Honda Giken Kogyo Kabushiki Kaisha

Kouji Yamaguchi

Yoshikazu Ishikawa

Koji Sasajima

Kazuya Maki

Takeo Suzuta

Eiichiro Kawahara

Junichi Miyake

Hideo Koyama

Noboru Yamamoto

Takashi Aoki

Masao Nishikawa

Takamichi Shimada

Yoshimi Sakurai

Noboru Ashikawa

Takafumi Tsurumi

Mitsumasa Furumoto

Kenichi Ikejiri

Kouji Sasajima

Hisashi Kunii

Akihito Ohhashi

Toshihiro Kameda

Kiyoshi Oikawa

Shogo Hattori

A hydraulic servo unit for changing the swash plate angle of a continuously variable transmission to vary its speed reduction ratio comprises a cylinder whose chamber is divided into a rod-side chamber and a head-side chamber by a piston slidably fitted therein. The rod-side chamber is supplied with working oil under predetermined hydraulic pressure through a first hydraulic pressure supply passage. A second hydraulic pressure supply passage is connected to the head-side chamber through a duty-cycle-controlled first solenoid-operated valve, and a drain hydraulic passage is connected to the second hydraulic pressure supply passage through a second duty-cycle-controlled solenoid-operated valve. The first and second solenoid-operated valves are simultaneously actuated with different duty cycles. The difference between the different duty ratios is varied to vary the rate at which the working oil flows into or out of the head-side chamber through the second hydraulic pressure supply passage, in a wide range from a very low rate to a high rate. The working oil can accurately be controlled especially in a very low rate range for operating the hydraulic servo unit at very low speed. Therefore, continuously variable transmission can precisely and smoothly be controlled for varying the speed reduction ratio.

Hydraulic servo unit with solenoid operated valves having variable duty

A shift control system for a vehicle transmission with multiple gear trains and a main shaft connected to an engine crankshaft through a clutch. The shift control system allowing shifting without disengaging the clutch. In conducting a shifting operation through a roller synchro mechanism associated with a gear train, the number of revolutions per minute of the engine crankshaft is promptly decreased through at least one of an ignition control device and a fuel supply control means to synchronize the number of revolutions per minute of a main shaft and a counter shaft of the transmission when the number of revolutions per minute of the main shaft is larger than the number of revolutions per minute for synchronizing with the counter shaft and the number of revolutions per minute of the engine crankshaft is increased to synchronize the number of revolutions per minute of the main shaft and the counter shaft when the number of revolutions per minute of the main shaft is less than the number of revolutions per minute for synchronizing with the counter shaft. This enables a prompt shifting.

Shift control system

A continuously variable transmission on a motor vehicle is controlled by establishing a target terminal acceleration GO to be reached according to an indication of the driver's intention for acceleration or deceleration, such as the amount of depression of the accelerator pedal, and also to an indication of the speed of the motor vehicle. A present calculative acceleration G.sub.CAL is calculated on the basis of a marginal power Pa of the engine which drives the continuously variable transmission. A target present acceleration Gon required at the present time to vary the present acceleration up to the target terminal acceleration Go to be reached along a desired characteristic curve is established according to the difference .DELTA.G (=Go-G.sub.CAL) between the target terminal acceleration Go to be reached and the calculative acceleration G.sub.CAL. Then, the throttle valve of the engine on the motor vehicle and the continuously variable transmission are controlled so that the target terminal acceleration Gon will be reached.

Method of controlling continuously variable transmission in combination

A method of controlling speed reduction ratio in a continuously variable speed transmission comprises the steps of setting a prescribed parameter corresponding an accelerator opening which is opened to a certain extent from a fully closed condition setting a reference engine speed corresponding to a parameter which represents a driver's intention of acceleration so as to increase as said parameter increase from said prescribed parameter when said parameter is in a range higher than said prescribed parameter setting said reference engine speed so as to increase as said parameter decreases from said prescribed parameter when said parameter is in a range lower than said prescribed parameter, and controlling said speed reduction ratio so that the engine speed coincides with said reference engine speed.

Method of controlling speed reduction ratio in a continuously variable

In a hydraulic servo unit comprising a cylinder and a piston slidably inserted therein, the cylinder chamber being divided by a piston portion into a rod-side cylinder chamber and a head-side cylinder chamber, a control apparatus for the hydraulic servo unit includes but is not limited to a first hydraulic line connecting the rod-side cylinder chamber with the hydraulic pressure source which supplies working fluid of a predetermined pressure, a second hydraulic line connecting the head-side cylinder chamber with the first hydraulic line through a first solenoid valve of duty-ratio-control, and a drain hydraulic line connecting the head-side cylinder chamber with drain through a second solenoid valve of duty-ratio-control.

Differential area motor circuit for hydrostatic transmission control

A time-dependent engine output power characteristic curve for an engine output power to vary therealong to a target value which corresponds to an indication of intention of the driver for acceleration or deceleration (e.g., the amount of depression of the accelerator pedal) is established based on the difference between a target engine output power and an actual engine output power. Then, a target rate of change of the rotational speed of the engine and a target rate of change of an indication of an engine load are established so that the actual engine output power varies along the engine output power characteristic curve, and the throttle valve and the continuously variable transmission are controlled using the target rates thus established.

