JPH0620827B2 - Transfer clutch device for four-wheel drive vehicle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a part-time four-wheel drive vehicle (4WD vehicle) capable of driving front wheels and rear wheels with the same engine, and more particularly to a transfer clutch device thereof.

[Conventional technology]

BACKGROUND ART Conventionally, for example, in a front-wheel drive base (FF base) part-time four-wheel drive vehicle, various types have been developed in which drive coupling of rear wheels can be achieved by engagement of hydraulically actuated clutches.

Then, in order to operate such a clutch, an oil pump is provided separately (the electric oil pump or the oil pump for an automatic transmission is used as this oil pump), and the discharge pressure of this oil pump is appropriately adjusted to the clutch. It is supposed to be supplied.

[Problems to be solved by the invention]

However, in such a conventional transfer clutch device for a four-wheel drive vehicle, the oil pump must be provided separately, and the means for adjusting the discharge pressure of the oil pump becomes complicated.

Further, in such a conventional transfer clutch device for a four-wheel drive vehicle, since the oil pump and the clutch are arranged side by side in the axial direction of the rotating shaft, the axial dimension is large and the entire device becomes large-scale. There is a problem that it ends up.

The present invention is intended to solve such a problem, has a compact structure, and enables automatic adjustment of the discharge pressure from the oil pump with a simple structure. Can be smaller,
Moreover, it is an object of the present invention to provide a transfer clutch device for a four-wheel drive vehicle in which the torque transmission capacity of the clutch can be sufficiently secured.

[Means for solving problems]

Therefore, the transfer clutch device for a four-wheel drive vehicle according to the present invention is a first four-wheel drive vehicle that can drive front wheels and rear wheels with the same engine.
The rotating shaft and a second rotating shaft for transmitting driving force to the rear wheels are provided, and one of these rotating shafts is provided with a power transmission system for transmitting power from the engine.
An oil pump driven by a rotation speed difference between the rotating shaft and the second rotating shaft, and a clutch interposed between the first rotating shaft and the second rotating shaft are provided, and the rotating speed difference is provided. An oil passage connecting the oil pump and the clutch is provided to supply the discharge pressure of the oil pump according to the above to the contact direction control side oil chamber, and the oil pump and the clutch are respectively provided. It is characterized in that it is arranged coaxially with the rotary shaft, and is arranged substantially in alignment with the radial direction of the rotary shaft, and the clutch is provided on the outer peripheral side of the oil pump.

[Work]

With the above configuration, when a rotation speed difference occurs between the front wheel-side first rotation shaft and the rear wheel-side second rotation shaft, a discharge pressure according to the rotation speed difference is discharged from the oil pump,
This discharge pressure is supplied to the tangential direction control side oil chamber of the clutch via the oil passage, and the oil pressure in the oil chamber rises quickly, and the clutch torque according to the differential rotation speed is obtained.
Further, since it is provided on the outer peripheral side of the clutch oil pump, a sufficient torque transmission capacity can be secured.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 to 6 show a transfer clutch device for a four-wheel drive vehicle as an embodiment of the present invention. FIG. 1 is a longitudinal sectional view showing the main part thereof, and FIG. 2 is a vehicle equipped with this device. FIG. 3 is a schematic sectional view showing the power system of FIG. 3, FIG. 3 is a longitudinal sectional view showing the relief valve, FIG. 4 is a lateral sectional view of the main part thereof, FIG. 5 is a hydraulic circuit diagram for the oil pump, and FIG. The figure is a graph for explaining the operation.

The present invention relates to a part-time four-wheel drive vehicle in which front wheels 43 and 44 and rear wheels 52 and 53 can be driven by the same engine 1, as shown in FIG. 2, and the details thereof will be described. As shown in FIGS. 1 and 2, a transmission 2 that constitutes a power transmission system T is connected to a horizontally installed engine 1.
The drive gear (or fourth speed counter gear) 3 is
A gear 7 that is integral with the sheath shafts 5 and 5'constituting the first rotation shaft that transmits the driving force to the front wheels 43 and 44 meshes.

The sheath shafts 5 and 5'are fixed by bolts 55.

A shaft 4 for driving the front wheels (hereinafter referred to as "front wheel output shaft 4") is spline-fitted to the sheath shafts 5 and 5'with gears 7. The front wheel output shaft 4 and the sheath shafts 5, 5'constitutes the first rotation shaft.

In this way, the power from the power transmission system T is always transmitted to the first rotary shaft.

In addition, the transfer clutch device 13 includes the sheath shafts 5 and 5 ′ that form the first rotation shaft and the rear wheel drive shaft 6 that forms the second rotation shaft that transmits the driving force to the rear wheels 52 and 53. Hereinafter, it will be referred to as "rear wheel output shaft 6").

