Komatsu Corporation

Kabushiki Kaisha Komatsu Seisakusho

Toshikazu Okada

Shigeru Yamamoto

Tomohiro Nakagawa

Hidekazu Nagase

Nobuhisa Kamikawa

Noriaki Namiki

Ikuo Kita

Masahiro Funato

Naoki Ishizaki

Hikosaburo Hiraki

Takashi Kuse

Hiroshi Itogawa

Shunji Oka

Norihisa Matsumoto

Naomi Kobayashi

Hisao Asada

Atsushi Uemura

A shift control device and a shift control method for a vehicle for reducing shift shock by taking into account the difference in vehicle speeds before and after shifting. In one of the main inventions, the clutch pressure of another clutch (forward clutch) is controlled to match a target vehicle speed to a calculated actual vehicle speed by the time of start of the connecting operation of a selected speed stage clutch. Since such control is performed so that the vehicle speed is caused to match the target vehicle speed, an actual vehicle speed change rate is held within a predetermined range in at least the instant that the connecting operation of the selected speed stage clutch is started. Also, in another one of the main inventions, as shown in FIG., control is performed to adjust the clutch pressure of the other clutch (forward clutch) so that the vehicle speed change rate reaches a predetermined value in the period from when the connecting operation of the selected speed stage clutch is started until when the connecting operation is completed.

Shift control device and shift control method for vehicle

A transmission is provided which has a very compact system configuration and is capable of exerting high energy efficiency over all speed regions from a low speed region to a high speed region, while providing improved operability free from a torque shortage. To this end, the transmission has an input shaft, an intermediate output shaft, a planetary gear mechanism, a first pump-motor, and a second pump-motor connected to the first pump-motor, the input shaft being coupled to a first element of the planetary gear mechanism, the second pump-motor being coupled to a second element of the planetary gear mechanism, the intermediate output shaft being coupled to a third element of the planetary gear mechanism, and the transmission further comprising a switching mechanism for selectively coupling the first pump-motor to either the input shaft or the intermediate output shaft.

Speed-changing device

A transmission is provided which has a very compact system configuration and is capable of exerting high energy efficiency over all speed regions from a low speed region to a high speed region, while providing improved operability free from a torque shortage. To this end, the transmission has an input shaft, an intermediate output shaft, a planetary gear mechanism, a first pump-motor, and a second pump-motorconnected to the first pump-motor, the input shaftbeing coupled to a first element (planetary carrier) of the planetary gear mechanism, the second pump-motorbeing coupled to a second element (sun gear) of the planetary gear mechanism, the intermediate output shaftbeing coupled to a third element (ring gear) of the planetary gear mechanism, and the transmission further comprising a switching mechanism (synchromesh mechanism) for selectively coupling the first pump-motorto either the input shaftor the intermediate output shaft

The present invention provides a drive device for a working vehicle whereby gear change shock during the forward/reverse running changeover action can be reduced while achieving shortening of cycle time and protecting various clutch mechanisms in the transmission. If a reverse running command is output from a running control device while the vehicle is running forward, an ECMV controls a braking force of a brake device so as to reduce a vehicle speed through a first prescribed speed to a second prescribed speed, and disengages the forward clutch. When the vehicle speed reaches the first prescribed speed, the ECMV puts the reverse clutch in a slipping action condition and, after the vehicle speed reaches the second prescribed speed, gradually engages the reverse clutch.

Drive device for working vehicle and method of controlling the drive of working vehicle

A vehicle control system which is capable of performing a quick decelerating operation in all vehicle speed regions and setting a direct region where power from an engine is transmitted through a mechanical transmission unit only in a hydro-mechanical transmission. The vehicle control system includes an engine and a hydro-mechanical transmission and is designed to set a tractive force-vehicle speed characteristic corresponding to the direct region where power transmission from the input shaft to the intermediate output shaft of the hydro-mechanical transmission is done by the mechanical transmission unit alone in a specified engine speed region. An engine control system controls the engine and a decelerator outputs a deceleration command according to an operating amount thereof. The engine control system controls the engine to reduce engine output torque corresponding to a specified engine speed region in response to the deceleration command.

