Abstract: The present disclosure is directed toward a method for dissipating power through a machine. The method may include directing power into a power system of the machine. The method may further include controlling a parasitic load of the power system to increase dissipation of the power system, the controlling of the parasitic load being a function of a power dissipation limit of the power system.

Abstract: A process for assisting the driving of a vehicle provided with a braking system including brake calipers able to be activated as a function of a target braking force, including the steps of: determining an instantaneous state of the vehicle defined by state variables measured by sensors with which the vehicle is provided; testing a logical entry condition verified when the velocity of the vehicle is zero and when the slope is greater than a pre-defined slope; when the logical entry condition is verified, testing a logical exit condition; automatically operating the braking system to keep the vehicle static on the slope while the logical exit condition is not verified; and automatically releasing the activation of the braking system when the logical exit condition is verified.

Abstract: A method of controlling a drivetrain of a vehicle in which the drivetrain comprises a motor, a transmission with starting gears and a clutch located between the motor and transmission, a manual shift lever, and a control unit, for controlling the transmission and clutch, that communicates with a speed sensor, and an accelerator pedal and shift lever actuation sensors. When starting off from coasting, a starting gear is determined in a manner that can be influenced by the driver via actuating the manual shift lever. To assist the driver, it is checked whether the transmission is in neutral and the clutch is engaged, if the vehicle speed is within a specified speed range. If so, the clutch is disengaged, another gear is engaged, and starting is initiated in combination with situation-dependent clutch engagement and carried out as a function of accelerator pedal actuation, provided the shift lever has not been actuated.

Abstract: There is provided a retarder control device which is simple in constitution and can reliably apply braking. An engine rotational speed detector detects an engine rotational speed, gear step detection means detects a gear step of a transmission, an accelerator operation detector detects the operated state of an accelerator, and a retarder controller previously stores automatic braking amount determination data representing the relation between the engine rotational speed and the automatic braking amount of a retarder corresponding to each gear step of the transmission and controls the retarder according to the automatic braking amount of the retarder calculated from the automatic braking amount determination data based on the detected engine rotational speed and gear step of the transmission when the accelerator is judged to be off from the detected operated state of the accelerator.

Abstract: A system for braking a vehicle includes a transmission having a plurality of gear sets for establishing a plurality of forward and reverse gear ratios and an actuator for changing the gear ratios. The system also includes a plurality of sensors for detecting a plurality of vehicle operating parameters and an auxiliary brake for reducing a speed of the vehicle. A controller having a processor configured to receive a plurality of output signals from the plurality of sensors has control logic for activating one of the actuator and the auxiliary brake based on the received output signals. A method for operating the system for braking is also provided. The method includes determining road grade, determining an acceleration of the vehicle, determining an activation status of the primary brake, determining a position of the throttle, determining whether extra braking is and activating the auxiliary brake based on the extra braking determination.

Abstract: A retarding system for a mobile machine is disclosed. The machine may have a power source and a traction device driven by the power source. The retarding system may have a speed sensor configured to generate a speed signal indicative of a speed of the machine. Additionally, the retarding system may have a service brake configured to retard motion of the traction device. The retarding system may also have an engine brake configured to retard motion of the power source. In addition, the retarding system may have a controller in communication with the speed sensor, the service brake, and the engine brake. The controller may be configured to substantially concurrently retard motion of the traction device based on the speed signal and retard motion of the power source based on the speed signal.

Abstract: A system for controlling the engagement and disengagement of one or more clutches that are adapted to operatively connect an engine and an automatic transmission includes a control device for determining if a negative torque condition exists and for providing an output or signal to decrease the rotational speed of the engine in response to the determination of the existence of the negative torque condition.

