JPH0829683B2 - Vehicle drive force distribution control device - Google Patents

Description

The present invention is used as a drive force distribution control device for a four-wheel drive vehicle (including a differential limiting clutch control device for a center differential mechanism between front and rear drive shafts). The present invention relates to a driving force distribution control device for a vehicle.

(Prior Art) Conventionally, as a driving force distribution control device for a four-wheel drive vehicle, for example, a device described in JP-A-61-157437 is known.

This conventional device is a device that controls the driving force distribution on the two-wheel drive side in a region where the front-rear wheel rotational speed difference is small, and shifts to the four-wheel drive side driving force distribution as the front-rear wheel rotational speed difference increases. Since the multi-disc friction clutch used for this drive force distribution control is mainly used for slip engagement by sequentially changing the transmission torque, the lubrication oil is introduced to the inner position of the multi-disc friction clutch by a lubrication pump dedicated to lubrication and cooling. A method of forcibly cooling and preventing seizure of the clutch to ensure normal operation is used.

(Problems to be Solved by the Invention) However, a lubricating pump used in such a conventional driving force distribution control device is usually a pump that is provided on the input side of an engine driving force that has passed through a transmission and that is driven by the engine. Therefore, the suction and the discharge are reversed when the rotation direction is forward and reverse.

Therefore, in general, a lubrication pump is provided so as to lubricate and cool the multi-plate friction clutch during forward movement, where the traveling ratio is overwhelmingly high.
Since the cooling cannot be performed, as described above, when the clutch engagement control mainly based on the slip engagement is performed based on the difference between the front and rear wheel rotation speeds, the multi-plate friction clutch is seized.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above problems. To achieve this object, the present invention can distribute the engine driving force to the front and rear wheels. A multi-disc friction clutch that is provided at a position and is fastened by a pressing mechanism that is operated by an external control hydraulic pressure, and a lubrication that is provided on the input side of the engine driving force that has passed through the transmission and that lubricates and cools the multi-disc friction clutch. In a vehicle drive force distribution control device comprising a pump and a clutch engagement force control means which is provided outside the multi-disc friction clutch and produces the control hydraulic pressure based on predetermined input information and control content,
The clutch engagement force control means releases the clutch until the front and rear wheel rotation speed difference exceeds a predetermined value when the vehicle is moving backward, and does not allow the relative rotation of the clutch at once when the front and rear wheel rotation speed difference exceeds the predetermined value. It is a means for bringing the clutch into the engaged state.

(Operation) When the vehicle is moving forward, the lubricating pump operates in response to the forward rotation direction input rotation of the engine drive force that has passed through the transmission, and the forced cooling effect of cooling the lubricating oil by guiding it to the inside position of the multi-plate friction clutch Cooling of the torque transmission unit centered on the multi-disc friction clutch is performed.

When the vehicle moves backward, the lubricating pump does not perform the forced cooling action by receiving the input rotation in the reverse direction of the engine driving force that has passed through the transmission.

On the other hand, the clutch engagement force control means keeps the clutch released until the difference between the front and rear wheel rotation speeds exceeds a predetermined value.
When the difference between the front and rear wheel rotation speeds exceeds a predetermined value, control is performed to bring the clutch into a clutch engaged state in which the relative rotation of the clutch is not permitted at once.

Therefore, when the vehicle is moving forward, the clutch engagement control, which mainly consists of the slip engagement, is secured by the forced cooling action, and when the vehicle is retracting, the slip engagement state of the multi-disc friction clutch is avoided. As a result, seizure of the multi-plate friction clutch can be prevented even though the forced cooling action by the lubrication pump is not performed.

(Example) Hereinafter, the Example of this invention is described based on drawing.

In describing this embodiment, a driving force distribution control device for a four-wheel drive vehicle will be described as an example.

 First, the configuration will be described.

As shown in FIG. 1, the drive system of a four-wheel drive vehicle to which the drive force distribution control device of the embodiment is applied has an engine 1, a transmission 2, a transfer input shaft 3, a transfer clutch device A, a rear propeller shaft 4, The rear differential 5, rear wheels 6, transfer output shaft 7, front propeller shaft 8, front differential 9, front wheels 10 are provided, and the engine driving force that has passed through the transmission 2 is directly transmitted to the rear wheels to the front wheels 10. Is transmitted via a transfer clutch device A provided between the transfer input / output shafts 3 and 7.

The control hydraulic pressure Pc is provided outside the transfer clutch device A based on predetermined input information and control contents.
Hydraulic control device as clutch engagement force control means that creates
20 are provided.

The hydraulic control device 20 includes a motor 22 that is driven or stopped by a relief switch 21, a hydraulic pump 24 that is driven by the motor 22 to suck up from a reservoir tank 23, and a pump discharge pressure (primary pressure) from the hydraulic pump 24. An accumulator 26 that stores via a check valve 25 and an electromagnetic proportional pressure valve 28 that adjusts a line pressure (secondary pressure) from the accumulator 26 to a predetermined control hydraulic pressure Pc by a control current i from a control unit 27 are provided. It is supplied to the control hydraulic port 30 through the control hydraulic pipe 29.

