JPS6237221A - Four-wheel-drive vehicle - Google Patents

Abstract

PURPOSE:To improve the power performance, maneuverability and stability of variable torque distribution 4WD vehicle by connecting the output side of transmission through hydraulic clutch with front and rear wheels and controlling independently through duty signal from a controller. CONSTITUTION:Voltage A set through manual operating section 40 and triangular voltage B from triangular wave generating circuit 42 are processed through a comparator 43 to provide a duty signal to a solenoid valve 30. Consequently, power conduction and interruption of solenoid valve 30 are repeated to connect/ disconnect the hydraulic clutch 20 with constant period thus to transmit the power from the output shaft 5 of transmission 4 to the front wheel periodically. Similarly, the driving torque of rear wheel is controlled through manual operating section 40', triangular wave generating circuit 42', comparator 43' and solenoid valve 30'. With such arrangement, maneuverability and stability as well as the power performance are improved.

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD 1 The present invention relates to a four-wheel drive vehicle that enables distribution of drive torque between front and rear wheels, and particularly relates to a four-wheel drive vehicle that changes torque distribution according to vehicle running conditions. A full-time type with a center differential as a four-wheel drive vehicle,
FF with a transfer clutch instead of a center differential
There are various part-time systems based on , RR, and FR. [Prior Art] Conventionally, in each type of four-wheel drive vehicle, those with a center differential naturally distribute drive torque equally to the #J rear wheels via the center differential. In addition, even in the case of a part-time type, for example, as shown in Japanese Patent Laid-Open No. 55-4292, a direct-coupled type that uses a dog clutch for the transfer clutch does not distribute drive torque to the front and rear wheels according to the weight distribution during four-wheel drive. Ru. Furthermore, for example, JP-A-56-430
As shown in Publication No. 31, even when a hydraulic clutch is used as a transfer clutch, when the four-wheel drive is operating under a predetermined load or more, the clutch torque is set to be larger than the drive torque, resulting in a direct connection state. In this way, in any four-wheel drive system, the torque distribution between the front and rear wheels is fixed. [Problems to be Solved by the Invention] By the way, in the above conventional four-wheel drive vehicle, the torque distribution between the front and rear wheels is uniquely determined.
It simply distributes torque to the rear wheels to compensate for the lack of grip in the front wheels. Therefore, under driving conditions such as paved roads where the grip of the front wheels is large, the front wheel drive tends to be close to the 11-wheel drive system, which provides good stability but lacks maneuverability. On the other hand, in driving conditions where the grip of the front wheels is reduced, such as on a slippery road such as on a hill, on a snowy road, or when loaded with luggage, more torque is distributed to the rear wheels and the performance of four-wheel drive is achieved. It cannot be said that it is sufficient in terms of stability. Thus, in four-wheel drive under driving conditions that take into account road surface conditions, vehicle speed, loading conditions, etc., there is a problem in that not only power performance but also maneuverability, vehicle stability, etc. are not satisfactory. The present invention was created in view of these points, and an object of the present invention is to provide a four-wheel drive vehicle that can improve maneuverability, stability, etc. in addition to the power performance of four-wheel drive under various driving conditions. It is an object.

[Means to solve the problem]

In order to achieve the above object, the present invention has a configuration in which the transmission output side is transmitted to the front wheels via a hydraulic clutch for front wheel contact, and to the rear wheel via a hydraulic clutch for rear wheel contact. The engagement time of the two hydraulic clutches is controlled separately based on the duty signal, and the torque distribution between the front and rear wheels is made variable depending on driving conditions including road surface conditions.