Abstract: To provide a control system for a power transmission system capable of speed change control in conformity of a deceleration demand. For this purpose, there is provided a control system for a power transmission system, which has at least two transmission units having different responsiveness to a speed change and capable of setting a speed change ratio individually, and in which a total speed change ratio is determined according to the speed change ratios of the transmission units, comprising: a speed change control means for changing a priority order to carry out a speed change operation of the individual transmission units to achieve a predetermined deceleration in conformity with a content of the deceleration demand, when the predetermined deceleration is demanded.

Abstract: A method of controlling an automatic transmission includes determining whether a coast-down control condition is met, and performing coast-down control if the condition is met. The coast-down control includes selectively downshifting, such that engine speed is maintained above a fuel-cut threshold speed. The coast-down control condition may include a throttle opening being below a threshold opening, a shift-speed being higher than or equal to a threshold shift-speed, and a road slope being smaller than a predetermined slope. The method may also include determining whether a deceleration lock-up control condition is met, and performing deceleration lock-up control, including engaging a lock-up clutch, if the condition is met. The deceleration lock-up control condition may include a throttle opening being below a threshold opening, a shift-speed being below a threshold shift-speed, a brake not being operated, and a difference between an engine speed and a turbine speed being smaller than a reference value.

Abstract: In performing a down-shift based on a driver's intention of deceleration, an engine output increasing control is started at a time when a transfer torque capacity of the releasing clutch becomes small or zero and the actual oil pressure decreases to an initial oil pressure, not causing an acceleration feeling even upon the engine output increase. For estimating a time when which the real pressure of the releasing clutch decreases to a level of not higher than the initial pressure, the response of the real pressure relative to an oil pressure command value for the releasing clutch is approximated using a transfer characteristic of “first order lag+time delay.” An estimated real oil pressure obtained based on the transfer characteristic is compared with the initial pressure. It is determined a start timing of the engine output increasing control has been reached upon decrease of the estimated pressure to the initial pressure.

Abstract: An automotive automatic transmission control system is provided which is designed to increase the output of an engine in response to a driver's request to downshift a transmission for setting up the engine braking and to load the amount of working fluid to an on-coming clutch quickly during the downshift. The system works to determine whether the loaded amount of working fluid is excessive or lacking using the speeds of an input shaft of the transmission and the engine to correct the amount of working fluid to be used upon a subsequent downshift request. The use of the two speeds enables the fact that the loaded fluid amount is excessive which arises from a rise in the speed of the input shaft caused by the engine output increasing control, not by completion of the loading of the working fluid to the on-coming clutch to be found accurately.

Abstract: A throttle control method includes generating a throttle request based on a drag torque request and setting a throttle command equal to the throttle request when the throttle request is less than a throttle idle maximum. A throttle maximum increase is determined when the throttle request is greater than the throttle idle maximum and the throttle command is determined based on the throttle maximum increase. The throttle is controlled based on the throttle command.

Abstract: An automotive automatic transmission control apparatus is provided which works to increase the power of an engine in response to a request to down-shift the gear of an automatic transmission for developing the engine braking. The control apparatus includes a fail-safe circuit working to stop increasing the power of the engine when a defect in operation of a transmission hydraulic control circuit is detected after the hydraulic control circuit starts to control the hydraulic pressures to achieve the downshift of the automatic transmission. This eliminates or alleviates a problem, such as unwanted acceleration of the vehicle during the control of the downshift in the transmission.

Abstract: An automatic shift control is executed in an automatic transmission with 5 shift speeds of range hold type in the highest gear stage of a shift range at the manual shift mode. Upon selection of a shift mode from the automatic shift mode to the manual shift mode, the shift range at the manual shift mode is selected in accordance with the vehicle speed detected at the automatic shift mode. If the vehicle speed is in the low-speed range, the shift range 3 is selected. If the vehicle speed is in the medium-speed range, the shift range 4 is selected. If the vehicle speed is in t he high-speed range, the shift range 5 is selected.

