JPH02169328A - Control method and device for four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To make an almost equal torque distribution to both front and rear wheels performable at all times by controlling a supply of hydraulic pressure conformed to a vehicle running state generated by an automatic transmission so to be controlled on the basis of a speed difference between input and output shafts, so as to cause a differential speed ratio between both these shafts to be kept in a specified value. CONSTITUTION:In the rear stage of an automatic transmission 120 shifting the speed torque of an engine 110 and outputting it, there are provided with a first differential gear 130 dividing power into symmetrical front wheels and transmitting it, a torque transfer coupling 200 transmitting the torque transferred to this differential gear 130 to a propeller shaft 140, and a second differential gear 150 dividing the transferred torque into symmetrical rear wheels and transmitting it. This torque transfer coupling 200 consists of a differential pump 500 being driven by a speed difference between input and output shafts 300 and 400 and generating hydraulic pressure, a friction clutch mechanism 600 being disengaged by the generated hydraulic pressure, a hydraulic supply means 700 or the like, thereby making this hydraulic supply means 700 control a differential speed ratio between these input and output shafts 300 and 400 so as to keep a range of 0.02.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a control method for four wheels that are always connected via a clutch that allows slippage between the front wheel system and the rear wheel system] 11 and its 5A Regarding the location.

[Prior Art] Conventionally, as this type of technology, for example, a pump hydraulic pressure is generated by a rotational speed difference between a first rotating shaft that transmits power to the front wheels and a second rotating shaft that transmits power to the rear wheels. The hydraulic pressure is supplied to a clutch interposed between the first rotating shaft and the second rotating shaft, and the clutch engages the first rotating shaft and the second rotating shaft. Related technologies such as publications are known.

[Problems to be Solved by the Invention] However, although a clutch coupling mechanism consisting of a differential pump, a clutch coupling, etc. has been disclosed in the conventionally known system, the differential rotation speed ratio between the input shaft and the output shaft has not been disclosed. Not seen. Then, the input shaft and the output are connected only by hydraulic pressure according to the rotational speed difference between the first rotating shaft (for example, an input shaft that is drive-coupled to a driving wheel) and the second rotary shaft (for example, an output shaft that is drive-coupled to a driven wheel). The engagement with the shaft was controlled.

According to this technique, when driving on a road surface with a low coefficient of friction such as a road surface or an icy road surface, the slip ratio between the drive wheels b and the road surface can increase to the extent of 10% without sudden acceleration. Therefore, when driving on a road surface with a low coefficient of friction,
Even without sudden acceleration, the difference in rotational speed between the input shaft and the output shaft becomes sufficiently large, and the hydraulic pressure corresponding to the difference in rotational speed becomes louder.The engagement force between the input and output shafts becomes stronger, and the driving wheels and the driven wheel are approaching a state in which they are almost directly connected.

However, when driving on a road surface with a high coefficient of friction, such as a paved road, the driven wheels are driven by the road surface, and there is no large difference in rotational speed between the input shaft and the output shaft.

As a result, in conventional well-known systems, especially when the vehicle is running at low speeds such as starting, the drive wheels generate slip between them and the road surface, and a large slip of 4 to 5% or more occurs between the input shaft and the output shaft. Even if a differential rotation speed ratio occurs, the absolute value of the input shaft rotation speed is small, so the rotation speed difference between the input shaft and output shaft is small, the hydraulic pressure generated by the differential pump is low, and the input shaft and output shaft The engagement force was weak.

In other words, in the well-known technology, when running on a road surface with a high coefficient of friction, the torque distribution between the driving wheels and the driven wheels at low speeds is approximately 95:5, and even at high speeds, the torque distribution between the driving wheels and the driven wheels is approximately 95:5. The distribution was set to be approximately 65:35, which was far from a direct connection between the front and rear wheels, and there remained technical issues such as the inability to fully demonstrate the capabilities of a four-wheel drive vehicle.

[Objective of the Invention 1 The present invention was made in view of how to control the clutch joints disclosed so far in order to use them practically, and its purpose is to 4
An object of the present invention is to provide a control method and device for a four-wheel drive vehicle that can fully utilize the characteristics of a four-wheel drive vehicle.

