JP2006046595A - Differential rotation control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce slapping sound when differential rotations of left and right wheels are reversed. <P>SOLUTION: This differential rotation control system is composed of a differential mechanism 31 for transmitting the driving force from an engine 1 to left and right rear wheel sides, and permitting differential rotation between left and right rear wheels, a main clutch 67 capable of applying and releasing pressing force for controlling differential rotation, a pilot clutch 69 connected by the action of an electromagnet 73, a cam mechanism 70 operated by the connection of the pilot clutch 69 and the differential rotation, a planetary carrier 51 transmitting the pressing force to the main clutch 69 in interlocking with the operation of a cam mechanism 70, and a controller for controlling the action of the electromagnet 73. A detecting means is mounted to detect the difference in torque between the left and right rear wheels, and the controller controls the electromagnet 73 to weaken or release the connection of the pilot clutch 69 when the difference in torque between the left and right rear wheels is zero or approximately zero after swiveling running of a vehicle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a differential rotation control system used for a vehicle or the like.

  As a conventional differential rotation control system, for example, there is a system that controls the differential limiting force of a rear differential device by controlling energization of an electromagnet.

  The rear differential device can transmit the driving force from the engine to the left and right rear wheels and allow differential rotation between the left and right rear wheels.

  The differential rotation is limited by energization control to the electromagnet. That is, when the electromagnet is energized, the armature is attracted and the pilot clutch is engaged between the armature and the differential case. The ball cam works by the engagement of the pilot clutch, and the main clutch is engaged through the planetary carrier by the cam thrust force. When the main clutch j is engaged, the differential of the differential gear mechanism constituted by the planetary gear is limited.

  By such differential limitation, for example, cornering traveling, slalom traveling, and the like can be stably performed.

  However, for example, when the differential rotation of the left and right wheels is reversed in slalom running or the like, there is a problem that the torsion torque accumulated on the wheel shaft is suddenly released and a hitting sound is generated.

JP-A-4-107347

  The problem to be solved is that a hitting sound is generated due to the cam mechanism when the differential rotation of the left and right wheels is reversed.

  The present invention controls the actuator to adjust the engagement of the pilot clutch based on the change in the torque difference between the left and right wheels after turning the vehicle in order to suppress the noise when the differential rotation of the left and right wheels is reversed. Is the most important feature.

  Since the differential rotation control system of the present invention controls the actuator to adjust the engagement of the pilot clutch based on the change in the torque difference between the left and right wheels after turning the vehicle, the differential rotation of the left and right wheels is reversed in slalom running etc. In doing so, it is possible to suppress the hitting sound caused by the sudden release of the twisting torque of the wheel axle.

  The control means controls the actuator so as to weaken or release the engagement of the pilot clutch when the torque difference between the left and right wheels changes to zero or near zero after turning the vehicle. When the differential rotation is reversed, it is possible to reliably suppress the hitting sound caused by the sudden release of the twisting torque of the wheel shaft.

  The detection means includes a yaw rate sensor that detects the yaw rate of the vehicle, and detects that the torque difference between the left and right wheels has changed by comparing the detected yaw rate or the yaw angle of the vehicle integrated with the yaw rate with a threshold value. In this case, the actuator can be controlled by accurately detecting the change in the torque difference, and the hitting sound can be more accurately suppressed.

  The detecting means determines that the vehicle has started turning when the yaw rate or yaw angle reaches the first threshold after yaw rate zero has continued for a certain time, and the yaw rate or yaw angle becomes the first after the yaw rate sign is reversed. When it is determined that the torque difference between the left and right wheels is zero or near zero when the threshold value of 2 is reached, it is possible to accurately detect the start of vehicle turning and the torque difference between the left and right wheels being zero or near zero. In addition, it is possible to accurately control the actuator and accurately suppress the hitting sound.

  When the actuator is an electromagnet and an armature, and the control means attracts the armature by performing energization control of the electromagnet to perform the fastening, and the torque difference between the left and right wheels becomes zero or near zero after turning the vehicle. When the energization ratio of the energization control is weakened or energization is stopped, the energization of the electromagnet can be accurately controlled to suppress the hitting sound accurately.

