Abstract: An automatic transmission comprises a forward/reverse selection hydraulic servomechanism 70 which actuates a dog clutch and a plurality of clutches 11, 12, 13, 14 and 15. For this automatic transmission, a control system comprises first˜fifth on/off solenoid valves 81˜85 and first˜third linear solenoid valves 86˜88. These valves are used to control the supply and drain of a line pressure to and from the forward/reverse selection hydraulic servomechanism 70 and first˜fifth shift valves 60, 62, 64, 66 and 68 so as to control the actuation thereof for the selective engagement of the clutches. This system, when it detects, by a hydraulic switch 93, a condition that the D range is selected and that the actuation command signals being sent to the solenoid valves correspond to one of the signal combinations which are used for setting the driving modes of the D range, allows the actuation of the solenoid valves by these actuation command signals.

Abstract: The present invention provides a shift control valve that controls the supply of engagement control hydraulic pressure to a drive friction engagement element and a reverse friction engagement element, having first and second main pressure oil lines (such as oil lines 151, 152, and 155) provided in parallel between a manual valve 58 and an oil line 100 (main pressure supply source) linked to a main regulator valve 50, oil lines 121, 122, and 156 that connect the manual valve 58 to a LOW clutch 11, and oil lines 130, 131, 132, and 133 that connect the manual valve 58 to a reverse clutch 14, and a first linear solenoid valve 86 (linear A) that allows the main pressure to be set as desired being provided to at least one of the first and second main pressure oil lines.

Abstract: A parallel shaft transmission comprising: an input shaft 1, first counter shaft 2, second counter shaft 3, output shaft 4 that are parallel to each other; set of two first change gear trains 21a, 22a, 21b, 22b disposed between the input shaft 1 and first conter shaft 2; first and second clutch means 11, 12 for connecting and disconnecting the input shaft 1 and first change drive gear; set of two second change gear trains 22a, 23a, 22c, 23c disposed between the first counter shaft 2 and second counter shaft 3; third and fourth clutch means for connecting ad disconnecting the second counter shaft 3 and second change driven gear; third change gear trains 23d, 24d disposed between the second counter shaft 3 and output shaft 4; and fifth clutch means 15 for connecting and disconnecting the first counter shaft 2 and output shaft 4.

Abstract: A system for controlling an automatic transmission of a vehicle which determines a downgrade or upgrade parameter based on the vehicle acceleration and selects one from among a plurality of shift programs based on the determined grade parameter to determine a gear ratio based on the selected shift program. The system includes a navigation system which determines the instantaneous vehicle position and outputs road information including upgrade/downgrade condition of road including the determined instantaneous vehicle position. In the system, the grade parameter is corrected based on the navigation information and the grade parameter such that the one from among a plurality of shift programs is selected based on the corrected grade parameter, thereby enhancing drivability during downgrade running, without being affected even if the navigation information is temporarily invalid.

Abstract: A shift control system for an automatic transmission comprises a shift lever 201, which is shifted among a “P” position, an “N” position and an “S” position. A first shift guide path 211 is provided to guide the shift lever from the “P” position through the “N” position to the “S” position, and a second shift guide path 212 is provided to guide the shift lever which has been positioned at the “S” position in a direction different from that of the first shift guide path. Along this second shift guide path, the shift lever is shifted to select and set a plurality of ranges necessary for driving a vehicle, including a forward drive range, a neutral range and a reverse drive range.

Abstract: A shift control system is arranged such that a shift lever 201 is movable to a “P” position, an “R” position, an “N” position, a “D5” position and a “D4” position along a first shift guide path 211, it is movable also from the “D4” position to a “3/M” position along a connection shift guide path 212, and it is movable also along a second shift guide path 213, from the “3/M” position into a direction different from that of the connection shift guide path 212. When the shift lever is shifted to the “D5” position, the transmission is set into an automatic shift control with forward drive speed ratios up to the FIFTH speed ratio. When the shift lever is shifted to the “D4” position, the transmission is set into an automatic shift control with forward drive speed ratios up to the FOURTH speed ratio.

Abstract: A system for controlling an automatic transmission of a vehicle which determines a downgrade or upgrade parameter based on the vehicle acceleration and selects one from among a plurality of shift maps (programs) based on the determined grade parameter to determine a gear ratio based on the selected shift program. The system includes a navigation system which stores the road information including the kinds of road. The system determines whether the vehicle runs on a relative road such an alley or a traffic jammed expressway based on the vehicle speed change, the vehicle-stopping-time and the navigation information and if it does, changes the upshift line of the level-road map in the direction in which the vehicle speed increases such that upshift is not likely to occur, or in the direction in which the vehicle speed decreases such that the upshift is more likely to occur, thereby enhancing driveability.