The transfer clutch device 13 is driven by a rotational speed difference between the sheath shafts 5 and 5'and by extension the front wheel output shaft 4 and the rear wheel output shaft 6, and a gear type oil pump 14 that discharges oil at a pressure corresponding to the rotational speed difference. And this oil pump 1
A clutch 32 configured to receive the oil discharged from No. 4 via the oil passage to adjust the degree of coupling between the front wheel output shaft 4 side and the rear wheel output shaft 6 side to suppress the rotational speed difference. There is.

Next, the arrangement of the oil pump 14 and the clutch 32 will be described.

As shown in FIG. 1, a pump case 15 is attached to the sheath shaft 5 '.
Is spline-fitted, and a clutch 32 is provided on the outer diameter side of the pump case 15.
An oil pump 14 is provided on the inner diameter side of 5 so as to be housed between the ends of the clutch 32 in the axial direction.

As the oil pump 14, for example, a crescent-free internal gear pump (rotor pump) is used. The oil pump 14 includes an inner gear 17 as an external gear (pinion) spline-fitted to the rear wheel output shaft 6. The inner gear 17 is provided with an outer gear 18 that meshes with the inner gear 17 but is eccentrically arranged with respect to the inner gear 17 as an internal gear.
The outer gear 18 and the outer gear 18 are formed such that their tooth shapes form a hypocycloid curve, and
6 is provided.

The pump case 16 is fixed to the case 15 with bolts 19.

As shown in FIG. 5, the oil pump 14 is provided with two ports 20 and 21, and one port 20 is provided with an oil passage 292, a check valve 24 and an intake oil passage 291. The oil passage 294 is connected to the oil suction port 22 opening at the shaft end of the rear wheel output shaft 6
And the discharge oil passage 29 through the check valve 28, and the other port 21 is connected through the oil passage 293, the check valve 25, and the suction oil passage 291 to the oil intake port 22. It is connected to the discharge oil passage 29 'through an oil passage 295 and a check valve 28'.

Further, an oil passage 296 with a relief valve 26 is interposed between the oil passage 291 and an oil passage 298 communicating with the contact direction control side oil chamber 37 of the clutch 32.

Further, from the oil chamber 37, an atmosphere opening oil passage 297 with an orifice 30 formed in the piston 36 of the clutch 32 is branched.

As a result, if a rotation speed difference occurs between the front wheel output shaft 4 side and the rear wheel output shaft 6 side, and the inner gear 17 rotates in the direction of arrow a, the oil is absorbed in the oil intake port 22, the oil passage 29.
1, check valve 25, oil passage 293 to port 21
After being sucked in, it is discharged from the oil passage 29 through the port 20, the oil passage 294, and the check valve 28. The discharge pressure characteristic at this time is as indicated by reference character A in FIG.

On the contrary, when the inner gear 17 rotates in the direction of the arrow b, oil is sucked into the port 20 through the oil suction port 22, the oil passage 291, the check valve 24, and the oil passage 292, and then the port 21, the oil passage 295, and the oil. It is discharged from the oil passage 29 through the check valve 28. The discharge pressure characteristic at this time is also 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 increases because the relief valve 26 opens when the discharge pressure is equal to or higher than each predetermined value.

The characteristic portion of the characteristic A before the relief valve 26 is opened is proportional to the square of the rotational speed difference due to the action of the orifice 30.

Here, the opening characteristic of the relief valve 26 and the orifice 30
Since the degree of aperture is set appropriately, the characteristic A can be set to a desired value.

A part of the oil passage 291 is bored in the rear wheel output shaft 6, and an oil filter 23 is provided in a portion of the oil passage 291 near the oil intake port 22.

By the way, as shown in FIG. 1, an annular step portion 16a is formed on the outer circumference of the pump case 16.
An annular piston 36 is fitted in 6a. As a result, the oil chamber 37 is formed between the piston 36 and the cylinder 37a (the pump case 16 and the sleeve 35). Then, in the oil chamber 37, the oil passage 29,
29 'communicates.

Therefore, the piston 36 is pushed out by the oil discharged from the oil passages 29, 29 '.

In this way, the clutch 32, which is in the contact state when the piston 36 is pushed out, is provided adjacent to the piston 36.

In the oil chamber 37, an annular spring 56 as an urging mechanism is interposed between the inner wall 37b of the cylinder 37a and the piston 36, and the piston 36 is preliminarily attached to the piston 36 as shown by the symbol B in FIG. A biasing force (initial limiting torque) is applied in the contact direction of the clutch 32.

