JPS62292529A - Power distribution controller for four wheel drive vehicle - Google Patents

Abstract

PURPOSE:To aim at improvement in stack escapability as well as improvement in accelerability at a low friction factor passage, by installing a device which interlocks the clutch clamping force control actuation of a differential limiting controller with the clutch clamping force control actuation of an all wheel driving force distribution controller. CONSTITUTION:An all wheel driving force distribution controller 1 makes clutch clamping force variable according to driving conditions of a vehicle, and clutch clamping force control actuation of this controller 1 and another clutch clamping force control actuation of a differential limiting controller are interlocked with each other via an interlocking device 3. This clutch clamping force of the differential limiting controller 2 is given as the value conformed to the clutch clamping force of the all wheel driving force distribution controller 1. With this constitution, when it comes to driving force distribution at the 4WD side, differential limiting actuation is also performed by the interlocking device 3, increasing driving force at the low speed side of left and right wheels. Therefore, stack escapability and accelerability at a low friction factor passage are all improved.

Description

Detailed Description of the Invention 3. ET Detailed Description of the Invention (Field of Industrial Application) The present invention provides a
1. This invention relates to a four-wheel drive 11 (driving force distribution control device) that controls a power distribution control device for both rear wheels and left and right wheels.

(Prior Art) As a conventional four-wheel drive Ichikawa drive force distribution control device, for example, the device described in 11.1 of the 11F Opening/Closing 61-67632-inch publication is known.

This conventional device is capable of preventing stuck escape, etc. by engaging a clutch connected to the drive shaft of the vehicle to connect the front wheels and the rear wheels. In a drive system switching device for switching from two-wheel drive to four-wheel drive, a rotation speed sensor is attached to the front wheel and the rear wheel described in 1111 and constantly detects the rotation speed of the 1i single wheel and the rear wheel, respectively, and a small wheel on the side that is constantly driven. and other rotational speed sensors that constantly detect the rotational speed of each of the left and right wheels, and if the difference in rotational speed between the front and rear wheels is larger than a predetermined value from the value obtained by these rotational speed sensors. In this case, the vehicle is first switched to four-wheel drive, and then the difference in rotational speed between the left and right wheels of the wheel that is constantly driven is compared with a reference value, and it is determined that there is a gap between the left and right wheels. In this case, a differential limiting mechanism is activated to prevent differential movement due to slippage between the left and right wheels.

(Problems to be Solved by the Invention) However, in the conventional four-wheel drive system 11 (circular power distribution control device), the drive wheels become stuck (when one of the drive wheels spins in a two-wheel drive state, the other wheel is still +17- L
, a phenomenon in which the vehicle stops moving), the system switches from two-wheel drive to four-wheel drive, and if there is slippage between the left and right wheels of the wheels that are constantly being driven, the differential between the left and right wheels is also limited. However, since the foot lock control was mutually controlled by the signals from each rotation speed sensor, there were problems as listed below. was there.

・□() Always requires four rotational speed sensors, increasing cost.

('2) On road surfaces where there is slippage between the front and rear wheels,
Although there is a high possibility that slipping will occur between the left and right wheels that are constantly driven, the differential limiting mechanism starts operating only after detecting the difference in rotation between the left and right wheels, so the left and right wheels are wasted. It is not possible to prevent slippage between the parts.

(3) Since the means for preventing slippage between the front and rear wheels and the left and right wheels is switched in an ON-OFF manner, it causes a switching shock and a sudden change in the steering characteristics of the vehicle.

(Means for solving the problems) The present invention aims to solve the problems as described in 11.
In order to achieve this objective, the present invention employs the following solution.

