JP2006088763A - Control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of a vehicle capable of suppressing a vibration in starting at a high steering angle. <P>SOLUTION: An ECU executes a program including a step (S100) which detects a throttle opening, a vehicle speed, the gear step of a transmission, a steering angle, and an acceleration in the longitudinal direction of a vehicle, as the information required for determining whether or not it is necessary to control a control clutch of a control coupling, and a step (S400) which applies an engagement torque to the control clutch when it is determined that it is necessary to control the control clutch (YES at S200) since there is a possibility of occurrence of a stick slip when the steering angle is larger than a predetermined steering angle and the vehicle is in starting. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle control device, and more particularly to a vehicle control device equipped with a center differential.

  Conventionally, in a four-wheel drive vehicle, the torque output from the engine is distributed to the front and rear wheels, and if a difference in rotation between the front and rear wheels occurs during turning, a center differential that absorbs the rotation difference has been installed. There is something. Some vehicles equipped with such a center differential include a differential limiting device that limits the differential of the center differential to vary the torque distribution to the front and rear wheels.

  Japanese Patent Laid-Open No. 9-86201 (Patent Document 1) discloses a vehicle four-wheel drive device in which the torque distribution of front and rear wheels and the rear wheel rotation speed with respect to the front wheels are made variable in accordance with the gears used in the transmission. In the four-wheel drive system for a vehicle described in Patent Document 1, an engine output is guided to a carrier of a planetary gear type center differential (center differential), a ring gear meshing with a pinion gear on the carrier is set to a front wheel side axle, a sun gear is set to a transmission, A four-wheel drive device for a vehicle configured to be guided to a rear wheel side axle via a drive shaft. This four-wheel drive system for a vehicle is a planetary gear type differential comprising a carrier configured to be transmitted via an engine and a clutch, a sun gear configured to be transmitted on the input side of a transmission, and a ring gear configured to be transmitted to a rear drive shaft. Including restriction devices. The gear ratio of the planetary gear type differential limiting device is slightly different from the gear ratio of the planetary gear type center differential.

  According to the four-wheel drive system for a vehicle described in Japanese Patent Laid-Open No. 9-86201, when the clutch is turned off, the output of the engine transmits a driving force to the front and rear wheels with a predetermined torque distribution ratio by a planetary gear type center differential. The rotational speed is set to a predetermined reduction ratio set by the transmission. In this case, since the distributed rear wheel torque is transmitted through the transmission, the rear wheel is deviated in the low speed gear and the front wheel is deviated in the high speed gear. When the clutch is off, the planetary gear type differential limiting device does not function as a differential limiting device.

  On the other hand, in a state where the clutch is turned on, the driving force of the engine is input from two systems to the planetary gear type differential limiting device. In one system, the driving force of the engine is input to the sun gear of the planetary gear type differential limiting device via the sun gear of the planetary gear type center differential as in the case where the control clutch is off. On the other hand, the driving force of the engine is input to the pinion gear via the clutch and the carrier of the planetary gear type differential limiting device. The ring gear is transmitted to the rear drive shaft.

  For this reason, in the planetary gear type differential limiting device, the speed of the ring gear is increased by revolving while rotating the sun gear corresponding to the front wheel speed and the ring gear speed corresponding to the rear wheel speed directly rotating to the engine. Rotate. In this case, the low speed gear with the larger input / output rotational speed difference of the transmission also increases the differential rotational speed of the planetary gear type differential limiting device, and the rotational speed difference is caused by a slight gear ratio difference set with the center differential. Since it is further increased, a difference in rotational speed between the front and rear wheels occurs. Therefore, the slip ratio of the rear wheel can be increased as the speed is lower. In addition, the higher the speed gear, the smaller the front-rear wheel rotational speed difference and the direct-coupled four-wheel drive.

  For this reason, it is possible to increase the torque distribution with the rear wheel biased with the low speed gear and make the rear wheel rotational speed larger than that with the front wheel, and to make the torque distribution with the front wheel biased with the high speed gear nearly equal to the front wheel.

  Some planetary gear type center differentials limit differentials by the function of the center differential itself.