The clutch 32 is a pump case 1 as a clutch bab.
A plurality of (4 in this case) annular clutch plates 33 that are spline-engaged with the outer peripheral portions of 5, 16 and a plurality of annular rings that are spline-engaged with the inner peripheral portion of the sleeve 35 that serves as the clutch cylinder 37a with the rear wheel output shaft 6. The clutch plates 34 and 34 are arranged alternately, and the clutch plates 33 and 34 are alternately arranged to form a friction engagement element.

Therefore, the pressure oil is supplied to the oil chamber 37, and the piston 3
When 6 is pushed out, the clutch plates 33 and 34 are brought into close contact with each other, and the pump case 15 and the sleeve 35, that is, the front wheel output shaft 4 side and the rear wheel output shaft 6 side are engaged.
At this time, depending on the discharge pressure of the oil pump 14, the piston 3
Since the force for pushing 6 changes, the degree of engagement of the clutch 32,
That is, the degree of torque transmission also changes accordingly. Reference numerals 54 and 54 'in FIG. 1 denote stopper members.

Further, the oil passage 297 is the clutch plate 3 of the clutch 32.
3,34 (The pressure of this part is almost atmospheric pressure)
The clutch 32 can be cooled or lubricated by the oil from the oil passage 279.

As shown in FIG. 2, a gear 38 is attached to the front wheel output shaft 4, 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 4 is divided by the front wheel differential 40 and transmitted to the left and right front wheel drive shafts 41, 42 to rotationally drive the front wheels 43, 44.

Further, the rear wheel output shaft 6 is connected to a propeller shaft 47 via a bevel gear mechanism 45, and a bevel gear 47a at the rear portion of the propeller shaft 47 has a rear wheel differential mechanism 49 (hereinafter, referred to as a rear wheel differential mechanism 49).
It is meshed with the ring gear 48 of "the rear wheel differential 49"). As a result, the torque from the rear wheel output shaft 6 is split by the rear wheel differential 49 and transmitted to the left and right rear wheel drive shafts 50 and 51, thereby rotating the rear wheels 52 and 53.

Since the transfer clutch device for a four-wheel drive vehicle according to the embodiment of the present invention is configured as described above, the front wheels 43 and 44 cause a slip during traveling in the front wheel drive,
When the rotation speed on the front wheel output shaft 4 side becomes faster than the rotation speed on the rear wheel output shaft 6 side, the inner gear 17 rotates in the direction of arrow a.

As a result, the oil flows into the oil suction port 22 and the oil passage 29.
1, check valve 25, oil passage 293 to port 21
From the oil passage 29 into the oil chamber 37 through the port 20, the oil passage 294, and the check valve 28.

Since this discharge pressure is a value corresponding to the rotational speed difference between the front wheel output shaft 4 side and the rear wheel output shaft 6 side, the force with which the piston 36 presses the clutch plates 33, 34 is also determined according to the rotational speed difference.

As a result, the magnitude of the torque transmitted by the clutch 32 also changes according to the difference in rotational speed.

When the rotational speed difference is generated in this way, the clutch 32 is brought into the engagement state with the coupling degree according to the difference, so that the rotational speed difference is suppressed, and as a result, the rear wheel output shaft 6 side is moved. Torque is also transmitted. As a result, when the front wheels 43, 44 idle, the four wheels are automatically switched to the four-wheel drive state, and the rear wheels 52, 53 can be rotationally driven.

At this time, since the amount of torque transmitted by the clutch 32 is automatically controlled according to the difference in rotational speed, driving feeling and steering stability are not deteriorated.

Further, the piston 36 is constantly urged against the clutch plate 34 by the annular spring 56, and the clutch plates 33, 3
Since there is no clearance between the clutch plate 3 and the clutch plate 3 as soon as the oil pump 14 starts discharging due to a rotation difference.
3, 34 is pressed, and after the differential rotation speed is generated, the hydraulic pressure rises quickly, and the clutch torque corresponding to the differential rotation speed is instantaneously obtained.

Then, by the annular spring 56, the symbol C in FIG.
A large initial limiting torque B can be applied as compared with a conventional one that does not have a biasing mechanism shown by, and the value of the initial limiting torque B can be set to an arbitrary value by the annular spring 56.

In particular, the rising portion of the characteristic A shown in FIG. 6 is proportional to the square of the rotation speed difference, so that a small rotation speed difference
There is also the advantage that the torque does not change so much, and this can reduce the reduction in braking during low-speed turning.