The solution of the present invention will be explained with reference to the conceptual diagram of the claim shown in FIG. 1. A front and rear wheel drive force distribution control device that makes the clutch engagement force variable according to the driving situation of the vehicle and controls the drive force distribution to the front and rear wheels. 1, and a differential limiting control device 2 that makes the clutch engagement force variable depending on the driving condition of the vehicle and controls the distribution of driving force to the left and right wheels, the differential limiting control device 2
The flanch engagement force control operation of the front and rear wheel drive force distribution control device 1 is linked with the clutch engagement force control operation of the front and rear wheel drive force distribution control device 1. It is characterized in that it is given as a value according to the flanch fastening force of the force distribution control device 1.

(Function) In the driving force distribution control device for a four-wheel drive vehicle of the present invention, 1. By using the above-mentioned means, when the clutch engagement of the front and rear wheel drive force distribution control device causes the drive force to be distributed to the four-wheel drive side, such as when stuck or when driving on a road with a low friction coefficient, the interlocking means can make a difference. A motion limiting operation is also performed, and a differential limiting torque is generated that increases the driving force on the low rotation side of the left and right wheels.

Therefore, it is possible to improve the ability to get out of the stack, and to improve acceleration and climbing performance on roads with a low friction coefficient.

In addition, during normal driving on asphalt dry roads, etc., when the clutch of the front and rear wheel drive gradient control device is released to distribute the driving force to the two-wheel drive side, the interlocking means does not operate to limit the differential, so the difference between the left and right wheels is reduced. Smooth turning movement is possible due to the movement.

Furthermore, if the sensitivity of the clutch engagement force control characteristic of the left and right wheel differential limiting control device is set to be lower than the sensitivity of the clutch engagement force control characteristic of the front and rear wheel drive force distribution control device, It will not be suddenly controlled by the lock side,
Sudden changes in the vehicle's steering characteristics can be prevented.

(Example) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In describing this embodiment, a driving force distribution control system for a four-wheel drive Qj, which is based on rear wheel drive and has a rear differential device provided with a differential limiting clutch, will be taken as an example.

First, the configuration of the embodiment will be explained.

As shown in FIG. 2, the drive system of the four-wheel drive 11 (to which the driving force distribution control device AI of the first embodiment is applied) includes an engine 10, a transmission 11, a mission output fit
h12, transfer device 13, rear propeller shaft 14, rear differential device 15, rear drive shafts 16, 17, rear wheels 18, 19, front propeller shaft 20, front differential 9212
1. It is equipped with a front drive shaft of 22.23 degrees and a front wheel of 24 degrees and 25 degrees.

The transfer device 113 includes a transfer clutch 30 having a wet multi-plate clutch structure that distributes the engine driving force to the front wheels 24.25 side according to the clutch engagement force, and a transfer clutch 30 as a means for transmitting the driving force to the front wheels 24.25 side. A gear train 31 is provided inside a transfer case 32, and a clutch engagement force is applied to the transfer clutch 30 by a clutch hydraulic pressure P applied to a clutch piston 33 from the outside.

The mission output shaft 12, which is the input shaft to the transfer device 13, is provided with a rear propeller shaft 14, which is one of the output shafts, in a coaxially directly connected state, and the front propeller shaft 20, which is the other output shaft, is connected to the transfer clutch 30. and a gear I lane 31.

The rear differential device 15 described in 1ii includes a differential gear 40 that distributes engine driving force while allowing differential movement between the left and right rear wheels 18 and 19, and a drive manual section and a drive output section for the differential gear 40. A differential limiting clutch 41 having a wet multi-disc clutch structure is provided between the differential wheels 18 and 19 to limit the differential movement between the left and right rear wheels 18 and 19 according to the clutch engagement force, and is provided inside the differential case 42. A clutch engagement force is applied to the differential limiting clutch 41 by external clutch oil pressure P' applied to the clutch piston 43.

Incidentally, as the front differential device 21, a normal differential device in which only a differential gear 40 is housed in a differential case 45 is used.