[Description of the Invention] (Structure of the Method Invention) In the control method for a four-wheel drive vehicle according to the present invention, an automatic transmission driven by an engine generates hydraulic pressure according to the vehicle running condition, and the automatic transmission An input shaft that is drive-coupled to a first differential that drives the wheel system of one of the front wheels or the rear wheels, and a second differential that drives the other wheel system of the front wheels or the rear wheels. A differential pump that is controlled based on the rotational speed difference between the output shaft and the output shaft that is drive-coupled to the device, and is driven by the engine via the automatic transmission, controls the input shaft and the output shaft based on the controlled hydraulic pressure. A friction clutch mechanism generates a hydraulic pressure proportional to a rotational speed difference between the differential pump and the differential pump, and controls an engagement ratio between the input shaft and the output shaft using the hydraulic pressure according to the rotational speed difference supplied from the differential pump. , the differential rotational speed ratio between the input shaft and the output shaft is 0.
The configuration is such that maintenance control is performed to maintain the value at 0.02.

(Operations and Effects of the Method Invention) In the present invention having the above-mentioned configuration, the automatic transmission is configured such that the differential rotation speed ratio between the input shaft and the output shaft is maintained at 0.02. The supply of hydraulic pressure according to vehicle running conditions is controlled based on the rotational speed difference between the input shaft and the output shaft. Then, based on the controlled oil pressure, a differential pump supplies oil pressure according to the differential rotation, and based on this oil pressure, a friction clutch mechanism efficiently and precisely controls the engagement relationship between the input shaft and the output shaft. Ru. As a result, torque is distributed almost equally between the front wheels and the rear wheels even when driving at low speeds or at high speeds on roads with a high coefficient of friction.

In other words, regardless of the coefficient of friction of the road surface, vehicle speed, etc.
Even under any driving condition, the engine's output of 1 lk transmitted through the transmission can be distributed almost evenly between the front wheels and the rear wheels, thereby solving the problems of the prior art.

(Explanation of other method inventions) The present invention can be implemented as follows.

The invention of another method is to maintain and control the differential rotation speed between the input shaft and the output shaft by maintaining the differential pump at 0.5 rps per second. The hydraulic pressure set depending on the state is supplied to the differential pump to engage the friction clutch mechanism, and when the differential rotation speed ratio between the input shaft and the output shaft exceeds 0.02, the vehicle running state is determined. The hydraulic pressure set by the hydraulic pressure is further increased and supplied.

The oil pressure is set so that the differential rotational speed ratio between the input shaft and the output shaft is maintained at 0.02 depending on the vehicle running condition.
By being supplied to the differential pump, the friction clutch mechanism is strongly engaged and the input shaft is The differential rotation speed ratio between the output shaft and the output shaft is maintained within a certain range.

In addition, when the differential rotation speed ratio between the input shaft and the output shaft exceeds 0.02, the hydraulic pressure supplied to the differential pump is further increased and is supplied to the differential pump, which is set according to the vehicle running condition. Therefore, it is possible to limit an increase in the differential rotation speed and avoid a decrease thereof, thereby suppressing fluctuations in the differential rotation speed ratio between the input shaft and the output shaft. As a result, large changes in the input torque caused by vehicle running conditions such as the automatic transmission's gear ratio and throttle sensitivity can be handled by changing the set oil pressure and adjusting the setting in line with the input torque.
After the pressure reaches ff111, precise feedback control is performed to maintain the differential rotation speed ratio of 0.02 by making the oil pressure generated by the differential pump proportional to the differential rotation speed. Therefore, the differential rotational speed ratio of 0.02 can be appropriately maintained and controlled with good response.

(Configuration of Apparatus Invention) A control apparatus for a four-wheel drive vehicle according to the present invention is a first differential control apparatus which is driven by an engine via a transmission and drives one of the front wheels or the rear wheels. An input shaft connected to the II device and the drive 1+, an output shaft drivingly connected to the second differential device that drives the other wheel system of the front wheels or the rear wheels, and the rotational speed of the input shaft and the output shaft. A differential pump that generates hydraulic pressure according to the difference, and a hydraulic pressure received from the differential pump to engage the input shaft and the output shaft? j) a friction clutch mechanism for controlling the input shaft; and an input rotation for supplying hydraulic pressure according to the load condition of the engine and hydraulic pressure according to the shifting condition of the transmission to the differential pump, and detecting the rotational speed of the input shaft. It has a speed sensor and an output rotation speed sensor that detects the rotation speed of the output shaft, and a differential rotation speed ratio between the input shaft and the output shaft detected by the input rotation sensor and the output rotation sensor is a set value. It is equipped with a control device that outputs a signal when the vehicle exceeds the previous limit based on the signal output from this control device. ! [! The technical means is to include a hydraulic pressure supply means for increasing the hydraulic pressure supplied to the differential pump.