A speed control apparatus for a continuously variable speed transmission comprises ratio control units for controlling a speed reduction ratio and a manual value for selecting either a running range where engine power is transmitted to the wheels or a neutral range where the engine power is not transmitted to the wheels. The speed reduction ratio is controlled by the ratio control units so as to coincide with a reference speed reduction ratio corresponding to the vehicle speed detected by a speed sensor when the neutral range is selected by manual valve.

Speed control apparatus for a continuously variable speed

In a continuously variable speed transmission having a hydraulic pump, a hydraulic motor, a hydraulic closed circuit hydraulically connecting the pump with the motor, a control apparatus has a slip sensor for detecting slip of the driving wheels and a hydraulic control apparatus for lowering hydraulic pressure in the hydraulic closed circuit in accordance with magnitude of the slip of the wheels in such a way that the driving force of the driving wheels is reduced so as to be less than a slip limit force, the slip of the driving wheels being increased when the driving force applied to the driving wheels exceeds the slip limit force.

Control apparatus for hydraulic continuously variable speed transmission

A hydraulic continuously variable speed transmission includes means for detecting a speed reduction ratio of said continuously variable speed transmission, means for detecting an accelerator opening, and means for detecting vehicle speed. During running, when the means for detecting the accelerator opening detects that the accelerator opening has been fully closed, the means for detecting speed the reduction ratio detects the speed reduction ratio at the moment, and then an operation initiating vehicle speed of said clutch valve is determined based on the detected speed reduction ratio, and when the vehicle speed detected by the means for detecting vehicle speed is reduced to the operation initiating vehicle speed, the clutch valve starts to open.

Hydraulic continuously variable speed transmission

A method of controlling speed reduction ratio comprises the following steps: determining 'EB-REF-engine speed' which is higher than 'R-REF-engine speed' when the accelerator opening is substantially closed and the vehicle brake is applied simultaneously, and controlling speed reduction ratio so that the actual engine speed coincides with the EB-REF engine speed. Although the above method also comprises the following steps as a normal ratio control: setting the R-REF engine speed in relation to the accelerator opening, and controlling speed reduction ratio so that the actual engine speed coincides with the R-REF engine speed.

Method of controlling speed reduction ratio for continuously variable

The speed reduction ratio of a continuously variable speed transmission is controlled by setting a reference engine speed according to a parameter representing a driver's intention of acceleration, such as the depression of an accelerator pedal, and controlling the speed reduction ratio so as to equalize the engine rotational speed with the reference engine speed. When the parameter is lowered such as by releasing the accelerator pedal, the process of controlling the speed reduction ratio due to a reduction in the reference engine speed caused by the reduction in the parameter is started after a certain time delay.

Method of controlling speed reduction ratio for a continuously variable

A method of controlling a speed reduction ratio includes setting a reference engine speed in correspondence with an accelerator opening, measuring the atmospheric pressure, correcting the reference engine speed in correspondence with a change of the atmospheric pressure to compensate for a change in engine output power caused by the change of the atmospheric pressure, and controlling the speed reduction ratio so that the engine speed coincides with the corrected reference engine speed.

Method of controlling speed reduction ratio of continuously variable

A continuously variable speed transmission in which a bypass line is formed between two hydraulic lines disposed between a hydraulic pump and a hydraulic motor to constitute a hydraulic closed circuit, and a opening control valve is disposed to open or close the bypass line. The opening control valve is opened when the reduction rate of the engine speed or the vehicle speed exceeds a given in order to short-cut the two lines and create a neutral condition.

Controller for continuously variable speed transmission

A hydraulic differential cylinder comprises a cylinder, a piston slidably fitted in a cylinder chamber, a piston rod with one end coupled to said piston and an inner valve disposed in said piston rod. The cylinder chamber is divided by the piston into a rod-side cylinder chamber and a head-side cylinder chamber. The piston-pressure-bearing area of the head-side cylinder chamber is greater than the piston-pressure-bearing area of the rod-side cylinder chamber. The rod-side cylinder chamber is connected via the inner valve to a constant hydraulic pressure source. The head-side cylinder chamber is connected to a control hydraulic pressure source. The inner valve has means for communicating the constanbt hydraulic pressure source with the rod-side cylinder chamber when the hydraulic pressure of the working fluid supplied from the control hydraulic pressure source to the head-side cylinder chamber is lower than a critical hydraulic pressure, and for shutting off the communication between the constant hydraulic pressure source and the rod-side cylinder chamber and for communicating the rod-side cylinder chamber with a drain when the hydraulic pressure of the working fluid supplied from the control hydraulic pressure source to the head-side cylinder chamber is higher than the critical hydraulic pressure.

Hydraulic differential cylinder

A method of controlling clutch operation, for a vehicle having a transmission and clutch means comprises setting a reference capacity of said clutch means corresponding to a parameter representing vehicle speed and an accelerator opening representing the driver's intention of acceleration or deceleration: and controlling said degree of the engine power transmitted to the wheels by adjusting the capacity of said clutch means so as to coincide with said reference capacity. An embodiment of the method includes a method of determining clutch engagement completion in continuously variable speed transmission comprises setting a lower limit of an expected clutch engagement completion vehicle speed corresponding to an accelerator opening representing operator's intention of acceleration and deceleration, determining, in vehicle start, that said clutch valve is closed to engage the clutch completely when it is detected that vehicle speed has been below the lower limit and the opening of said clutch valve has been below a given opening, and permitting successive speed ratio control.

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Saitama, Japan

Kouji Yamaguchi