Abstract: A shift control apparatus for a vehicular automatic transmission provided with a fuel cut apparatus which cuts off fuel supplied to an engine when an engine speed exceeds a predetermined value during deceleration of a vehicle, and an automatic transmission in which a gearshift is achieved with a clutch-to-clutch downshift in which a hydraulic friction device to be released is released and a hydraulic friction device to be applied is applied, further includes a controller. The controller corrects, through learning control, an apply pressure of at least one of the hydraulic friction devices to be operated for the clutch-to-clutch downshift such that an amount of drop in a rotational speed of an input shaft of the automatic transmission increases when that amount of drop is less than a predetermined value during the clutch-to-clutch downshift.

Abstract: A shift control apparatus for a vehicular automatic transmission provided with a fuel cut apparatus which cuts off fuel supplied to an engine when an engine speed exceeds a predetermined value during deceleration of a vehicle, and an automatic transmission in which a gear shift is achieved with a clutch-to-clutch downshift in which a hydraulic friction device to be released is released and a hydraulic friction device to be applied is applied, further includes a controller. The controller corrects, through learning control, an apply pressure of at least one of the hydraulic friction devices to be operated for the clutch-to-clutch downshift such that an amount of drop in a rotational speed of an input shaft of the automatic transmission decreases when that amount of drop exceeds a predetermined value during the clutch-to-clutch downshift.

Abstract: In the case where a signal for coasting time downshifting is output while fuel cut is performed and fuel supply is stopped, and a hydraulic pressure PC1 of a low speed side frictional engagement device is being gradually increased and an engine speed NE is being increased, when the fuel cut is cancelled and the fuel supply is restarted, the hydraulic pressure PC1 is reduced to a hydraulic pressure value immediately before an amount of torque is applied to the low speed side frictional engagement device.

Abstract: When an operator takes his foot from an accelerator pedal, a returning speed of the accelerator pedal is calculated from a signal of an accelerator sensor. In case where the returning speed is larger than a reference value, it is judged that the operator intends to decelerate a vehicle with an engine brake applied and the speed ratio of the continuously variable transmission is fixed to a value at the moment when the operator releases the accelerator pedal. As a result, the vehicle decelerates while the engine brake is exerted. In case where the returning speed is smaller than the reference value, it is judged that the operator intends to run the vehicle by inertia and the speed ratio of the transmission is changed to a speed ratio on an overdrive side so as to allow a coasting operation.

Abstract: The technique of the invention sets a relationship between the throttle opening (corresponding to the accelerator opening), the vehicle speed, and the target torque of a drive shaft, so as to enable a greater braking torque to be output in a working status of a cruise control system than a braking torque, which is output to the drive shaft in a full closed position of the accelerator opening in a non-working status of the cruise control system. This arrangement ensures output of a sufficient braking force to the drive shaft even under the condition of a relatively large drive load applied to the drive shaft, for example, during a downslope run, thus enabling the vehicle speed to be certainly kept at a preset level under the control of the cruise control system.

Abstract: A gear stage detection device according to the present invention comprises output shaft side pulse generating mechanism (21) for generating a pulse in a number which corresponds to a rotary phase of an output shaft (9) of a transmission (T/M), input shaft side pulse generating mechanism (20) for generating a pulse in a number which corresponds to a rotary phase of an input shaft (8) of the transmission (T/M), and gear stage determining mechanism (16) for determining the current gear stage by inputting the output shaft side pulse and input shaft side pulse generated respectively by the pulse generating mechanism, counting the number of input shaft side pulses generated when a unitary number (25 pls) of output shaft side pulses has been reached, and comparing the counted input shaft side pulse number with the unitary number of input shaft side pulses which is predetermined for each gear stage of the transmission.

Abstract: A method and system of automatically controlling engine speed of a vehicle in a turn employs an engine control system (10) to determine an optimal engine speed for the turn and an actual engine speed as sensed by an engine speed sensor (38). Engine control system (10) determines the difference between optimal engine speed and actual engine speed and compares this difference to current engine load. Based on this comparison, engine control system (10) then determines whether to alter engine speed and, if so, determines an amount to reduce the difference between optimal engine speed and actual engine speed.

