JPH0623015B2 - Drive coupling device for four-wheel drive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a four-wheel drive vehicle for driving front wheels and rear wheels with the same engine, and particularly to a front wheel drive shaft and a rear wheel drive shaft. The present invention relates to a drive connecting device for four-wheel drive of a four-wheel drive vehicle having a hydraulic pump type connecting mechanism between the two.

[Conventional technology]

In a four-wheel drive (4WD) vehicle in which the front and rear wheels are driven by the same engine, there are some differences in the effective radii of the tires of the front and rear wheels, and the front wheels are compared to the rear wheels when turning. Due to the large turning radius,
When trying to rotate at high speed, a torsion torque is generated between the front and rear drive shafts, and the same state as when braking is applied, causing a so-called tight corner braking phenomenon, which deteriorates drivability and wears tires. There is a need for means to prevent this.

Therefore, the conventional four-wheel drive vehicle is
The front wheel side and the rear wheel side are connected by a dog clutch etc.,
During cornering, the front and rear wheels rotate at a constant speed, even though the front and rear wheels have different rotational speeds, so braking torque is applied from the rear wheels to the front wheels. In order to reduce this phenomenon, a wet multi-plate clutch is used in the connecting part to slide the clutch during cornering to absorb the rotational speed difference between the front and rear wheels. There was a risk of burning.

[Problems to be solved by the invention]

In such a conventional four-wheel drive vehicle using means for absorbing a difference in rotation speed between front wheels and rear wheels, a loose characteristic allowing a difference in rotation speed between front and rear wheels and a difference in rotation speed between front and rear wheels are provided. It is desirable to switch to tight properties that allow only a small amount.

That is, when suddenly starting, traveling on a low μ road, when the road surface condition changes abruptly (when changing from a paved road to a dirt road or a snowy road) and when riding on a curb, the characteristics are tight and the front and rear wheels are It is desirable to generate torque from each wheel so that the wheels are driven by four wheels.

Also, when tight cornering on a high μ road, when it is desired to absorb the tire radius difference, and during general running on a high μ road, loose characteristics cause torque to be generated from one of the front and rear wheels, and the two wheels are driven. Is desirable.

However, heretofore, there has been no proposal to switch between such tight characteristics and loose characteristics.

The present invention is intended to solve such a problem, and it is possible to adjust the allowable state of the rotational speed difference between the front wheels and the rear wheels according to the running state of the vehicle.
An object is to provide a drive coupling device for four-wheel drive.

[Means for solving problems]

Therefore, the four-wheel drive drive coupling device of the present invention includes the first rotating shaft that transmits the driving force to the front wheels of the vehicle, the second rotating shaft that transmits the driving force of the rear wheels, and the first rotating shaft described above. Rotation axis and second
And a hydraulic coupling mechanism that is capable of transmitting driving force to each other, and the hydraulic coupling mechanism is configured as a hydraulic pump type coupling mechanism, and is connected to the discharge port of the coupling mechanism. Suction port of the same connection mechanism as the oil passage to be connected (including oil sump)
A communication oil passage communicating with the oil passage subsequent to the oil passage, and the flow rate of the hydraulic oil passing through the communication oil passage (from zero flow rate to unrestricted flow rate)
A flow rate control mechanism capable of controlling the flow rate, a manual type limit flow rate setting means for outputting a control signal for setting the flow rate limit to the flow rate control mechanism, and a driving state sensor for detecting a driving state in the vehicle. And an automatic limiting flow rate setting means for receiving a detection signal from the operating state sensor and outputting a control signal for setting the limiting flow rate to the flow rate control mechanism, the manual limiting flow rate setting means and the automatic type A switching mechanism for selectively sending only a control signal from one of the limited flow rate setting means to the flow rate control mechanism is provided.

[Action]

In the above-described four-wheel drive drive coupling device of the present invention, the switching mechanism selects between the control by the manual limiting flow rate setting means and the control by the automatic limiting flow rate setting means, and from the selected limiting flow rate setting means. The flow rate of the hydraulic oil passing through the communication oil passage is controlled by the control signal output to the flow rate control mechanism.

Along with this, the differential pressure between the discharge port and the suction port of the hydraulic pump type coupling mechanism or the pressure at the discharge port is controlled, and the torque transmitted between the first rotating shaft and the second rotating shaft is controlled. To be done.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 to 9 show a drive connecting device for four-wheel drive as one embodiment of the present invention. FIG. 1 is a hydraulic system diagram showing a hydraulic pump type connecting mechanism and a hydraulic circuit, and FIG. FIG. 3 is a schematic configuration diagram showing a power system of a vehicle equipped with the device, FIG. 3 is a sectional view of an essential part thereof, FIG. 4 is a block diagram thereof, and FIG.
(d) is a flow chart for explaining the action, and FIGS. 6 to 9 are graphs for explaining the action.

As shown in FIGS. 1 to 3, an automatic transmission 2 is connected to a horizontally installed engine 1 via a torque converter 1a and an input shaft (inner shaft) 142, and a gear 3 of an output shaft of the automatic transmission 2 is The gear 3'of the intermediate shaft meshes with the gear 3 '.
A gear 38 'on one end side of the output shaft 38a is meshed with.

As shown in FIG. 2, a gear 38 is attached to the other end of the output shaft 38a. The gear 38 is a ring gear 39 of a front wheel differential mechanism 40 (hereinafter referred to as "front wheel differential 40"). Meshes with. As a result, the torque from the output shaft 38a is divided by the front wheel differential 40 and the left and right front wheel shafts 4 are separated.
1, 42 are transmitted to drive the front wheels 43, 44 in rotation.

The side gears 11 and 12 are meshed with the pinions 9 and 10 with the differential case 8 which are integral with the ring gear 39, and the front wheel shaft 41 is connected to the side gear 11.
A front wheel shaft 42 is connected to the side gear 12.

Further, a gear 39 'meshing with the ring gear 39 is provided, and the gear 39' is fixed to the front wheel output shaft 5 as the first rotating shaft.

A four-wheel drive drive connection device 13 as a hydraulic pump type connection mechanism is interposed between the front wheel output shaft 5 and the rear wheel output shaft 4 as a second rotating shaft.