(Operations and Effects of the Device Invention) The hydraulic pressure supply means is configured such that when the engine load is large or the gear ratio of the transmission is large (low gear), the differential rotation speed ratio between the input shaft and the output shaft is lower than the set value. When the hydraulic pressure is large, a large hydraulic pressure is supplied to the differential pump.

As a result, even if the hydraulic pressure generated by the differential pump is low, such as at low speeds or on paved roads, when the single engine load is large or the gear ratio of the transmission is large, the input transmitted to the input shaft via the transmission can be reduced. When the torque is large, or when the differential rotation speed ratio between the input shaft and the output shaft is larger than the set value, large hydraulic pressure is supplied to the friction clutch mechanism from the hydraulic pressure supply means via the differential pump. , limiting the increase in differential rotational speed,
As a result, the differential rotational speed ratio between the input shaft and the output shaft is maintained within a certain range.

Note that when driving at high speeds, the absolute value of the rotational speed of the input shaft increases, so even if the differential rotational speed ratio is 0.02, the differential rotational speed per second increases, causing heat generation and frictional engagement. There is a risk that the heat generation of the lining of the member will increase, causing problems with the durability of the lining.

However, the method of controlling a four-wheel drive vehicle of the present invention and its
During high-speed running, the differential rotation speed ratio between the input shaft and the output shaft is changed from 0.02 to 0.5 rps per second, and the differential rotation speed is maintained and maintained. Therefore, the above-mentioned heat generation and the related inconveniences are prevented.

[Embodiment] Next, a method and apparatus for controlling a four-wheel drive vehicle according to the present invention will be described based on an embodiment shown in the drawings.

FIG. 1 shows a schematic diagram of a four-wheel drive vehicle to which the present invention is applied.

The four-wheeled III vehicle 100 of this embodiment includes an engine 110 that generates rotational torque, and an automatic transmission 1 with four forward speeds in this embodiment that changes the speed and outputs the rotational torque of the engine 110.
20, and the front middle right wheel 1 is driven by an automatic transmission 120.
01 and the left wheel 102, a torque transmission joint 200 that transmits the rotational torque transmitted to the first differential @ 130 to the propeller shaft 140, and a torque transmission joint 200. and a second motor which divides and transmits the rotational torque transmitted via the propeller shaft 140 to the right wheel 103 and the left wheel 104 of the WIiI wheels.
A differential device 15G is provided.

Transmission of power from the first differential device 130 to the torque transmission joint 200 is performed by a transfer 160. This transfer 160 includes an idle gear 161 that meshes with the large gear 131 of the first differential device 130, a transmission gear 162 that meshes with this idle gear 161, and a transmission gear 16
2 and a bevel gear 164 attached to a transmission shaft 163 that rotates integrally with the torque transmission joint 200. , which converts the direction of rotation transmitted to the transmission shaft 163 to a right angle.

As shown in FIG. 2, the torque transmission joint 200 is driven by an input shaft 300, an output shaft 400 connected to the propeller shaft 140, and a rotational difference between the input shaft 300 and the output shaft 400 to generate hydraulic pressure. a friction clutch mechanism 600 that engages and disengages the input shaft 300 and the output shaft 400 according to the hydraulic pressure generated by the differential pump 500.
, a hydraulic oil supply means 700 for supplying hydraulic oil to the differential pump 500 , and a hydraulic oil painting 171 means 800 for guiding the hydraulic oil generated by the hydraulic supply means 700 to the differential pump 500 .

In addition, in this embodiment, the input shaft 3 of the torque transmission joint 20G
00 and the output shaft 40G are the same, the front wheels and the rear wheels are provided so that the rotation speeds are the same.

This torque transmission joint 200 will be explained in detail using FIG. 2.

The case 210 of the torque transmission joint 200 has a differential pump 500 inside and a 600% friction clutch mechanism! The input shaft 300 is rotated by a bearing 310 attached to the inner periphery of the cylindrical portion 211 and a bearing (not shown) provided at the base of the heavy ring gear 165. freely supported.

In addition, on the outer periphery of the rear part of the input shaft 300 (right side in FIG. 2),
7 langes 301 are formed. In addition, the input shaft 30
A rearward sliding contact hole 302 into which the front end of the output shaft 400 is inserted is formed at the rear center of the output shaft 400 . On the other hand, the lid part 21
The output shaft 400 is rotatably supported by a bearing 410 attached to the inner periphery of the shaft 2. This output shaft 40
0 (left side in Figure 2) is the sliding contact hole 30 of the input shaft 300.
2 and is concentric with the input shaft 300 via a metal bearing 420. As a result, the input shaft 300 and the output shaft 400 are rotatably supported by the bearings 310 and 410, and the alignment of the input shaft 300 and the output @400 is ensured by the metal bearing 420.