Abstract: A shift control ECU includes the steps of storing a position of a shift lever; starting a count-up timer when the shift lever comes to a neutral position; and recognizing a driver's request for the neutral position when a count-up timer value attains TN(1) if the stored shift lever position is a home position and when a count-up timer value attains TN(2) if the stored shift lever position is not the home position. Here, TN(1) is set to be smaller than TN(2).

Abstract: A control device for an automatic transmission which prevents an automatic transmission from executing a “busy-shift” caused by a lower gear ratio of the highest gear, and which reduces revolutions of a driving power source at high speed. The control device includes an automatic shift mode, an independent manual shift mode, and a highest gear control. The automatic shift mode automatically determines a gear ratio of the automatic transmission on the basis of a driving condition of a vehicle having the automatic transmission. The manual shift mode determines a gear ratio of the automatic transmission by a driver's intention. The highest gear control controls the automatic transmission, so that the smallest gear ratio set by the manual shift mode is smaller than the smallest gear ratio set by the automatic shift mode. If the gear ratio of the highest gear of the automatic shift mode is not so small, a shift caused by a change of a driving condition does not easily occur.

Abstract: Automated multi-stage gearbox, includes a basic gearbox with a number of gears and a two-stage split gearing coupled in front of and in series with the basic gearbox. Shifting is effected by compressed-air cylinders which are controlled by a control computer (45) which is programmed to put the split gearing in a neutral position in the event of an input signal representing zero throttle.

Abstract: A method of operating a retarder control system for a drivetrain retarder such as an engine compression brake of a heavy-duty truck vehicle is disclosed. The method of operation includes three novel subsets each of which controls the operational state and the resistance level at which the drivetrain retarder is operated dependent at least partially upon one or more factors including speeds of one or more drivetrain components, vehicle speed, rotational speed of one or more undriven wheels, position of a brake control member, elapsed time of activation of a brake control member and/or elapsed time from a change in a selected resistance level at which the retarder control system is commanded to effect operation of the drivetrain retarder.

Abstract: A static hydraulic continuously variable transmission includes a fixed capacity swash type hydraulic pump and a variable capacity swash type hydraulic motor, connected by a hydraulic closed circuit. A control system and method controls hydraulic pressure in the variable transmission, and thereby reduces the likelihood of noise in the variable transmission under certain driving conditions. The hydraulic pressure is controlled by changing the inclination angle of a movable swash plate. The driving conditions which prompt the control system may include: (1) A signal voltage of a throttle sensor indicates the throttle opening is lower than a first threshold value; (2) A vehicle speed is over a second threshold value; (3) An acceleration is over a third threshold value; (4) An engine speed is below a fourth threshold value; and (5) Conditions (1) through (4) last for a predetermined period of time.

Abstract: The trunnion (23) of a vehicle toroidal continuously variable transmission is displaced by a step motor (52) via a control valve (56) and oil pressure servo cylinder (50) in order to vary a speed ratio of the transmission. A controller (80) calculates a target value (z*) of a control variable (z) based on an accelerator pedal depression amount (APS) and output disk rotation speed (&ohgr;co) (S5). Further, a time-variant coefficient (f) showing the relation between the trunnion displacement (y) and variation rate ({dot over (&phgr;)}) of the gyration angle (&phgr;) of the power roller, is calculated (S10). The error between the speed change response of the transmission and a target linear characteristic can be decreased by determining a command value (u) to the step motor (52) under a control gain determined based on a time differential ({dot over (f)}) of the coefficient (f) (S20).

Abstract: Given a method for controlling the trailing throttle of automotive drives, in which, assuming an automatic transmission whose control is equipped with various shift programs, the specific shift program being selected automatically as a function of the actuation of the accelerator and the transmission being in operative connection with a selector lever to be operated by the driver, for the selection of factors influencing the drag torque of the automotive drive and therefore for the drivetrain control or transmission-shift control, a specific range of a drag torque is assigned an operating mode, in which, after the system start-up and the setting of the selector lever in the permanent position for forward gear D, steps for controlling the drivetrain or the transmission are carried out individually or in combination, in each case according to the drag torque demanded, but also according to the coasting operation.