Further, the rear wheel output shaft 4 is connected to the gears 45a, 4 of the bevel gear mechanism 45.
It is connected to a propeller shaft 47 with a transfer via 6a, and a bevel gear 47a of the propeller shaft 47 meshes with a ring gear 48 of a rear wheel differential mechanism 49 (hereinafter referred to as "rear wheel differential 49"). . As a result, the rear wheel output shaft 4
Is divided by the rear wheel diff 49 and transmitted to the left and right rear wheel shafts 50, 51 to rotationally drive the rear wheels 52, 53.

Further, as shown in FIGS. 2 and 4, the rotation speed sensor (pickup) as a first rotation speed detector is arranged so as to face the tooth portion of the gear 39 'of the front wheel output shaft 5 as a first rotation shaft. 12
7 is provided, and the detection signal from the sensor 127 is input to the counter 128b of the control unit 128.

Then, the gear 45a of the rear wheel output shaft 4 as the second rotating shaft
A rotation speed sensor (pickup) 126 as a second rotation speed detector is provided to face the tooth portion of the control unit 1.
It is adapted to be input to 28 counters 128a.

These counters 128a and 128b use the count (detection signal) from the timer 128c or the like for each predetermined time width as an arithmetic unit (CP).
U) It is designed to send to 128d, and this computing unit 128d
The count number of the front wheel output shaft 5 is converted into the rotational speed Rf of the front wheels 43 and 44 by using the ratio i of the gear 39 and the gear 39 '.

Then, the calculator 128d calculates the count number of the rear wheel output shaft 4 by
The ratio i _B between the gear 45a and the gear 46a and the ratio i _D between the gear 47a and the gear 48 are used to convert the rotational speed Rr of the rear wheels 52 and 53.

The calculator 128d calculates the front wheel speed Rf and the rear wheel speed Rf.
The difference between Rr is calculated and output to the display device 129 as a display signal.

Then, the display device 129 receives the display signal and turns on the LED 129a when the rotational speed difference is 0 to 20 (rpm), and turns on the LED 129b when the rotational speed difference is 20 to 30 (rpm), and 30 to 30. If it is 40 (rpm), the LED 129c is turned on, and if it is 40 (rpm) or more, the LED 129d is turned on.

Further, the control unit 128 is configured so that a steering angle signal from a steering angle detector (steering angle sensor) 130 is input.
8 and the display device 129 are connected to a warning light 131, and an alarm can be issued by the warning light 131.

The drive coupling device 13 includes a front shaft output shaft 5 and a rear wheel output shaft 4.
Between the output shafts 4 and 5 by controlling the pressure of oil discharged from the oil pump (vane pump) 14 that is driven by the difference in rotation speed between And a discharge pressure control mechanism (hydraulic circuit) 71 capable of suppressing the difference in rotational speed.

Next, the arrangement of the oil pump 14 and the discharge pressure control mechanism 71 will be described.

As shown in FIGS. 1 and 3, the oil pump 14 and the discharge pressure control mechanism 71 are provided in the housing 70.

In the oil pump (vane pump) 14, as shown in FIG. 1, a large number (here, 10) of holes 69b are formed on the outer circumferential surface 69a of the rotor 69 at equal intervals in the circumferential direction. A vane 68 capable of sliding contact with the inner peripheral surface of the cam ring portion 70a is fitted into each of the multiple holes 69b.

Further, each part is formed so that the axial gap between the interposing member 70d of the housing 70 and the vane 68 and the rotor 69 is equal to or less than a predetermined value, and the oil film is prevented from being cut off. Insert 70e and vane 68
Similarly, the respective portions are formed so that the axial gap between the rotor 69 and the rotor 69 is also a predetermined value or less.

Then, the sum of these gaps is set to be a predetermined value or less.

The vane pump 14 discharges an oil amount proportional to the number of rotations of the vane pump 14.
When the relative rotation occurs between the rear wheel output shaft 4 and the front wheel output shaft 5, it functions as a hydraulic pump to generate hydraulic pressure.

Discharge port of the vane pump 14 (suction discharge ports 72 to 77 at the tip of the vane 68 relative to the housing 70 in the direction of relative rotation).
(Corresponding to this), the rotor 69 and the cam ring portion 70a become a rigid body and are integrally rotated by the static pressure via oil.

Therefore, between the cam ring portion 70a and the rotor 69,
Three pump chambers 86-8 at 120 ° intervals from the rotation center line
8 are formed, and six suction / discharge ports 72 to 77, which are suction ports when positioned on the base end side in the rotational direction and serve as discharge ports when positioned on the tip end side, are formed at approximately 120 ° intervals, and are the same. Suction and discharge ports 72, 7 at 120 ° intervals that function
4, 76 are a cover 70b of the housing 70, a flange 70c,
The first oil passage OL ₁ communicates with each other through the interposing members 70d and 70e.

The suction / discharge ports 73, 75, 77 are
0 of the cover 70b, the flange 70c, while挿材70d, are communicated by the second oil passage OL ₂ through 70e.

Further, the first oil passage OL ₁ and the second oil passage OL ₂ are communicated with oil reservoirs (oil tanks) 80 at the bottom of the transmission case 94 via check valves 78 and 79, respectively, and the oil reservoirs 80 are connected to the respective oil reservoirs 80. Only the flow to the passages OL ₁ and OL ₂ is allowed, and the first oil passage OL ₁ and the second oil passage O
If the discharge pressure between L ₂ and the pressure becomes equal to or higher than a predetermined pressure, both oil passages O
Two discharge pressure control relief valves 83 and 84 are provided for communicating L ₁ and OL ₂ with each other.

These relief valves 83 and 84 are springs, respectively.
It is biased in the closing direction by 83a and 84a.

A communication passage 89 for relieving the discharge pressure to the oil reservoir 80 is connected to the second oil passage OL ₂ between the check valve 79 and the suction / discharge ports 73, 75, 77.
A check valve 81 with an orifice 81a for preventing air from entering is inserted in the valve 9.

Further, a communication passage 90 for relieving the discharge pressure to the oil sump 80 is connected to the first oil passage OL ₁ between the check valve 78 and the suction / discharge ports 72, 74, 76, and this connection is established. An air intrusion check valve 82 having an orifice 82a is inserted in the passage 90.

