JPH0617710B2 - Differential limiting device for front-rear differential mechanism in four-wheel drive vehicle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a front and rear wheel differential mechanism in a four-wheel drive vehicle that divides torque from an input shaft and applies the divided torque to two output shafts. Restriction device.

[Conventional technology]

Conventionally, Limited Slip Differential (hereinafter, “Limited Slip Differential”; “LSD”)
Say. ) Is proposed, and such L
In SD, if the differential case torque transmitted from the engine is Td and the value determined structurally (this value is constant) is α, regardless of the difference in rotational speed between the output shafts, the faster output shaft ( Td / 2) -α, (Td / 2) on the slower output shaft
The torque of (/ 2) + α is transmitted.

Further, in the case shown in FIG. 7, the differential case c is provided by the drive pinion a through the drive gear b.
Is rotated, the pressure rings d, d meshing with the differential case c rotate at the same speed, and the left and right side gears e, e differ from the differential case c due to the differential action due to the difference in road surface resistance. Rotate at the desired speed.

And side gears e, e and differential case c
One of the pressure rings d increases in rotation speed due to the frictional force between the clutch plates f and f meshing with each other.
The other slows down.

Further, the pressure ring d is pushed by pushing the tapered portion of the pinion shaft g which is in contact with the pressure ring d.
Receives a reaction force in the lateral direction and the rotational direction, and the reaction force in the lateral direction is
Friction for crimping the clutch plate f is increased, and driving force is increased.

[Problems to be solved by the invention]

However, in the former one (LSD), if there is even a slight difference in rotational speed between the two shafts, the differential limiting function is exerted. Therefore, when the vehicle is equipped with this, the driving feeling is deteriorated and steering stability is reduced. There is a problem of causing deterioration.

Further, in such a conventional differential limiting device of a differential mechanism, there is a problem that the friction material used for the clutch is worn or burned, and when a rotation difference occurs due to deterioration of hydraulic oil or the like. In addition, there is a problem that stick-slip (judder) occurs, which may cause vibration.

The present invention is intended to solve such a problem, and suppresses the relative rotation of the two output shafts, and the difference in the four-wheel drive vehicle in which the control characteristics are made different according to the direction of the relative rotation. An object is to provide a differential limiting device for a dynamic mechanism.

[Means for solving problems]

Therefore, the present invention, in a differential limiting device for a differential mechanism in a four-wheel drive vehicle, includes an input shaft and two output shafts that can take out torque from the input shaft in a divided manner. An oil pump driven by relative rotation between the shaft and one of the two output shafts or relative rotation of the two output shafts, and controlling the discharge pressure of the oil pump. Thus, a discharge pressure control mechanism that suppresses relative rotation of the output shafts of the two output shafts and has different control characteristics according to the directions of the relative rotations is provided.

[Action]

In the above-described differential control device for the differential mechanism in the four-wheel drive vehicle of the present invention, when the relative rotation between the input shaft and one output shaft or the relative rotation between the two output shafts occurs, the oil pump moves relative to each other. The operating shaft having the discharge pressure corresponding to the rotation is discharged. Then, the discharge pressure control mechanism controls the discharge pressure based on different control characteristics depending on the direction of relative rotation, thereby performing an action of suppressing relative rotation between the two output shafts.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 to 4 show a differential limiting device for a front and rear wheel differential mechanism in a four-wheel drive vehicle as a first embodiment of the present invention. FIG. 1 is a partial cross-sectional view showing a main part thereof, and FIG. FIG. 4 is a schematic configuration diagram showing a power system of a vehicle equipped with the present device, FIG. 3 is a hydraulic circuit diagram for the oil pump, and FIG. 4 is a graph for explaining its operation. FIG. 1 is a schematic diagram of a main part of a differential limiting device for front and rear wheel differential mechanisms in a four-wheel drive vehicle as second and third embodiments of the present invention.

As shown in FIGS. 1 and 2, in the first embodiment of the present invention, a transmission 2 is connected to a horizontally mounted engine 1 via a clutch 1a, and its drive gear (or fourth speed counter gear) 3 is connected.
The torque from the shaft (input shaft) with the drive gear 3 is equally divided into two output shafts 4, 5 [one output shaft 4
Is a rear-wheel drive shaft (hereinafter referred to as "rear-wheel output shaft"),
The other output shaft 5 is a shaft for driving front wheels (hereinafter, referred to as “front wheel output shaft”)] and is engaged with a ring gear 7 of a differential mechanism 6 (hereinafter, this differential mechanism is referred to as “center differential 6”). ing.

