JPH06473B2 - Drive coupling device for four-wheel drive - Google Patents

Description

The present invention relates to a drive coupling device for driving front wheels and rear wheels with the same engine.

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 for the front and rear wheels, and there is a difference in the rolling paths of the wheels during turning. Since an unreasonable force acts on the drive system with slippage, it is necessary to provide a means for preventing this.

Therefore, conventionally, in a full-time four-wheel drive vehicle, even if there is a difference in rotational speed between the first rotating shaft that transmits the driving force to the front wheels and the second rotating shaft that transmits the driving force to the rear wheels, the driving is performed. A differential device called a center differential is used to transmit force, and is disadvantageous compared to a part-time four-wheel drive vehicle in terms of weight, size, and cost, and differential rotation is also possible, so four-wheel drive is possible. In some cases, four-wheel drive cannot be achieved when driving is required, which further complicates the apparatus such as requiring a diff lock mechanism.

On the other hand, in many part-time four-wheel drive vehicles, a center differential is not installed, and if there is a problem due to four-wheel drive such as a tight corner braking phenomenon caused by turning traveling, two-wheel drive is operated by the driver. However, there is a drawback that the driving operation becomes complicated.

Therefore, a four-wheel drive drive connecting device having a hydraulic connecting mechanism capable of mutually transmitting a driving force between the first rotating shaft and the second rotating shaft is also conceivable, but as a hydraulic connecting mechanism, a vane pump is used. When the vane of the vane pump is fitted to the rotor so that it can be projected by the centrifugal force generated by the rotation of the rotor, the vane at the upper part of the rotor slides sufficiently on the inner peripheral surface of the casing when the rotor is stopped. Since they are not in contact with each other, such a hydraulic coupling mechanism has a problem that it is not possible to sufficiently transmit the driving force when the vehicle starts or operates at low speed.

The present invention is intended to solve such a problem, and the driving force transmission efficiency at the time of starting rotation of the vane pump type coupling mechanism and at the time of low speed operation while automatically switching between front wheel drive and four wheel drive. It is an object of the present invention to provide a drive coupling device for four-wheel drive, which is capable of increasing the driving force.

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 to the rear wheels, and the above-mentioned first rotating shaft. Rotation axis and second
And a hydraulic coupling mechanism that is capable of transmitting a driving force to each other, and the hydraulic coupling mechanism is configured as a vane pump type coupling mechanism. A casing connected to one of the first rotating shaft and the second rotating shaft and a rotor connected to the other of the first rotating shaft and housed in the casing are provided, and are attached to an outer peripheral surface of the rotor. A large number of vanes that are in sliding contact with the inner peripheral surface of the casing and a vane urging mechanism that urges the large number of vanes toward the inner peripheral surface of the casing are provided. Is introduced through the check valve into the rotor, and a hydraulic pressure supply mechanism for hydraulically urging the inner diameter side of the vane is configured.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 to 4 show a drive connecting device for four-wheel drive as one embodiment of the present invention, FIG. 1 is a schematic configuration diagram showing a drive system of a vehicle, and FIG. 2 is a cross-sectional view of the device. 3, FIG. 3 is a longitudinal sectional view of the present apparatus, and FIG. 4 is a transverse sectional view corresponding to FIG.

As shown in FIG. 1, a transmission 2 is attached to an engine 1 placed horizontally.
Drive gear 4 attached to its output shaft 3
The driving force is taken out from and is transmitted to the intermediate transmission shaft 8 having gears 6 and 7 at both ends via the idle gear 5.

Then, the driving force is transmitted from one gear 7 of the intermediate transmission shaft 8 to the differential device 10 for the front wheels 9 to drive the front wheels 9, while the driving force transmitted to the front wheels 9 is directly transmitted to the first rotation. It is transmitted to the shaft 11 via the gear 12, and further transmitted to the four wheel drive drive coupling device main body 13 as a vane pump type coupling mechanism.

The driving force that has passed through the four-wheel drive drive coupling device body 13 is transmitted to the second rotary shaft 14.
The rear wheel 16 via the gear mechanism 15 for converting the rotational take-out direction.
The driving force is transmitted to the differential device 17 for driving the rear wheels 16.

As shown in FIGS. 2 and 3, the four-wheel drive drive coupling device main body 13 is composed of a vane pump VP as a hydraulic pump (hydraulic coupling mechanism) and a hydraulic circuit 21 attached to the vane pump VP. The VP rotor 19 has the front wheels 9
Is connected to the first rotary shaft 11 that transmits the driving force to the rear wheel 16, and the cam ring portion 20a and the output side plate 20c that form the casing 20 are connected to the second rotary shaft 14 that transmits the driving force to the rear wheel 16. Has been done.