With such a hydraulic circuit 71, the discharge pressure always acts on the relief valve 83 or the valve element of the relief valve 84 regardless of the relative rotation direction of the rotor 69 and the cam ring portion 70a, and the oil sump 80 sucks the suction port. Will be in communication with.

Further, the flange 70c forming the housing 70 of the vane pump 14 is pivotally supported by the transmission case 94 via the bearing 93, and the rear wheel output shaft 4 integrated with the cover 70b is a bearing on the left side in FIG. It is pivotally supported by the transmission case 94 via a portion (not shown).

The rotor 69 of the vane pump 14 has a spline engagement portion 64a.
The front wheel output shaft 5 connected via the
Both sides of 64a are pivotally supported by the cover 70b and the interposing member 70e via bushings (bearings) 95 and 96, respectively.

The bottom 68b of the vane 68 has oil passages OL ₁ , OL ₂
Among these, the discharge pressure from the oil passage on the discharge side (here, the first oil passage OL ₁ ) is adjusted to the flow passage 121 with the check valve 123 (122).
The tip 68a of the vane 68 is urged toward the inner peripheral surface of the housing 70 by receiving the working pressure reduced through (120).

Further, five springs or rings are attached to both end surfaces of the rotor 69 via the shafts, and the vanes 68 are attached.
Alternatively, each bottom portion 68b may be pressed.

Further, as shown in FIGS. 1 and 3, the axial sliding portion 106 in which the rotor 69 and the interposing material 70d are in sliding contact and the axial sliding portion 106 in which the rotor 69 and the interposing material 70e are in sliding contact, The annular hydraulic chambers 109, 109 are formed, and the hydraulic chambers 109, 109 communicate with the holes 69b of the rotor 69 and also with the oil passages 89, 90.

That is, the hydraulic chambers 109, 109 are provided in the suction / discharge ports 7 respectively.
The second oil passages that communicate with the first oil passages OL ₁ connected to 2, 74, 76 via the flow passage 121 with the check valve 123 to receive high hydraulic pressure and that are connected to the respective suction / discharge ports 73, 75, 77. High pressure is communicated with the OL ₂ through the flow passage 120 with the check valve 122.

Further, the flow passage 120 with the check valve 122 and the flow passage 121 with the check valve 123 may not be provided.

In addition, reference numeral 69c in the drawing denotes a bottom portion of the rotor 69 on the inner diameter side,
Reference numerals 1 and 92 denote bearings that support the front wheel output shaft 5, and reference numerals 101 denote bolts.

Due to the hydraulic circuit 71, a rotational speed difference is generated between the differential case 8 side and the rear wheel output shaft 4 side, so that the rotor 69 moves toward the arrow a.
When rotated relative to each other, the oil will
After being sucked into the suction discharge ports 73, 75, 77 from 0 through the second oil passage OL ₂ via the check valve 79, the pump chamber 8
6 to 88 suction / discharge ports 72, 74, 76 to the first oil passage O
Through L ₁ is discharged from the orifice 82a with a check valve 82 to the oil tank 80. The discharge pressure characteristic at this time is as shown by the symbol A in FIG.

On the contrary, when the rotor 69 rotates in the direction of arrow b, the oil flows from the oil tank 80 through the check valve 78 to the first
After being sucked into the suction / discharge ports 72, 74, 76 through the oil passage OL ₁ , the suction / discharge ports 73, 7 of the pump chambers 86-88.
It ejected from the orifice 81a with a check valve 81 to the oil tank 80 from 5,77 via the second oil path OL _2. The discharge pressure characteristic at this time is as shown by the symbol A in FIG.

In the characteristic A, when the rotational speed difference exceeds a certain value, the discharge pressure hardly rises because the relief valves 83 and 84 open when the discharge pressure is equal to or higher than each predetermined value.

Further, the characteristic portion of each characteristic A before the relief valves 83 and 84 are opened is due to the action of the orifices 81a and 82a.
It is proportional to the square of the rotational speed difference.

Here, the opening characteristics of the relief valves 83 and 84 and the degree of throttling of the orifices 81a and 82a may be appropriately changed.

A part of the oil passage 104 is bored in the rear wheel output shaft 4, and an oil filter is provided in a portion of the oil passage 104 near the oil intake port so that the oil is supplied through the oil supply passage. The iron powder and the like contained in the oil to be prevented from entering the oil pump 14 by the magnet of the magnet mounting portion and the oil filter.

Between the first oil passage OL ₁ connected to the suction / discharge ports 72, 74, 76 of the oil pump 14 and the second oil passage OL ₂ connected to the suction / discharge ports 73, 75, 77 of the oil pump 14, Communication oil passages 207 and 208 are provided, and an orifice valve 214 is interposed in the communication oil passages 207 and 208 as a flow rate control mechanism M ₁ .

The orifice valve 214 receives the control oil pressure on the land 214a on the right side, and the control oil pressure and the spring 214b on the left side.
Since the position of the spool 214c and the size of the orifice of the orifice valve 214 are determined by the pressing force of, the flow rate of the hydraulic oil passing through the communication oil passages 207 and 208 is determined.

The control oil pressure supplied to the land 214a of the orifice valve 214 can be controlled by the duty solenoid valve 213 that can open the oil pressure of the oil passage 206 to the oil reservoir 80 through the return oil passage 209. Is controlled by receiving a control signal from a control unit 128 which also serves as an automatic limiting flow rate setting means M ₃ , a switching mechanism M ₄ and an operating state calculating means M _5. The control unit 128 is manually operated. A control signal is supplied from a manual control device (changeover switch) 215 as the formula-limited flow rate setting means M ₂ .

The manual control device 215 is arranged near the driver's seat and can remotely control the 4WD ratio of the four-wheel drive coupling device 13.

The control oil pressure supplied to this oil passage 206 is the first oil passage OL.
₁ and 0 according to the pump speed from the second oil passage OL _2.
The discharge pressure of up to 120 atm is received via the oil passages 201 and 202 and the switching valve 210, and the switching valve 210 causes the oil passage 203.
Through a pressure reducing valve 211 to a pressure of 0 to 10 atmospheres and is sent to a regulator valve 212 through an orifice 204a of an oil passage 204.
The pressure is reduced to 0 to 8 atmospheres and is sent to the oil passage 206 through the oil passage 205 with the orifice 205a.