The side gears 11 and 12 are meshed with the pinions 9 and 10 having the differential case 8 integrated with the ring gear 7. The side gear 11 is connected to the rear wheel output shaft 4, and the side gear 12 is connected to the front wheel output. The shaft 5 is connected.

Further, the differential limiting device 13 is interposed between the differential case 8 side and the rear wheel output shaft 4.

This differential limiting device 13 includes a differential case 8 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 FIG. 1, the ring gear 7 bolted to the differential case 8 is spline-fitted with the flange 70c of the housing 70, and 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. 3, a large number (here, 10) of holes 69b are formed in 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 70d of the cam ring portion 70a is fitted into each of the plurality of holes 69b.

Further, each part is formed so that the axial gap between the cover 70b of the housing 70 and the vanes 68 and the rotor 69 is not more than a predetermined value, and the oil film is not cut off, and the flange 70c of the housing 70 is prevented. Similarly, each portion is formed so that the axial gap between the vane 68 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, respectively. The suction and discharge ports 72, 74, 76 and the suction and discharge ports 73, 75, 77 having the same function at 120 ° intervals are
Each of the first oil passage OL ₁ and the second oil passage OL ₂ is provided with a mechanism capable of sending oil to the fixed side even when the cam ring portion 70a is rotated.
It is communicated with.

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 OL ₂ are allowed.
If the discharge pressure becomes higher than a predetermined pressure between the two oil passages OL ₁ , O
_Two relief valves 83 and 84 for controlling the discharge pressure are provided to make L ₂ communicate 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 sump 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 communication passage 90 is connected. 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.

In addition, the cover 70b and the flange 70c forming the housing 70 of the vane pump 14 are indirectly supported by the bearing 91.
And the transmission case 9 via the bearing 97.
It is pivotally supported by 4.

The rotor 69 of the vane pump 14 has a spline engagement portion 64a.
The rear wheel output shaft 4 connected via the
The cover 70b and the flange 70c are axially supported by bushings (bearings) 95 and 96 on both sides of the shaft 64a, respectively.

The bottom portion 68b of the vane 68 has a check valve 123 (122) -equipped flow passage 121 for measuring the discharge pressure from the discharge-side oil passage (here, the first oil passage OL ₁ ) of the oil passages OL ₁ and OL _2.
The tip portion 68a of the vane 68 is urged toward the inner peripheral surface 70d of the housing 70 by being received via (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.

Furthermore, as shown in FIGS. 1 and 3, in the axial sliding portion 106 in which the rotor 69 and the cover 70b are in sliding contact and in the axial sliding portion 106 in which the rotor 69 and the flange 70c 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 are connected to the first oil passages OL ₁ that are 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. It communicates with OL ₂ via a flow path 120 with a check valve 122 to receive high hydraulic pressure.

In addition, reference numeral 69c in the drawing denotes a bottom portion of the rotor 69 on the inner diameter side,
Reference numerals 2 and 93 denote bearings that respectively support the differential case 8 and the front wheel output shaft 5, 98 is an oil supply passage, 99 is a filter, 100 is a magnet mounting portion, 10
Reference numeral 1 indicates a bolt, and 104 indicates an oil passage.

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
0 through the check valve 79 and the second oil passage OL ₂ to the suction / discharge ports 73, 75, 77, and then the pump chamber 8
6 to 88 suction / discharge ports 72, 74, 76 to the first oil passage O
It is discharged from the check valve 82 with the orifice 82a to the oil tank 80 via L ₁ . The discharge pressure characteristic at this time is the fourth
This is as indicated by the symbol A in the figure.

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 are taken.
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 B in FIG.

In each of the characteristics A and B, when the rotational speed difference exceeds a certain value, the discharge pressure hardly increases because the relief valves 83 and 84 open when the discharge pressure is equal to or more than each predetermined value.

In addition, the relief valves 83 and 84 for the respective characteristics A and B
The characteristic portion before opening is proportional to the square of the rotational speed difference due to the action of the orifices 81a and 82a.

Here, the opening pressure of the relief valve 83 is set to the relief valve 84.
The discharge pressure rising characteristic as shown in FIG. 4 can be obtained by increasing the throttle amount of the orifice 81a to be larger than that of the orifice 82a.