Next, as shown in FIGS. 2 and 3, the driving force distribution control device A1 of the first embodiment includes the transfer clutch 3.
0 and the differential limiting clutch 41, and a hydraulic pressure generating device 50 as an external device that generates hydraulic pressure for engaging the differential limiting clutch 41, and the hydraulic pressure from the hydraulic pressure generating device 50 is set to a predetermined clutch hydraulic pressure P.
, P'.

In addition, in the first embodiment, the transfer clutch pressure oil passage 53
The differential limiting clutch pressure oil passage 54 is branched from the differential limiting clutch pressure oil passage 54, and the clutch hydraulic pressures P and P' having the same pressure level are applied to the transfer clutch 30 and the differential limiting clutch 41, thereby controlling the front and rear wheel drive force distribution and adjusting the difference between the left and right rear wheels. It has an interlocking relationship with motion restriction control. However, the differential limiting clutch 41
Compared to the clutch hydraulic pressure P on the transfer clutch 30 side, the clutch hydraulic pressure P' on the transfer clutch 30 side is configured such that the rising time of the hydraulic pressure is delayed by a delay circuit 70 having an orifice 70a.

The hydraulic pressure generating device 50 includes an oil pump 51, a pump pressure oil path 52, a transfer clutch pressure oil path 53, a differential limiting clutch pressure oil path 54, a branch drain oil path 55. A reserve tank 56 and a suction oil passage 57 are provided.

151 The hydraulic control device 60 includes a left front wheel rotation sensor 61. as a detection means. Right front wheel rotation sensor 62. Equipped with a rear wheel rotation sensor 63, and a control unit 64 as a control circuit.
As a control actuator, an electromagnetic proportional pressure reducing valve 65 is provided in the middle of the branch drain oil passage 55 and is opened and closed by hydraulic pressure from the check oil passage 65a and electromagnetic force from a valve solenoid 65b.

Left front wheel rotation sensor 61. The right front wheel rotation sensor 62 and the rear wheel rotation sensor 63 are connected to the front drive shaft 2, respectively.
2.23 and a sensor fixed to the rear propeller shaft 14 A sensor or the like is used that is placed close to the rotor and converts changes in magnetic flux due to rotation into a sinusoidal voltage signal. Rotation signals (nf+), (nf2), and (nr) corresponding to the rotational speed are output.

Incidentally, as these rotation sensors 61, 62, and 63, sensors used in an anti-skid brake control device may be used in common.

The control unit 64 is mainly an in-vehicle microcomputer, and has an interface, RAM, and ROM.
A control circuit having an internal circuit such as a CPU or the like is used, and the control content uses signals from the rotation sensors 61, 62, and 63 as input information, and as the rotational speed difference ΔN between the front and rear wheels increases, the clutch oil pressure P, P' is increased, driving force distribution is brought closer to the four-wheel drive side, and the left and right rear wheels 18.
19 to generate differential limiting torque.

As shown in FIG. 3, the control characteristic map M of the rotational speed difference ΔN between the front and rear wheels and the command current value i'x is stored in advance in the memory circuit of the control unit 64 in the form of a table. The control unit 64 also includes a calculation circuit 641 that calculates the front wheel rotation speed Nf from the left front wheel rotation speed Nf+ and the right front wheel rotation speed Nf2.
, an arithmetic circuit 642 that calculates the rotational speed difference ΔN (=Nr-Nf) between the front and rear wheels, and a control current value i that changes the command current value is.
It is equipped with an amplifier 643 that amplifies the signal up to .

The electromagnetic proportional pressure reducing valve 65 is a valve that is operated by a control current signal - (i) based on a control electric value i from the control unit 64, and when the control current value i=0, the oil from the oil pump 51 is When all of the oil is drained, the clutch oil pressures P and P' become zero, and as the control current value i increases, the drain oil j1;' decreases, increasing the clutch oil pressures P and P' as shown in the hydraulic characteristics in Fig. 5. Can be done.

Note that the clutch oil pressures P, P', the torque transmitted to the front wheels, and the differential limiting torque are in a proportional relationship.