The differential pump 500 is a toroidal pump in this embodiment, and its dimensions, discharge amount, pressure, etc. are known. A flange portion 301 of the input shaft 300, a rotor case 52 with an eccentric inner periphery attached to the outer periphery of the flange portion 301, and mounted in a hydraulic nobo drum 510 that is open at the rear.
1. A pump housing 520 is constructed from a pump rear case 522 installed in a hydraulic servo drum 510,
The flange portion 301, rotor case 521, and pump rear case 522 are fastened together with bolts (not shown).

Inside the pump housing 520 is a rotor case 52.
The outer rotor (inner tooth width) 530 is rotatably disposed within the outer rotor 530 and meshes with the outer rotor 530, and has one fewer tooth than the outer rotor 530, and has an inner periphery similar to that of the output shaft 400. An inner rotor (outer mI!1 car) 540 is provided with spline fitting on the outer periphery. Then, due to the relative rotation between the inner rotor 540 and the pump housing 520, the outer rotor 530 revolves and performs a pumping action.

In this embodiment, the friction clutch mechanism 600 is a hydraulic multi-plate clutch structure, and has a spline attached to an inner circumferential spline 511 formed on the inner circumference of a hydraulic servo drum 510 fixed to the outer circumference of the flange portion 301 of the input shaft 300. One multi-plate engagement member group 610 is connected and rotates integrally with the input shaft 300 and is spline-coupled to an outer circumferential spline 621 formed on the outer circumference of a clutch hub 620 spline-coupled to the outer circumference of the output shaft 400 for output. The above-mentioned shaft rotates integrally with the shaft 400.
The other multi-plate engaging member group 630 disposed between each of the two multi-plate engaging member groups 610 and the outer circumferential seal ring 641 and the inner circumferential seal ring 641 within the annular four parts 523 formed on the rear surface of the pump rear case 522. A ring-shaped f! is fitted liquid-tightly through a circumferential seal ring 642 and presses one multi-plate engaging member group 610 and the other multi-plate engaging member group 630. It consists of a JI engagement piston 640, four parts 523 and a friction engagement piston 6.
A hydraulic servo chamber 650 is formed between the hydraulic servo chamber 40 and the hydraulic servo chamber 650 .

Hydraulic pressure supply means 700 is supplied from a hydraulic control circuit (not shown) that controls automatic transmission 120 to a slower! - Receives oil pressure according to the pressure, regulates the oil pressure with a leveling valve 710 shown in FIG. 3, and supplies it to the differential pump 500.

This leveling valve 710 controls the oil pressure according to the throttle opening degree, that is, the oil pressure according to the negative balance of the engine 110.
Automatic transmission I! Differential pump 5 depending on the speed change state of 1120
00, it has a spool 730 that is biased leftward in the drawing by a spring 720.

This spool 730 has a left land 731 on the left side in the drawing,
A right land 732 is provided on the right side. The left land 731 is provided with a small diameter on the left side with a first step 731a and a second step 731b interposed therebetween. Further, the right land 732 has a first step 732a, a second step 732b, and a third step 73.
It is provided with a small diameter toward the right side via the 2C1 fourth step 732d.

The housing 740 that accommodates the spool 730 includes, from the left side in the figure, a first oil chamber 741, a second oil chamber 742, a third oil chamber 743, a fourth oil chamber 744, a fifth oil chamber 745, and a sixth oil chamber 744.
An oil chamber 746, a seventh oil chamber 747, an eighth oil chamber 748, and a ninth oil chamber 749 are formed.

The first oil chamber 741 communicates with the drain boat 741a.

The second oil chamber 742J accommodates the first step 731a, and the oil pressure P (θ) is controlled by the oil pressure control circuit of the automatic transmission 120 via the orifice 142b according to the throttle opening.
It is provided in communication with the first boat 742a that receives the first boat 742a. The third oil chamber 743 accommodates the second step 131b and communicates with a second boat 743a that communicates with the hydraulic oil supply and discharge means 800. The left end of the fourth oil chamber 744 in the figure communicates with the third boat 744a, which receives the hydraulic pressure P (θ) according to the throttle opening from the hydraulic control circuit of the automatic change machine 120, and the middle part communicates with the third boat 744a for supplying and discharging hydraulic oil. Fourth boat 744b communicating with means 800
The right end in the figure communicates with the drain boat 144C. Note that the third boat 144a has a spool 730
When located on the left side in the figure, it is blocked by the left side land 731, and the fourth boat 744b and drain boat 744C
are provided so as to communicate with each other via a fourth oil chamber 144. In addition, the drain boat 744C has a spool 73
0 is located on the right side in the figure, it is blocked by the right land 732, and the third boat 744a and the fourth boat 1-744b
are provided so as to communicate with each other via a fourth oil chamber 744.

