Abstract:
A load control structure for a work vehicle comprises: a device for detecting operating position of a manually operated speed change operating element; an engine load detection device for detecting load on an engine of the work vehicle; a swash plate position detecting device for detecting an operating position of a swash plate of a variable displacement pump of a hydrostatic continuously variable speed change device; a pump operating device for steplessly operating the swash plate of the variable displacement pump; a motor operating device for operating a swash plate of a variable displacement motor of the hydrostatic continuously variable speed change device between at least two speed change positions including a higher speed position and a lower speed position; a control device for controlling the operations of the pump operating device and the motor operating device. The control device has a automatic pump swash plate control device for controlling the operation of the pump operating device, based on detected information from the load detection device and detected information from the swash plate position detecting device, such that the greater an engine load is, greater is the extent to which the swash plate of the variable displacement pump is operated to a low speed side; and a motor swash plate control device for controlling the motor operating device so as to change the position of the swash plate of the variable displacement motor between the at least two speed change positions.
Abstract:
A method/system for controlling an automated mechanical transmission system (10) utilized on a vehicle. To protect from driveline damage due to clutch "popping," upon sensing vehicle launch conditions (clutch (16) not engaged, transmission (14) engaged (THL>REF.sub.THL and OS
Abstract:
An automatic transmission on an automobile has an input shaft, an output shaft, a plurality of power transmitting paths disposed between the input and output shafts for establishing respective gear positions, and a plurality of engaging elements for selecting one of the power transmitting paths at a time. A shift controller disengages a previous-position engaging element and engages a next-position engaging element to switch from one of the power transmitting paths to another for thereby effecting a shift from a previous gear position to a next gear position. The shift controller provides a plurality of previous-position stages for controlling the previous-position engaging element with respective different characteristics to vary forces to disengage the previous-position engaging element in each of the gear positions, and a plurality of next-position stages for controlling the next-position engaging element with respective different characteristics to vary forces to engage the next-position engaging element in each of the gear positions. The shift controller executes the previous-position stages and the next-position stages to effect a shift between gear positions according to a change in the rotational speed of the input shaft, and executes all or selected ones of the previous-position stages and the next-position stages successively in order.
Abstract:
An electronic transmission control system for a self-propelled off-road vehicle having an internal combustion engine and multiple gear powershift transmission. The control system controls the powershift transmission and provides at least one control signal to the engine for selecting the speed at which the engine is to operate. The system includes a first electronic controller that provides transmission control signals required to command the powershift transmission to shift to and operate in any particular one of its forward gears, and second electronic controller that provides at least one engine control signal required to command the engine to operate at one of a number of different desired engine speeds and to monitor the actual engine speed. By use of gear ranges which overlap slightly, and a throttle that is infinitely adjustable within a range of engine speeds, any given ground speed within the range of possible vehicle speeds can be achieved and maintained, as long as engine is operating within its overall power envelope. Once the desired ground speed is specified by the operator, the control system automatically selects the specific transmission gear and engine speed required to achieve the desired ground speed. The control system also performs automatic upshifts or downshifts, as required, to achieve the desired ground speed. The system has a comfort mode, fuel economy mode, and a maximum horsepower mode, all selectable by the operator. The system also supports a pseudo-gear mode where the operator interface indicates there are more gears in the transmission than actually exist.
Abstract:
In a system for controlling the output power of a power train an overall control is carried out so that a mismatch is not caused between the output characteristic changeover control of a variable output characteristic engine and the speed change control of an automatic transmission. From the requested driving force and the revolution speed that are respectively found by the requested driving force detection device and the speed detection device the control output determination device finds a combination of at least two of the engine output characteristic, the speed change stage and the engine throttle opening according to the two dimensional map of the requested driving force and the revolution speed, and the changeover executing device conducts total control on the power train so that the combination can be attained. When the power train is controlled totally as the combination, a mismatch between the changeover control of engine output characteristics and the speed change control can be avoided.