The delay circuit 70 is connected to the differential limiting clutch pressure oil passage 54.
An orifice 70a is provided in the middle of the hole.

Orifice bypass oil passage 70b, check valve 70c
It is equipped with

Furthermore, due to +fii orifice 70a, there is a difference! IJJ
The flow rate restriction effect when supplying hydraulic oil to the 11th limit clutch 41 temporally delays the Koehli characteristic of the clutch oil pressure P'. The removal is performed at the same timing as the transfer clutch 30 so that there is no time delay.

Next, the operation of the first embodiment will be explained.

First, the flow of the driving force distribution control operation will be described with reference to the flowchart shown in FIG.

Drive force distribution control is activated by O from the ignition switch.
Started by N signal, step 100 → step 10
1-Step 102 → Step 103 Pass Step 104
→The flow of proceeding to step 105 is performed every control activation time.

Step 100 is a step of reading the left front wheel rotation speed Nf+ and the right front wheel rotation speed Nf2.

In step 101, the left and right front wheel rotational speed Nf+,
Front wheel rotation speed Nf from Nf2 and final gear ratio iF
This is a calculation step for calculating .

F The rejection f formula is Nf=-.(Nf++Nf2).

Step 102 is a step of reading the rear wheel rotational speed Nr.

Step 103 is a calculation step for calculating the rotational speed difference ΔN between the front and rear wheels from the front wheel rotational speed Nf and the rear wheel rotational speed Nr.

Note that the arithmetic expression is ΔN=Nr−Nf.

Step 104 is a step in which the command current value iX is table-shifted based on the rotational speed difference ΔN between the front and rear wheels and the control characteristic map M.

Step 105 is an output step of amplifying one command current value to a predetermined control current value i and outputting the control current signal (i) to the electromagnetic proportional pressure reducing valve 65, as shown in FIG. A clutch oil pressure P can be obtained depending on the magnitude of the current value i.

Here, the spring rising characteristics of the clutch oil pressures P and P' are expressed as
To describe it in a diagram, when a predetermined control current value i is applied from a flow value i=0 under control 'Iti, the clutch oil pressure P on the transfer clutch 30 side becomes an oil pressure 1"'t-1 as shown by the solid line.
The clutch oil pressure P reaches the 11 mark. On the other hand, the clutch oil pressure P′ on the differential limiting clutch 41 side
As shown by the dashed line, passing through the orifice 70a, the clutch pressure p,
The relationship of p' is P≧P', and the latch oil pressure P' has smoother hydraulic characteristics than the clutch oil pressure P.

Here, the reason why the clutch oil pressure P' is made to have a smooth characteristic with a lagging delay compared to the clutch oil pressure P is to avoid sudden changes in the steering characteristics of the vehicle when the rear differential system 115 is suddenly controlled to the lock side. This is to prevent this. (If you place emphasis on quick response, it is desirable for both clutch oil pressures P and P' to rise quickly, but in the case of clutch oil pressure P', there are many factors that affect steering characteristics in particular, so the oil pressure characteristics will rise gradually. As described above, in the driving force distribution control device A1 of the first embodiment, the control oil pressure generated based on the same control content is the same as the both clutch oil pressures P.

By sharing it as P', transfer clutch 3
0 and the clutch engagement force operation of the differential limiting clutch 41, the following effects can be obtained.

, p When one of the rear wheels 18.19, which is the drive wheel, falls off or idles and becomes stuck, a large rotational speed difference ΔN occurs between the front and rear wheels, so a high clutch oil pressure P , P ' acts on the transfer clutch 30 and differential limiting clutch 41, and drives the front wheels to the 24.25 side.
When the force is transmitted, it also prevents the rear wheels from spinning.

Therefore, the driving force from the engine jO is transmitted to the front and rear wheels, and drive loss due to idling is suppressed, resulting in high stuck escape performance.