Further, since the clutch 32 of the type in which the piston 36 presses the clutch plates 33 and 34 and the rotor pump having a small radius without a crescent are used as the oil pump 14, the structure can be made compact and the oil pump 14 can be used as a clutch. Since it is arranged on the inner diameter side of the clutch 32 so as to fit within the axial width of 32, the size can be further reduced.

That is, the oil pump 14 and the clutch 32 are arranged coaxially with the rotating shafts 4, 6 and the rotating shafts 4, 6 are provided.
Since they are arranged in alignment with each other in the radial direction, the size in the radial direction can be reduced.

What should be noted here is that since the clutch 32 is provided on the outer peripheral side of the oil pump 14, the clutch plates 33, 34 having the same diameter as the conventional one can be used. That is, the torque transmission capacity of the clutch 32 is sufficiently secured.

If the rotation speed difference exceeds a certain value, for safety,
The relief valve 26 prevents the discharge pressure from rising.

Conversely, when the rear wheels 52, 53 turn faster than the front wheels 43, 44, the inner gear 17 automatically rotates in the direction of arrow b.

As a result, the oil supply path is automatically switched, and oil is sucked from the port 20 through the oil suction port 22, the oil path 291, the check valve 24, and the oil path 292, and the port 21, the oil path 295, and the check valve 28. After that, the oil is discharged from the oil passage 29 into the oil chamber 37.

Since this discharge pressure also has a value corresponding to the rotational speed difference between the front wheel output shaft 4 side and the rear wheel output shaft 6 side, the force with which the piston 36 presses the clutch plates 33, 34 is determined according to the rotational speed difference.

As a result, the magnitude of the torque transmitted by the clutch 32 also changes according to the difference in rotational speed.

In this case as well, the clutch 32 is connected with the degree of coupling according to the rotational speed difference.
Are brought into contact with each other, the difference in rotational speed is suppressed, and as a result, torque is transmitted to the front wheel output shaft 4 side. As a result, the rotation of the rear wheels 52, 53 can be suppressed and the front wheels 43, 44 can be rotationally driven.

And in this case also, the clutch 3
Since the amount of torque transmitted by 2 is automatically controlled, 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 26 prevents the discharge pressure from rising.

By the way, the oil pump 14 composed of a rotor pump
Has a meshing portion 14 as compared with a gerotor pump.
The a, the tooth tip seal portion 14b, and the port portion 14c have the following features.

I) At the meshing portion 14a 1. Since the closing volume is very small, there is little leakage,
The pulsation is also small.

2. Since the pressure angle is small, the radial force of the aura roller is small. Therefore, the bearing load of the outer rotor is reduced and the torque loss is reduced.

3. Since the amount of slip is small, wear on the meshing surface is low and friction loss is low.

In the part where the slip speed becomes faster, the meshing of the teeth is disengaged.

II) In the tooth tip seal portion 14b, the IN port 21 (20) and the OUT port 20 (21) are sealed with a few teeth. Further, the clearance at the tip of the tooth becomes smaller as the pressure becomes higher. Therefore, high volume efficiency can be obtained.

III) In the IN and OUT port portions 14c, there is no tooth meshing portion, and the gear chambers are continuously connected. Therefore, the suction portion is easily filled with oil and cavitation is less likely to occur. Further, since the teeth are not in contact with each other, noise is not generated and teeth are not worn.

In addition, it has excellent characteristics compared to the TC pump (internal gear pump with crescent). 1) Since there is no cricent, it contributes to ease of body processing and cost reduction.

2) The difference in the number of teeth between the pinion 17 and the internal gear 18 is small (for example, 1), the outer diameter of the internal gear 18 is reduced, and the mounting size and torque loss are reduced.

3) The tooth profile is made based on the hypocycloid curve, and it is possible to reduce slippage of teeth and improve quietness.

4) There is a large amount of discharge on one rotation axis, so to obtain the same amount of discharge,
Small installation dimensions are required.

5) The meshing ratio is close to 1, and when one tooth meshes, the meshing of the other teeth ends, and this is effective in reducing the sound of meshing and reducing tooth surface wear.

Further, in the present device, the product of the transmission torque and the rotational speed difference causes energy loss and heat is generated. However, a part of the oil passes through the oil passage 297 and the clutch plates 33, 3 of the clutch 32.
Since it is discharged toward the clutch 4, there is also an advantage that the clutch 32 can be sufficiently cooled and lubricated.

The present device can be applied to a four-wheel drive vehicle based on a rear wheel drive, but in this case, the power from the engine is always transmitted to the second rotary shaft.

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

Various springs and the like are used as the biasing mechanism.