Abstract:
A cruise control apparatus for a vehicle includes an automatic transmission with a predetermined gear shift characteristic for automatically shifting a gear ratio based on a relationship between the speed of the vehicle and the opening degree of a throttle valve. The apparatus is able to prevent an unwanted gear shift in the automatic transmission during cruise control without requiring a throttle sensor output indicative of the opening degree of a throttle valve. A vehicle speed sensor senses the actual speed of the vehicle and generates a corresponding output signal. A cruise control instructor generates an instruction signal for instructing a specific one among various cruise control modes. A cruise controller performs cruise control on the vehicle based on the actual vehicle speed as sensed by a vehicle speed sensor and the output signal from the cruise control instructor. An actuator is operatively connected with the throttle valve for driving it in accordance with the output signal from the cruise controller. An actuator-displacement detector is responsive to the output signals from the cruise control instructor and the cruise controller for successively detecting a displacement of the actuator. The detector compares the thus detected displacement of the actuator with a predetermined threshold value for the current gear ratio of the transmission, generate an output signal as a result of the comparison and supply it to the cruise controller, whereby the cruise controller controls the displacement of the actuator so as not to cause a gear shift in the transmission.
Abstract:
The present invention relates to a semiautomatic transmission for vehicles, construction machines or similar equipment. In one embodiment of the invention, the semiautomatic transmission comprises a synchro-mesh transmission which has an electrically controlled gear shift mechanism, an electric control unit, for controlling the gear shift mechanism, and sensors, for measuring the torque of the engine, the rotating speed of the output shaft of the transmission and the driving speed. The sensors are arranged to transmit corresponding to measured quantities to the electric control unit for selecting a gear suiting the actual driving situation. Between the output shaft, of the transmission and the drive shaft, with which the power is transmitted to the drive gear, there is, in accordance with the invention, a bidirectionally engaging overrunning clutch to connect shaft, with each other. The engaging circuit of the transmission is an electric power circuit that is opened and closed by the accelerator pedal of the engine or with a similar power regulator.
Abstract:
A hydraulic transmission control uses a plurality of solenoid valves to control the engagement of friction devices during the shifting of a transmission between gear ratios. A clutch priority valve is provided to prevent the continuous simultaneous engagement of friction devices which will establish more than one ratio. Also provided is a manually controlled valve which permits the operator to determine the range in which the transmission will operate.If the clutch priority valve has been actuated, the transmission ratio can be controlled between a low ratio, for example, second gear, and a high ratio, for example, third or fourth gear, by use of the manual valve in combination with an actuator mode valve. The clutch priority valve, when actuated, is also operable to disengage a torque converter clutch.
Abstract:
In a four wheel drive vehicle, a central differential device receives rotational power from an engine and provides it to the combination of the front wheels of the vehicle and also to the combination of the rear wheels of the vehicle. This central differential device includes a device for selectively restricting its operation. A control device is provided for this central differential device operation restriction device, and includes: (a) a means for detecting a condition representative of the road speed of the vehicle and of the load on the engine; and (b) a means for controlling the device for selectively restricting the operation of the central differential device, so that the operation of the central differential device is less restricted than otherwise, when the vehicle speed is relatively high and also the engine output is not relatively high. Various specializations of this control device, and also the method of operation thereof, are also disclosed.
Abstract:
A method and a circuit for determining the optimum gear, in terms of fuel consumption, of a motor vehicle drive is proposed, in which after upshifting, a driving power sufficient for accelerating the vehicle is to be made available regardless of such power parameters as total vehicle weight, roadway grades and the like and also regardless of the gear ratios of the gear steps. To this end, during driving, the gear ratios of the gear steps are ascertained by comparing the speeds (n, n.sub.1) before and after the transmission (12). Furthermore, these speed values (n, n.sub.1) as well as the gas pedal position (.phi.) are continuously stored briefly in memory during the drive, and a standardized power is ascertained based on the change in the driving speed (n.sub.1). After a gear shifting operation, the newly ascertained standardized power is compared with the standardized power ascertained prior to shifting, and if the new standardized power is the same or greater, the values for the driving speed (n.sub.1) and gas pedal position (.phi.) measured prior to the upshifting are recorded in a threshold value memory (24). An upshifting indication is always effected whenever the instantaneous measured values (n.sub.1, .phi.) exceed the stored threshold values in the direction of an unfavorable operating range in terms of fuel consumption. The method is applicable to both Diesel and gasoline engines as well as to large and small motors and to any arbitrary, but fixed, gear step ratios.