Abstract: A control system for an automatic vehicle transmission which has auto-shifting means or auto-shift mode for determining a gear to be shifted to in accordance with predetermined gearshift scheduling characteristics in response to the detected vehicle speed and the engine load, and manual-shifting means or manual-shift mode for determining a gear to be shifted to in response to a manual-shift command generated by the vehicle driver. The system further includes auto-downshifting means or sub-auto-shift mode for determining a gear to be downshifted to if the detected vehicle speed is less than a threshold value when the manual-shifting means is in operation. In the system it is estimated whether the vehicle is hill climbing or hill descending, and the threshold value is increasing when the vehicle is hill climbing or descending. With the arrangement, it becomes possible to downshift before the drivability or driver's comfort is degraded during the hill climbing or descending.

Abstract: At downshifting, hydraulic pressure of hydraulic clutch on engaging side (ON clutch pressure) is increased when an input and output speed ratio ("Gratio") has fallen below a predetermined value YGDNS. YGDNS is variably set depending on the vehicle speed and the engine temperature so that it becomes a lower value at a high vehicle speed than at a low vehicle speed, and a higher value at a low engine temperature than at a high temperature. When a downshifting command to a still lower speed stage is issued during downshifting control (when FTBD=1), a downshifting completion processing is performed in the course of the downshifting control (step in S111). Oil pressure in a hydraulic engaging element on the disengaging side QDNOFF and oil pressure in a hydraulic engaging element on the engaging side QDNON are switched to the oil pressures at the time of completion of downshifting, to thereby complete the first step downshifting control at an early time.

Abstract: A system for controlling an automatic transmission mounted on a vehicle, including an automatic mode in which a gear is retrieved from predetermined gearshift characteristics by the detected vehicle speed and the engine load and a manual mode in which a gear is designated by a device manually operated by a vehicle driver. In the system, a temperature in an exhaust pipe of the vehicle is estimated based on the detecting operating conditions and the gear designated in the manual mode is corrected to upshift by one gear, if the estimated exhaust pipe temperature is found to exceed a predetermined temperature, thereby improving avoidance of the occurrence of excessive thermal load of components in the vicinity of the exhaust pipe, and that, by not conducting forced upshift until such time, fully exploits the features of the manual mode and, by this, makes the product more appealing to customers.

Abstract: Upshifting is performed in a short time without giving rise to shocks. For that purpose, at the time of upshifting, a hydraulic pressure (QUPOFF) of a hydraulic engaging element on disengaging side is controlled such that the input and output speed ratio ("Gratio") of a transmission is decreased to, and held at, a predetermined slipping region (YG(N)S) that is lower than an engaging region (YG(N)L)-YG(N)H) to be set based on a gear ratio which is established by the engagement of the hydraulic engaging element on the disengaging side. The hydraulic pressure (QUPON) of a hydraulic engaging element on engaging side is gradually increased. When "Gratio" once falls below YG(N)L and then increases up again to YGCONOK, QUPOFF is lowered to a predetermined low pressure (QUPOFFB) at a lapse of a predetermined time (YTMUP8). Once "Gratio">YGCONOK, QUPON is increased to a predetermined high pressure QUPONB at a lapse of a second predetermined time YTMUP3.

Abstract: Even if a rotational speed of an engine has already increased due to slipping of a fluid torque converter at the time of start of downshifting, a smooth downshifting is performed. For that purpose, there is obtained a speed change developing degree function K(etrm) of the rotational speed of the engine at the time of start of downshifting, the developing degree being dependent on an increase in the rotational speed of the engine due to slipping in the fluid torque converter. The function K(etrm) is obtained with a speed ratio "etrm" of the fluid torque converter at the time of starting of downshifting as a parameter. A boosting correction value QDNOFFZ is computed by multiplying a reference correction value QDNOFFZO by K(etrm) (step S108-5). The hydraulic pressure of the hydraulic engaging element on the disengaging side during downshifting is boosted by the amount of QDNOFFZ (step S108-6).

Abstract: A system for controlling an automatic vehicle transmission, including a gear system and hydraulic clutches which hold a member of the gear system stationary to produce gear reduction or reverse, having an oil line which connects the clutches to an oil pressure source, a pressure control valve having a solenoid provided in the oil line which generates a regulated oil pressure to be supplied to the clutches in response to a current supplied to the solenoid, a switch valve provided in the oil line which switches the oil pressure to be supplied to the one of the clutches between the regulated oil pressure and a line pressure. In the system, it is discriminated whether the pressure control valve does not supply the regulated oil pressure to the clutches and if so, a dither current is supplied to the solenoid such that the valve repeatedly performs a vibrational motion to remove any grit therefrom, thereby removing grit without causing gear-shift shock or clutch vibration.