Each sensor is connected to the control unit 128, and the rotation speed sensor 12 as the above-mentioned operation state sensor is connected.
6, 127 and a steering angle detector 130 as a driving state sensor, as well as a gear position sensor (inhibitor switch) 1 as a driving state sensor for detecting a gear position.
32, an accelerator opening sensor (throttle opening sensor) 133 as an operating condition sensor for detecting an accelerator pedal depression amount (or throttle valve opening) 133, a driving condition sensor for detecting a brake pedal depression condition or an engine braking condition State sensor 134 as an example, an oil temperature sensor 13 as an operation state sensor for detecting lubricating oil, etc.
5 is provided, and in addition to the rotation speed sensors 126 and 127, an engine rotation speed sensor 136 as an operating state sensor.
A vehicle speed sensor 137 may be provided.

In FIG. 3, 81 'shows a modified example of the air intrusion prevention check valve, 81'a is an orifice, and 89'
a, respectively 90a centrifuge passage 89b, 90b are respectively represents the release passage, further memory code 128e is the control unit 128 in the figure, the change-over switch constituting the switching mechanism M ₄ 138, 140 Is an oil pump,
Reference numeral 140a denotes an outer toothed inner gear connected to the side outer shaft 143 of the torque converter, and 140b denotes an inner toothed outer gear.

The drive coupling device for four-wheel drive as the embodiment of the present invention is configured as described above, and therefore, while traveling in four-wheel drive,
When the rear wheels 52, 53 slip and the rotation speed on the rear wheel output shaft 4 side becomes faster than the rotation speed on the front wheel output shaft 5 side, the rotor 69 relatively rotates in the direction of arrow a.

As a result, oil is drawn from the oil tank 80 through the check valve 79 and the second oil passage OL ₂ into the suction / discharge ports 73, 7
5, 77, and the suction outlets 72, 74, 76 of the pump chambers 86 to 88 through the first oil passage OL ₁ and the orifice.
The oil is discharged from the check valve 82 with 82a to the oil tank 80.

Since this discharge pressure is a value corresponding to the rotational speed difference between the rear wheel output shaft 4 side and the front wheel output shaft 5 side, if the orifice valve 214 of the flow control mechanism M ₁ is fully closed, the oil pump 14 The magnitude of the torque transmitted by the variable torque also changes according to the difference in rotation speed [see the tight characteristics (small orifice diameter) in FIG. 8].

When the rotational speed difference occurs in this way, the four-wheel drive drive coupling device 13 is brought into contact with the coupling degree according to the difference, so that the rotational speed difference is suppressed, and as a result, the front wheels are connected. The torque is also transmitted to the output shaft 5 side. As a result, even if the rear wheels 52, 53 idle, the front wheels 43, 44 can be driven to rotate.

At this time, the amount of torque transmitted by the four-wheel drive drive coupling device 13 is automatically controlled according to the difference in rotational speed.
The driving feeling and driving stability are not deteriorated.

If the rotation speed difference exceeds a certain value, for safety,
Due to the action of the relief valve 84, the rise of the discharge pressure is suppressed to a constant value, and the transmission torque between the shafts 4 and 5 does not exceed a certain value.

Conversely, when the front wheels 43, 44 slip, the rotor 69 automatically rotates relatively in the direction of arrow b.

As a result, the oil supply path is automatically switched, and the oil flows from the oil tank 80 through the check valve 78,
It is sucked into the suction / discharge ports 72, 74, 76 through the first oil passage OL _1, and the suction / discharge ports 73, 75 of the pump chambers 86 to 88,
The oil is discharged from 77 through the second oil passage OL ₂ to the oil tank 80 through the check valve 81 with the orifice 81a. Since this discharge pressure also has a value corresponding to the rotational speed difference between the rear wheel output shaft 4 side and the front wheel output shaft 5 side, the magnitude of the torque transmitted by the oil pump 14 also changes according to the rotational speed difference.

Also in this case, since the four-wheel drive drive coupling device 13 is brought into contact with the coupling degree according to the rotational speed difference, the rotational speed difference is suppressed and, as a result, the rear wheel output shaft 4 side is moved. Torque is also transmitted. As a result, the rear wheels 52, 53 can be rotationally driven even when the front wheels 43, 44 idle.

Also in this case, since the transmission torque amount by the four-wheel drive drive coupling device 13 is automatically controlled according to the difference in rotation speed, the driving feeling and the steering stability are not deteriorated.

Even in this case, if the rotation speed difference exceeds a certain value,
For safety, the relief valve 83 prevents the discharge pressure from increasing and becomes a constant value, and the transmission torque between the shafts 4 and 5 does not exceed a certain value.

Further, in this device, the product of the transmission torque and the rotational speed difference causes energy loss to generate heat, but part of the oil is discharged to the oil tank 80 through the communication passages 89 and 90. There is also an advantage that the working oil of the oil pump 14 can be sufficiently cooled and lubricated.

Further, the open / closed state of the orifice valve 214 of the flow rate control mechanism M ₁ will be described. As a manual type limit flow rate setting means M ₂ , a control signal from a manual control device 215 [four steps (from a tight characteristic to a loose characteristic) (2
WD, 4WD-Lo, 4WD, 4WD-Hi and the switching signal] to switch over), automatic limit flow rate setting means control signal from the control unit 128 as _{M 3} [each operation state detection sensors 126,127,130, 132-
Control signal generated in the control unit 128 according to the driving state of the vehicle detected from 137] is received by the changeover switch 138 of the changeover mechanism M ₄ , and from the manual control device 215 as the manual type limit flow rate setting means M ₂ . In response to the ON / OFF signal of, the control signal from the manual type limit flow rate setting means M ₂ is sent to the duty solenoid valve 213 constituting the flow rate control mechanism M ₁ at the time of ON, and the automatic limit flow rate setting means M ₃ at the time of OFF. Is sent to the duty solenoid valve 213.