The control unit 27 has an electronic control circuit configuration, and includes a front wheel rotation speed sensor 31, a rear wheel rotation speed sensor 32, a reverse switch 33, and the like as information input sensors. The optimum front-rear wheel driving force distribution ratio is obtained, and when the vehicle is reversing, the clutch is released until the front-rear wheel rotation speed difference ΔN exceeds a predetermined value ΔN _T that can avoid tight corner braking, and the front-rear wheel rotation speed difference ΔN Exceeds a predetermined value ΔN _T , the control current i is output so that a clutch engagement state in which relative rotation of the clutch is not permitted is obtained at once.

As shown in FIG. 2, the transfer clutch device A includes a multi-plate friction clutch 60 that is engaged by a pressing mechanism 40 that is operated by a control hydraulic pressure Pc from an external hydraulic control device 20,
A lubricating oil 15 for cooling the clutch provided in the transfer input shaft 3 and in the transfer case 11 and the case cover 12.
To remove the lubricating oil 15 inside the multi-plate friction clutch 60.
And a lubrication pump 70 that guides.

The pressing mechanism 40 of the multi-plate friction clutch 60 includes a cylinder block 41, a piston chamber 42, a piston 43, a piston rod 44, a swing plate 45, a swing pin 46, a fixed pressure plate 47, a bearing 48, and a rotary pressure plate.
It is equipped with 49, pressure block 50, and return spring 51.

The multi-plate friction clutch 60 includes a clutch drum 61 that is spline-coupled to the transfer input shaft 3, a drive plate 62 that is spline-fitted to the clutch drum 61,
The driven plate 63 sandwiched between the drive plates 62 and the driven plate 63 are spline-fitted,
Needle bearing 64 for transfer input shaft 3
And a clutch hub 65 rotatably supported by the clutch hub 65.

From the clutch hub 65, the first sprocket 66
→ Chain 67 → Drive torque is transmitted to the transfer output shaft 7 through the second sprocket 68.

The lubrication pump 70 is of a trochoid pump type provided in a pump housing 71 and a pump cover 72 at the inlet of the transfer input shaft 3, and has a suction port 73.
Communicates with a suction tube 75 having a suction port 74, and its discharge port 76 is connected to a radial oil passage 77, an axial oil passage 78, a radial oil passage 79 and a clutch hub 65 formed in the transfer input shaft 3. It communicates with the formed oil holes 80, 81, sucks up the lubricating oil 15 for cooling the clutch in the transfer case 11, guides the lubricating oil 15 to the multi-plate friction clutch 60, and discharges it through the oil hole 82.

The transfer output shaft 7 and the chain 67 to the front wheel 10 provided offset from the transfer input shaft 3 are immersed in the clutch cooling lubricating oil 15 stored in the lower portion of the transfer case 11, Lubrication pump
70 inlets 74 are arranged.

In FIG. 2, 90 is a joint flange, 91, 92, 93 are seals, and 94, 95, 96, 97, 98 are bearings.

 Next, the operation will be described.

First, the flow of the driving force distribution control operation performed by the control unit 27 will be described with reference to the flow chart shown in FIG.

At step a, the front wheel rotation speed Nf, the rear wheel rotation speed Nr, and the reverse switch signal S are read.

In step b, the front and rear wheel rotation speed difference Δf is calculated by the front wheel rotation speed Nf and the rear wheel rotation speed Nr read in step a.
N is calculated.

In step c, it is determined whether the river switch signal S read in step a is ON (OFF when moving forward and ON when moving backward).

If S = OFF in step c, the process proceeds to step d, and ΔN-ΔT as described in the frame of step d.
Based on the characteristics, the front-wheel-side transmission torque ΔT corresponding to the front-rear wheel rotation speed difference ΔN obtained in step b is obtained.

In step e, the control current i is set as the above-mentioned step d.
I = i _T, which gives the front-wheel-side transmission torque ΔT obtained in step 1, is output.

If S = ON in step c, go to step f,
It is determined whether or not the front-rear wheel rotation speed difference ΔN is equal to or greater than a predetermined value ΔN _T , and when ΔN <ΔN _T , the process proceeds to step g, and the control current i is set to release the multi-plate friction clutch 60 i = 0. Is output.

When ΔN ≧ N _T in step f, the control current i
As the maximum fastening force is applied to the multi-plate friction clutch i
= I _max is output.

Next, the operation centered on the cooling of the multi-plate friction clutch 60 will be described separately for the forward movement of the vehicle and the backward movement of the vehicle.