A part of the oil passage 104 is bored in the rear wheel output shaft 4, and an oil filter 99 is provided in a portion of the oil passage 104 near the oil intake port, and an oil supply passage 98 is provided. Iron powder or the like in the oil supplied through the oil is prevented from entering the oil pump 14 by the magnet of the magnet mounting portion 100 and the oil filter 99.

As shown in FIG. 2, a gear 38 is attached to the front wheel output shaft 5, and the gear 38 meshes with a ring gear 39 of a front wheel differential mechanism 40 (hereinafter referred to as "front wheel differential 40"). is doing. As a result, the torque from the front wheel output shaft 5 is divided by the front wheel differential 40 and is transmitted to the left and right front wheel shafts 41, 42 to rotationally drive the front wheels 43, 44.

Further, the rear wheel output shaft 4 is connected to a propeller shaft 47 with a transfer 46 via a bevel gear mechanism 45, and a bevel gear 47a of the propeller shaft 47 is connected to the rear wheel differential mechanism 4
9 (hereinafter referred to as "rear wheel differential 49") ring gear 4
It meshes with 8. As a result, the torque from the rear wheel output shaft 4 is divided by the rear wheel differential 49 and the left and right rear wheel shafts 50, 5 are separated.
1 is transmitted to drive the rear wheels 52 and 53 in rotation.

Since the differential limiting device for the front and rear wheel differential mechanism in the four-wheel drive vehicle as the first embodiment of the present invention is configured as described above, the front wheels 43, 44 will not slip while traveling in four-wheel drive. Then, when the rotation speed of the front wheel output shaft 5 side becomes higher than the rotation speed of the rear wheel output shaft 4 side, the rotor 69 relatively rotates in the direction of arrow a.

As a result, the oil flows 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 is sucked from the suction / discharge ports 72, 74, 76 of the pump chambers 86-88 through the first oil passage OL ₁ and the orifice 8
It is discharged from the check valve 82 with 2a 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, the magnitude of the torque transmitted by the oil pump 14 also changes according to the rotational speed difference.

When the rotation speed difference occurs in this way, the differential limiting device 13 is brought into contact with the coupling degree according to the difference, so that the rotation speed difference is suppressed, and as a result, the rear wheel output shaft Four
The torque is also transmitted to the side. As a result, even if the front wheels 43, 44 idle, the rear wheels 52, 53 can be rotationally driven.

At this time, since the transmission torque amount by the differential limiting device 13 is automatically controlled according to the rotational speed difference, driving feeling and steering 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 rear wheels 52, 53 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,
The air 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 86-88,
It is discharged from the check valve 81 with the orifice 81a to the oil tank 80 through the second oil passage OL ₂ from 77. 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.

In this case as well, since the differential limiting 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, torque is transmitted to the front wheel output shaft 5 side. To be done. As a result, even if the rear wheels 52, 53 idle, the front wheels 43, 44 can be driven to rotate.

Also in this case, since the transmission torque amount by the differential limiting device 13 is automatically controlled according to the rotational speed difference, driving feeling and 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.

As described above, in the present embodiment, when one of the front and rear wheels slips and slips, torque can be transmitted to the other wheel that is not slipping to ensure traveling stability, and the front wheel is the rear wheel. Since the rising characteristic of the discharge pressure when rotating faster is made gentler than the opposite case, the so-called tight corner braking phenomenon can be prevented from occurring during normal cornering where the front wheels rotate slightly faster.

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 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.

Further, in the second embodiment of the present invention, as shown in FIG.
The differential limiting device 13 using the vane pump 14 is built in the differential device 6, the rear wheel output shaft 4 is connected to the side gear 11 and the rotor 69, and the front wheel output shaft 5 is connected to the side gear 12 and the housing 70. ing.

The other structure of the second embodiment is the same as that of the first embodiment, and the same reference numerals as those in FIGS. 1 to 4 in FIG.

The function and effect of the second embodiment are almost the same as those of the first embodiment, and a more compact device can be realized.

In the third embodiment of the present invention, as shown in FIG.
The differential limiting device 13 using the oil pump 14 is built in the rear wheel differential device 49 ′, and the rear wheel shaft 50 of this differential device 49 ′ is connected to the side gear 12 and the housing 70, and the rear wheel shaft 51.
Are connected to the side gear 11 and the rotor 69.

The other configuration in the third embodiment is the first and second
This is similar to the embodiment, and in FIG. 6, the same reference numerals as in FIGS.