Vehicle control system

A variable relief valve is inserted in a hydraulic piping for connecting a first pump/motor to a second pump/motor. The variable relief valve is controlled such that when shifting the transmission from forward to reverse or vice versa, a relief set pressure of the variable relief valve is reduced in response to switching of a forward/reverse shifting clutch mechanism and after completion of the switching of the forward/reverse shifting clutch mechanism, the relief set value is increased.

Control system for a hydro-mechanical transmission

A transmission system for a work vehicle, which is capable of reliably mitigating, with relatively simple arrangement, shocks caused by speed changes even in a work vehicle such as a bulldozer in which almost all operations are performed with the engine operating at full load. In the transmission system which converts the output torque of an engine into torque according to work load by operations for shifting speed gears through disengagement/engagement of friction clutches, if a downshift from a higher speed gear to a lower speed gear is effected while the engine operating at full load, the friction clutch controlling valves, controller and friction clutches allows the friction clutch corresponding to the higher speed gear to slide so as to enable power transmission and the engine controlling fuel injection system and controller allows the engine to perform high power operation (overload operation) during the sliding of the friction clutch.

Transmission system for work vehicle

A vehicle control system having an engine and a hydro-mechanical transmission, which further comprises a decelerator for changing target engine speed according to the operating amount of a decelerator pedal; a hydrostatic transmission unit controlling means for controlling a hydrostatic transmission unit so as to make the actual speed of the engine coincident with the target engine speed; and engine controlling means for controlling the engine such that if the target engine speed is changed from a first target value to a second target value lower than the first target value by the decelerator, the output torque of the engine is reduced, while keeping the ratio of the amount of change in the output torque of the engine to the amount of change in the target engine speed constant or substantially constant.

To provide a dual tilt control system for a work vehicle, the system being capable of using a switching valve adapted to low pressure and low flow rates and left and right tilt cylinders of the same diameter and yielding large force during pitch and dual tilt operations and requiring no piston valve. A left tilt cylinder driving hydraulic circuit and a right tilt cylinder driving hydraulic circuit for respectively supplying pressure oil from a hydraulic pump to the left and right cylinders are arranged in parallel and comprise a left tilt cylinder actuation switching valve and a right tilt cylinder actuation switching valve, respectively. In a pilot pressure signal circuit for controlling the tilt cylinder actuation switching valves, a pilot switching valve for switching a blade between the pitch operation, a single tilt operation and the dual tilt operation by means of the left and right cylinders is provided.

Dual tilt control system for work vehicle

A steering method and steering system which enable a minimum turn radius more than the discharge capacities of a hydraulic motor and a hydraulic pump and which positively prevent the unstable traveling and turning behavior of a vehicle when the vehicle makes a pivot turn. The vehicle is provided with a pair of brakes for right and left output shafts and designed to transmit the driving force of the hydraulic motor to the output shafts through planetary gear mechanisms. During a pivot turn of the vehicle, an operation of the brake of either one of the right and left output shafts and a transmission of a driving force from the hydraulic motor to a planetary gear mechanism are simultaneously carried out for a specified period of time and thereafter, the transmission of the driving force from the hydraulic motor to the planetary gear mechanism is interrupted.