On the other hand, the ninth oil chamber 749 communicates with a drain boat 749a. The eighth oil chamber 748 accommodates the fourth step 742d and receives the hydraulic pressure P (θ) according to the throttle opening from the hydraulic control circuit of the automatic transmission 120.
48a. The seventh oil chamber 747 is
In addition to housing the third step 742C, the orifice 74
The seventh boat 747a is connected to the eighth boat 748a via the seventh boat 747b.

The sixth oil chamber 746 accommodates the second step 732b, and the seventh ball 1-747a through the orifice 746b.
The sixth boat 746a is connected to the sixth boat 746a. The fifth oil chamber 145 accommodates the first step 132a, and also connects the sixth boat 74 through an orifice 745b.
The fifth boat 745a is connected to the fifth boat 745a.

Note that the mounting load of the spring 72G that urges the spool 730 in the right direction in the drawing is due to the second step 7 of the left land 731.
The drain boat 144C is adapted to such an extent that when hydraulic pressure is applied to the drain boat 31b, the drain boat 144C is pushed back to the right by the spool 720.

The first boat 742a is provided with a first solenoid valve S1 that discharges pressure by being energized with the hydraulic pressure supplied to the first boat 742a. Also, the fifth boat 74
5a is provided with a second solenoid valve S2 that discharges the hydraulic pressure supplied to the fifth boat 745a by being energized. 6th boat)-746a, 6th boat 7
A third solenoid valve S3 is provided which discharges the hydraulic pressure supplied to 46a by being energized. The seventh boat 141a is provided with a fourth solenoid valve S4 that discharges pressure by being energized with the hydraulic pressure supplied to the seventh boat 747a.

The first solenoid valve S1, the second solenoid valve 82, the third solenoid valve 83, and the fourth solenoid valve S4 are energized and controlled by the electronic control device 750.

This electronic control I equipment jfi 750 is equipped with an input shaft rotational speed sensor (which detects the speed by the reciprocal of the passing time of one tooth, fast one) 752
and a second gear 751 having the same diameter and the same number of teeth as the first gear 751 fixed to the outer periphery of the inner cylindrical portion 622 of the clutch hub 620.
It is equipped with an output shaft rotation speed sensor 754 that detects the passing of the cutting edge of the 11i wheel 153, and inputs signals from the input shaft rotation speed sensor 752 and the output shaft rotation speed sensor 754, and also inputs signals from the automatic transmission 120 to the M in the shifting state. Entering @.

The first solenoid valve S1 has a differential rotation speed ratio between the rotation speed of the input shaft 300 detected by the input shaft rotation speed sensor 752 and the rotation speed of the output shaft 400 detected by the output shaft rotation speed sensor 754. When the set value (0.02-2%) is exceeded, it is turned on by the electronic control unit 750.

When the first solenoid valve S1 is turned on, the pressure in the second oil chamber 742 is exhausted. As a result, the force pressing the spool 730 to the right in the drawing is weakened, the spool 73G moves to the left in the drawing, and the oil pressure supplied to the differential pump 500 increases.

This differential rotation speed ratio is expressed as nl-n2/nl.

In addition, 01 is the rotation speed of the input shaft 300, and n2 is the output shaft 4.
Indicates the rotation speed of OO.

In addition, a second solenoid valve S2, a third solenoid valve S3,
The fourth solenoid valve S4 is energized and controlled by the electronic control unit 150 according to the speed change state of the automatic transmission 120.

That is, when the automatic transmission 120 is set to the first speed, the second solenoid valve S2, the third solenoid valve S3,
If all the fourth solenoid valves S4 are set to F and the second speed is set, the second solenoid valve S2 is ONL, and the third solenoid valve S4 is ON.
Solenoid valve S3 and fourth solenoid valve S4 are OFF L
, if the third speed is set, the third solenoid valve S
3 is ONL, and the second solenoid valve S2 and the fourth solenoid valve S4 are OFF. If the fourth speed is set to L, the fourth solenoid valve S4 is ONL, and the second solenoid valve S2 and the third solenoid valve are OFF. A valve S3 is provided to turn off.

