JPS647895B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive coupling device when 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 tire may slip due to the difference in the rolling path of the tire. As a result, an unreasonable force is applied to the drive system, so 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 rotational speed difference between the first rotating shaft that transmits driving force to the front wheels and the second rotating shaft that transmits driving force to the rear wheels, the driving force is transmitted. A third differential device called a center differential is used to allow the vehicle to rotate, which is disadvantageous compared to a part-time 4-wheel drive vehicle in terms of weight, size, and cost. There are cases where four-wheel drive cannot be achieved when a drive is required, and the device becomes even more complex, such as requiring a deflock mechanism.

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

It is an object of the present invention to eliminate the drawbacks that occur in conventional four-wheel drive vehicles and to provide a small and lightweight four-wheel drive drive coupling device. The configuration of the present invention that achieves such an object includes a first rotating shaft that transmits driving force to the front wheels and a second rotating shaft that transmits driving force to the rear wheels. The first rotating shaft and the second rotating shaft are connected to each other via a hydraulic pump that is driven by a speed difference and discharges an amount of oil according to the rotational speed difference, and the suction port and discharge port of the hydraulic pump are connected to the first rotating shaft and the second rotating shaft.
A hydraulic control circuit that switches depending on the direction of rotation relative to the rotating shaft, and a control device that is installed in the hydraulic control circuit and controls the maximum value of the discharge pressure discharged from the hydraulic pump according to the running state of the vehicle. It is characterized by:

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

FIG. 1 is a schematic diagram of an embodiment of a four-wheel drive drive coupling device of the present invention.

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 transmission, and an intermediate transmission shaft is provided with gears 6 and 7 at both ends via an idle gear 5. 8, and from one gear 7 of this intermediate transmission shaft 8 to the front wheel 9
The driving force is transmitted to the differential gear 10 for driving the front wheels 9, while the driving force transmitted to the front wheels 9 is directly transmitted to the first rotating shaft 11 via the gear 12 to form a four-wheel drive drive connection. The driving force is transmitted to the second rotating shaft 14 via the device 13, and is transmitted to the differential device 17 for the rear wheels 16 via the gear mechanism 15 that changes the direction of rotation. to drive.

This four-wheel drive drive coupling device 13 includes a vane pump 20, which is a hydraulic pump, and a hydraulic control circuit 2 attached thereto, as shown in FIG.
1, the rotor 20a of the vane pump 20 is connected to the first rotating shaft 11 through which the driving force to the front wheels 9 is directly transmitted, and the cam ring 20b is connected to the second rotating shaft through which the driving force is transmitted to the rear wheels 16. It is connected to a shaft 14. The vane pump 20, which serves as a hydraulic pump, discharges an amount of oil proportional to its rotation speed, and has a rotor 20a and a cam ring 2.
0b, relative rotation, that is, the first rotation axis 11
When a relative rotation occurs between the shaft and the second rotating shaft 14, it functions as a hydraulic pump and generates hydraulic pressure, and the discharge port of the vane pump 20 (the suction and discharge port at the tip in the relative rotation direction corresponds to this). By blocking the rotor 20a and the cam ring 2, the static pressure is applied via oil.
0b become like a rigid body and are rotated together. For this reason, two pump chambers are formed at diagonal positions in the cam ring 20b, and four suction and discharge ports 22, 23, 24 and 25 are formed at almost diagonal positions, and the suction and discharge ports 22 and 24 and the suction and discharge ports 23 and 25, which are located diagonally and have the same function, respectively, send oil to the stationary side even when the cam ring 20b is rotating. The first oil passage 26 and the second oil passage 27 are in communication with each other via a mechanism that allows passage therethrough. Further, an oil reservoir 30 is communicated between the first oil passage 26 and the second oil passage 27 via check valves 28 and 29, respectively, and only flow from the oil reservoir 30 is allowed, and the first oil passage 27 The oil passages 26 and 27 communicate with each other through two check valves 31 and 32 facing each other, which allow only outflow, and the intermediate portion between the two check valves 31 and 32 is connected to the second oil passage 27. It communicates with the relief valve 33. A communication path 35 between the oil reservoir 30 and the intermediate portions up to the two check valves 28 and 29 is provided in the intermediate portion of the relief valve 33 on the spring 34 side.
A piston 36 is provided at the other end of the piston 36 for controlling the opening pressure of the relief valve 33 by a spring 34, and a control hydraulic pressure that is duty-controlled acts on the other end of the piston 36. Then, for duty control, a constant pressure of oil pressure supplied through an orifice 37 is applied to a solenoid valve 38.
This solenoid valve 38 is electrically connected to a computer 39, and is controlled by the engine speed input to the computer, the rotation speed of the first rotating shaft 11, the rotating speed of the second rotating shaft 14, the throttle opening,
The hydraulic pressure acting on the other end of the piston 36 is controlled by the brake operation detection switch and the steering angle detection signal. Note that the constant pressure oil pressure supplied through the orifice 37 may be used for control if the transmission 2 is an automatic transmission, or an oil pump may be installed if it is a manual transmission. Secure this oil pressure by etc.