  The Hilux Surf New Car Manual (Non-Patent Document 1) discloses a center differential that employs a torque-sensitive LSD (Limited Slip Differential). The center differential described in Non-Patent Document 1 includes a differential case, a differential carrier meshing with the differential case and rotating together with the differential case, a pinion gear held by the differential carrier, and a sun gear and a ring gear meshing with the pinion gear. The differential case has a cylindrical shape, and a differential carrier is fitted therein. The differential carrier holds a plurality of pinion gears. Helical teeth are formed on the surface of the pinion gear, and a ring gear is disposed outside the track on which the pinion gear is disposed. A sun gear is disposed inside the track on which the pinion gear is disposed. Helical teeth are formed on the surfaces of the ring gear and the sun gear, respectively, and the helical teeth mesh with the helical teeth of the pinion gear. Torque from the engine is input to the pinion gear through the differential case and the differential carrier. Torque input to the pinion gear is finally distributed to the front wheels and the rear wheels via the sun gear and the ring gear. The ratio of torque distribution to the front and rear wheels is changed by the frictional force of the sliding surface between the sun gear and the differential carrier and the frictional force of the sliding surface between the differential case and the ring gear.

  According to the center differential described in the Hilux Surf new model car manual, part of the torque input to the pinion gear via the sun gear is distributed to the front wheels when going straight. A part of the torque input to the pinion gear via the ring gear is distributed to the rear wheels. The ratio of torque distribution during straight traveling is 40 (front wheels) vs. 60 (rear wheels).

During a turn in which a rotational difference occurs between the front and rear wheels, a thrust force is generated by the helical teeth of the pinion gear meshing with other helical teeth. With this thrust force, the sun gear is pressed against the differential carrier, and the ring gear is pressed against the differential case. Thus, the differential between the sun gear and the differential carrier is limited by the frictional force of the sliding surface between the sun gear and the differential carrier. In addition, the differential force between the differential case and the ring gear is limited by the frictional force of the sliding surface between the differential case and the ring gear. Therefore, a part of the torque input to the sun gear is transmitted to the differential carrier, and finally transmitted to the ring gear through the differential case. As a result, the differential differential of the center differential is performed, and the torque distribution from the rear is further increased than the torque distribution at the time of straight traveling.
JP-A-9-86201 "Hilux Surf New Car Manual (Part No. 71051)", Toyota Motor Corporation, October 7, 2002

  In the center differential described in the Hilux Surf new model vehicle manual, for example, when starting at a high rudder angle state, stick slip may occur on the friction sliding surface that performs differential restriction. Here, the stick slip refers to a phenomenon in which a sudden slip occurs instantaneously. When a stick-slip occurs, the torque distribution to the front and rear wheels changes abruptly, which induces torsional resonance of the drive system (such as a shaft that transmits torque). As a result, there is a problem that the floor surface of the vehicle may vibrate. However, the vehicle four-wheel drive device described in Japanese Patent Laid-Open No. 9-86201 does not consider anything about the problem of vibration of the floor surface due to stick-slip.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle control device that can suppress vibration at the time of start in a high steering angle state. .

  A vehicle control device according to a first aspect of the present invention is a vehicle control device that travels by transmitting driving force to a first wheel and a second wheel. The first wheel and the second wheel are connected via a differential. The differential device has a ratio of torque transmitted to the first wheel and the second wheel according to a rotational difference between the first wheel and the second wheel due to a frictional force of members constituting the differential device. change. The control device includes a limiting unit for limiting the differential of the differential device, a determining unit for determining whether or not the vehicle is in a starting state, and a rudder angle detecting unit for detecting the rudder angle of the vehicle And a control means for controlling the limiting means so as to limit the differential of the differential device when it is determined that the vehicle is starting and the steering angle is larger than a predetermined angle.

  According to the first aspect of the present invention, when it is determined by the determining means that the vehicle is in a starting state and the rudder angle is larger than a predetermined angle, the limiting means is controlled by the control means, and the differential of the differential device Is limited. Thus, if the differential of the differential device is limited before stick slip occurs, the occurrence of stick slip can be suppressed. Therefore, generation | occurrence | production of the vibration by a slick slip can be suppressed. If the differential of the differential device is limited at a timing opposite to that of the vibration due to stick-slip, the torque distribution to the first wheel and the second wheel is suddenly changed by the limiting means, and the reverse of the vibration due to stick-slip. Phase oscillation can be generated. Therefore, the vibration caused by the stick slip can be canceled by the vibration having the opposite phase, and the vibration caused by the stick slip can be suppressed. As a result, it is possible to provide a vehicle control device that can suppress vibration at the time of start in a high steering angle state.

  In the vehicle control apparatus according to the second invention, in addition to the configuration of the first invention, the first wheel is a front wheel. The second wheel is a rear wheel. The differential is a center differential.

  According to the second invention, it is possible to suppress vibration that may occur in the center differential that distributes torque to the front and rear wheels.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  A vehicle equipped with a control device according to an embodiment of the present invention will be described with reference to FIG. This vehicle is a four-wheel drive vehicle. Torque generated in engine 100 is input to center differential 300 through transmission 200.

