JPH0215698Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a four-wheel drive drive coupling device in which front wheels and rear wheels are driven by the same engine.

In a four-wheel drive vehicle where the front and rear wheels are driven by the same engine, there is a slight difference in the effective radius of the front and rear tires, and when driving in turns, the difference in the rolling path of the tires causes the tires to Since unreasonable force is applied to the drive system due to slippage, it is necessary to provide a means to prevent this.

For this reason, in conventional full-time four-wheel drive vehicles, even if there is a difference in rotational speed between the first rotating shaft that transmits the driving force for the front wheels and the second rotating shaft that transmits the driving force to the rear wheels, the driving force is transmitted. To achieve this, a third differential device called a center differential is used. However, this device is disadvantageous compared to part-time 4-wheel drive vehicles in terms of weight and cost, and because it allows differential rotation, there are cases where 4-wheel drive cannot be achieved when 4-wheel drive is required. This results in further complication of the device, such as the need for a deflock mechanism.

On the other hand, many part-time 4-wheel drive vehicles do not have a center differential, and if there is a problem with 4-wheel drive, such as tight corner braking caused by cornering, the driver can switch to 2-wheel drive. This has the disadvantage that driving operations are complicated.

The present invention was developed to solve the above-mentioned drawbacks of conventional four-wheel drive vehicles, and its purpose is to automatically achieve two-wheel drive and four-wheel drive depending on the driving condition. , yet small and lightweight 4
The object is to obtain a drive coupling device for wheel drive.

In order to achieve the above object, the four-wheel drive drive coupling device according to the present invention includes a first rotating shaft that transmits driving force to the front wheels, a second rotating shaft that transmits driving force to the rear wheels, and a second rotating shaft that transmits driving force to the rear wheels. A four-wheel drive drive connection comprising a hydraulic pump that connects a first rotating shaft and a second rotating shaft, is driven by the difference in rotational speed between the two rotating shafts, and discharges an amount of oil according to the difference in rotational speed. The device includes: a sub-oil passage that communicates an oil passage on the discharge port side and an oil passage on the suction port side of the hydraulic pump; a variable throttle mechanism provided in the sub-oil passage and capable of changing the flow resistance of the sub-oil passage; The invention is characterized by further comprising a control means for increasing the aperture amount of the variable aperture mechanism in proportion to .

Hereinafter, one embodiment of the connecting device according to the present invention will be described based on the drawings.

Fig. 1 shows an outline of the drive system of a four-wheel drive vehicle equipped with a coupling device according to an embodiment, Fig. 2 shows a cross section of the coupling device, and Fig. 3 shows a longitudinal section thereof. , FIGS. 4a, 4b and 4c show cross-sections of the variable diaphragm mechanism.

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

Then, the driving force is transmitted from one gear 7 of this 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. The power is transmitted to the shaft 11 via the gear 12, and further to the four-wheel drive drive coupling device main body 13, which is a vane pump type coupling mechanism. This four-wheel drive force is transmitted to the second rotating shaft 14, and the drive force is transmitted to the differential device 17 for the rear wheels 16 via a gear mechanism 15 that changes the direction of rotation. , drives the rear wheels 16.

As shown in FIGS. 2 and 3, this four-wheel drive drive coupling device body 13 is composed of a vane pump VP as a hydraulic pump and a hydraulic circuit 21 attached thereto, and a rotor 19 of the vane pump VP.
is the first rotating shaft 11 that transmits the driving force to the front wheels 9.
The cam ring portion 20a, the annular plate 20b, and the output side plate 20c, which constitute the casing 20, are connected to the second rotating shaft 14 that transmits driving force to the rear wheel 16.

This vane pump VP as a hydraulic pump has
A large number (8 in this case) of holes 19b are formed at equal intervals in the circumferential direction on the outer circumferential surface 19a of the rotor 19, and each of the large number of holes 19b is provided on the inner circumferential surface of the cam ring portion 20a. A vane 18 that can be slidably contacted with 20d is fitted.

Further, the vane pump VP discharges an amount of oil proportional to its rotation speed, and there is a relative rotation between the rotor 19 and the cam ring part 20a, that is,
When relative rotation occurs between the first rotating shaft 11 and the second rotating shaft 14, it functions as a hydraulic pump and generates hydraulic pressure.