Abstract: A system and method for braking a vehicle 12 having a variable compression ratio engine 14 and a compression braking system 16. System 10 is adapted to utilize the variable compression ratio engine 14 and the compression braking system 16 in a synergistic manner to selectively control and/or vary the generated compression braking torque.

Abstract: A shift control system and a method thereof for an automatic transmission of a vehicle are provided. A shift range assembly permits selection of a specific shift range of automatic shift mode ranges and manual shift mode ranges. The automatic shift mode ranges include a park range, a reverse range, a neutral range, a drive range, and an engine-brake range. A shift lever position sensor detects the specific shift range selected by the shift lever assembly and outputs a corresponding signal. A shift controller outputs a shift signal for down-shifting from a current shift speed to a shift speed lower by 1 shift speed, if the detected specific shift range is the engine-brake range.

Abstract: A method for controlling an electronically controlled automatic transmission wherein the spontaneous gas/pedal release (FastOff) is detected and an upshift prevention system is activated when a pedal position gradient (PSTG) is lower than a pedal position gradient threshold (KF_PSTG); the state of the upshift prevention system (FFO=1) is active until a) a traction operation is detected when the actual pedal position value (PST) exceeds a traction-thrust characteristic line (KF_ZS) and of an acceleration potential value (FBN) equivalent to a road gradient value; and/or b) a time (T1, T2) has elapsed after a defined time period (THSV1, THSV2) wherein the state of the upshift prevention system (FFO=1) is abandoned.

Abstract: A shift control method and a system thereof of an automatic transmission equipped with a manual shift lever apply a modified shift pattern when a vehicle driving state satisfies a predetermined condition for changing a shift pattern during driving in a second speed range “22”. This allows shifting to be managed suitably when a vehicle is either in a heavy-load state or a base state.

Abstract: Apparatus for controlling a vehicle drive system including a drive power source, a fluid-operated power transmitting device connected to the drive power source, and an automatic transmission for transmitting a rotary motion of the fluid-operated power transmitting device to vehicle drive wheels such that a speed ratio of the automatic transmission is variable, the apparatus being arranged to increase an output of the drive power source for increasing its speed upon a shift-down action of the automatic transmission so as to increase its speed ratio during a coasting run of the vehicle, and including an output controlling element operable to control the output of the drive power source, and a gradually output increasing device operable upon the shift-down action during the coasting run, for controlling the output controlling element so as to gradually increase the speed of the drive power source at a predetermined rate.

Abstract: A method/system for controlling shifting in an automated mechanical transmission system (10) utilized on a vehicle having an engine brake (ECB), preferably controlled by an ECU (28). Shifts to be initiated while the engine brake is active and engine brake assisted upshifts are evaluated with regard to the engine built in engine brake deactivation response delay (TECBDEACTIVATE).

Abstract: A vehicle deceleration controller which is able to relatively reliably satisfy the intended deceleration of the driver irrespective of changes in the vehicle speed, the gradient of the driving road surface and the total weight of the vehicle includes a deceleration determining device that determines a required deceleration in accordance with the vehicle speed and the gradient of the driving road surface with reference to stored characteristic information, and an operation mode determining device that determines the required operation mode in accordance with the required deceleration determined by the deceleration determining device and the vehicle speed and the total vehicle weight with reference to stored characteristic information. An outputting device operates a braking force generating device with the required operation mode when it is determined that the accelerator has been released.

Abstract: A control system for an automatic vehicle transmission, in which the running resistance acting on the vehicle and the driving force generated by the vehicle are calculated, and a slope of a road on which the vehicle travels is estimated based on at least the calculated running resistance and the driving force. The vehicle running state is then discriminated by comparing the estimated slope with a predetermined value. The maximum driving force to be generated by the vehicle at the current gear ratio is calculated to determine a driving force difference from the calculated driving force and the gear ratio of the transmission is determined such that the driving force difference is a predetermined value in response to the discriminated running state, thereby enhancing the drivability.