[Function 1] Based on the above configuration, the duty signal from the control unit determines the torque transmitted to the front wheels by the hydraulic clutch for front wheel engagement/disconnection, and the torque transmitted to the rear wheels by the hydraulic clutch for rear wheel engagement/disconnection. It becomes possible to arbitrarily set torque distribution. As a result, on paved roads, it is possible to increase the torque transmitted to the rear wheels to obtain maneuverability similar to that of an R car, and conversely, on snowy roads, it is possible to increase the torque transmitted to the front wheels to ensure stability. [Embodiment] Hereinafter, an embodiment of the present invention will be explained in detail based on the drawings.In Fig. 1, a transmission system of a four-wheel drive vehicle according to the present invention will be explained. The clutch 2 and the transmission 4 are placed in the longitudinal direction of the vehicle body, and the front differential device 1G is assembled and installed inside the transmission case at the bottom between the clutch 2 and the transmission 4, resulting in a transaxle type. The transmission 4 is of a constant mesh type, and the input shaft 3
The output shaft 5 is arranged parallel to the
．． 5 is provided with four sets of transmission gears 6 to 9 that mesh with each other, for example, first to fourth speeds, and a synchronization mechanism 10 between gears 6 and 7 and a synchronization mechanism between gears 8 and 9. By selectively operating the mechanism 11, each forward gear stage from first speed to fourth speed is obtained. Further, the reverse gear is obtained by meshing the sleeve-side gear 13 of the synchronization mechanism 10 with the reverse gear gear 12 provided on the input shaft 3 via an idler gear (not shown). The output shaft 5 is a hollow shaft, into which a front drive shaft 14 is inserted, and a drive pinion 15 at the front end of the front drive shaft 14 meshes with a crown gear 17 of a front differential device 16. Transmission is configured to the front wheels. In addition, a transfer device 1 disposed at the rear of the transmission 4
At 8, a transfer drive gear 19 integrated with the output shaft 5 is connected to the front drive shaft 14 via a front wheel disconnection hydraulic clutch 20. The driven gear 21, which is always in mesh with the transfer drive gear 19, is connected to the rear drive shaft 22 via the rear wheel contact hydraulic clutch 20-.
The rear drive shaft 22 is further connected to a propeller shaft 23.
Power is transmitted to the rear wheels via the rear differential @24. As the hydraulic pressure/circuit of the hydraulic clutch 20, 20', the oil passage 2G on the discharge side of the oil pump 25 is connected to a solenoid valve 30,
It communicates with the front wheel disconnection hydraulic clutch 20 via an oil passage 27. The solenoid valve 30 has a valve body 31, a spool 32, and a coil 33. A plunge t34 on the side of the coil 33 is connected to one of the spools 32, and a spring 35 is biased when the plunger t34 is used. Then, by energizing the coil 33, the plunger 3
4 moves the spool 32 against the spring 35,
The inlet boat 31a of the oil passage 26 is connected to the outlet boat 3 of the oil passage 27.
1b, and when the coil 33 is de-energized, the Boolean 3
2 to 1 m, and connect the exit boat 31b to the drain port 31c.
It is configured so that it communicates with the In addition, drain boat 31c
communicates with the oil reservoir side via an oil passage 28. Further, regarding the hydraulic clutch 20' for rear wheel engagement, in the same manner as described above, an oil passage 26' branching from the oil passage 2 on the discharge side of the oil pump 25 is connected to the solenoid valves 30' and 2.
7'. As an electric control system, a manual operation section 40 is provided, and the voltage level of a potentiometer 41 can be arbitrarily changed by this operation section 40. The voltage A of the potentiometer 41 and the triangular wave voltage B of the triangular wave generating circuit 42 are input to a comparator 43, and compared as shown in FIG. 2 (2), a duty signal shown in Φ) is output.
This signal is input to the solenoid valve 30 via the driving transistor 44. Thus, the voltage A
The lower the level, the longer the ON time of the duty signal becomes, and the longer the engagement time of the clutch 20 due to refueling of the solenoid valve 30 becomes longer. Also, regarding the hydraulic clutch 20', in the same manner as described above, a manual operation section 40', a potentiometer 41',
A square wave generating circuit 42' and a comparator 43'. A transistor 44' is provided, by means of which the engagement time of the clutch 20' can be changed individually. Next, the operation of the four-wheel drive vehicle configured as described above will be explained. First, the potentiometer 41 is activated by the manual operation section 40.
When the level of voltage A is set, a duty signal is output based on this and triangular wave voltage B, and this signal causes the solenoid valve 30 to repeat oil supply by energizing and draining oil by de-energizing, so that the hydraulic clutch 20 is turned on and off at a constant cycle. I will do it. Therefore, the power from output 4 @ 5 for shifting is intermittently applied to the front drive shaft 1 only when the hydraulic clutch 20 is connected.
4. The power is transmitted to the front wheels via the front differential device 16, and the longer the clutch 20 is engaged, the more power is transmitted to the front wheels and the driving torque becomes larger. On the other hand, when the level of the voltage A' of the potentiometer 41' is set using another manual operation section 40', a corresponding duty signal is output and the solenoid valve 30'
By operating the hydraulic clutch 20', the hydraulic clutch 20' similarly engages and engages. Therefore, the power from the transmission 4 is intermittently transferred to the transfer gear 19 only when the hydraulic clutch 20' is engaged.
．． 21. The power is also transmitted to the hydraulic clutch 20' and the rear wheels after the rear drive shaft 22, resulting in four-wheel drive driving. Here, in the case of a paved road surface condition, for example, if the duty ratio by the manual operation part 40 is set to 43% and the duty ratio by the manual operation part 40' is set to 100%, the torque distribution between the front and rear wheels is 0.43%. :100=3
It becomes a driving mode similar to that of an FR car. On the other hand, in the case of a snowy road, the duty ratio can be determined in the same way, and the torque distribution between the front and rear wheels can be set to 6 = 4, for example, to create a driving mode similar to that of the F car. By setting the duty ratio of one of the hydraulic clutches 20 and 20' to 100% and the duty ratio of the other to 0%, only one of the hydraulic clutches is always engaged and the "F" or "F"
ll two-wheel drive driving mode. Although one embodiment of the present invention has been described above, torque distribution can be made variable depending on vehicle speed, loading conditions, etc., or can be done automatically. [Effect of explanation 1] As described above, according to the present invention, the torque distribution between the front and rear wheels during four-wheel drive is changed, and for example, on a paved road, the drive torque is distributed to the rear wheels to become larger. Since it is closer to the R car, you can get nimble maneuverability.Also,
On snowy roads, on the other hand, the front wheel drive torque is distributed so that it is closer to that of an F vehicle, ensuring vehicle stability.In the hydraulic circuit, the solenoid valve that supplies and drains oil is activated by the duty signal The structure is simple because it operates and directly sets the clutch torque of each hydraulic clutch.In contrast to changing the clutch oil pressure, the clutch engagement time is changed, so the engine output does not change. The torque distribution between the front and rear wheels can always be maintained as set.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of a four-wheel drive vehicle according to the present invention;
FIGS. 2(a) and 2(b) are signal waveform diagrams. 4...Transmission 20...Hydraulic clutch for front wheel engagement/disconnection 20'...Hydraulic clutch for model wheel engagement 30, 30'
... Solenoid 45 ... Control unit patent applicant Fuji Heavy Industries Co., Ltd. agent Patent attorney Nobuko Kofuku Ukasa Patent attorney Susumu Murai Figure 2

Claims (1)

[Scope of Claims] The output side of the transmission is configured to be transmitted to the front wheels via a front wheel disconnection/disconnection hydraulic clutch, and to the rear wheels via a rear wheel disconnection/disconnection hydraulic clutch, and based on a duty signal from a control unit. A four-wheel drive vehicle that controls the engagement time of both hydraulic clutches separately, and varies torque distribution between the front and rear wheels depending on driving conditions including road surface conditions.