As a result, the flow rate of the hydraulic oil passing through the communication oil passages 207 and 208 is controlled by the orifice valve 214 that constitutes the flow rate control mechanism M ₁ .

Hereinafter, as shown in FIGS. 5 (a) to 5 (d), a detailed description will be given in accordance with a flowchart.

First, in the control unit 128, the memory
The reference slip ratio C ₀ or the like is called from 128e (step a1), and then the engine speed signal Ne from the speed sensor 127 (or the engine speed sensor 136 may be used) and the steering angle signal from the steering angle detector 130. f,
The gear position signal Sp from the gear position sensor 132, the accelerator opening signal θa from the accelerator position sensor 133, the brake state signal Bc from the brake state sensor 134, and the oil temperature signal T from the oil temperature sensor 135 are received. (Step a2).

In the braking state (brake on), the control unit 1 is set to reduce (throttle) the on / off diameter of the orifice valve 214 because it is in the deceleration state.
A control signal is sent from 28 to the flow rate control mechanism M ₁ (step a11).

That is, when the rear wheels 52, 53 at the time of braking become slightly locked, the difference in rotational speed between the first rotating shaft 5 and the second rotating shaft 4 connected to the four-wheel drive coupling device body 13 is increased. Will be very large.

As a result, in the vane pump 14, a large amount of oil pressure is generated due to the oil flow in the state shown by the solid line in FIG. 2, but when the predetermined value is exceeded, the relief valve 83 opens against the spring 83a and the discharge pressure is almost the same. The rear wheels 52, 53 are controlled to be constant.
A constant driving force corresponding to a constant discharge pressure was transmitted to 4
Wheel drive state.

Then, the rotational speeds of the front wheels 43 and 44 decrease and the rotational speeds of the rear wheels 52 and 53 increase, so that the rotational speed difference is reduced (the same function as the non-slip differential).

Thus, when the front wheels 43, 44 are in the slip state, the rear wheels 5
It can be avoided that the driving torque to the wheels 2, 53 is increased and the vehicle cannot run, and if the rear wheels 52, 53 tend to be locked, the braking torque of the rear wheels 43, 44 is increased to increase the rear wheels 52, 53. Prevent lock of 53.

When the oil temperature T is higher than the set value To (step a4) when the brake is not operated, the flow rate control is performed from the control unit 128 so that the orifice diameter of the orifice valve 214 is increased (opened) as the overheated state. A control signal is sent to the mechanism M ₁ (step a12).

As a result, when the temperature of the hydraulic oil is high, the discharge pressure is relieved and the four-wheel drive state is not established, but the torque transmitted to the rear wheel drive system is reduced, and the FF drive state is reached, resulting in an oil temperature change. The rise is suppressed.

That is, in the case of such a differential pump such as the vane pump 14, a relief valve for discharge pressure control (reference numeral 8 in FIG. 1 is used.
Before the opening of the relief valve, the discharged oil leaks from the sliding portion clearance, and after the relief valve opens, all of the oil leaks from the sliding portion clearance and the relief hole. At this time, heat is generated, and the generated amount is the discharge pressure P.
And is proportional to the product of the discharge amount Q.

The product (P × Q) is proportional to the product of the pump torque T _P and the rotational speed difference .DELTA.N, between the pump torque T _P and the rotational speed difference .DELTA.N, as shown in FIG. 8 relationship If there is, the amount of heat generation increases as the rotation speed difference ΔN increases.

Therefore, in the present embodiment, when the state where the rotational speed difference ΔN between the front and rear wheels is large continues, the oil temperature does not rise above 200 ° C. and the viscosity of the hydraulic oil decreases, so that the vane pump 14 The sliding part is seized, and the vane pump 1
It is possible to solve the problem that the rubber component such as the sealing material in 4 is deformed and damaged, and the function as the pump is impaired.

In addition, it is possible to solve the problem that the function as a four-wheel drive vehicle may be lost, such as a decrease in the transmission pressure to the wheel that switches between a driving state and a driven state due to a decrease in the discharge pressure.

It should be noted that the process is returned after the operations of steps a11 and a12 are completed.

Further, from the rear wheel rotation speed Rr converted from the rotation speed signal from the rotation speed sensor 126 and the front wheel rotation speed Rf converted from the rotation speed signal from the rotation speed sensor 127, the actual slip ratio is calculated based on the following equation. C ₁ is calculated (step a5).

C ₁ = (Rf−Rr) / Rf (1) The LEDs 129a to 129d of the above-described display device 129 may display according to the slip ratio C ₁ .

In addition, steady running with small fluctuations in front and rear wheel speeds Rf and Rr (4
0-60 km / h), if there is a large difference in rotation speed between the front wheels 43, 44 and the rear wheels 52, 53, the warning light 1
31 is turned on or blinked to give a stop warning.

Further, the steering angle (steering angle) f and the front wheel rotation speed
Depending on Rf and the rear wheel rotation speed Rr, the warning lamp 131 is turned on or blinks when an abnormal driving state is reached.

Next, if the manual control signal from the manual control device 215 is on (step a6), the process of the manual 4WD (four-wheel drive) routine is performed, and in other cases, the engine torque T _E is calculated. At the same time (step a7), the tire driving torque Tt is calculated by the following equation (step a8).

Tt = T _E × (total reduction ratio) (2) Next, the tire driving torque Tt is predetermined value (as much as possible small value) Tto below (step a9), and the steering angle f substantially zero (or , | F | <ε ₁ ) (step a10),
The process proceeds to the process of the reference slip ratio update routine.

When the tire driving torque Tt is larger than the predetermined value Tto, and when the steering angle f is not substantially zero (| f | ≧ ε ₁ ),
The process proceeds to the automatic 4WD (four-wheel drive) routine process.

The reference slip rate update routine, as shown in FIG. 5 (b), the difference C ₃ of the actual slip rate C ₁ and the reference slip ratio C ₀ computed based on the following equation (step b1).

C ₃ = C ₁ −C ₀ (3) Then, if the slip ratio C _{3 of} this difference is not substantially zero (or | C ₃ | ≧ ε ₂ , step b 2), the actual slip ratio C ₁ Is newly set as the reference slip ratio C ₀ (step b4).