・2) 1 [Low yf on i roads, snowy roads, etc.: When accelerating on friction coefficient roads or climbing a hill, when slipping occurs in the rear wheels (18.19), which are the driving wheels, the transfer clutch 30
and a high clutch oil pressure P for the differential limiting clutch 41,
P' acts, and the driving force distribution is changed to the four-wheel drive side, and a high differential limiting torque is applied to the left and right rear wheels 18, 19 even if there is no difference in rotational speed.

Therefore, when accelerating on a low-friction coefficient road or when climbing a hill, driving force is transmitted equally to the left and right rear wheels18.19 in a four-wheel drive state, which improves acceleration performance and climbing performance. It increases.

(■ Transfer clutch 30 and differential limiting clutch 4
Since the clutch engagement force control in 1 is interlocked with each other,
When the clutch oil pressures p and p' are not generated or are very small, that is, when the rear wheels are driven, no differential limiting torque is generated.

Therefore, when turning in a rear wheel drive state, the left and right rear wheels 18
．． No differential limiting torque is generated in the steering wheel 19, and the turning performance is prevented, especially in the early stages of turning, where the left and right rear wheels 18.degree. 19 are difficult to turn due to differential limiting.

Furthermore, in the driving force distribution control device A1 of the first embodiment, an R extension path 70 is provided in the differential limiting clutch pressure oil path 54, and the rise sensitivity of the clutch oil pressure P' with respect to the clutch oil pressure P is The effect described below can be obtained by making it dull.

・4) The differential limiting torque control, which has a large effect on steering characteristics, follows the drive force distribution control to the four-wheel drive side with a slight delay, resulting in Sudden changes in steering characteristics can be prevented.

Next, the driving force distribution control device A2 of the second embodiment will be explained.

As shown in FIG. 7, in this second embodiment device A2, the human power information to the control unit 64 is the same as that in the first embodiment, but the control characteristic map is different from the front and rear wheel drive force distribution control characteristic map M1. 2 with motion limit opening control characteristic map M2
The control actuator, which is set with two maps and performs hydraulic control, also includes a first:B magnetic proportional pressure reducing valve 65 and a second electromagnetic proportional pressure reducing valve 66.

In addition, both control characteristic maps Ml and M2 are one command current value for the rotational speed difference ΔN between the two front and rear wheels, as shown in FIG.
The control unit 64 includes two amplifiers 643.
．． 644 are provided.

Further, the second electromagnetic proportional pressure reducing valve 67 is connected to the oil pump 5.
Although one oil pump is sunk in the middle of the branch pump pressure line 58 so that the oil pump 1 is shared, separate oil pumps may be used.

Therefore, in this second embodiment P1A2, as shown in FIG. (Step 106→
In step 107), control current value signals (i) and (i') are output, respectively.

As shown in Fig. 9, the rise characteristics of the clutch oil pressures P and P' are such that the clutch oil pressure P' lags behind the clutch oil pressure P in terms of time and has a lower oil pressure level. show.

Next, a driving force distribution control device A3 according to a third embodiment will be explained.

As shown in FIG. 10, the third embodiment device A3 has the same control unit 64 as the first embodiment, but
A second proportional electromagnetic pressure reducing valve 67 whose primary pressure is the clutch oil pressure P that has passed through the first proportional electromagnetic pressure reducing valve 65 which is a control actuator is provided.

This is an example in which the pressure level of clutch oil pressure P' is set to be lower than the pressure level of clutch oil pressure P.

Therefore, in the device A3 of the third embodiment, the clutch hydraulic pressure V1
As shown in FIG. 11, the lowering characteristic indicates a characteristic in which the pressure level of the clutch oil pressure P' is lower than the clutch oil pressure P.

The operations of the second and third embodiments are the same as those of the first embodiment, although the way in which the sensitivity of the clutch oil pressure P' is dulled with respect to the clutch oil pressure characteristic P is different.

Hereinafter, the embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment.
Even if there are design changes within the scope of the present invention, they are included in the present invention.