In the vane pump VP as the hydraulic pump, a large number (here, eight) of holes 19b are formed on the outer peripheral surface 19a of the rotor 19 at equal intervals in the circumferential direction, and each of the holes 19b is formed. A vane 18 is slidably fitted in the inner peripheral surface 20b of the cam ring portion 20a.

Further, the vane 18 of the vane pump VP is provided with a cam ring portion 20a by a hydraulic pressure supply mechanism M as a vane urging mechanism.
The rotor 19 is always urged toward the inner peripheral surface 20d thereof, and the rotor 19 is formed with a ring-shaped recess 38 communicating with the bottom portion (inner diameter side portion) 19c of each hole 19b. Is communicated with the pressure accumulator 36 via an oil passage 39 formed in the input side plate 20b of the casing 20, and the oil passage 39 is provided with a check valve 37 having a parasol-shaped valve body 37a. The oil passage 39 is connected to an oil passage 40 described later.

The vane pump VP discharges an oil amount proportional to the number of rotations of the vane pump VP.
When relative rotation occurs with respect to a, that is, relative rotation occurs between the first rotary shaft 11 and the second rotary shaft 14, it functions as a hydraulic pump to generate hydraulic pressure.

Discharge port of the vane pump VP (suction discharge ports 22 to 25 at the tip of the vane 18 relative to the casing 20 in the direction of relative rotation)
(Corresponding to this), the rotor 19 and the cam ring portion 20a are integrally rotated as a rigid body by the static pressure through the oil.

For this reason, two pump chambers are formed between the cam ring portion 20a and the rotor 19 at diagonal positions, and serve as a suction port when located at the base end side in the rotational direction and as a discharge port when located at the tip end side. The four suction / discharge ports 22 to 25 are formed substantially at diagonal positions, and the suction / discharge ports 22 and 24 and the suction / discharge ports 23 and 25 at the diagonal positions having the same function respectively,
Each of the first oil passage 26 and the second oil passage 27 is provided with a mechanism capable of sending oil to the fixed side even when the cam ring portion 20a is rotated.
It is communicated with.

Further, an oil reservoir 30 is connected between the first oil passage 26 and the second oil passage 27 via check valves 28, 29, 29 ′, respectively, and the flow from the oil reservoir 30 to each oil passage 26, 27 is increased. Only allowed, and the first oil passage 26 and the second oil passage 2
Both oil passages 26 and 27 are communicated with each other via two check valves 31 and 32 that face each other and allow only the outflow.
An intermediate portion of the two check valves 31, 32 communicates with the relief valve 33 via the oil passage 40.

A communication passage 35 is provided between the oil reservoir 30 and the check valve 29 ′ and the two check valves 28, 29 through an intermediate portion of the relief valve 33 on the spring 34 side.

With such a hydraulic circuit 21, the discharge pressure always acts on the valve body of the relief valve 33 regardless of the relative rotation direction of the rotor 19 and the cam ring portion 20a, and the oil sump 30 communicates with the suction port. become.

Incidentally, reference numeral 36a in the drawing indicates a piston,
Reference numeral b represents a spring, and 41 represents a return spring.

Since the four-wheel drive drive coupling device of the present invention is configured as described above, in the normal straight traveling state of the vehicle, the effective radii of the tires of the front wheels 9 and the rear wheels 16 are the same, and the slip rotation speeds of the tires are the same. Due to the small number, the first rotary shaft 11 and the second rotary shaft 1 connected to the four-wheel drive drive coupling device body 13 are connected.
There is no difference in rotational speed between No. 4 and No. 4.

Therefore, no oil pressure is generated in the vane pump VP,
The driving force is not transmitted to the rear wheels 16 and only the front wheels 9 drive the front wheels.

However, when the front wheels 9 usually slip within about 1% 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 first rotating shaft 11 and the second rotating shaft 14 to rotate. Between the rotor 19 and the vane pump VP, hydraulic pressure is generated according to the rotational speed difference, and the rotor 19
And the cam ring portion 20a rotate integrally, and the driving force corresponding to the hydraulic pressure and the pressure receiving area of the vane is transmitted to the rear wheels 16 to bring about the four-wheel drive state.

In this case, the flow of oil in the vane pump VP causes the rotor 19 to relatively rotate (see reference numeral A in FIG. 2), and the suction and discharge ports 22 and 24 serve as suction ports and pass through the check valve 28. While the oil is sucked from the oil sump 30 while the suction discharge ports 23 and 25 serve as discharge ports and close the check valves 29 and 31, at the same time, the check valve 32 and the oil passage 40 are closed.
The oil is guided to the relief valve 33 via.