By blocking the discharge ports of the vane pump VP (corresponding to the suction and discharge ports 22 to 25 at the tip of the vane 18 in the relative rotational direction with respect to the casing 20), the rotor 19 and the cam ring portion 20a are connected to each other by the static pressure through the oil. It becomes like a rigid body and rotates as one.

Therefore, two pump chambers 36 and 37 are formed at diagonal positions between the cam ring part 20a and the rotor 19, and when it is located on the base end side in the rotational direction, it becomes a suction port, and when it is located on the distal end side, it becomes a discharge port. Four suction/discharge ports 22 to 25 serving as outlets are formed at substantially diagonal positions, and the diagonally positioned suction/discharge ports 22, 24 and suction/discharge ports 23, 25, each having the same function, are connected to the cam ring. The first oil passage 26 and the second oil passage are connected through a mechanism that allows oil to flow even when the portion 20a is in rotation.
It is communicated with the oil passage 27.

Moreover, between the first oil passage 26 and the second oil passage 27,
The oil reservoir 30 is communicated with each other through check valves 28, 29, 29', and only the flow from the oil reservoir 30 to each oil passage 26, 27 is allowed, and the first oil passage 26 and the second oil passage 27 two opposing check valves 31 that allow only outflow between the
Both oil passages 26 and 27 communicate with each other through a check valve 32, and an intermediate portion between these two check valves 31 and 32 is connected to an oil passage 40.
It communicates with the relief valve 33 via.

Through the middle part of the relief valve 33 on the spring 34 side, there is a connection between the oil reservoir 30 and the check valve 29' and the two check valves 28 and 29.
A communication path 35 is provided.

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 between the rotor 19 and the cam ring portion 20a, and the oil reservoir 30 communicates with the suction port. become.

Further, an auxiliary oil passage 38 is provided which communicates the oil passage 26 connected to the suction discharge port 24 and the oil passage 27 connected to the suction discharge port 23.
An auxiliary oil passage 39 is provided that communicates the oil passage 26 connected to the suction and discharge port 25 with the oil passage 27 connected to the suction discharge port 25. A variable aperture mechanism M that can change the amount of aperture depending on the speed is provided. The variable throttle mechanism M includes a spool 46 that is slidably housed in a case 45 of the sub oil passages 38 and 39, and a spool 46 that is slidably housed in a case 45 of the sub oil passages 38 and 39.
It consists of a spring 47 etc. that always presses the spool 46 so as to open the spool 39. The spool 46 is controlled so as to throttle the auxiliary oil passages 38 and 39 in proportion to the traveling speed of the vehicle. As the control device, when the coupling device is mounted on an automatic transmission, a mechanism for guiding transmission governor pressure to the passage 48 at one end of the spool 46 can be considered. Furthermore, instead of applying governor pressure to the passage 48, hydraulic pressure may be applied to the passage 48 with duty controlled according to the vehicle speed. Furthermore, the stepping motor is directly connected to the spool 46 without providing the spring 47, and the vehicle speed is detected.
Based on this, a computer may issue an operating command to the stepping motor, and various other control methods are possible, such as one using centrifugal force and one using negative intake pressure.

When the front wheels 9 normally slip within about 1%, such as when the vehicle is accelerating straight ahead, even if there is no large slip, the difference in rotational speed caused by this causes the difference in rotational speed between the first rotational shaft 11 and the second rotational shaft 14 If this occurs between the rotor 19 and the cam ring portion 20a, the vane pump VP functions to generate oil pressure according to this rotational speed difference.
The two rotate as one, and a driving force corresponding to this oil pressure and the pressure receiving area of the vane is transmitted to the rear wheels 16, resulting in a four-wheel drive state.

In this case, the oil flow in the vane pump VP is caused by the relative rotation of the rotor 19 (see symbol A in FIG. 2), and the suction and discharge ports 22, 24
serves as a suction port and oil is sucked in from the oil reservoir 30 via the check valve 28, while the suction and discharge port 2
3 and 25 serve as discharge ports and check valves 29 and 31
At the same time as the valve is closed, oil is introduced to the relief valve 33 via the check valve 32 and the oil passage 40.