〔The invention's effect〕

As described above in detail, according to the transfer clutch device for a four-wheel drive vehicle of the present invention, in the four-wheel drive vehicle in which the front wheel and the rear wheel can be driven by the same engine, the first transmission force is transmitted to the front wheel. A rotary shaft and a second rotary shaft for transmitting driving force to the rear wheels are provided, and a power transmission system for transmitting power from the engine to one of the rotary shafts is provided. An oil pump driven by a rotation speed difference between the two rotation shafts, and a clutch interposed between the first rotation shaft and the second rotation shaft are provided, and the oil pump according to the rotation speed difference is provided. An oil passage that connects the oil pump and the clutch is provided to supply the discharge pressure of the oil pump to the contact direction control side oil chamber of the clutch, and the oil pump and the clutch are respectively connected to the rotary shaft and the rotary shaft. Arranged coaxially Together they are, are arranged substantially aligned in the radial direction of the rotary shaft, the configuration that the clutch is provided on the outer peripheral side of the oil pump, effects and the following advantages are obtained.

(1) When a rotation speed difference occurs between the front and rear wheels, the discharge pressure of the oil pump rises and the clutch is differentially moved in the contact direction. Therefore, the four-wheel drive mode is automatically selected, and the rotation speed difference depends on the difference. Since the amount of torque transmitted by the clutch can be automatically controlled, driving feeling and steering stability are not deteriorated.

(2) Since the oil pump and the clutch are arranged coaxially and substantially aligned in the radial direction of the rotary shaft, the axial space of the device can be shortened.

(3) Since the clutch is provided on the outer peripheral side of the oil pump, there is an advantage that the torque transmission capacity of the clutch can be sufficiently secured.

[Brief description of drawings]

1 to 6 show a transfer clutch device for a four-wheel drive vehicle as an embodiment of the present invention. FIG. 1 is a longitudinal sectional view showing the main part thereof, and FIG. 2 is a vehicle equipped with this device. FIG. 3 is a schematic cross-sectional view showing the power system of FIG. 3, FIG. 3 is a vertical cross-sectional view showing the relief valve, FIG. 4 is a schematic view showing a cross-section of the main part of the relief valve, and FIG. , FIG. 6 is a graph for explaining the operation. 1 ... engine, 2 ... transmission, 3 ... drive gear,
4 ... front wheel output shafts constituting the first rotary shaft, 5, 5 '...
Sheath shaft, 6 ... Rear wheel output shaft that constitutes the second rotating shaft, 7 ...
Gear, 13 ... Transfer clutch device, 14 ... Oil pump, 14a ... Engagement portion, 14b ... Tooth tip seal portion, 14c ... Port portion, 15, 16 ... Pump case, 16a. …… Inner gear, 18 ……
Outer gear, 19 ... bolt, 20,21 ... port,
22 ... Oil inlet, 23 ... Oil filter, 2
4, 25 ... Check valve, 26 ... Relief valve, 28, 28 '... Check valve, 29, 29' ...
... oil passage, 30 ... orifice, 32 ... clutch, 3
3, 34 ... Clutch plate, 35 ... Sleeve, 36 ...
Piston, 37 ... Oil chamber, 37a ... Cylinder, 37b
...... Inner wall, 38 ... Gear, 39 ... Ring gear, 40 ...
... front wheel differential, 41, 42 ... front wheel drive shaft, 43, 44
...... Front wheel, 45 …… Bevel gear mechanism, 47 …… Propeller shaft, 47 a …… Bevel gear, 48 …… Ring gear, 49
…… Rear wheel differential, 50, 51 …… Rear wheel drive shaft, 52, 5
3 ... rear wheel, 54, 54 '... stopper member, 55 ...
Bolt, 56 ... Annular spring as urging mechanism, 2
91 to 298 ... Oil passage, T ... Power transmission system.

Claims (1)

[Claims] 1. A four-wheel drive vehicle capable of driving front wheels and rear wheels with the same engine, a first rotary shaft transmitting a drive force to the front wheels, and a second rotary shaft transmitting a drive force to the rear wheels. And an oil pump driven by a rotational speed difference between the first rotary shaft and the second rotary shaft, the power transmission system transmitting power from the engine to one of the rotary shafts, And a clutch interposed between the first rotating shaft and the second rotating shaft of the first rotating shaft, and supplies the discharge pressure of the oil pump according to the difference in the rotating speed to the oil chamber on the tangential direction control side of the clutch. In order to do so, an oil passage connecting the oil pump and the clutch is provided, and the oil pump and the clutch are respectively arranged coaxially with the rotary shaft and in the radial direction of the rotary shaft. Almost aligned, Serial characterized in that said clutch is provided on an outer peripheral side of the oil pump, the transfer clutch device for a four wheel drive vehicle.