If the slip ratio C _{3 is} almost zero (or | C ₃ | <ε
₂ ) Hold the value of the reference slip ratio C ₀ (step b
3).

Thus, if the tire radii of the front wheels 43, 44 and the rear wheels 52, 53 are exactly the same, no differential rotation occurs in a straight running state, but the tire wear (generally, the front wheels 43, 44 wear quickly. ), Tire rotation, or the like, the front wheels 43, 44 and the rear wheels 52, 53 cause differential rotation even in a straight traveling state.

Therefore, by constantly detecting the slip ratios of the front and rear wheels in a straight running state and storing the same as the reference slip ratio C _α , the difference between the tire radii of the front and rear wheels changes due to tire rotation and the like. Also in this case, the reference slip ratio C ₀ can be stored again by detecting the slip ratio in the subsequent straight traveling state.

In the automatic 4WD routine, as shown in FIG. 5 (c), the theoretical slip ratio C _α according to the steering angle f is calculated based on the following equation (step c1, see FIG. 9).

C _α = C ₀ + α · f (4) Here, α represents the ratio of the slip ratio C _α to the steering angle f, as shown in FIG. 9.

The theoretical slip ratio C _α and the actual slip ratio C
The difference C ₂ from ₁ is calculated based on the following equation (step e2).

C ₂ = C ₁ −C _α (5) The theoretical slip ratio C _α according to the steering angle f and the actual slip ratio C ₁ are compared, and the front wheels 43 and 44 are rear wheels 5
The actual slip rate C ₁ that occurs when the front wheels 43, 44 rotate idly during rotation (C ₁ ≧ 0) faster than 2, 53 is equal to or greater than the theoretical slip rate C _α (C
₂ ≧ 0) (step c3), the front wheels 43, 44
Rotates slower than the rear wheels 52, 53 (C ₁ <
0), and the front wheels 43 and 44 tend to lock due to engine braking or foot braking, and the actual slip ratio C ₁ is smaller than the theoretical slip ratio C _α (C ₂
In <0, step c4), a control signal is sent from the control unit 128 to the flow rate control mechanism M ₁ so as to reduce (throttle) the orifice diameter of the orifice valve 214 (step c5).

As a result, the four-wheel drive ratio (4WD) corresponding to the ratio (T _P / ΔN) of the transmission torque T _P to the front / rear wheel rotation speed difference ΔN is obtained.
Rate) can be increased.

When the slip ratios C ₁ , C ₂ , and C _α are in other states, the control unit 12 increases the orifice diameter of the orifice valve 214 (opens it).
A control signal is sent from 8 to the flow rate control mechanism M ₁ (step c6).

In this way, the actual slip ratio C ₁ is controlled to be the theoretical slip ratio C _α .

In the manual 4WD routine, as shown in FIG. 5 (d), the theoretical slip ratio C _α according to the steering angle f is calculated based on the following equation (step d1).

C _α = C ₀ + α · f (6) Then, the theoretical slip ratio C _α and the actual slip ratio C
The difference C ₂ from ₁ is calculated based on the following equation (step d ₂ ).

C ₂ = C ₁ −C _α (7) Even when the vehicle is traveling with the orifice diameter selected by the manual control device 215, the front wheels 4
3,44 rotate faster than the rear wheels 52,53 (C ₁ ≧
0) and the actual slip ratio C ₁ is the theoretical slip ratio C
_When it is extremely larger than _α (C ₂ ≧ C ₂ ′, where C ₂ ′ is the set value of the slip ratio) (step d3), the front wheels 43 and 44 rotate slower than the rear wheels 52 and 53. (C ₁ <0) and the actual slip ratio C ₁ is extremely smaller than the theoretical slip ratio C _α (C ₂ ≦ −C ₂ ′,
In the case of step d4), a control signal is sent from the control unit 128 to the flow rate control mechanism M ₁ so as to reduce (throttle) the orifice diameter of the orifice valve 214 (step d5).

As a result, the four-wheel drive ratio (4WD ratio) can be increased.

When the slip ratios C ₁ , C ₂ , and C ₃ are in other states, four stages (2WD, 4WD-Lo, 4WD, 4WD- selected by the manual control device 215 are selected.
A control signal is sent from the control unit 128 to the flow rate control mechanism M ₁ so that the orifice diameter becomes Hi) (step d6).

Thus, in the manual 4WD routine, the automatic 4WD
The tolerance of the actual slip rate C ₁ with respect to the theoretical slip rate C _α can be made larger than that in the routine, and the special taste of the manual can be sufficiently exhibited.

When the vehicle is in a normal straight traveling state, the front wheels 43, 44 are
Since the effective radii of the tires of the rear wheels 52 and 53 are the same and the slip rotation speed of the tires is low, the first rotary shaft 5 and the second rotary shaft 4 connected to the four-wheel drive coupling device 13 are connected.
There is no difference in rotation speed between

Therefore, no oil pressure is generated in the vane pump 14,
The driving force is not transmitted to the rear wheels 52, 53, and the front wheels 43, 44
Front wheel drive by only.

In this state, the front wheels 43 and 44 and the rear wheels 52 and 53
Since the difference in rotational speed between and is small and is 0 to 20 (rpm), the LED 129a is turned on and "2WD" is displayed.

However, in the state where the front wheels 43 and 44 slip within about 2% even when there is no large slip, such as when the vehicle is accelerating straight, the difference in rotational speed due to this causes the difference in rotational speed between the first rotating shaft 5 and the first rotating shaft 5.
Between the second rotary shaft 4 and the second rotary shaft 4, the vane pump 14
Functioning to generate a hydraulic pressure corresponding to the rotational speed difference, the rotor 69 and the cam ring portion 70a rotate integrally, and a driving force corresponding to the hydraulic pressure and the pressure receiving area of the vane 68 is applied to the rear wheel 52, It is transmitted to 53 and becomes a four-wheel drive state.

In this state, the front wheels 43 and 44 and the rear wheels 52 and 53
One of the LEDs 129a to 129d is turned on as appropriate in accordance with the difference in the rotational speed between the and, and the driver is displayed an intermediate state from 2WD to 4WD or a 4WD state.