As a result, when the automatic transmission 120 is set to the first speed, the fifth oil chamber 745, the sixth oil chamber 746, and the seventh oil chamber 7
47 and the eighth oil chamber 748 from the hydraulic control circuit of the automatic transmission 120, a hydraulic pressure P(0) corresponding to the throttle opening is supplied, and the spool 730 is strongly pushed to the left in the drawing.

Further, when the automatic transmission 120 is set to the second speed, the pressure in the fifth oil chamber 145 is exhausted, and the pressure in the sixth oil chamber 146 and the seventh oil chamber 145 is exhausted.
Hydraulic pressure P (θ) according to the throttle opening is sent from the hydraulic control circuit of the automatic transmission 1120 to the oil chamber 747 and the eighth oil chamber 748.
is supplied. As a result, the spool 730 is pushed to the left in the figure a little weaker than when in the first speed.

When the automatic transmission 120 is set to the third speed, the pressure in the fifth oil chamber 745 and the sixth oil chamber 746 is exhausted, and the oil pressure of the automatic transmission 120 is transferred to the seventh oil chamber 747 and the eighth oil chamber 748. A control circuit supplies oil pressure P(θ) according to the throttle opening. As a result, the spool 730 is pushed to the left in the drawing more weakly than in the second speed.

If automatic transmission @ 120 is set to 4th gear,
Fifth oil chamber 745, sixth oil chamber 746 and seventh oil chamber 747
is discharged, and the hydraulic pressure P (θ) corresponding to the throttle opening is sent to the eighth oil chamber 748 from the hydraulic control circuit of the automatic gear shift II1120.
is supplied. As a result, the spool 730 is pushed to the left in the drawing more weakly than in the third speed.

The first step 732a and the second step 73 of the spool 730
2b, the area of the third step 732C1 and the fourth step 732d is
For example, the gear ratio of the first gear of the automatic transmission 1120 is 2.5, the gear ratio of the second gear is 1.5, the gear ratio of the third gear is 1.0, and the gear ratio of the fourth gear is 1.5.
The gear ratio of the speed is 0.7, and the area of the first step 731a is 1.
00, 0.33.0.17.0.10, 0
．． It is located at 23.

The area of each step is determined as follows.

Since engine torque Te and oil pressure P(θ) are proportional to the throttle opening, engine torque Te and oil pressure P(θ) are proportional to the throttle opening.
There is a proportional relationship with θ). Furthermore, if the gear ratio of the automatic transmission 120 is i, then the output torque iT of the automatic transmission 120
e enters the input shaft 300.

A part of the output torque iTe of the automatic transmission 120 is transmitted to the first differential device 130, and the rest is transmitted to the torque transmission joint 2.
2nd difference through 00! It is branched and transmitted to 1lIA and 1so. When the output J torque iTe of the automatic transmission 120 is equally divided between the first differential IJI device 130 and the second differential device 150, the torque distribution between the front wheel system and the rear wheel system is 50+5.
It becomes 0. In this case, if 1 transmission herk of the torque transmission joint 200 is FC, 1Te-2c, i/2
Dinge=TC. Then, the transmission torque T of the torque transmission joint 200
When O is 1.5Te of hydraulic pressure supply pressure P(θ),
It is assumed that the above formula holds true. In addition, the engine torque Te
is the oil pressure P (θ) and the transmission torque T of the torque transmission joint 200.
If c is represented by the oil pressure Pi(θ) supplied to the differential pump 500, PI(θ) is lower than P(θ).

When the speed ratio of 1st gear is iw2.5, 2.5/2P
(θ) = 1.5P1(θ),', P 1 (θ)
= 0.83P (θ) When the speed ratio of 2nd speed is 1 = 15, 1.5/2P (θ) = 1.5P1 (θ),',
P 1 (θ) = 0.5P (θ) 3rd gear speed) α ratio i
・When set to -10, 1.0/2P (θ) = 1
．． 5P1(θ),', P1(θ)=0.33P(
θ) If the speed ratio of 4th gear is i=0.7, then 0.7/2
P (θ) = 1.5P1 (θ),', P 1 (
θ) = 0.23 P (θ) or more From the coefficient of P(θ), the area of each step on the right land 732 of the leveling valve 710 is determined, and the signal of the first solenoid valve S1 becomes O.
It is provided so that when the oil pressure reaches a certain value P1 (θ) in the FF state, the torque distribution between the front wheel system and the rear wheel system becomes close to 50:50.