For example, although the example shows a four-wheel drive vehicle based on rear wheel drive, it can also be applied to a four-wheel drive vehicle based on front wheel drive, and the differential limiting clutch may also be applied to the front wheels or front and rear wheels. .

Further, in the embodiment, an example has been shown in which the clutch engagement force is obtained by hydraulic pressure, but an electromagnetic clutch may be used as the clutch and it may be obtained by electromagnetic force.

Further, the control content of the clutch engagement force is not limited to the content shown in the control characteristic mark 7 of the embodiment, but may be performed by adding input information such as the coefficient of friction of the road surface, or using completely different input information. Good too.

Specifically, the application state of the driving force may be estimated from the accelerator opening degree, and the control shown in the present invention may be implemented in order to prevent the driving wheels from spinning.

(Effects of the Invention) As explained above, in the drive force distribution control device for a four-wheel drive vehicle of the present invention, the clutch engagement force control operation of the differential limiting control device is controlled by the front and rear wheel drive force distribution control. Since it has an interlocking means that interlocks with the clutch 2 clutch engagement force control operation of the device, the clutch engagement operation is performed in conjunction without detecting the occurrence of slippage 7M on each wheel, which improves the ability to escape from the stuck. It is possible to improve the direction of the vehicle, acceleration performance on a road with a low friction coefficient, climbing performance, etc., and since the clutch release is also performed in conjunction with this, it is possible to obtain the effect of ensuring smooth cornering.

In each embodiment, in addition to the two-wheel common effect, the sensitivity of the clutch engagement force control characteristic of the left and right wheel differential limiting control device is greater than the sensitivity of the clutch engagement force control characteristic of the front and rear wheel drive force distribution control device. Since it is set to be dull, it is possible to prevent sudden changes in steering characteristics.

Furthermore, since the clutch engagement control is performed continuously rather than in an ON-OFF manner, there is an effect (11) in that the shock caused by engagement can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of the claim of the four-wheel drive/IT short drive force distribution control device of the present invention, Fig. 2 is a diagram showing a four-wheel drive vehicle to which the drive force distribution control device of the first embodiment is applied, and Fig. 3 The figure is a block diagram showing the control system of the device of the first embodiment, FIG. 4 is a flowchart showing the flow of driving force distribution control operation in the control unit of the device of the first embodiment, and FIG. Fig. 6 is a hydraulic characteristic diagram of the clutch oil pressure of the device of the first embodiment, Fig. 7 is a block diagram showing the control system of the device of the second embodiment, and Fig. 8 is a diagram of the control system of the device of the second embodiment. 9 is a flowchart showing the flow of the driving force distribution control operation in the control unit, FIG. 9 is a diagram showing the rise characteristics of the clutch oil pressure of the device of the second embodiment, and FIG. 10 is a block diagram showing the control system of the device of the third embodiment. , FIG. 11 is a clutch oil pressure rise characteristic diagram of the third embodiment device. 1... Front and rear wheel drive force distribution control device 2... Differential M1 limit control device 3... Interlocking means patent applicant (] San Jidosha Co., Ltd. Figure 4 Figure 5 Figure 6 t (vTI 4) Figure 9

Claims (1)

[Scope of Claims] 1) A front and rear wheel drive force distribution control device that varies clutch engagement force according to vehicle running conditions and controls drive force distribution to front and rear wheels; a differential limiting control device that makes the force variable and controls driving force distribution to the left and right wheels; A four-wheel drive vehicle, characterized in that it has an interlocking means that interlocks with the control operation, and applies the clutch engagement force of the differential limiting control device as a value corresponding to the clutch engagement force of the front and rear wheel drive force distribution control device. Driving force distribution control device. 2) The sensitivity of the clutch engagement force control characteristic of the left and right wheel differential limiting control device is set to be lower than the sensitivity of the clutch engagement force control characteristic of the front and rear wheel drive force distribution control device. The driving force distribution control device for a four-wheel drive vehicle according to item 1.