  Torque input to the center differential 300 is distributed to two paths. One is a route distributed to the front wheels 406 via the front propeller shaft 400, the front differential 402 and the front drive shaft 404. The other is a path distributed to the rear wheels 506 via the rear propeller shaft 500, the rear differential 502 and the rear drive shaft 504.

  The center differential 300 is a torque sensitive LSD. When the vehicle travels straight, center differential 300 distributes torque to the front and rear wheels at a predetermined ratio. When a difference occurs in the rotational speeds of the front and rear wheels during turning, the center differential 300 changes the ratio of torque distributed to the front and rear wheels. Further, the differential of the center differential 300 is limited by the control coupling 600.

  Engine 100, transmission 200, and control coupling 600 are controlled by an ECU (Electronic Control Unit) 700. The control device according to the present embodiment is realized by a program executed by ECU 700, for example.

  In this embodiment, engine 100, transmission 200, and control coupling 600 are controlled by one ECU 700, but a plurality of ECUs may be provided.

  The ECU 700 receives detection results from a throttle opening sensor 702, a steering angle sensor 704, a G sensor 706, a front wheel speed sensor 708, a rear wheel speed sensor 710, an accelerator opening sensor 712, a stop lamp switch 714, and a position sensor 716. The signal to represent is input.

  The throttle opening sensor 702 detects the opening of a throttle valve (not shown). The steering angle sensor 704 detects the steering angle of the steering wheel. The G sensor 706 detects the longitudinal acceleration of the vehicle. Front wheel speed sensor 708 detects the number of rotations of front wheel 406. Rear wheel speed sensor 710 detects the rotational speed of rear wheel 506. The accelerator opening sensor 712 detects the amount of depression of the accelerator pedal. The stop lamp switch 714 detects whether or not the brake pedal has been depressed. The position sensor 716 detects the position of the shift lever.

  ECU 700 performs arithmetic processing based on signals transmitted from these sensors and switches, a map and a program stored in a memory (not shown). Thereby, ECU 700 controls equipment mounted on the vehicle so that the vehicle is in a desired driving state. In the present embodiment, ECU 700 controls control coupling 600 by controlling the hydraulic pressure supplied to control coupling 600 by linear solenoid 800.

  The center differential 300 and the control coupling 600 will be further described with reference to FIG.

  The center differential 300 is composed of planetary gears. Center differential 300 includes a differential carrier 302, a pinion gear 304, a ring gear 306, a sun gear 308, and a differential case 310.

  The differential carrier 302 is connected to an input shaft 900 that is connected to the output shaft of the transmission 200. Further, the differential carrier 302 is fitted into the cylindrical differential case 310. Therefore, the differential carrier 302 rotates together with the input shaft 900 and the differential case 310.

  A plurality of pinion gears 304 are rotatably held in the internal space of the differential carrier 302. The torque of engine 100 transmitted through transmission 200 is input to pinion gear 304 through differential carrier 302. Helical teeth are provided on the surface of the pinion gear 304.

  A ring gear 306 is disposed outside the track on which the pinion gear 304 is disposed. A sun gear 308 is disposed inside the track on which the pinion gear 304 is disposed. Helical teeth are provided on the surfaces of the ring gear 306 and the sun gear 308. The helical teeth of the ring gear 306 and the helical teeth of the sun gear 308 mesh with the helical teeth of the pinion gear 304. Note that inclined teeth may be provided instead of helical teeth.

  Ring gear 306 is connected to rear output shaft 1000 for driving the rear wheels. Sun gear 308 is coupled to drive gear 1100. Drive gear 1100 is connected to driven gear 1102 via a chain. The driven gear 1102 is connected to a front output shaft 1104 for driving front wheels.

  When the vehicle travels straight, part of the torque input to the pinion gear 304 is distributed to the front wheels 406 via the sun gear 308. Further, part of the torque input to the pinion gear 304 is distributed to the rear wheel 506 via the ring gear 306. The ratio of torque distribution to the front and rear wheels is, for example, 40:60. The torque may be distributed at a ratio other than this.

  At the time of turning where a difference in rotation occurs between the front and rear wheels, a thrust force is generated by the helical teeth of the pinion gear 304 meshing with other helical teeth. Due to this thrust force, the sun gear 308 is pressed against the differential carrier 302. For this reason, the differential is limited so that the rotational difference among the differential carrier 302, the ring gear 306, and the sun gear 308 is reduced by the frictional force of the sliding surface.