Steering method and steering system for tracklaying vehicle

A controlling device for a hydraulically operated cooling fan capable of obtaining optimum cooling efficiency by continuously controlling a rotational frequency of the cooling fan according to a cooling water temperature, a hydraulic oil temperature, and an engine speed is provided. To this end, the controlling device includes a hydraulic motor ( ) for driving a cooling fan ( ), a variable displacement hydraulic pump ( ) capable of controlling the rotational frequency of the hydraulic motor ( ), a cooling water temperature sensor ( ) for detecting a cooling water temperature (TW), a hydraulic oil temperature sensor (22) for detecting a hydraulic oil temperature (To), an engine speed sensor ( ) for detecting an engine speed (E), and a controller ( ) which inputs detected signals from these sensors ( ), computes and outputs a discharge capacity command value of the variable displacement hydraulic pump ( ) according to the inputted cooling water temperature (Tw), hydraulic oil temperature (To), and engine speed (E), and continuously controls a rotational frequency (N) of the cooling fan ( ) by means of the variable displacement hydraulic pump ( ).

Controlling device for hydraulically operated cooling fan

There is provided an engine speed control system for a work vehicle which is designed to reduce engine noise and suppress fuel consumption during vehicle suspension, the control system being capable of reducing possible instantaneous impact load caused by gear shift clutch engagement when the work vehicle resumes operation after suspension. If it is determined the state of the vehicle is changed from a work-loaded condition to a non-loaded condition, the engine speed of the vehicle is decreased to a first specified engine speed and after the first specified engine speed is maintained for a first specified period of time, the engine speed is further decreased to a second specified engine speed. In addition, if it is determined the vehicle has restored its work-loaded condition while the first or second specified engine speed being maintained, the limitation of the engine speed to the first or second specified engine speed is cancelled after an elapse of a second specified period of time after the determination.

Engine speed control system for work vehicle

Tractive force control apparatus and method for construction equipment

A bulldozer blade (10) is automatically reset to a predetermined excavating pitch while the bulldozer (20) is traveling backwardly after it has completed an operation of excavating, carrying, or dumping earth. The bulldozer blade (10) can be set to an excavating pitch, a carrying pitch, or a dumping pitch when excavating, carrying, or dumping earth while the bulldozer is traveling forwardly, the bulldozer blade being attached to the leading ends of frame members (15A, 15B) which are pivotally mounted on opposite sides of the vehicle body (20a) in such a manner that the bulldozer blade can swing longitudinally. The rotational angles of left and right lifting cylinders (21A, 21B), which are attached to the bulldozer blade, are detected by first detectors (23a, 23b) while the bulldozer is traveling backwardly after it has completed an operation of excavating, carrying, or dumping earth, and the bulldozer blade is automatically reset to a predetermined excavating pitch from the carrying pitch or the dumping pitch in response to a command issued by a controller (50) which receives detection signals from the first detectors.

Bulldozer blade pitch control method and controller for the same

A hydraulic drive system for the pitch cylinders (4A, 4B) of a bulldozer blade apparatus can include (a) main hydraulic pumps (30A, 30B) and an assistant hydraulic pump (31) to make up the assistant hydraulic circuit, (b) variable displacement hydraulic pumps (21A, 21B), or (c) fixed displacement hydraulic pumps (30A, 30B) and a plurality of solenoid selector valves such that the pitch cylinders can be connected in series. The assistant hydraulic pump (31) is connectable to delivery lines of the main hydraulic pumps through an assistant solenoid selector valve (32) which is controlled by an external signal. The blade (10) can be formed so that a line (14) tangential to the lower edge of the curved panel of the blade is inclined rearwardly with respect to the front face (13) of the blade edge member (12). Earth-moving work can be performed by inclining the blade (10) rearwardly by an angle (.theta..sub.1) with respect to its posture in digging work, and earth-dumping work can be performed by inclining the blade (10) forwardly by an angle (.theta..sub.2) with respect to its posture in digging work. The coupling positions of the two pitch cylinders (4A, 4B) can be in asymmetrical relation to each other. Control signals can be provided by a blade lever (23), tilt/pitch changeover switch (24), and pitch speed changeover switch (25). The tilt/pitch changeover switch (24) and pitch speed changeover switch (25) can be replaced by pitch-dump selector switch (25A) and pitch-back selector switch (24A).

Growing community of inventors

Osaka, Japan

Toshikazu Okada