Abstract: A system for estimating a temperature of a vehicle hydraulically-operated transmission including a hydraulic torque converter, a plurality of frictional engaging elements such as clutches installed in the transmission and a hydraulic pressure supplying circuit for discharging hydraulic fluid from one of said plurality of frictional engaging elements and for supplying hydraulic fluid to another to bring said one and another one of said plurality of frictional engaging elements into operation such that gear-shift is effected in the transmission. A heat quantity generated by the hydraulic coupling means (.DELTA.Ttr), a heat quantity generated by at least one of the frictional engaging elements at gearshift (.DELTA.Tcl(No)), a heat quantity generated by stirring of the hydraulic fluid (.notident.Tst), a heat quantity generated or absorbed at a heat exchanger which exchanges heat from the fluid (.DELTA.

Abstract: There are prevented shocks that will occur when a switchover speed changing is made to transfer from one speed changing, in the midst of that speed changing, to another speed changing when the input and output speed ratio "Gratio", which serves a control parameter, is not accurately detected. For that purpose, there is used a flag FGFAIL for setting "1" when the input and output speed ratio "Gratio", at the time of non-speed changing, does not lie within a predetermined range based on the gear ratio of the speed stage that is being established at that time. A switchover speed changing in which switching to another speed changing is made during a speed changing is prohibited when FGFAIL=1.

Abstract: Manual speed changing is performed in a shorter time without giving rise to shocks. For that purpose, at the time of manual speed changing, a hydraulic pressure QUPON of a hydraulic engaging element on the engaging side is corrected by boosting. A correction value QUPONX before starting of an inertia phase and a correction value QUPONY after starting of the inertia phase are separately set. By making QUPONX>QUPONY, the time required for manual speed changing as well as the shocks at the time of speed changing are reduced.

Abstract: A control system for an automatic vehicle transmission having an auto-shifting device for determining an auto-shifting gearshift signal indicative of a gear to be shifted to in accordance with predetermined gearshift scheduling characteristics in response to a detected vehicle speed and an engine load, and a manual-shifting device for determining a manual-shifting signal indicative of a gear to be shifted to in response to a manual-shift command. A gearshift is conducted in response to one of the auto-shifting gearshift signal and the manual-shifting gearshift signal. In the system, the manual-shifting command is inhibited from being accepted for a predetermined period since the gearshift device conducted a gearshift in response to the auto-shifting gearshift signal. With this arrangement, it is possible to prevent down shifting from occurring consecutively so as to prevent drivability or driver's comfort from being degraded.

Abstract: A changeover valve (13) connected to a shift valve unit (12) via four oil passages L3-L6, and two pressure regulating valves (14.sub.1, 14.sub.2) are provided. At speed changing when the changeover valve (13) is in a first (right) position, an off-going hydraulic clutch is connected to oil passage L3 to control its pressure drop by the pressure regulating valve (14.sub.1) and an on-coming hydraulic clutch is connected to L5 to control its pressure rise by the pressure regulating valve (14.sub.2). After completion of the speed changing, the changeover valve (13) is switched to a second (left) position. At speed changing when the changeover valve (13) is in the second position, an on-coming hydraulic clutch is connected to L4 to control its pressure rise by the pressure regulating valve (14.sub.1) and an off-going hydraulic clutch is connected to the L6 to control its pressure drop by the pressure regulating valve (14).

Abstract: When switching to a forward running is made while a vehicle is running in a reverse direction, a switching to the forward running condition is made at an early time to thereby prevent the deterioration of the durability of the hydraulic engaging element due to slipping. For that purpose, when a vehicle speed (V) has exceeded a predetermined value (YVa) in a reverse range (R) and also when the vehicle speed (V) has never fallen below the predetermined value (YVa) in a neutral range (N), a reverse signal (FREV=1) is outputted. If FREV=1 at the time of switching to the forward range, the relationship between the vehicle speed and the speed stage (speed change map) is set to one (a reverse-running-measure speed change map) which is different from that at an ordinary time, to thereby determine the speed stage to be established. Then, a low speed stage is established even at a relatively high vehicle speed.

Abstract: A vehicle automatic transmission control system which makes it possible to estimate an ATF temperature without using an expensive ATF temperature sensor. The estimation of the ATF temperature is configured such that based on the coolant temperature at engine starting, the temperature increase owing to heat inflow to the ATF per unit time and the temperature decrease owing to heat outflow from the ATF per unit time are calculated quantitatively and the sum of the calculated values is used to determine the estimated ATF temperature TATF. More specifically, when it is found that only a short time has passed between engine turnoff and restarting, the ATF temperature is estimated at engine restarting from the coolant temperature at engine turnoff, the estimated ATF temperature at engine turnoff and the coolant temperature at engine restarting.