  The purpose of suppressing the hitting sound when the differential rotation of the left and right wheels is reversed is realized by controlling the actuator.

  FIG. 1 is a skeleton plan view showing a power system of a vehicle to which this embodiment is applied.

  As shown in FIG. 1, this vehicle includes an engine 1 (drive source of the embodiment), a transmission 3, a propeller shaft 5, a rear differential device 7, rear wheel shafts 9, 11, and left and right rear wheels 13, 15 (of the embodiment). Left and right wheels), left and right front wheels 17, 19 and the like, and a yaw rate sensor 21 as a part of the detection means 20 and a controller 22 by electronic control as a control means.

  The rear differential device 7 transmits the driving force from the engine 1 to the rear wheels 13 and 15 side and allows differential rotation between the rear wheels 13 and 15. The rear differential device 7 is rotatably disposed in the differential carrier 23, and a ring gear 25 is fixed to the rear differential device 7. The ring gear 25 meshes with the drive pinion gear 27, and the drive pinion gear 27 is formed integrally with a drive pinion shaft 29 connected to the propeller shaft 5 side. Thus, the driving force of the engine 1 is transmitted from the transmission 3 to the rear differential device 7 via the propeller shaft 5. A driving force is transmitted from the rear differential device 7 to the left and right rear wheels 13 and 15 via the rear wheel shafts 9 and 11.

  The detection means 20 includes the yaw rate sensor 21 for detecting the yaw rate of the vehicle, and for example, the detected yaw rate or the yaw angle of the vehicle integrated with the yaw rate is compared with a threshold value to compare the torque difference between the left and right wheels after the vehicle turns. Is detected to be zero.

  In other words, the detection means 20 determines that the vehicle has started turning when the yaw rate or yaw angle reaches the first threshold after yaw rate zero has continued for a certain period of time, and after the sign of the yaw rate is reversed, the yaw rate or When the yaw angle reaches the second threshold, it is determined that the torque difference between the left and right wheels is zero. Details will be described later.

  In addition, although the torque difference between the left and right wheels will be explained as being zero, it is not limited to the case where it is clearly detected that the torque is zero, and the actuator is controlled based on the fact that it is near zero. You can also As an example, being close to zero is defined within a range in which a second threshold set with zero as a boundary is used as an upper and lower limit value. Furthermore, a predetermined value within the above range can be set.

  The controller 22 compares the yaw rate or yaw angle with a threshold value. Therefore, the controller 22 also constitutes a part of the detection means 20.

  The controller 22 attracts an armature, which will be described later, by energizing control of an electromagnet, which will be described later, and engages a pilot clutch, which will be described later. As described above, the energization ratio of the energization control is weakened or energization is stopped.

  The specific structure of the rear differential device 1 is as shown in the cross-sectional view of FIG.

  As shown in FIG. 2, the rear differential device 1 includes a differential mechanism 31 formed of a planetary gear mechanism in a differential case 30. The differential mechanism 31 includes an internal gear 33, an outer planetary gear 35, an inner planetary gear 37, a sun gear 39, and the like.

  The internal gear 33 is formed on the inner periphery of the differential case 30, and the sun gear 39 is formed on one hub 41.

  The planetary gears 35 and 37 mesh with each other, the outer planetary gear 35 meshes with the internal gear 33, and the inner planetary gear 37 meshes with the sun gear 39.

  The planetary gears 35 and 37 are respectively supported by left and right planetary carriers 49 and 51 by means of metal bearings 47 at the shafts 43 and 45 at both ends.

  The planetary carriers 49 and 51 are integrated with each other by welding, and the other hub 53 is integrally formed with the planetary carrier 51. The planetary carrier 51 constitutes a pressing means for transmitting a pressing force to a main clutch (to be described later) in conjunction with an operation of a cam mechanism (to be described later).

  The left and right wheel shafts 9 and 11 penetrate the differential case 30 and are splined to the left and right hubs 41 and 53. A thrust washer 59 is disposed between the left and right hubs 41 and 53 to prevent these contacts.

  In addition to the differential mechanism 31, the rear differential device 7 includes a main clutch 67 capable of applying and releasing a pressing force to control the differential rotation, and a pilot clutch that is fastened by the action of an actuator described later. 69 and a cam mechanism 70 that operates by engaging the pilot clutch 69 and the differential rotation.

  The main clutch 67 and the pilot clutch 69 are composed of a wet multi-plate clutch.

  The main clutch 67 is disposed between the planetary carrier 49 and the hub 41. A pressure receiving plate 79 is disposed between the main clutch 67 and the differential case 30.

  The pilot clutch 69 is disposed between the differential case 30 and the cam ring 75. The outer plate 81 of the pilot clutch 69 is splined to the inner periphery of the differential case 30. An inner plate 85 of the pilot clutch 69 is splined to the outer periphery of the cam ring 75.

  The cam mechanism 70 is constituted by a ball cam, and a cam ball 77 is disposed between the cam surfaces of the cam ring 75 and the planetary carrier 51. The cam surfaces of the cam ring 75 and the planetary carrier 51 are constituted by circumferential chevron cams, so that the cam action is caused by either forward or reverse rotation. A thrust bearing 89 is disposed between the cam ring 75 and the differential case 30. The thrust bearing 89 receives the cam reaction force of the cam ball 77 and allows the cam ring 75 to rotate while the pilot clutch 69 is released.

  The actuator is an electromagnetic actuator and includes an armature 71 and an electromagnet 73.

  The armature 71 is disposed adjacent to one side of the pilot clutch 69 and is positioned by a retaining ring 87.

  The electromagnet 73 is formed by winding an electromagnetic coil 93 around a yoke 91. The yoke 91 is supported on the differential case 30 side by a bearing 95 and is fixed to the differential carrier 23 side to prevent rotation.

  A stainless steel non-magnetic ring 99 is provided on the differential case 30 side in order to prevent a short circuit of the magnetic flux of the electromagnet 73.

  The electromagnet 73 is connected to a battery, and the controller 22 performs excitation, excitation power control, and excitation stop energization control.

  When the electromagnet 73 is excited, the armature 71 is attracted, the pilot clutch 69 is engaged, and a pilot torque is generated.

  When the left and right rear wheels 13 and 15 start differential rotation in a state where pilot torque is generated in the pilot clutch 69, the differential rotation is transmitted between the planetary carrier 51 and the cam ring 75 and is applied to the cam ball 77. The planetary carrier 51 and the cam surface of the cam ring 75 are displaced in the front-rear direction. The cam ball 77 rides on the cam surface due to the displacement of the cam surface, and the cam mechanism 70 works by the cam ball 77 to generate thrust.

  The thrust is transmitted to the differential case 30 via the thrust bearing 89, and a moving force acts on the planetary carrier 51 as a reaction force. The main clutch 67 is fastened by the movement of the planetary carrier 51. When the main clutch 67 is engaged, the relative rotation between the differential case 30 and the hub 41 is restricted, and as a result, the relative rotation between the hubs 41 and 53 is restricted. Due to the limitation of the relative rotation, a differential limiting force acts between the left and right rear wheels 13 and 15.

  Such differential limiting force greatly improves running performance on rough roads. Further, when turning, if the strength of the magnetic force is controlled by the controller 22 by energization control of the electromagnet 73 by the controller 22 and the pilot clutch 69 is appropriately slid, the pilot torque changes and the cam thrust force of the cam mechanism 70 changes. The fastening force of the main clutch 67 can be adjusted and slipped appropriately. By appropriately sliding the main clutch 67, the turning performance and the stability of the vehicle body during turning can be greatly improved.

  When the energization control of the electromagnet 73 is stopped, the pilot torque of the pilot clutch 69 disappears, the cam thrust force of the cam mechanism 70 is released, the main clutch 67 is released, and the differential restriction is released.

  By the way, in the control as described above, when the main clutch 67 is engaged, a twisting torque is accumulated between the left and right wheel shafts 9 and 11 when the vehicle turns. Even if the vehicle changes from turning to straight running, the engagement of the pilot clutch 69 is released unless the rear wheels 13 and 15 cause differential rotation in the opposite direction due to turning in the opposite direction. The main clutch 67 maintains the engaged state.

  When the pilot clutch 69 and the main clutch 67 are turned in the reverse direction while maintaining the engaged state, a reverse twist torque is generated between the left and right wheel shafts 9 and 11, and the cam surface of the cam mechanism 70 is reverse in the circumferential direction. Start to move. Due to the movement of the cam mechanism 70, the applied pressure of the main clutch 67 is suddenly released, and the torsional torque accumulated between the wheel shafts 9 and 11 is suddenly released. That is, the elastic energy accumulated in the left and right wheel shafts 9, 11 and the like is suddenly released, and a large hitting sound is generated in the portion that has been restrained until then. That is, when the differential rotation of the left and right rear wheels 13 and 15 is reversed, a hitting sound is caused.

  In the embodiment of the present invention, the hitting sound is suppressed by the determination by the detection means 20 and the control signal by the controller 22 based on the determination as described above.

  FIGS. 3A and 3B are graphs for explaining the determination and control signal. FIG. 3A shows a change in the detected value of the yaw rate sensor 21, and FIG. 3B shows the control signal.

  FIG. 3A shows a change in the detection signal X of the yaw rate sensor 21 when the vehicle travels, for example, in slalom. The change of ± in FIG. 3A indicates that the turning direction has changed. As shown in FIG. 3A, threshold values ± A and ± B are taken, and the intersections of the threshold value and the detected yaw rate are shown as a to h. The threshold values ± A and ± B are obtained by experiments according to the running conditions.

  The detection means 20 determines that the vehicle has started turning when the detected yaw rate reaches the first threshold value + A (intersection point a or b). When the turning direction is changed from this state and the detected yaw rate becomes the second threshold −B (intersection point d), the detecting means 20 determines that the torque difference between the left and right rear wheels 13 and 15 is zero. That is, the torsional torque does not work between the wheel shafts 9 and 11.

  The controller 22 temporarily stops energization control of the electromagnet 73 at the timing when the detected yaw rate becomes the second threshold −B as shown in FIG.

  The same applies when the vehicle turns again in the opposite direction. That is, the detecting means 20 determines that the vehicle has started turning when the detected yaw rate reaches the first threshold value -A (intersection e or f). When the detected yaw rate becomes the second threshold value + B (intersection point h), it is determined that the torque difference between the left and right rear wheels 13 and 15 is zero.

  FIG. 4 is a chart showing the relationship between the threshold judgment and the control signal. In FIG. 4, when the detected yaw rate exceeds the threshold values ± A and ± B, that is, when the intersection point a or the like exists, it is indicated as ◯, and when it does not exist, it is indicated as ×. Further, the chart of FIG. 4 is shown in chronological order from the left side in accordance with the change of the detected yaw rate of FIG.

  As shown in FIG. 4, for example, when the detected yaw rate becomes the first threshold value + A (◯) and becomes the second threshold value −B (◯), the control signal Y is output.

  FIG. 5 is a flowchart of the above control.

  In step S <b> 1 of FIG. 5, a determination process of “whether a or b existed” is executed. In this process, as described above, when the detected yaw rate becomes the first threshold value + A (intersection point a or b), it is determined that the vehicle has started turning. When a or b exists (YES), the process proceeds to step S2, and when it does not exist (NO), the process ends.

  In step S2, a determination process of “whether or not d exists” is executed. In this process, as described above, when the detected yaw rate becomes the second threshold value −B (intersection point d), it is determined that the torque difference between the left and right rear wheels 13 and 15 is zero. If d exists (YES), the process proceeds to step S3, and if it does not exist (NO), the process returns.

  In step S3, the process of “decrease control signal I and increase it quickly” is executed. That is, the energization control of the electromagnet 73 is temporarily stopped. Subsequently, in order to respond to the change in the turning direction, the process proceeds to step S4.

  In step S4, a determination process of “whether e or f existed” is executed. In this process, as described above, when the turning direction of the vehicle changes and the detected yaw rate reaches the first threshold −A (intersection e or f), it is determined that the vehicle has started turning. When e or f exists (YES), the process proceeds to step S5, and when it does not exist (NO), the process returns.

  In step S5, a determination process of “has h existed” is executed. In this process, as described above, when the detected yaw rate becomes the second threshold value + B (intersection point h), it is determined that the torque difference between the left and right rear wheels 13 and 15 is zero. If d exists (YES), the process proceeds to step S6, and if it does not exist (NO), the process returns.

  In step S6, a process of “decrease control signal I and increase it quickly” is executed. That is, the energization control of the electromagnet 73 is temporarily stopped. Subsequently, the process returns to respond to the change in the turning direction.

  Note that the temporary stop of the energization control in step S3 or step S6 is to turn off the control current instantaneously or decrease it with a predetermined continuous slope, or decrease it with a predetermined number of steps. It can also be turned off. The control current is not limited to a temporary stop when it is completely reduced to OFF (0), but may be a temporary stop with a predetermined minimum value.

  By such control, when the differential rotation of the left and right rear wheels 13 and 15 is reversed in slalom running or the like, the pilot clutch 69 and the main clutch 67 are reversed from one direction as described above while maintaining the engaged state. When turning in the direction, the energization control of the electromagnetic clutch 73 is temporarily stopped and the engagement of the pilot clutch 69 and the main clutch 67 is released before the reverse twist torque is generated between the left and right wheel shafts 9 and 11. In the meantime, the cam mechanism 70 can be opened. Therefore, it is possible to suppress the collision between the cam ball 77 of the cam mechanism 70 and the cam surface, and to suppress the hitting sound when the differential rotation of the left and right rear wheels 13 and 15 is reversed.

  Thus, the differential rotation control system of the embodiment of the present invention energizes the electromagnet 73 so as to release the engagement of the pilot clutch 69 when the torque difference between the left and right rear wheels 13, 15 becomes zero after the vehicle turns. Therefore, when the differential rotation of the left and right rear wheels 13 and 15 is reversed during slalom running or the like, it is possible to suppress the hitting sound of the cam mechanism 70 due to the sudden release of the twisting torque of the wheel shafts 9 and 11. .

  The detection means 20 includes a yaw rate sensor 21 that detects the yaw rate of the vehicle, and compares the detected yaw rate with a threshold value, so that the torque difference between the left and right rear wheels 13, 15 becomes zero after the vehicle turns. Therefore, the electromagnet 73 can be controlled by accurate detection, and the hitting sound of the cam mechanism 70 can be accurately suppressed.

  The detection means 20 determines that the vehicle has started turning when the yaw rate becomes the first threshold after yaw rate zero has continued for a certain time, and the yaw rate becomes the second threshold after the sign of the yaw rate is reversed. Since the torque difference between the left and right rear wheels 13 and 15 is determined to be zero, the start of vehicle turning and zero torque difference between the left and right rear wheels 13 and 15 can be accurately detected, and the electromagnet 73 can be accurately detected. By controlling, it is possible to accurately suppress the hitting sound of the cam mechanism 70.

  In the above embodiment, the detected yaw rate is compared with a threshold value to detect that the torque difference between the left and right wheels becomes zero after the vehicle turns, but the yaw rate is integrated as shown in FIG. It is also possible to detect that the torque difference between the left and right wheels becomes zero after the vehicle turns by comparing the vehicle yaw angle (shaded portion) with a threshold value. That is, in FIG. 6, when the yaw rate is detected from the yaw rate zero state, the value is integrated, and the same control can be performed by comparing with the threshold values ± A and ± B.