In addition, in FIG. 2, the solid line arrow shows the flow of discharge oil, and the broken line arrow has shown the flow of suction oil.

Further, the oil supplied from the check valve 32 to the oil passage 40 is
The check valve 37 interposed in the oil passage 39 is returned to the spring 4
In the opened state against 1 and is supplied to the hole portion 19b through the oil passage 39 and the ring-shaped recess 38, the bottom surface of the vane 18 fitted into the hole portion 19b is pressed to push the vane 18 into the cam ring portion. The inner peripheral surface 20d of 20a is slidably contacted.

Further, the oil that flows in through the check valve 37 is supplied to the pressure accumulator 36, and the high pressure hydraulic oil is stored in the pressure accumulator 36.

The pressure difference is reduced between the first rotating shaft 11 and the second rotating shaft 14 to reduce the hydraulic pressure, and as shown in FIG. Bowl 36
High-pressure hydraulic oil is stored in the vane 18, and the state in which the vane 18 closely contacts and slides on the inner peripheral surface 20d of the cam ring portion 20a is maintained.

As described above, in the state where the high pressure hydraulic oil is stored in the pressure accumulator 36, even if the vehicle stops and the first rotating shaft 11 and the second rotating shaft 14 do not rotate, respectively, the vane 18 remains Since the vane pump VP is constantly biased in the protruding direction, the coupling function of the vane pump VP is maintained sufficiently high.

In addition, the gap between the vane 18 and the hole 19b and the rotor 19
Even if oil leaks from the gap between the first rotating shaft 11 and the casing 20, the pressure oil is replenished from the pressure accumulator 36,
Since the hydraulic pressure is substantially constant, the thrust output of the vane 18 is maintained.

Next, when the rotation speed of the front wheels 9 is much higher than the rotation speed of the rear wheels 16, for example, when the front wheels slip on a snowy road, when sudden acceleration occurs, or when the rear wheels tend to lock when braking. The difference in rotational speed between the first rotary shaft 11 and the second rotary shaft 14 connected to the four-wheel drive drive coupling device main body 13 becomes very large.

As a result, in the vane pump VP, the oil flow in the state shown in FIG. 2 occurs and a large hydraulic pressure is generated, but when the predetermined value is exceeded, the relief valve 33 opens against the spring 34 and the discharge pressure becomes substantially constant. The four-wheel drive state is achieved in which a constant drive force corresponding to a constant discharge pressure is transmitted to the rear wheels 16 under control.

Then, as the rotation speed of the front wheels 9 decreases, the rear wheels 1
The rotation speed of 6 increases, and the difference in rotation speed is reduced (the same function as the non-slip differential).

As described above, in the slip state of the front wheels 9, it can be avoided that the driving torque to the rear wheels 16 is increased and the vehicle cannot run, and when the rear wheels 16 tend to be locked, the braking torque of the front wheels 9 is increased. To prevent the rear wheel 16 from locking.

On the other hand, when the rotational speed of the rear wheels 16 is much higher than the rotational speed of the front wheels 9, for example, when the front wheels 9 are in a locked state and are in a locked state, the first connection to the four-wheel drive drive coupling device body 13 is made. A very large rotational speed difference is generated between the rotating shaft 11 and the second rotating shaft 14 in the opposite direction to the above.

As a result, in the vane pump VP, an oil flow in the opposite direction to the oil flow shown in FIG.
Serves as a suction port, and oil is sucked from the oil reservoir 30 via the check valves 29, 29 ', while the suction discharge ports 22, 2
4 serves as a discharge port, a check valve 28 through the first oil passage 26,
Although the large hydraulic pressure introduced from the check valve 32 to the relief valve 33 is applied by closing 32, this hydraulic pressure is also kept constant by the relief valve 33 and a constant driving force is transmitted to the rear wheels 16 to drive the four wheels. Becomes

Then, the brake torque to the rear wheels 16 is increased to increase the front wheels 9
Prevent locking.

Further, during normal turning traveling, the rotation speed of the front wheels 9 is slightly higher than the rotation speed of the rear wheels 16, brake torque acts on the front wheels 9, and drive torque acts on the rear wheels 16, resulting in a four-wheel drive state. A turn is made.

In this way, in the case where the conventional four-wheel drive vehicle requires a four-wheel drive state, the relief valve 33 controls the discharge pressure in the four-wheel drive drive coupling device main body 13 so as not to exceed a certain value. Requires a driver's operation, but automatically switches between four-wheel drive and two-wheel drive, and the four wheels are driven by a driving force according to the rotational speed difference between the front wheels 9 and the rear wheels 16. The drive state is obtained.