The control signal from the control unit 128 is
The duty ratio of the duty solenoid valve 213 is automatically determined according to the traveling condition, and when the orifice of the orifice valve 214 is throttled,
In addition to the above, the accelerator may be depressed in automatic 4WD.

That is, the accelerator opening θa and the engine speed Ne (rp
m) The gear position Sp is detected, and as the torque input to the tire increases, the orifice of the orifice valve 214 is narrowed to increase the 4WD ratio and accelerate with four wheels.

Further, in addition to the above-mentioned cases, the case where the orifice of the orifice valve 214 is opened is as follows.

(1) In the automatic 4WD and the manual 4WD, when the oil temperature T is below a certain value T ₀ ′ (<T ₀ ), the viscosity of the oil is large, so the orifice is opened and the braking phenomenon by the oil pump 14 occurs. To avoid.

(2) In the manual 4WD, the 4WD rate is reduced to prevent the braking phenomenon during cornering (especially when the steering angle f is large) even during 4WD traveling.

Further, the duty ratio of the duty solenoid valve 213 can be controlled as follows, and the orifice valve 214 interposed in the communication oil passages 207 and 208 can be controlled.
When the diameter of the orifice becomes large, the communication oil passages 207, 20
Since the amount of oil flowing through 8 increases, when a sharp turn is made, the discharge pressure can be lowered and the 4WD ratio can be lowered, as shown in FIG. 7.

Further, as shown in FIG. 6, the front wheels 43, 44 and the rear wheels 5
It is also possible to change the orifice diameter of the orifice valve 214 in accordance with the rotational speed difference ΔN with respect to 2, 53 and the vehicle speed V. In this case, the orifice diameter can be made smaller as the vehicle travels at a higher speed. The straight running stability by wheel drive is improved.

In this way, since the turning radius is large when turning at high speed,
The braking phenomenon is very slight, and the steering stability by four-wheel drive is secured.

According to the embodiment of the present invention, the following effects and advantages can be obtained.

(1) Since the difference in rotational speed between the front wheels and the rear wheels can be displayed on the display device arranged in the driver's seat or the like, the driver can be made aware of the driving state from moment to moment.

(2) By comparing the display obtained in advance according to the driving state of the mounted non-direct coupling type (hydraulic pump type) coupling mechanism with the display in the current driving state of the vehicle according to the first paragraph, The driver can know that the vehicle is in the four-wheel drive state.

(3) From the above item 2, it is possible to confirm that four-wheel drive is used during acceleration / deceleration, high-speed running, low friction roads, bad roads, etc., and this allows the four-wheel drive characteristics (turning Stability, steering stability, rough road running performance, etc.) can be utilized.

(4) During steady running on a dry road, it is possible to detect that there is a large difference in rotational speed between the front and rear wheels, and for example, it is possible to detect a case where the tire radii of the front and rear wheels are not the same. Poor mounting can be determined.

(5) According to the above item (4), it is possible to prevent the occurrence of power circulation in the drive system, and prevent deterioration of fuel consumption and damage to the drive system.

As a means for determining the priority order of the manual limit flow rate setting means M ₂ and the automatic limit flow rate setting means M ₃ , a manual priority order setting means which always gives priority to either one or a manual limit flow rate in an emergency. can be used emergency automatic 4WD priority setting means for controlling the automatic restriction from the control of the setting means M ₂ flow rate setting means M ₃ with priority.

Further, as a communication oil passage that connects the discharge side of the suction / discharge ports 72 to 77 and the suction side, an oil sump 80 as an oil sump that is the atmosphere side in the transmission case 94 from the discharge side.
Via, may form a communicating oil passage to supply the working oil from the oil passage 104 to the suction side, i.e., as shown by two-dot chain line in FIG. 1, the first oil passage OL ₁ (Or second
A communication oil passage 207 ′ that connects the oil passage OL ₂ ) or the oil passage 203 and the oil reservoir 80 is provided, and this communication oil passage 207 ′ is provided.
An orifice valve 214 as the flow rate control mechanism M ₁ may be inserted in the above.

Then, the operation and effect of the above-described embodiment can be obtained.

Further, the oil pump 14 is not limited to the vane pump, and other oil pumps can be incorporated and used as in the above-described embodiment.

The front wheel output shaft 5 of the four-wheel drive drive connection device 13 may be connected to the output shaft of the automatic transmission 2.

Further, it goes without saying that the present embodiment can be applied to an automobile equipped with a manual transmission.

〔The invention's effect〕

As described above in detail, according to the four-wheel drive drive coupling device of the present invention, the first rotating shaft that transmits the driving force to the front wheels of the vehicle and the second rotating shaft that transmits the driving force of the rear wheels. And a hydraulic connecting mechanism that is interposed between the first rotating shaft and the second rotating shaft and can transmit a driving force to each other, and the hydraulic connecting mechanism is a hydraulic pump type connecting mechanism. And an oil passage connected to the discharge port of the connection mechanism and an oil passage connected to the suction port (including an oil sump) of the connection mechanism, and a communication oil passage passing through the communication oil passage. A flow rate control mechanism capable of controlling the flow rate of hydraulic oil (from zero flow rate to an unrestricted flow rate) is provided, and a manual type limited flow rate setting means for outputting a control signal for setting the limited flow rate to the flow rate control mechanism. And a driving state sensor that detects the driving state of the vehicle, Of the automatic limit flow rate setting means and the manual limit flow rate setting means and the automatic limit flow rate setting means for receiving a detection signal from the controller and outputting a control signal for setting the limit flow rate to the flow rate control mechanism. With a simple structure in which a switching mechanism that selectively sends only the control signal from one of them to the flow rate control mechanism is provided, the following effects or advantages can be obtained.

(1) Since the differential rotation between the front wheels and the rear wheels is allowed, problems such as tight corner braking phenomenon of a part-time four-wheel drive vehicle and complexity of driving operation can be eliminated.

(2) Since the force is transmitted between the first rotating shaft and the second rotating shaft from the faster rotating one to the slower rotating one, it is possible that one of the front wheels or the rear wheels is excessively rotated. Wheel spin can be reliably prevented, which can contribute to vehicle stability.

(3) Compared to the center differential that was conventionally equipped in a full-time four-wheel drive vehicle, it can be made smaller and lighter, which can contribute to cost reduction.