  In addition to the yaw rate signal, the processing value such as the steering wheel angle or its differential integral, the lateral G or its processing value, the steering force or its processing value, the left-right twist torque or its processing value, the roll angle or its processing value, four wheels It is also possible to use the wheel speed or the processing value thereof.

  In the above embodiment, the control current of the electromagnet 73 is controlled to be temporarily stopped. However, in addition to the control current ON / OFF control, the control is performed even if the predetermined minimum value described above is not specified as a numerical value. It is also possible to control to reduce the current addition ratio to 20%, 50%, 80% or the like.

  In the control in which the control current of the electromagnet 73 is temporarily stopped or reduced to 20%, 50%, 80% or the like, the control current value can be gradually decreased. The change of the control current value can be performed in stages.

  In addition, the actuator may be a current controlled by an electromagnetic solenoid valve or the like using a hydraulic actuator, or may be another applicable actuator.

  Further, the differential device is not limited to the planetary gear type, but may be a bevel gear type or another type. The location of the pilot clutch or the main clutch is not limited as long as the pilot clutch or the main clutch is provided between two members of the differential case and the left and right wheel shafts.

  The differential device may be a front differential, a center differential, or a coupling that connects the front and rear wheels, and the control system of the present invention is widely applicable.

(Example 1) which is a skeleton top view which shows the motive power system of a vehicle. (Example 1) which is sectional drawing of a rear differential apparatus. 7 is a graph for explaining determination by a detection unit and a control signal by a controller (Example 1). 6 is a chart showing a relationship between threshold judgment and control signals (Example 1). It is a flowchart (Example 1). It is a graph explaining the judgment by a detection means, and the control signal by a controller.

Explanation of symbols

1 Engine (drive source)
13, 15 Rear wheels (left and right wheels)
20 detection means 21 yaw rate sensor 22 controller (control means)
31 differential mechanism 51 planetary carrier (pressing means)
67 Main clutch 69 Pilot clutch 70 Cam mechanism 71 Armature (actuator)
73 Electromagnet (actuator)

Claims (5)

A differential mechanism that transmits the driving force from the drive source to the left and right wheels and allows differential rotation between the left and right wheels;
A main clutch capable of applying and releasing a pressing force to control the differential rotation;
A pilot clutch fastened by the action of the actuator;
A cam mechanism that operates by engagement of the pilot clutch and the differential rotation;
A pressing means for transmitting a pressing force to the main clutch in conjunction with the operation of the cam mechanism;
Comprising control means for controlling the action of the actuator,
Detecting means for detecting a change in torque difference between the left and right wheels;
The differential rotation control system characterized in that the control means controls the actuator to adjust the engagement of the pilot clutch based on a change in the torque difference between the left and right wheels after the vehicle turns. The differential rotation control system according to claim 1,
The control means controls the actuator so as to weaken or release the engagement of the pilot clutch when the torque difference between the left and right wheels changes to zero or near zero after turning the vehicle. Control system. The differential rotation control system according to claim 1 or 2,
The detection means includes a yaw rate sensor for detecting the yaw rate of the vehicle, and detects that the torque difference between the left and right wheels has changed by comparing the detected yaw rate or the yaw angle of the vehicle integrating the yaw rate with a threshold value. A differential rotation control system characterized by A differential rotation control system according to claim 3,
The detecting means determines that the vehicle has started turning when the yaw rate or yaw angle reaches a first threshold after yaw rate zero has continued for a certain time, and the yaw rate or yaw angle is determined after the sign of the yaw rate is reversed. A differential rotation control system characterized by determining that the torque difference between the left and right wheels is zero or near zero when the second threshold value is reached. The differential rotation control system according to any one of claims 1 to 4,
The actuator is an electromagnet and an armature,
The control means attracts the armature by energization control of the electromagnet to perform the fastening, and weakens or energizes the energization control when the torque difference between the left and right wheels becomes zero or near zero after turning the vehicle. A differential rotation control system characterized by stopping.

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