The hydraulic oil supply/discharge means 800 supplies the hydraulic pressure generated by the leveling valve 710 attached to the lower part of the case 210 of the torque transmission joint 200 to the differential pump 500, and is connected to the outside of the case 210 where the housing 740 is arranged. A first oil passage 811 that communicates with the inner circumference, a second oil passage 812 that is an outer circumferential groove that is formed on the outer circumference of the input shaft 300 and always communicates with the inner circumference opening of the first oil passage 811, and the input shaft 300. A third oil passage 8 is formed in the radial direction and whose outer periphery communicates with the second oil passage 812.
13 and a fourth oil passage 814 whose rear part communicates with the inside of the sliding contact hole 302 and which communicates with the inner circumferential side of the third oil passage 813. A fifth oil passage 815 that opens within the sliding contact hole 302 and the input shaft 30
0, outside i! l gear 540, a sixth oil passage 811 that communicates between a space 816 surrounded by the pump rear case 522 and the fifth oil passage 815; 7th oilway 81
8 and a seventh oil passage 818 provided in the rotor case 521.
and an eighth oil passage 819 that communicates with the low pressure chamber 501 of the trochoidal pump, which is the differential pump 500. The high pressure chamber 502 of the differential pump 500 communicates with the hydraulic servo chamber 650 via a ninth oil passage 820 provided in the rotor case 521 and a tenth oil passage 821 provided in the pump rear case 522. .

Note that the balls arranged in the eighth oil passage 819 and the ninth oil passage 820 are check valves that prevent backflow of hydraulic oil. Further, the piston 640 is provided with a relief hole 520a that adapts the pressure reduction rate of the hydraulic vacuum chamber 650 and supplies lubricating oil to the multi-plate engagement member group 630.

Next, the operation of the above embodiment will be briefly explained.

When the gear ratio of automatic transmission 120 is large, automatic transmission 1
20 has a large output torque, it is necessary to strongly engage one multi-plate engaging member fif610 and the other multi-plate engaging member group 630 in order to bring the rotational speeds of the front wheels and rear wheels close to each other.

In this embodiment, when the vehicle is running, the mounted hydraulic pressure supply means 500 generates hydraulic pressure according to the throttle opening and the gear ratio of the automatic gear change t1120, regardless of the friction coefficient of the road surface on which the vehicle is running. Specifically, the throttle opening becomes larger,
As the output torque of automatic transmission 120 increases,
Alternatively, as the gear ratio of the automatic transmission ill 12G increases and the output torque of the automatic transmission 311 machine 120 increases, the hydraulic pressure supplied by the hydraulic pressure supply means 500 to the differential pump 500 is increased.

As a result, as the output torque of the automatic transmission I 120 increases, one multi-plate engaging member group 610 and the other multi-plate engaging member group 630 are strongly engaged, and the input shaft 300 and the output shaft 400 are The differential rotational speed ratio of is o.

It is kept around 2. For this reason, even on road surfaces with a high coefficient of friction such as paved roads, torque is distributed almost equally between the front wheels and the rear wheels. It can fully demonstrate the performance of wheel drive.

Further, when the differential rotational speed ratio between the input shaft 300 and the output shaft 400 exceeds 0.02, the hydraulic pressure supply means 500 immediately connects the input shaft 300 and the output shaft in order to further increase the hydraulic pressure supplied to the differential pump 500. The differential rotation speed ratio with the shaft 400 is 0.
0.02 or less, and the differential rotational speed ratio between the input shaft 300 and the output shaft 400 is kept close to 0.02 fj.

Additionally, the speed at which the vehicle is traveling is a certain speed (for example, 40 km/h).
l ), the input shaft 300 and output shaft 400
Even if the differential rotational speed ratio with the input shaft 300 is maintained at 2χ, the absolute value of the rotational speed of the input shaft 300 increases, so that the differential rotational speed per second becomes 0.5 rps or more.

This differential rotation speed drives the differential pump 500 to 05 rpm per second.
If the friction clutch mechanism 600 is rotated at a speed greater than s, there is a risk that the friction clutch mechanism 600 will generate a large amount of heat. However, in this embodiment, during such high-speed running, the differential rotation speed ratio is 0.02.
The differential rotation speed is changed from 0.5 rps to 0.5 rps and controlled to be maintained within this range. As a result, the above-mentioned heat generation and the associated inconveniences do not occur. This differential rotation speed ratio is 0.02
The electronic control unit 750 is responsible for changing the differential rotation speed from 0.5 rps to 0.5 rps.

In addition, the torsional torque (tight corner braking phenomenon) that occurs when driving at low speed and sharp turns is caused by rN friction machine 4f.
Since the ii600 allows slipping up to a differential rotation speed of 0.02, the return torque generated in the front and rear wheels is absorbed by the friction clutch mechanism 600, and there is no problem in practical use.

[Modification] In the above embodiment, a horizontally installed four-wheel drive vehicle is shown, but the present invention may also be applied to a vertically installed four-wheel drive vehicle. In addition, although the above embodiment shows the front-mounted four-wheel drive mode, the rear engine,
It may also be applied to rear-mounted four-wheel drive vehicles such as midships. Furthermore, in the above embodiment, the first differential device drives the front wheels, and the second differential device drives the rear wheels. Although a PJI vehicle is shown, the present invention may also be applied to a four-wheel drive vehicle in which the first differential 1tlI device drives the rear wheels and the second differential device drives the front wheels.

The above example shows an example in which a trochoid pump is applied to a differential pump, but there are also other pumps with input shafts and outputs, such as external gear pumps, internal gear pumps, radial oil pumps, vane pumps, roots pumps, and swash plate type axial pumps. Other types of oil pumps that are inserted between the shafts and generate hydraulic pressure using their relative rotation may also be used.

In the above embodiment, a hydraulic multi-disc clutch mechanism is shown as the friction clutch mechanism, but if it can be constructed as a speed proportional type that can transmit data while allowing slippage, it is possible to use a hydraulic multi-disc clutch mechanism such as a single-disc clutch type or a conical clutch type. Other clutch mechanisms that engage and disengage may also be applied.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a four-wheel drive vehicle to which the present invention is applied;
FIG. 2 is a sectional view of the torque transmission joint, and FIG. 3 is a schematic diagram of the leveling valve. In the figure: 100... Four-wheel drive vehicle 110... Engine 120... Automatic transmission 130... First differential gear 150... Second differential gear 200... Torque transmission joint 300...・Input shaft 400...Output shaft 50
0...Differential pump 600...Friction clutch mechanism
700...Hydraulic pressure supply means 750...Electronic control device

Claims (1)

[Scope of Claims] 1) An automatic transmission driven by an engine generates hydraulic pressure according to vehicle running conditions, and supplies the hydraulic pressure generated by the automatic transmission to one of the front wheels or the rear wheels. Based on the rotational speed difference between the input shaft that is drivingly connected to the first differential device that drives the system and the output shaft that is drivingly connected to the second differential device that drives the other wheel system of the front wheels or the rear wheels. and a differential pump driven by the engine via the automatic transmission generates hydraulic pressure proportional to a rotational speed difference between the input shaft and the output shaft based on the hydraulic pressure whose supply is controlled; A friction clutch mechanism controls the engagement ratio between the input shaft and the output shaft using oil pressure according to the rotational speed difference supplied from the differential pump, and differential rotation between the input shaft and the output shaft is achieved. Speed ratio 0.02
A control method for a four-wheel drive vehicle, characterized by performing maintenance control so as to maintain the same. 2) The method for controlling a four-wheel drive vehicle according to claim 1, characterized in that the differential rotational speed between the input shaft and the output shaft is maintained and controlled by maintaining the differential rotation speed at 0.5 rps per second. 3) (a) an input shaft driven by an engine via an automatic transmission and drivingly connected to a first differential device that drives one of the front wheels or the rear wheels; and (b) an input shaft of the front wheels or the rear wheels. (c) an output shaft drivingly connected to a second differential device that drives the other wheel system; (c) a differential pump that generates oil pressure according to a rotational speed difference between the input shaft and the output shaft; d) a friction clutch mechanism that receives hydraulic pressure from the differential pump to engage the input shaft and the output shaft; (e) a friction clutch mechanism that receives hydraulic pressure from the differential pump and engages the input shaft and the output shaft; an input rotational speed sensor that supplies a corresponding hydraulic pressure to the differential pump and detects the rotational speed of the input shaft;
and an output rotation speed sensor that detects the rotation speed of the output shaft, and the differential rotation speed ratio between the input shaft and the output shaft detected by the input rotation sensor and the output rotation sensor exceeds a set value. A control device for a four-wheel drive vehicle, comprising: a control device that sometimes outputs a signal; and a hydraulic pressure supply means for increasing the hydraulic pressure supplied to the differential pump based on the signal from the control device. 4) The four-wheel drive according to claim 3, further comprising a control device that maintains and controls the differential rotational speed of the input shaft and the output shaft by maintaining the differential pump at 0.5 rps per second. car control device.