The effect of this third embodiment is that the oil pump 14
The differential rotation between the rotor 69 and the housing 70 can be doubled as compared with the first embodiment, and as a result, the torque capacity can be increased, so that the size of the pump can be reduced.

〔The invention's effect〕

As described above in detail, according to the differential limiting device for the front and rear wheel differential mechanism in the four-wheel drive vehicle of the present invention, the following effects and advantages are obtained.

(1) The discharge pressure control mechanism controls the discharge pressure of an oil pump driven according to the relative rotation between the input shaft and one of the two output shafts or the relative rotation of the two output shafts. Control by controlling the relative rotation of the above two output shafts and automatically controlling the torque transmitted to both output shafts by the oil pump, resulting in deterioration of driving feeling and steering stability. Without it, it can fully demonstrate its function.

(2) Because the discharge pressure rise characteristics differ depending on the direction of relative rotation of the oil pump, when one of the front and rear wheels slips and running stability is impaired, the other wheel that is not slipping It is possible to prevent the braking torque from being transmitted to the front wheels as much as possible while turning while driving in a tight corner or the like, while transmitting a strong torque to the vehicle to ensure traveling stability.

(3) By configuring the differential mechanism by combining the differential pump and the differential mechanism, there is no stick slip generated by the conventional differential mechanism, and
The number of parts can be reduced, which can contribute to weight reduction.

[Brief description of drawings]

1 to 4 show a differential limiting device for a front and rear wheel differential mechanism in a four-wheel drive vehicle as a first embodiment of the present invention. FIG. 1 is a partial cross-sectional view showing a main part thereof, and FIG. FIG. 4 is a schematic configuration diagram showing a power system of a vehicle equipped with the present device, FIG. 3 is a hydraulic circuit diagram for the oil pump, and FIG. 4 is a graph for explaining its operation. FIGS. 7A and 7B are configuration diagrams of a main part of a differential limiting device for a front and rear wheel differential mechanism in a four-wheel drive vehicle as second and third embodiments of the present invention, respectively, and FIG. It is a principal part sectional drawing of a limiting device. 1 ... Engine, 1a ... Clutch, 2 ... Transmission, 3 ...
... drive gear, 4 ... rear wheel output shaft, 5 ... front wheel output shaft, 6 ... center differential, 7 ... ring gear, 8 ... differential case, 9, 10 ... pinion, 11, 12 ... side gear, 13 ... … Differential limiter, 14 …… Oil pump (vane pump), 38 …… Gear, 39 …… Ring gear, 40 …… Front wheel differential, 41,42 …… Front wheel axle, 4
3,44 ... front wheel, 45 ... bevel gear mechanism, 46 ...
Transfer, 47 ... Propeller shaft, 47a ... Bevel gear, 48 ... Ring gear, 49, 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 section, 70b ... Cover, 70c ... Flange, 70d ... Inner peripheral surface, 71 ... Hydraulic circuit as discharge pressure control mechanism, 72-77 ... Suction discharge port, 78,79
Check valve, 80 ... Oil sump (oil tank), 8
1,82 …… Check valve for preventing air intrusion, 81a, 82a ……
Orifices, 82, 84 ... Relief valve for discharge pressure control,
83a, 84a ...... spring, 86-88 ...... pump chamber, 8
9, 90 ... communication passage, 89a, 90a ... valve seat opening, 91-
93 ... Bearing, 94 ... Transmission case, 95, 96 ... Bushing (bearing), 97 ... Bearing part, 98 ... Oil supply passage, 99 ... Filter, 10
0 ... Magnet mounting part, 101 ... Bolt, 104 ...
… Oil passage, 105 …… Pulsation damper, 106 ……
Axial sliding part, 109 ... Hydraulic chamber, 120, 121 ...
Passage, 122, 123 ...... check valve, 124 ...... communicating passage, 125 ...... orifice, OL ₁ ...... first oil passage, OL ₂
...... Second oil passage.

Claims (1)

[Claims] 1. A front-rear wheel differential mechanism of a four-wheel drive vehicle, comprising: an input shaft; and two output shafts capable of splitting and extracting torque from the input shaft. The oil pump driven by the relative rotation with one of the output shafts or the relative rotation of the two output shafts is interposed, and the discharge pressure of the oil pump is controlled to control the two output shafts. A differential limitation of front and rear wheel differential mechanisms in a four-wheel drive vehicle, characterized in that a discharge pressure control mechanism that suppresses relative rotation of the output shaft and has different control characteristics according to the direction of the same relative rotation is provided. apparatus.