Abstract: A system and method for braking a vehicle 12 having a variable compression ratio engine 14 and a compression braking system 16. System 10 is adapted to utilize the variable compression ratio engine 14 and the compression braking system 16 in a synergistic manner to selectively control and/or vary the generated compression braking torque.

Abstract: A semi-automatic power shift transmission for use in a forklift truck includes a manual shift lever with first and second gear positions, a hydraulically shifted transmission gear mechanism operable in one of first and second gear ratios corresponding to the first and second gear positions, a plurality of solenoids for, when energized, causing the transmission gear mechanism to be either up-shifted from the first to the second gear ratio or down-shifted from the second to the first gear ratio, a transmission speed sensor for detecting the output speed of the transmission gear mechanism to generate a transmission speed signal, an engine speed sensor for picking up the speed of a vehicle engine to produce an engine speed signal, a steering wheel angle sensor for measuring the steering wheel angle to issue a wheel angle signal, and a transmission control unit responsive to the transmission speed signal, the engine speed signal and the wheel angle signal for selectively energizing the solenoids to thereby carry o

Abstract: A hydraulic pressure distributor includes a low control valve, an N-R control valve, a line pressure control switch valve, a first fail-safe valve controlled by control pressure supplied from the low control valve and from the second pressure control valve, the first fail-safe valve undergoing port conversion to supply hydraulic pressure supplied from the third pressure control valve to the second clutch in the third and fourth speeds of the drive D range, and hydraulic pressure supplied from the third pressure control valve to the first brake in the low L range, and a second fail-safe valve controlled by reverse pressure, hydraulic pressure supplied to a fourth clutch, and hydraulic pressure supplied to the third clutch, the second fail-safe valve supplying hydraulic pressure supplied from the second pressure control valve to the second brake in the second and fourth speeds of the drive D range, and an engine brake control switch valve for supplying D-range pressure to the fourth clutch in the first and thir

Abstract: A continuously variable transmission that can provide a sufficient engine braking during a downhill running time with neither complicating the control nor inviting an increase in the program capacity is established. In a gear ratio control system 60 for gear ratios in the continuously variable transmission coupled to an engine, setting means 51 to 55 set a target speed of an input unit 21 of the continuously variable transmission during the downhill running time on the basis of a target output of the engine. Control means 56 controls the gear ratios of the continuously variable transmission so that the real speed of the input unit 21 may become the target speed of the input unit 21.

Abstract: A system for controlling downhill vehicle operation includes an electronically actuatable engine compression brake unit associated with an internal combustion engine, an electronically controllable turbocharger boost pressure adjustment device, electronically actuatable service brakes and a transmission including a number of automatically selectable gear ratios, wherein each of these components are coupled to a control computer. In accordance with one aspect of the present invention, the control computer is operable to detect a potential runaway vehicle condition and control any one or combination of engine compression brake activity, turbocharger boost pressure, service brake activity and automatic transmission shifting to thereby provide for a controlled descent down a negative grade and thereby prevent a runaway vehicle condition.

Abstract: If a throttle valve is fully-closed, it is determined whether or not a transmission is to be downshifted, by determining whether or not an acceleration of the vehicle is equal to or greater than a downshift criterion value. The downshift criterion value is set as a value that decreases as the vehicle speed deviation, which is a difference between a vehicle speed and a target vehicle speed, increases. By using the downshift criterion value, an increase in the vehicle speed deviation resulting from a quick downshift on a steep downhill can be restrained. On a gentle downhill, a downshift is not performed even if the vehicle speed deviation assumes a significant value. Thus, it becomes possible to inhibit the vehicle speed from becoming lower than the target vehicle speed during a short period after downshift. Accordingly, an increase in fuel consumption and deterioration of noise of the engine can be restrained.