(4) During low-speed steep turns, a difference in rotational speed between the front wheel-side rotary shaft and the rear wheel-side rotary shaft can be allowed, and the braking phenomenon can be reliably prevented.

(5) When traveling at high speed, the straight running stability of the vehicle is secured.

(6) Since the control of the amount of torque transmitted by the oil pump can be selectively switched to one of manual control and automatic control according to the rotational speed difference between the first rotary shaft and the second rotary shaft. Therefore, the function can be sufficiently exerted without causing deterioration of driving feeling and steering stability.

[Brief description of drawings]

1 to 9 show a drive connecting device for four-wheel drive as one embodiment of the present invention. FIG. 1 is a hydraulic system diagram showing a hydraulic pump type connecting mechanism and a hydraulic circuit, and FIG. FIG. 3 is a schematic configuration diagram showing a power system of a vehicle equipped with the device, FIG. 3 is a sectional view of an essential part thereof, FIG. 4 is a block diagram thereof, and FIG.
(d) is a flow chart for explaining the action, and FIGS. 6 to 9 are graphs for explaining the action. 1 ... engine, 1a ... torque converter, 2 ... automatic transmission, 3,3 '... gear, 4 ... rear wheel output shaft as second rotary shaft, 5 ... as first rotary shaft Front wheel output shaft, 8 ... differential case, 9, 10 ... pinion, 11,
12 ... Kid gear, 13 ... Drive connecting device for four-wheel drive, 14 ... Oil pump (vane pump), 38,3
8 '... Gear, 38a ... Output shaft, 39 ... Ring gear,
39 '... Gear, 40 ... Front wheel differential, 41, 42 ...
Front wheel shaft, 43, 44 ... Front wheel, 45 ... Bevel gear mechanism, 45a, 46a ... Gear, 47 ... Propeller shaft, 47a ...
Bevel gear, 48 ... Ring gear, 49 ... Rear wheel differential, 50, 51 ... Rear wheel shaft, 52, 53 ... Rear wheel, 64a
...... Spline engaging part, 68 …… vane, 68a …… tip part, 68b …… bottom part, 69 …… rotor, 69a …… outer peripheral surface, 69
b: hole, 69c: inner diameter side bottom, 70: housing,
70a ... Cam ring portion, 70b ... Cover, 70c ... Flange, 70d, 70e ... Interposed material, 71 ... Hydraulic circuit as discharge pressure control mechanism, 72-77 ... Suction discharge port, 78,79
…… Check valve, 80 …… Oil sump (oil tank),
81, 81 ', 82 ... Check valve for preventing air intrusion, 81
a, 81'a, 82a ... Orifice, 83, 84 ... Discharge pressure control relief valve, 83a, 84a ... Spring, 86-
88 ... Pump room, 89, 90 ... Communication passage, 89a, 90a ...
... Passage for centrifuging, 89b, 90b ... Passage for discharge, 91-9
3 ... Bearing, 94 ... Transmission case, 95, 96 ... Bushing (bearing), 101 ... Bolt, 104 ... Oil passage, 106 ... Axial sliding portion, 10
9 ... Oil chamber, 120, 121 ... Flow path, 122, 123
...... Check valve, 126 ...... Rotation speed sensor (pickup) as second rotation speed detector (operating state sensor),
127 ... Rotation speed sensor (pickup) as first rotation speed detector (operating state sensor), 128 ... Control unit, 128a, 128b ... Counter, 128c ... Timer, 128d ... Arithmetic unit (CPU) , 128e …… Memory, 1
29 ... Display device, 129a to 129d ... LED, 130 ...
Steering angle detector (steering angle sensor) as a driving state sensor, 131 ... Warning light, 132 ... Gear shift stage sensor (inhibitor switch) as a driving state sensor, 133
...... Accelerator opening sensor (throttle opening sensor) as a driving state sensor, 134 ...... Brake state sensor as a driving state sensor, 135 ...... Oil temperature sensor as a driving state sensor, 136 ...... As a driving state sensor Engine speed sensor, 137 ... Vehicle speed sensor as operating state sensor, 138 ... Changeover switch, 140 ... Oil pump, 140a ... Outer tooth inner gear, 140b ... Inner tooth outer gear (casing), 142 ... Input Shaft (inner shaft), 143 ... Outer shaft on pump side of torque converter, 2
01 to 206 ... Oil passage, 204a, 205a ... Orifice, 2
07, 207 ', 208 ... Communication oil passage, 209 ... Return oil passage, 210 ... Switching valve, 211 ... Pressure reducing valve, 21
2 ... Regulator valve, 213 ... Duty solenoid valve, 214 ... Orifice valve, 214a ...
Land, 214b ... Spring, 214c ... Spool, 21
5 ...... manual control device, M 1 _...... the flow control mechanism, M 2 _...... manual limit flow rate setting unit, M 3 _...... automatic limit flow rate setting unit, M 4 _...... changeover mechanism, M 5 _...... operating conditions Computational means, OL ₁ ... 1st oil passage, OL ₂ ... 2nd oil passage.

Claims (1)

[Claims] 1. A first rotating shaft for transmitting a driving force to a front wheel of a vehicle, a second rotating shaft for transmitting a driving force of a rear wheel, the first rotating shaft and a second rotating shaft. And a hydraulic coupling mechanism capable of transmitting a driving force to each other, the hydraulic coupling mechanism being configured as a hydraulic pump type coupling mechanism,
A communication oil passage communicating with an oil passage connected to the discharge port of the connection mechanism and an oil passage connected to the suction port of the connection mechanism, and a flow rate control mechanism capable of controlling the flow rate of the working oil passing through the communication oil passage. And a manual type limit flow rate setting means for outputting a control signal for setting the limit flow rate to the flow rate control mechanism, a driving state sensor for detecting a driving state in the vehicle, and a driving state sensor Of the automatic limit flow rate setting means for outputting a control signal for setting the limit flow rate to the flow rate control mechanism in response to the detection signal of, and the manual type limit flow rate setting means and the automatic limit flow rate setting means. A drive coupling device for four-wheel drive, comprising a switching mechanism that selectively sends only a control signal from one side to the flow rate control mechanism.