In FIG. 2, solid line arrows indicate the flow of discharged oil, and broken line arrows indicate the flow of suction oil.

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

As a result, in the vane pump VP, the oil flow shown in Figure 2 occurs and a large hydraulic pressure is generated, but when a predetermined value occurs, the relief valve 33 opens against the spring 34 and the discharge pressure remains almost constant. A four-wheel drive state is established in which a constant driving force corresponding to a constant discharge pressure is transmitted to the rear wheels 16.

Then, as the rotational speed of the front wheels 9 decreases, the rotational speed of the rear wheels 16 increases, reducing the rotational speed difference (same function as a non-slip differential).
I come to do it.

In this way, when the front wheel 9 is in a slip state, the rear wheel 1
In addition, when the rear wheels 16 tend to lock up, the brake torque of the front wheels 9 is increased to prevent the rear wheels 16 from locking up.

On the other hand, if the rotational speed of the rear wheels 16 becomes very large compared to the rotational speed of the front wheels 9, for example, if the brakes of the front wheels 9 tend to lock up, the first A very large rotational speed difference occurs between the rotating shaft 11 and the second rotating shaft 14 in the opposite direction to that described above.

As a result, in the vane pump VP, a flow occurs in the opposite direction to the oil flow shown in FIG.
Oil is sucked in from the oil reservoir 30 through the oil reservoir 30 through the oil tank 9', while the suction and discharge ports 22 and 24 become discharge ports, passing through the second oil passage 26, closing the check valves 28 and 32, and flowing from the check valve 32 to the relief valve 33. The introduced large hydraulic pressure acts on the relief valve 33.
A four-wheel drive state is established in which the driving force is maintained constant and a constant driving force is transmitted to the rear wheels 16.

Then, the brake torque to the rear wheels 16 is increased to prevent the front wheels 9 from locking.

Furthermore, during normal cornering, the rotational speed of the front wheels 9 is slightly higher than the rotational speed of the rear wheels 16, resulting in a four-wheel drive state in which brake torque is applied to the front wheels 9 and drive torque is applied to the rear wheels 16. A turning run is made.

In this way, the four-wheel drive drive coupling device main body 13
By controlling the discharge pressure using the relief valve 33 so that it does not exceed a certain value, conventional part-time 4-wheel drive vehicles that require operation by the driver when 4-wheel drive is required can be removed. , automatically 4
Switching between wheel drive and two-wheel drive is performed, and a four-wheel drive state is obtained with a driving force according to the rotational speed difference between the front wheels 9 and the rear wheels 16.

By the way, when a four-wheel drive vehicle tries to turn a tight corner with front and rear wheel drive, the speed difference between the front and rear wheels increases due to the difference between the inner wheels, resulting in a tight corner braking phenomenon. In other words, while the front wheels try to turn quickly, the rear wheels try to turn slowly, and the front wheels are dragged by the rear wheels, which try to turn slowly, and stop turning. Therefore, when going around tight corners, you need to be in two-wheel drive.

Figure 5 shows the vehicle speed V (Km/
h), turning radius R (m), rotational speed difference ΔN between the first rotating shaft 11 and the second rotating shaft 14 in the coupling device
(rpm). Lateral G during normal turning is 0.5G
(G = 9.8m/s ² ) or less, so in this vehicle, the rotational speed difference ΔN at that time is the maximum
It will be about 60 rpm (R = 6 m, V = 20 Km/h).
Therefore, if the variable throttle mechanism M is set so that the discharge pressure does not increase even if there is a rotational speed difference of 60 rpm up to a vehicle speed of 20 km/h, no torque will be transmitted to the rear wheels, that is, the torque will not be transmitted to the rear wheels. Wheel drive is not achieved and tight corner braking phenomena can be avoided. In the throttle mechanism M as shown in FIG. 4, the spring force of the spring 47 and the size of the spool 46 may be determined so that the size of the oil passage (flow resistance) is determined according to the vehicle speed. For example, if the vehicle speed is 20km/
When the speed is less than h, the oil passage size is the orifice diameter and becomes φ3 (fully open), and when the speed is 40km/h, it corresponds to φ2,
If φ1 is set at 60km/h, the rotational speed difference ΔN and vane pump VP for the vehicle speed at that time
The relationship between the discharge pressure P (Kg/cm ² ) and the discharge pressure P (Kg/cm 2 ) is shown in FIG. Even if governor pressure acts on the passage 48, the vehicle speed
Spool 46 at governor pressure below 20Km/h
does not move, the oil passage remains open, the oil on the discharge side flows to the suction side, the discharge pressure does not increase, and four-wheel drive is not achieved. The relationship between the rotational speed difference, transmitted torque (Kgm), and discharge pressure when controlled in this way is shown by the thick solid line in FIG. The other curves have fixed orifices of different diameters in the auxiliary oil passages 38 and 39.
The case where it is set is shown below.