Further, in comparison with the center differential which is always equipped in the conventional full-time four-wheel drive vehicle, this device can be made compact and compact, and the weight can be reduced and the cost can be reduced.

As the hydraulic pressure supply mechanism M that constitutes the vane urging mechanism, a small hydraulic pump or the like may be interposed between the oil reservoir 30 and the oil passage 39.

Further, as a vane urging mechanism, the bottom portion 19c of the hole portion 19b is
You may make it provide a spring.

Further, in addition to a balanced vane pump having four suction and discharge ports, an unbalanced vane pump having two suction and discharge ports is used as the hydraulic pump of the drive coupling device main body 13 for four-wheel drive, depending on the amount of driving force transmitted. May be.

As described above in detail, according to the four-wheel drive drive coupling device of the present invention, the following effects and advantages can be obtained with a simple configuration.

(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 safety.

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

(4) Since the hydraulic pressure supply mechanism guides the hydraulic pressure discharged from the pump into the rotor via the check valve and biases the inner diameter side of the vane to the hydraulic pressure, the vane efficiently slides on the inner peripheral surface of the casing. In particular, the use of a check valve makes it possible to maintain the hydraulic pressure that urges the vanes even when the rotor is stopped or at low rotation, so the driving force at the start of rotation of the vane pump type coupling mechanism or at low speed rotation The transmission efficiency can be increased, which can improve the power transmission performance when the rotary shaft rotates at a low speed and also improve the startability of the vane pump.

(5) When a vehicle equipped with this device is started, if there is a difference in rotational speed between the front and rear wheels, it immediately switches to four-wheel drive.

[Brief description of drawings]

1 to 4 show a drive connecting device for four-wheel drive as one embodiment of the present invention, FIG. 1 is a schematic configuration diagram showing a drive system of a vehicle, and FIG. 2 is a cross-sectional view of the device. 3, FIG. 3 is a longitudinal sectional view of the present apparatus, and FIG. 4 is a transverse sectional view corresponding to FIG. 1 ... Horizontal engine, 2 ... Transmission, 3 ... Output shaft, 4
..Drive gears, 5..Idle gears, 6,7 ... Gear, 8 ... Intermediate transmission shaft, 9 ... Front wheel, 10 ... Differential device, 11 ... First rotary shaft, 12 ... Gear , 13 ··· 4 wheel drive coupling device body as vane pump type coupling mechanism, 14 · · 2nd rotating shaft, 15 · · gear mechanism, 16 ·
・ Rear wheel, 17 ・ ・ Differential gear, 18 ・ ・ Vane, 19 ・ ・
Rotor, 19a ... Outer peripheral surface, 19b ... Hole, 19c.
・ Bottom (inner diameter side), 20 ・ ・ Casing, 20a ・
・ Cam ring part, 20b ・ ・ Input side plate, 20c ・
・ Output side plate, 20d ・ ・ Inner peripheral surface, 21 ・ ・ Hydraulic circuit, 22-25 ・ ・ Suction / discharge port, 26 ・ ・ First oil passage, 2
7 ... Second oil passage, 28, 29, 29 '... Check valve,
30 ··· Oil sump, 31, 32 · · Check valve, 33 ·
.Relief valves, 34..Springs, 35..Communication passages,
36 .. Accumulator, 36a .. Piston, 36b .. Spring, 37 .. Check valve, 37a .. Parasol valve body, 38 .. Ring recess, 39, 40 .. Oil passage,
41 ··· Return spring, M · · · hydraulic supply mechanism as vane biasing mechanism, VP · · vane pump.

Claims (1)

[Claims] 1. A first rotating shaft for transmitting a driving force to front wheels of a vehicle, a second rotating shaft for transmitting a driving force to rear wheels, the first rotating shaft and the second rotating shaft. And a hydraulic coupling mechanism that is capable of transmitting a driving force to each other, and the hydraulic coupling mechanism is configured as a vane pump type coupling mechanism, and the coupling mechanism has the above-mentioned first rotation mechanism. A casing connected to one of the shaft and the second rotating shaft and a rotor connected to the other and housed in the casing are provided, and the rotor is attached to the outer peripheral surface of the rotor and the inner periphery of the casing is provided. A large number of vanes that are in sliding contact with the surface and a vane biasing mechanism that biases these multiple vanes toward the inner peripheral surface of the casing are provided, and the biasing mechanism checks the hydraulic pressure discharged from the pump. Through the vane of the vane And it is configured with a hydraulic pressure supply mechanism for a hydraulic biasing the diameter, characterized in that, four-wheel drive driving connection device.