  In this case, a part of the torque transmitted from the pinion gear 304 to the sun gear 308 is transmitted to the ring gear 306 via the differential carrier 302 and the differential case 310. As a result, the torque distribution is more deviated from the rear wheel than when traveling straight.

  The differential limitation is performed using the control coupling 600 in addition to the function of the center differential 300 itself. The control coupling 600 includes a control clutch 602 and an outer coupling 604. The control clutch 602 is provided between the rear output shaft 1000 and the outer coupling 604. The control clutch 602 is controlled by controlling the hydraulic pressure supplied to the piston of the control coupling 600 by the linear solenoid 800.

  The outer coupling 604 is connected to the differential case 310. That is, the outer coupling 604 is connected to the differential carrier 302 via the differential case 310.

  When hydraulic pressure is supplied to the piston of the control coupling 600 and the control clutch 602 is changed from the released state to the engaged state or the semi-engaged state, the differential between the rear output shaft 1000 and the outer coupling 604 is limited. As a result, the differential between the rear output shaft 1000 and the differential carrier 302 is limited.

  Here, the rear output shaft 1000 is connected to the ring gear 306. Therefore, the differential between the differential carrier 302 and the ring gear 306 is limited. As a result, the differential among the differential carrier 302, the ring gear 306, and the sun gear 308 is limited.

  A control structure of a program executed by ECU 700 of the control device according to the present embodiment will be described with reference to FIG.

  Information required to determine whether or not it is necessary to control the control clutch 602 of the control coupling 600 at step (hereinafter abbreviated as S) 100 includes throttle opening, vehicle speed, transmission 200 The gear stage, rudder angle, and vehicle longitudinal acceleration are detected. The throttle opening is detected based on a signal transmitted from the throttle opening sensor 702. The vehicle speed is detected based on signals transmitted from the front wheel speed sensor 708 and the rear wheel speed sensor 710. The gear stage of the transmission 200 is detected based on a shift diagram stored in the memory of the ECU 700. The steering angle is detected based on a signal transmitted from the steering angle sensor 704. The acceleration is detected based on the signal transmitted from the G sensor 706.

  In S200, ECU 700 determines whether or not control clutch 602 needs to be controlled based on the detected information. Here, the case where the control clutch 602 needs to be controlled means a case where stick slip may occur in the center differential 300. The conditions and timing at which stick slip occurs in the center differential 300 are obtained in advance by experiments or the like.

  In the present embodiment, when the rudder angle is larger than a predetermined angle and the vehicle is starting, it is determined that stick slip may occur and the control clutch 602 needs to be controlled. . If control clutch 602 needs to be controlled (YES in S200), the process proceeds to S300. If not (NO in S200), this process ends.

  In S300, ECU 700 calculates an engagement torque of control clutch 602. The engagement torque of the control clutch 602 is calculated to a value that does not limit the rotation difference between the front and rear wheels during turning more than necessary.

  In S400, ECU 700 controls the hydraulic pressure supplied to the piston of control coupling 600 by linear solenoid 800, and applies an engagement torque to control clutch 602. The application of the engagement torque to the control clutch 602 is performed before the occurrence of stick slip so as to suppress the occurrence of stick slip. Note that the engagement torque may be applied to the control clutch 602 at a timing opposite in phase to the vibration generated by stick-slip.

  An operation of control coupling 600 controlled by ECU 700 of the control device according to the present embodiment based on the above-described structure and flowchart will be described.

  When the throttle opening, the vehicle speed, the gear stage of the transmission 200, the steering angle, and the longitudinal acceleration of the vehicle are detected (S100), whether or not the control clutch 602 needs to be controlled based on the detected information. Is discriminated (S200).

  When the rudder angle is larger than a predetermined angle and the vehicle is starting, differential slip is performed by the function of the center differential 300 itself, and stick slip occurs on the sliding surface of the center differential 300. There is a fear. When stick-slip occurs, the ratio of torque distribution to the front and rear wheels changes suddenly, which may induce torsional resonance of the shaft that transmits torque. In this case, the floor surface of the vehicle may vibrate.

  Therefore, when the rudder angle is larger than a predetermined angle and the vehicle is at the start, it is determined that control clutch 602 needs to be controlled (YES in S200). In this case, the engagement torque of the control clutch 602 is calculated (S300), and the calculated engagement torque is applied to the control clutch 602 (S400). As a result, the control clutch 602 enters the engaged state or the half-engaged state.

  If the engagement torque is applied to the control clutch 602 before stick-slip occurs, the control coupling 600 limits the differential between the differential carrier 302, the ring gear 306, and the sun gear 308. Thereby, the sliding between the members which comprise the center differential 300 is suppressed, and generation | occurrence | production of a stick slip can be suppressed. Therefore, it is possible to suppress a sudden change in the ratio of torque distribution to the front and rear wheels. As a result, the occurrence of vibration due to stick-slip is suppressed.

  On the other hand, when the engagement torque is applied to the control clutch 602 at a timing opposite to the vibration generated by the stick slip, the ratio of the torque distribution to the front and rear wheels is suddenly changed by the control coupling 600, and the vibration caused by the stick slip. Anti-phase vibration occurs. As a result, vibration due to stick-slip can be canceled by vibration having an opposite phase. Therefore, vibration due to stick-slip can be suppressed.

  As described above, the ECU of the control device according to the present embodiment suppresses the occurrence of vibration due to stick-slip when the rudder angle is larger than a predetermined angle and the vehicle is starting. Engagement torque is applied to the control clutch. If engagement torque is applied to the control clutch before stick-slip occurs, the control coupling limits the differential between the differential carrier, the ring gear, and the sun gear. Thereby, the sliding between the members which comprise a center differential is suppressed, and generation | occurrence | production of a stick slip is suppressed. Therefore, it is possible to suppress a sudden change in the ratio of torque distribution to the front and rear wheels. As a result, the occurrence of vibration due to stick-slip can be suppressed.

  On the other hand, when the engagement torque is applied to the control clutch at the timing opposite to the vibration due to stick-slip, the ratio of torque distribution to the front and rear wheels is suddenly changed by the control coupling, and the phase opposite to that due to stick-slip vibration. Vibration occurs. As a result, vibration due to stick-slip can be canceled by vibration having an opposite phase. Therefore, vibration due to stick-slip can be suppressed.

  In the above-described embodiment, the center differential 300 and the control coupling 600 are arranged in series. However, as shown in FIG. 4, the center differential 300 and the control coupling 600 are arranged in parallel. Also good.

  In FIG. 4, an intermediate gear 1106 is provided so as to mesh with the drive gear 1100 and the driven gear 1102. A differential between the inner shaft 606 connected to the intermediate gear and the outer coupling 608 connected to the differential case 312 of the center differential 300 is limited by the control clutch 602. Thereby, the rotation difference between the front and rear wheels is limited.

  Further, a torque sensitive LSD may be used for the front differential or the rear differential, and the differential of the front differential or the rear differential (rotational difference between the left and right eyelids) may be limited by control coupling.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a control block diagram which shows the structure of the vehicle carrying the control apparatus which concerns on this Embodiment. It is sectional drawing which shows the center differential and control coupling which are arrange | positioned in series. It is a flowchart which shows the control structure of the program which ECU of the control apparatus which concerns on this Embodiment performs. It is sectional drawing which shows the center differential and control coupling which are arrange | positioned in parallel.

Explanation of symbols

  100 engine, 200 transmission, 300 center differential, 302 differential carrier, 304 pinion gear, 306 ring gear, 308 sun gear, 310, 312 differential case, 400 front propeller shaft, 402 front differential, 404 front drive shaft, 406 front wheel, 500 rear propeller shaft , 502 Rear differential, 504 Rear drive shaft, 506 Rear wheel, 600 Control coupling, 602 Control clutch, 604, 608 Outer coupling, 606 Inner shaft, 702 Throttle opening sensor, 704 Rudder angle sensor, 706 G sensor, 708 Front wheel speed sensor, 710 Rear wheel speed sensor, 7 2 accelerator opening sensor, 714 a stop lamp switch, 716 position sensor, 800 a linear solenoid, 900 input shaft, 1000 rear output shaft, 1100 drive gear, 1102 driven gear, 1104 front output shaft, 1106 intermediate gear.

Claims (2)

A control device for a vehicle that travels by transmitting driving force to a first wheel and a second wheel, wherein the first wheel and the second wheel are connected via a differential device, and The differential device is transmitted to the first wheel and the second wheel in accordance with a rotational difference between the first wheel and the second wheel due to a frictional force of members constituting the differential device. Change the torque ratio
Limiting means for limiting the differential of the differential device;
Determining means for determining whether or not the vehicle is in a starting state;
Rudder angle detecting means for detecting the rudder angle of the vehicle;
Control means for controlling the limiting means to limit the differential of the differential device when it is determined that the vehicle is starting and the steering angle is larger than a predetermined angle; A vehicle control device.   The vehicle control device according to claim 1, wherein the first wheel is a front wheel, the second wheel is a rear wheel, and the differential device is a center differential.

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