On the other hand, when driving at high speeds, four-wheel drive increases driving stability and reduces wobbling. Therefore, as mentioned above, when the vehicle speed increases,
The amount of throttle of the variable throttle mechanism M is set large, that is, the auxiliary oil passages 38, 39 are narrowed, and the auxiliary oil passages 38, 39 are narrowed.
The amount of oil flowing through the cylinders decreases, the discharge pressure increases, the driving force transmission efficiency increases, and four-wheel drive is achieved. As can be seen from FIG. 5, the allowable turning radius at high speeds is large, so braking phenomena are negligible, and the four-wheel drive ensures stable handling.

Furthermore, even at low speeds (here below 20 km/h), if the rotational speed difference exceeds 60 rpm, hydraulic pressure is generated and power is also transmitted to the rear wheels. In other words, it is designed to deal with problems such as wheel stacking.

As described above in detail based on one embodiment, according to the four-wheel drive drive coupling device according to the present invention,
An auxiliary oil passage is provided that communicates the outlet side oil passage and the suction side oil passage of a hydraulic pump that transmits driving force to the front wheels and rear wheels, and the flow resistance of the auxiliary oil passage can be changed in the auxiliary oil passage. A variable throttle mechanism is installed, and the throttle amount of the variable throttle mechanism is controlled to increase in proportion to the vehicle speed, so when the vehicle speed is low, four-wheel drive is not activated until the rotation speed reaches a certain rotational speed difference, so it is tight. Corner braking phenomenon can be prevented, and at high speeds, four-wheel drive is used to ensure steering stability.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing a drive system of a four-wheel drive vehicle as an embodiment of the present invention, and Fig. 2 is a cross-sectional view of a hydraulic pump provided in a drive coupling device as an embodiment of the present invention. , FIG. 3 is a longitudinal sectional view thereof, FIG. 4 a, b, and c are sectional views of the variable throttle mechanism, and FIG. 5 is a graph showing the relationship between vehicle speed, turning radius, and rotational speed difference.
Fig. 6 is a graph showing the relationship between the rotational speed difference and discharge pressure at a constant vehicle speed due to the difference in the size of the auxiliary oil passage, and Fig. 7 shows the control of the auxiliary oil passage by the four-wheel drive drive coupling device according to the present invention. It is a graph which shows the relationship between the rotational speed difference and the transmission torque in the case. In the drawing, 1 is a horizontal engine, 2 is a transmission, 1
0 is a differential gear, 11 is a first rotating shaft, 13 is a four-wheel drive coupling device body, 14 is a second rotating shaft, 18 is a vane, 19 is a rotor, 20 is a casing, 21 is a hydraulic circuit, 22 to 25 is the suction and discharge port, 29,2
9', 31, 32 are check valves, 33 is a relief valve, 38, 39 are auxiliary oil passages, 46 is a spool, 47
48 is a spring, 48 is a passage, and M is a variable throttle mechanism.

Claims (1)

[Scope of utility model registration request] a first rotating shaft that transmits driving force to the front wheels; a second rotating shaft that transmits driving force to the rear wheels; A four-wheel drive drive coupling device comprising a hydraulic pump that is driven by a hydraulic pump and discharges an amount of oil according to a rotational speed difference, in which an oil passage on a discharge port side and an oil passage on a suction port side of the hydraulic pump are communicated. A variable throttle mechanism provided in the subsidiary oil passage and capable of changing the flow resistance of the subsidiary oil passage, and a control means for increasing the throttle amount of the variable throttle mechanism in proportion to vehicle speed. A four-wheel drive drive coupling device characterized by: