Nissan Motor Company Limited

Other

Toshiharu Takasaki

Tomoyuki Hara

Hirotaka Kusukawa

Tadahiko Kato

Shigeo Murata

Kazuhisa Shimada

Hiroyuki Nakano

Osamu Sugitani

Akira Nakabayashi

Yoshiaki Tajima

Kiyonori Hirao

Masaki Nakamura

Tsutomu Niimi

Kenichi Tobita

Izumi Amemiya

Hidemitsu Sumino

Kotaro Tanaka

A device for controlling the distribution of drive force includes a driven wheel drive force distribution reference command value calculator configured to determine a driven-wheel-oriented drive force distribution reference command value from the estimated value of the drive force sent to the drive wheels and a drive force reference distribution ratio, and a driven wheel drive force distribution command value calculator configured to determine a driven-wheel-oriented drive force distribution command value by correcting the driven wheel drive force distribution reference command value by a correction amount that differs between the electric motor operating mode and the electric motor non-operating mode, and to make the correction amount for the electric motor operating mode greater than the correction amount for the electric motor non-operating mode.

Device for controlling distribution force in a four-wheel drive vehicle

A drive force distribution apparatus is provided with an input shaft, first and second output shafts, a first epicyclic gear group, a second epicyclic gear group and a motor/generator. The first epicyclic gear group has two degrees of freedom, with the first epicyclic gear group including a first gear coupled to the input shaft, a second gear coupled to the first output shaft and a third gear. The second epicyclic gear group has two degrees of freedom, with the second epicyclic gear group including a first gear coupled to the input shaft, a second gear coupled to the second output shaft and a third gear. The motor/generator is operatively coupled to the third gears of the first and second epicyclic gear groups so that mutually different drive forces are transmitted from the motor/generator to the first and second epicyclic gear groups.

Drive force distribution apparatus

In a transfer drive mode switching control system employing a shift actuator that switches from one of a plurality of drive mode positions of a transfer to the other, a drive mode position sensor is provided to detect the drive mode position switched by the shift actuator and to generate information regarding the drive mode position. A transfer control unit outputs a control command signal based on the drive mode position information to the shift actuator for controlling switching between the drive mode positions responsively to a driver-selected drive mode. The transfer control unit allows only a switching operation between predetermined two different drive mode positions corresponding to both ends of a working range of the shift actuator at which motion of the shift actuator is stopped mechanically, in presence of a failure in the drive mode position sensor.

Transfer drive mode switching control system

A limiter plug and a drain plug are juxtaposed in a valve block. The limiter plug is provided with a thermo-switch of which operation, when a predetermined temperature is reached, opens a communication passage for drainage by means of a limiter pin. The drain plug is provided with a drain pin for draining a high-pressure oil in conjunction with the drainage action of the limit pin induced by the thermo-switch so that, when the predetermined temperature is reached, it substantially nullifies the torque for switching from 4 wheel-drive to 2 wheel-drive. In the status of no operation of the thermo-switch, the drain pin when a predetermined torque is reached, gradually opens the drain hole while catching a balance, to limit the torque to a predetermined value.

Drain mechanism for hydraulic power transmission joint

A valve block coupled to a rotor is provided with a drain mechanism that includes a drain pin adapted to open and close a drain hole. The drain pin is incorporated in a drain plug by providing a support by a return spring. The drain pin has an orifice for generating a flow resistance. One end turn portion of the return spring is press fitted into the interior of the drain pin having the orifice, while the other end turn portion of the return spring is press fitted into the interior of a limiter plug having a limiter pin, whereby the drain pin is rotationally positioned to alleviate cavitation noises.

Hydraulic power transmission joint

A torque varying mechanism comprises an accommodation hole that has a relief hole formed in its bottom and that receives a check ball therein. The accommodation hole is configured so as to present a relationship in which the area of flow passage between the accommodation hole and the check ball increases linearly as a function of the amount of displacement of the check ball after opening of the relief hole, after which the flow passage area keeps a unvarying value. A hysteresis characteristic is imposed on a switching point where switching is made between a high torque transmission characteristic and a low torque transmission characteristic relative to an increase and a decrease of the vehicle velocity.

A joint includes therein a valve serving to cut off torque transmitted from a front wheel associated driving shaft to a rear wheel associated driven shaft by the action of a weight based on a centrifugal force when a predetermined number of rotations is reached. The valve is coupled to a rotor or a housing connected to the driven shaft so that the rotations of the valves are in synchronism with rotations of the driven shaft. For this reason, the number of rotations of the valve is determined by the number of rotations of the rear wheel associated with the driven shaft, allowing the torque to be cut off depending on the vehicle velocity.

A drain plug is disposed in a drain hole through which oil is discharged from a high-pressure chamber formed in a valve block. Within the drain plug there is arranged a drain pin that slidably opens and closes the drain hole. A fixed pin serves to restrict a displacement of the drain pin. A thermo-switch is located within a low-pressure chamber behind the drain pin in such a manner as to be urged by a return spring so that the drain pin is pressed to keep the drain hole closed. When a predetermined temperature is reached, the thermo-switch allows its head pin to extend, with the reaction force as a result of abutment of the head pin against the fixed pin causing the thermo-switch to retreat to release the pressing force exerted on the drain pin. In consequence, the drain pin is displaced by a high pressure toward the direction in which the drain hole is opened, allowing high-pressure oil to be drained into the low pressure side.

An axially extending extension is formed on a bearing retainer provided adjacent to a valve block of a joint and press-fitted into the interior of a housing. The extension has at its outer peripheral end a bearing by way of which the bearing retainer is rotatably supported by a differential gear case located outside thereof. This allows moment arising from rotational secondary torque received by the housing to be transmitted from the bearing retainer extension via the bearing to the outside differential gear case, thereby preventing the moment from acting on a main shaft which is a centrally located output shaft.

A torque characteristic shifting mechanism is provided in an accommodation hole of a rotary valve. The torque characteristic shifting mechanism changes over the torque characteristics in a multi-step manner with an increase of the vehicle velocity by setting the distances so as to meet the relationships R3&ap;R2>R1 or R2>R3>R1 where R1, R2 and R3 are the distance from a center of rotation of a weight member accommodated rockably around the center of rotation to a center of the ball blocking the drain hole, the distance from the center of rotation to a center of gravity of the weight member and the distance from the center of rotation to a center of a spring, respectively.

A plunger is accommodated in each of a plurality of plunger chambers formed axially in a rotor, with the plunger being displaced by rotation of a cam face associated with a housing. A first one way valve for intake is incorporated in the head of each plunger and a second one way valve for discharge is disposed within in a discharge hole leading to the plunger chambers. The intake stroke of the plunger caused by rotation of the cam opens the first one way valve to suck oil from a low pressure chamber into the plunger chamber. The discharge stroke of the plunger opens the second one way valve to allow the discharged oil to flow through the orifice into the low pressure chamber, whereby a torque corresponding to the relative rotational-speed difference is transmitted from the housing side to the rotor side.

A lubrication apparatus in a vehicular power transmission unit includes device pinion shaft which is rotatably supported by a bearing disposed at a rear end portion of a casing. The casing contains lubricating fluid. A pickup member is disposed on the drive pinion shaft and picks up lubricating fluid upon rotation of the drive pinion shaft. A trough is formed on a wall of the casing in an inclined relation to the axis of the drive pinion shaft. The trough receives the lubricating fluid which is picked up and allows the lubricating fluid to flow under the influence of gravity to the rear end portion of the casing for lubricating the bearing located thereof.

Lubrication apparatus in power transmission unit

In a four wheel drive system for an automotive vehicle, a detected value .DELTA.V.sub.W of difference of rotating speed between the front and rear wheels is compared with a threshold .DELTA.V.sub.W0 determined in accordance with a pseudo vehicle speed V.sub.FF (S116, S213). As a result of this, when a determination is made that the pseudo vehicle speed V.sub.FF is in a directly connecting four wheel drive condition inhibiting range, a directly connecting four wheel drive condition inhibiting signal S.sub.N is sent out (S121), so that a front wheel side torque distribution instruction value T.sub.2 is determined as a value preventing the directly connecting four wheel drive condition. Thereby, in case of using of the different diameter wheel, a deterioration of stability and an increase of load of power train system caused by the directly connecting four wheel drive condition can be prevented.

Four wheel drive system for automotive vehicle

A driving-torque control system for a four-wheel-drive vehicle includes a transfer clutch employed in a transfer of the four-wheel-drive vehicle for varying a distribution ratio of driving torque between front and rear road wheels depending on a front-and-rear wheel revolution-speed difference. A calculation unit derives a command value of the engaging force of the transfer clutch from the front-and-rear wheel revolution-speed difference. A load-condition detection unit detects an input load condition of the transfer clutch, on the basis of the front-and-rear wheel revolution-speed difference and the command value of the engaging force. A comparing unit compares the input load condition detected by the load-condition detection unit with a predetermined threshold. A compensation unit compensates the engaging force of the transfer clutch so that the transfer clutch is held in a completely engaged state for a predetermined holding time duration, when the input load condition exceeds the predetermined threshold.

Driving-torque control system for four-wheel-drive vehicle

A system for controlling a four-wheel drive for a motor vehicle comprises a drive mode switch for detecting a drive mode of the motor vehicle selectable between a two-wheel drive mode and a four-wheel drive mode. The four-wheel drive mode is selectable between a direct-coupled four-wheel drive mode. A an auto four-wheel drive mode, a controller controls the distribution of traction between main and secondary driving wheels. A traction transmission train distributes traction between the main and secondary driving wheels. The traction transmission train has an oil pressure supply system having a friction clutch and a solenoid.

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Kanagawa, Japan

Toshiharu Takasaki