 | 1982-02-17 | Control system for controlling a power transmission device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1144624A true CA1144624A (en) | 1983-04-12 |
Family
ID=27166727
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000396515A Expired CA1144624A (en) | 1979-06-28 | 1982-02-17 | Control system for controlling a power transmission device |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1144624A (en) |
-
1982
- 1982-02-17 CA CA000396515A patent/CA1144624A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |