JP3627289B2 - Driving force distribution device for four-wheel drive vehicles - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a driving force distribution device for a four-wheel drive vehicle that appropriately distributes driving force from an engine to front and rear wheels.
[0002]
[Prior art]
Four-wheel drive vehicles include a part-time system that switches between four-wheel drive and two-wheel drive as appropriate, and a full-time system that is always four-wheel drive. In general, the part-time system mechanically connects the front and rear wheels by manual operation as necessary. When the four wheels are on the road surface with the same coefficient of friction, the driving force (torque) distribution is the dynamic load of the front and rear wheels. Proportional to the distribution, even if one of the front and rear wheels slips, the driving force is distributed according to the grip force of the tire. The full-time system constantly transmits the driving force to the front and rear wheels while absorbing the difference in rotation between the front and rear wheels. There is a variable distribution system in which the driving force distribution is variable according to the driving state.
[0003]
In the variable distribution method for controlling the driving force distribution, the front and rear wheel speeds are detected by the vehicle speed sensor, and the hydraulic multi-plate clutch is controlled based on the vehicle speed difference, or the difference in the hydraulic load caused by the vehicle speed difference is detected. Driving stability is ensured by changing the distribution of driving force to the front wheels or the rear wheels.
[0004]
[Problems to be solved by the invention]
By the way, in the conventional driving force distribution control, since control is actually performed after the vehicle speed difference between the front and rear wheels occurs, it is only necessary to minimize the change in the behavior of the vehicle, and to prevent slipping and the like in advance. There wasn't. That is, there is a problem that a delay with respect to the behavior change cannot be avoided.
[0005]
Therefore, the present invention was created to provide a driving force distribution device for a four-wheel drive vehicle that can prevent a delay with respect to a change in the behavior of the vehicle.
[0006]
[Means for Solving the Problems]
The present invention relates to a clutch mechanism that transmits driving force from an engine to front and rear wheels at a ratio distribution determined according to the fastening force, a front wheel speed sensor for detecting the speed of the front wheel, and a speed of the rear wheel. In a driving force distribution device comprising: a rear wheel speed sensor; and a controller that operates a clutch mechanism to achieve an optimum engagement force based on a difference between detection values of the front wheel speed sensor and the rear wheel speed sensor . A throttle sensor for detecting the throttle opening is provided, and a map in which appropriate torque distribution of the front and rear wheels is determined based on the throttle opening and the front wheel and / or rear wheel speed is input to the controller. Prior to operating the clutch mechanism based on a difference between detection values of the front wheel speed sensor and the rear wheel speed sensor, the throttle sensor A detection value of, on the basis of the detected value of the front wheel speed sensor and / or the rear wheel speed sensors to determine the appropriate initial torque distribution between the front and rear wheels from the map, which actuate the clutch mechanism in accordance with the initial torque distribution It is.
[0007]
[Action]
With the above configuration, the arithmetic processing unit determines the driver's intention of acceleration / deceleration based on the detection value of the throttle sensor that changes in real time, and the speed of the front wheel and the rear wheel or the speed of either the front wheel or the rear wheel at that time, By determining the optimal driving force distribution value based on the throttle opening and determining the engaging force of the clutch mechanism before the speed difference between the front and rear wheels occurs, the delay with respect to the change in vehicle behavior is eliminated.
[0008]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0009]
1 and 2 show an embodiment of a driving force distribution device for a four-wheel drive vehicle according to the present invention. The four-wheel drive vehicle 4 is provided with a part-time drive system which is switched between two-wheel drive (2H) and four-wheel drive high speed (4H) and low speed (4L) by manual operation. Is transmitted to the rear propeller shaft 16 via the transfer portion 6 so that the rear wheel 2 is always driven, and the front wheel 1 is driven from the transfer portion 6 to the front propeller shaft 33 when the shift lever 7 is operated. Power is transmitted. A driving force distribution device that appropriately distributes the driving force includes a multi-plate clutch 9 as a clutch mechanism provided in the transfer unit 6, and wheel speed sensors 43 and 44 for detecting the speeds of the front and rear wheels 1 and 2, respectively. The controller 45 is configured mainly by a controller 45 that appropriately operates the multi-plate clutch 9 based on detection values of the wheel speed sensors 43 and 44.
[0010]
The transfer unit 6 includes a switching mechanism 8 that performs speed switching (4H-4L) in four-wheel drive by operating the shift lever 7, and a multi-plate clutch 9 that substantially distributes the driving force via the switching mechanism 8. ing. The switching mechanism 8 appropriately connects an input shaft 10 connected to the engine 3 via the transmission 5 and a first intermediate shaft 52 connected to the rear propeller shaft 16 via the universal joint 51 via the planetary gear mechanism 53. It connects and the structure is mentioned later. At the output end of the rear propeller shaft 16, there is provided a small gear 18 that forms a part of the final reduction gear 17, and the small gear 18 is engaged with a large gear 20 attached to a differential case 19. The large gear 20 transmits a rotational force to the rear wheel axle 22 and the rear wheel 2 via the left and right differential small gears 21.
[0011]
The multi-plate clutch 9 includes a plurality of inner plates 23 attached to the first intermediate shaft 52 and an outer plate 24 disposed between the inner plates 23, and the outer plate 24 is a clutch that covers these plates 23 and 24. It is attached to the inner wall of the housing 25. An outer cylinder portion 54 that extends coaxially with the first intermediate shaft 52 is attached to the front end of the clutch housing 25, and is formed to be rotatable with respect to the first intermediate shaft 52. The inner plate 23 and the outer plate 24 are adapted to be crimped in the direction of clutch engagement triggered by the magnetic force of the electromagnetic coil 26 fixed in the vicinity thereof. That is, according to the current value supplied to excite the electromagnetic coil 26, the contact state between the inner plate 23 and the outer plate 24 changes, and the clutch fastening force (pressing force) is increased or decreased. Further, a sprocket 55 is attached to the front end of the outer cylinder portion 54 and is connected to a sprocket 57 attached to the second intermediate shaft 56 via a chain 58. The second intermediate shaft 56 is provided in parallel with the first intermediate shaft 52 and is connected to the front propeller shaft 33 via the universal joint 51. A small gear 35 constituting the final reduction gear 34 is attached to the front end of the front propeller shaft 33, and the driving force from the small gear 35 is sequentially transmitted to the large gear 36, the differential case 37, and the differential small gear 38, The front wheel axle 39 and the front wheel 1 are rotated. That is, by controlling the power supply to the electromagnetic coil 26, the fastening force of the multi-plate clutch 9 is changed, and torque is transmitted to the front and rear wheels 1 and 2 at a ratio distribution (0: 100 to 50:50) determined according to the fastening force. Can be done.
[0012]
The controller 45 performs power supply control to the electromagnetic coil 26 mainly based on detection values of the wheel speed sensors 43 and 44. The wheel speed sensors 43, 44 are opposed to the front wheel speed sensor 43 facing the protruding disk (gear) 41 attached to the second intermediate shaft 56 and the protruding disk 42 attached to the first intermediate shaft 52. Rear wheel speed sensor 44. The protrusion-equipped disks 41 and 42 are formed with a plurality of protrusions at equal intervals on the periphery. The wheel speed sensors 43 and 44 sense the protrusion and output a pulse signal each time it passes, and input it to the input section 46 of the controller 45. In addition to the pulse signals from the wheel speed sensors 43 and 44, the throttle opening (TPS signal) of the engine 3 is input to the input unit 46. That is, the input unit 46 is connected to a throttle sensor 60 for detecting the opening of a throttle 59 provided in the intake system of the engine 3. These pieces of input information are subjected to arithmetic processing in the arithmetic processing unit 47 to determine an optimum current amount (voltage duty ratio) to be supplied to the electromagnetic coil 26. For example, when there is a speed difference between the front and rear wheels 1 and 2, it is considered that slip has occurred during traveling, and a voltage duty ratio that is an engaging force of the multi-plate clutch 9 is determined so as to eliminate the slip.