(B) When the vehicle is moving forward When the vehicle is moving forward, the lubricating pump 70 receives the input rotation of the engine driving force that has passed through the transmission 2 in the forward direction.
Is activated, and the lubricating oil 15 stored in the lower part of the transfer case 11 is sucked into the suction port 74 → the suction tube 75 →
Suction port 73 → Lubrication pump 70 → Discharge port 76 → Radial oil passage 77 → Axial oil passage 78 → Radial oil passage 79 → Oil hole 80 → Oil hole 81 Due to the forced cooling action of cooling by guiding, cooling of the torque transmission portion that suspends the multi-plate friction clutch 60 is performed.

At this time, the lubricating oil 15 stored in the lower portion of the transfer case 11 is stirred by the chain 67, and the stirring and cooling action of cooling the lubricating oil 15 scattered by the stirring is also performed in parallel.

Therefore, even if the control unit 27 controls the clutch engagement force mainly based on the slip engagement corresponding to the front-rear wheel rotation speed difference ΔN, and the amount of heat generated in the clutch portion becomes high, the above-mentioned forced cooling effect is exerted during forward movement. A high cooling effect that prevents a temperature rise is exhibited by a synergistic action with the stirring and cooling action.

(B) When the vehicle retreats When the vehicle retreats, the lubricating pump 70 does not perform the forced cooling action by receiving the input rotation of the engine driving force that has passed through the transmission 2 in the reverse direction.

However, the control unit 27, the front-rear rotational speed difference .DELTA.N is a clutch released state until it exceeds a predetermined value .DELTA.N _T, clutch engagement the front and rear wheel rotational speed difference .DELTA.N does not allow relative rotation once the clutch exceeds a predetermined value .DELTA.N _T The control for setting the state is performed.

Therefore, the slip-engaged state of the multi-plate friction clutch 60, which causes heat generation in the clutch portion, is avoided, and seizure of the multi-plate friction clutch 60 is prevented when retreating.

As described above, in the driving force distribution control device according to the embodiment, when the vehicle is moving forward, the clutch engagement control is mainly performed by the slippage engagement by the forced cooling action, and when the vehicle is retracting, the multi-disc friction clutch 60 is operated. By ensuring from the aspect of clutch engagement control that the slip engagement state is avoided, seizure of the multi-plate friction clutch 60 can be prevented even though the forced cooling action by the lubrication pump 70 is not performed.

As described above, the embodiments have been described based on the drawings. However, the specific configuration is not limited to the embodiments, and even if there is a design change or the like without departing from the gist of the present invention, it is included in the present invention. .

For example, the embodiment has shown an example of application to a transfer clutch device for a four-wheel drive vehicle that does not have a center differential mechanism, but a four-wheel drive vehicle with a center differential mechanism has a differential limit by external control hydraulic pressure. It can also be applied to a limited differential clutch device with a center differential mechanism that controls force.

(Effects of the Invention) As described above, in the vehicle driving force distribution control device of the present invention, the clutch engagement force control means of the multi-plate friction clutch is used to control the difference between the front and rear wheel rotational speeds when the vehicle is in reverse. The clutch release state is maintained until exceeds the predetermined value, and when the difference between the front and rear wheel rotation speeds exceeds the predetermined value, the clutch is engaged so that the relative rotation of the clutch is not permitted. The guarantee from the aspect of clutch engagement control that the slip engagement state is avoided has the effect of preventing seizure of the multi-plate friction clutch even though the forced cooling action by the lubrication pump is not performed.

[Brief description of drawings]

FIG. 1 is a diagram showing a drive system and a control system of a four-wheel drive vehicle to which a driving force distribution control device of an embodiment of the present invention is applied, and FIG. 2 is a sectional view showing a transfer clutch device used in the embodiment device, FIG. 3 is a flow chart showing the flow of driving force distribution control operation in the control unit of the embodiment apparatus. A: Transfer clutch device 1 ... Engine 2 ... Transmission 3 ... Transfer input shaft 7 ... Transfer output shaft 20 ... Hydraulic control device (clutch engagement force control means) 40 ... Pressing mechanism 60 ... Multi-disc friction Clutch 70 ... Lubrication pump

Claims (1)

[Claims] 1. A multi-disc friction clutch, which is provided at a position where engine driving force can be distributed to front and rear wheels and is engaged by a pressing mechanism operated by an external control hydraulic pressure, and an input side of the engine driving force which has passed through a transmission. A lubrication pump that lubricates and cools the multi-disc friction clutch, and clutch engagement force control means that is provided outside the multi-disc friction clutch and that generates the control hydraulic pressure based on predetermined input information and control content. In the vehicle driving force distribution control device, the clutch engagement force control means is in a clutch released state until the front / rear wheel rotation speed difference exceeds a predetermined value when the vehicle is in reverse, and the front / rear wheel rotation speed difference is predetermined. A driving force distribution control device for a vehicle, which is means for putting a clutch into a clutch engagement state in which the relative rotation of the clutch is not permitted at a stroke when the value exceeds a value.