Abstract: A three-way clutch unit (9) comprising a forward clutch (91), second clutch (92) and forward one way clutch (93) which sets a power recirculation mode, a high clutch (10) which sets a direct mode, and a mode change-over valve (175) which supplies an oil pressure to one of the high clutch (10) and second clutch (92), are provided.

Abstract: A brake signal which is triggered by the driver by activating the brake pedal is converted into a required braking torque. A setpoint value for the engine drag torque is determined on the basis of the braking torque. The transmission ratio of an automatic transmission is defined automatically as a function of the setpoint value for the engine drag torque by reference to a down-shift characteristic diagram. The characteristic curves of the diagram are defined with reference to the minimum engine torque.

Abstract: A vehicle deceleration controller which is able to relatively reliably satisfy the intended deceleration of the driver irrespective of changes in the vehicle speed, the gradient of the driving road surface and the total weight of the vehicle includes a deceleration determining device that determines a required deceleration in accordance with the vehicle speed and the gradient of the driving road surface with reference to stored characteristic information, and an operation mode determining device that determines the required operation mode in accordance with the required deceleration determined by the deceleration determining device and the vehicle speed and the total vehicle weight with reference to stored characteristic information. An outputting device operates a braking force generating device with the required operation mode when it is determined that the accelerator has been released.

Abstract: A method and a system for converting kinetic energy of a vehicle and part of energy supplied by its engine into energy of compressed air and using it to assist in vehicle propulsion later. A novel system of valves employing variable valve timing and valve deactivation is used to implement and control a two-way flow of compressed air between the engine and an air-reservoir where air-temperature control is maintained. During operation with compressed-air assist the engine operates both as an air-motor and as an internal combustion engine during each cycle in each cylinder. The engine can selectively and interchangeably operate either as a four-stroke or as a two-stroke internal combustion engine.

Abstract: A method/system for controlling downshifting in an automated mechanical transmission system (10) utilized on a vehicle having a manually controlled engine brake (46) and foot brake (44) system. The engine speed at which downshifts are commanded (ESD/S) is modified as a function of sensed operation of the engine brake (EB?) and foot brake (FB) systems.

Abstract: An automatic transmission control apparatus for a vehicle and a control method thereof keep the optimum vehicle speed even on a road with a gradient such as an up hill or an down hill in line. Whether or not it is necessary to change the gear ratio is determined based on a vehicle speed and the road gradient and for generating a command signal to change the gear ratio if necessary, thereby changing the gear ratio.

Abstract: A motor vehicle includes an internal combustion engine and an automatic transmission powered by the engine. The engine has a throttle valve for controlling the amount of air fed thereto. The transmission selectively assumes an Over-drive possible D-range wherein both a lock-up ON condition and a lock-up OFF condition are available and an Over-drive impossible D-range wherein only the lock-up OFF condition is kept. A control system comprises a first section for detecting a first condition of the engine wherein an open degree of the throttle valve is reduced to a certain degree; a second section for detecting a second condition of the transmission wherein the lock-up ON condition of the Over-drive possible D-range is kept; and a third section for engaging a friction element of the transmission to induce an engine brake when the first and second sections detect the first and second conditions respectively.

Abstract: A vehicle speed control system comprises a section for calculating a command driving force-required to make a sensed vehicle speed equal to a preset command vehicle speed, a section for calculating a command engine output in accordance with the command driving force and the command vehicle speed, a section for calculating a command engine speed corresponding to the command engine output from a predetermined engine torque-versus-speed characteristic relationship in an engine constraint state of minimum throttle setting and fuel cutoff inhibition when the command driving. force is negative, and a section for calculating a command transmission ratio in accordance with the command engine speed. When the driving force command is negative, the control system put the engine in the constraint state and controls a continuously variable transmission in response to the command transmission ratio so as to prevent undesired vehicle speed hunting.