[0013]
On the other hand, in addition to the front and rear wheel speeds, the throttle opening is taken into account in determining the initial voltage duty ratio where no slip occurs. In other words, the driver's intention of acceleration / deceleration is read based on the throttle opening, and optimal torque distribution according to the vehicle speed at that time is performed. This torque distribution is performed using a control map as shown in FIG. For example, as an example of this control map, the initial torque distribution is increased when the throttle opening is large during low-speed driving and high-speed driving (symbol ○), and torque distribution is performed when the low-speed driving / throttle opening is small. less (symbol ×), when the high-speed running, the throttle opening is small is set as to be intermediate the torque distribution (symbol △). This control content is set by matching with a vehicle to be mounted by experiment or simulation, and is input in advance to a storage unit (not shown) of the controller 45. That is, the arithmetic processing unit 47 determines the torque distribution based on the input information and this control map, and outputs the power supply having a voltage duty ratio corresponding to the torque distribution to the electromagnetic coil 26 via the output unit 48. In addition, information from position sensors 61 and 62 for detecting the position of the shift lever 7 is input to the input unit 46 of the controller 45, and the shift lever 7 is operated by four-wheel drive (4H). When this occurs, the multi-plate clutch 9 is operated to switch to the four-wheel drive mode, and torque distribution control is started.
[0014]
Next, the configuration of the switching mechanism 8 of the transfer unit 6 will be described. This switching mechanism 8 includes an input spline 11 and an input gear 12 provided on the input shaft 10, a planetary gear 14 that meshes between the input gear 12 that is a sun gear and a fixed gear 13, and the rotation of the planetary gear 14. And a cylindrical gear 15 that rotates about the input shaft 10. By operating the shift lever 7, the input spline 11 or the cylindrical gear 15 is selectively connected to the drive gear 63 attached to the input end of the first intermediate shaft 52 via a slidable shift sleeve 64. It has become so. FIG. 2 shows a state in which the high mode (4H) is selected. The shift sleeve 64 connects the input spline 11 and the drive gear 63 so that the input shaft 10 is directly connected to the first intermediate shaft 52. Let When the low mode (4L) is selected, the shift sleeve 64 connects the cylindrical gear 15 and the drive spline 63 to rotate the first intermediate shaft 52 at a reduced speed. The high mode (4H) is selected on the road surface conditions such as snowy roads and muddy roads that are relatively easy to slip in addition to normal driving, and the low mode (4L) is a relatively high driving force such as towing on steep slopes and violent roads. Is selected in situations that require
[0015]
The clutch housing 25 and the first intermediate shaft 52 are respectively provided with direct connection splines 27 and 28 serving as mechanical locks. These direct connection splines 27 and 28 are connected to each other by a slidable connection shift sleeve 29 when the low mode (4L) is selected. With this connection, the clutch housing 25 is directly connected to the first intermediate shaft 52 (rear propeller shaft 16), and torque distribution control by the multi-plate clutch 9 is not performed. When the two-wheel drive mode (2H) is selected, the positions of the shift sleeve 64 and the connection shift sleeve 29 are the same as those in the high mode (4H), but the multi-plate clutch 9 is in a disconnected state. Drive transmission to the propeller shaft 33 is not performed. The front wheel drive system (front propeller shaft 33) in the clutch disengaged state is held stationary by the axle intermittence mechanism 65.
[0016]
The axle interrupting mechanism 65 is provided at a split position of the front wheel axle 39 divided between the front wheel 1 and the final reduction gear 34, and is attached to spline 66, 67 attached to opposite ends of the split axles 39a, 39b, respectively. And a connection shift sleeve 68 for connecting and releasing the splines 66 and 67 by sliding, and an actuator 69 for operating the connection shift sleeve 68 as appropriate. Then, when the two-wheel drive (2H) is performed, the connection between the splines 66 and 67 is disconnected by the operation signal of the controller 45, so that the rotation from the front wheel 1 due to traveling becomes idle in the final reduction gear 34, and the front propeller shaft 33 Will not be transmitted to. By comprising in this way, useless energy consumption accompanying driving | running | working can be avoided. The actuator 69 may be composed of an air cylinder or a dashpot that operates by negative pressure.
[0017]
Next, the operation of this embodiment will be described.
[0018]
When the shift lever 7 is switched from the two-wheel drive (2H) to the four-wheel drive (4H), the controller 45 detects this by the signals from the position sensors 61 and 62, and firstly the electromagnetic coil with a predetermined voltage duty ratio. 26 is excited. By this excitation, the multi-plate clutch 25 exhibits an appropriate fastening force to transmit torque from the first intermediate shaft 52 to the second intermediate shaft 56, and rotates the stationary front propeller shaft 33. When the rotation of the front propeller shaft 33 is sufficiently increased, the axle intermittent mechanism 65 is operated to connect the front wheel 1 (front wheel axle 39) and the front propeller shaft 33 via the final reduction gear 34, and torque distribution control (this control) ).
[0019]
In this torque distribution control, it is predicted whether or not driving that causes a change in the behavior of the vehicle is performed. That is, as shown in FIG. 3, the controller 45 detects the TPS signal that is the throttle opening degree detection value from the throttle sensor 60, the front wheel speed detection value by the front wheel speed sensor 43, and the rear wheel speed sensor 44 by the rear wheel speed sensor 44. If the detected value is read, the initial torque distribution amount is determined based on the control map shown in FIG. 4, and the electromagnetic coil 26 is excited with a voltage duty ratio corresponding thereto, and the multi-plate clutch 25 is engaged. Adjust the force. For example, when trying to escape from sand, the driver tries to start sudden acceleration by depressing the accelerator in a low-speed driving state. In such a case, the initial torque distribution is increased (reference symbol ◯ in FIG. 4). ) To prevent slippage. For example, when a small turn is to be made in a parking lot or the like, the driving is to be decelerated during low-speed traveling, but torque distribution is reduced so as not to hinder the traveling (symbol x in FIG. 4). Following this initial torque distribution, voltage duty control based on the wheel speed difference is performed to perform optimum torque distribution.
[0020]
In this way, in addition to the front and rear wheel speeds, the traveling state of the vehicle is predicted based on the information of the throttle opening that changes in real time, and the engagement force of the multi-plate clutch 9 is set to an optimum value even before the vehicle speed difference occurs. Since the torque distribution is performed by controlling, a delay with respect to a change in the behavior of the vehicle can be prevented, and a further improvement in running stability is achieved. Further, the present invention is realized only by partially improving the arithmetic processing unit 47 of the controller 45, and is extremely versatile.
[0021]
In this embodiment, the present invention is applied to a switching type four-wheel drive vehicle. However, the present invention is also widely applicable to a full-time four-wheel drive vehicle that controls torque distribution of front and rear wheels. It is.
[0022]
【The invention's effect】
In short, according to the present invention, it is possible to prevent a delay with respect to a change in the behavior of the vehicle and to exhibit an excellent effect that a further improvement in running stability is achieved.
[Brief description of the drawings]
FIG. 1 is a plan view showing an embodiment of a driving force distribution device for a four-wheel drive vehicle according to the present invention.
FIG. 2 is a plan view showing the drive system of FIG. 1;
FIG. 3 is a flowchart for explaining the operation of FIG. 1;
4 is a diagram showing an example of a control map for explaining the control content of FIG. 3; FIG.
[Explanation of symbols]
1 Front wheel 2 Rear wheel 3 Engine 9 Multi-plate clutch (clutch mechanism)
43 Front wheel speed sensor (wheel speed sensor)
44 Rear wheel speed sensor (wheel speed sensor)
45 controller 47 arithmetic processing unit 60 throttle sensor

Claims (1)

A clutch mechanism that transmits driving force from the engine to the front and rear wheels in a ratio distribution determined according to the fastening force, a front wheel speed sensor for detecting the speed of the front wheel, and a rear wheel speed for detecting the speed of the rear wheel A driving force distribution device comprising: a sensor; and a controller that operates the clutch mechanism to have an optimum engagement force based on a difference between detection values of the front wheel speed sensor and the rear wheel speed sensor .
Has a throttle sensor to detect the throttle opening of the engine,
A map that defines an appropriate torque distribution for the front and rear wheels based on the throttle opening and the front and / or rear wheel speeds is input to the controller,
Prior to operating the clutch mechanism based on a difference between detected values of the front wheel speed sensor and the rear wheel speed sensor, the controller detects the detected value of the throttle sensor, the front wheel speed sensor and / or the rear wheel speed. A driving force distribution device for a four-wheel drive vehicle, wherein an appropriate initial torque distribution for front and rear wheels is determined from the map based on a detection value of a sensor, and the clutch mechanism is operated according to the initial torque distribution .

Images