With such a hydraulic control 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 20a and the cam ring 20b, and the oil reservoir 30 communicates with the suction port. .

The driving state of such a four-wheel drive drive coupling device will first be described in the case where the opening pressure of the relief valve 33 is kept constant only by the setting force of the spring 34.

In normal straight-ahead driving conditions, the effective radii of the tires of the front wheels 9 and rear wheels 16 are the same and the slip rotational speed of the tires is small. There is no difference in rotational speed between them. Therefore, the vane pump 20 does not generate hydraulic pressure, and no driving force is transmitted to the rear wheels 16, resulting in two-wheel drive by the front wheels 9 only.

However, even when the vehicle is running straight, the front wheels 9 usually slip within about 1%, even if there is no large slip as during acceleration. When this occurs, the vane pump 20 functions to generate oil pressure according to this rotational speed difference, and the rotor 20a and cam ring 20b
The two rotate together, 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 flow of oil in the vane pump 20 is caused by the relative rotation of the rotor 20a, as shown in FIG. While oil is sucked in from the reservoir 30, the suction and discharge ports 22 and 24 act as discharge ports, and when the check valves 28 and 32 are closed, the oil is led to the relief valve 33 via the check valve 31.
In the figure, 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 rear wheels tend to lock up when driving on a snowy road, when accelerating suddenly, or when braking, the four-wheel drive drive coupling device 13
The difference in rotational speed between the first rotating shaft 11 and the second rotating shaft 14 becomes very large, and the vane pump 20 generates a flow of oil as shown in FIG. 3a, generating a large hydraulic pressure. When this value is exceeded, the relief valve 33 opens against the spring 34 and the discharge pressure is controlled to be almost constant, resulting in a four-wheel drive state in which a constant driving force corresponding to the constant discharge pressure is transmitted to the rear wheels 16. . As a result, the rotational speed of the front wheels 9 decreases and the rotational speed of the rear wheels 16 increases, reducing the rotational speed difference (same function as a non-slip differential). It is possible to prevent the vehicle from being unable to travel due to an increase in the drive torque applied to the rear wheels 16, and when the rear wheels 16 are a little locked, the brake torque of the front wheels 9 is increased to prevent the rear wheels 16 from locking.

On the other hand, when the rotational speed of the rear wheels 16 becomes very large compared to the rotational speed of the front wheels 9, for example, when the brake state of the front wheels 9 becomes slightly locked, the first rotating shaft 11 of the four-wheel drive drive coupling device 13 A very large rotational speed difference occurs in the opposite direction to that described above between the third rotation shaft 14 and the second rotation shaft 14, and the third
A flow of oil as shown in Figure b occurs, and the suction/discharge port 2
2 and 24 serve as suction ports, and oil is sucked in from the oil reservoir 30 via the check valve 28, while the suction and discharge ports 23 and 25 serve as discharge ports, passing through the second oil passage 27 and closing the check valves 29 and 31. Check valve 32
A large hydraulic pressure is applied to the relief valve 33, but this hydraulic pressure is also kept constant by the relief valve 33, and a constant driving force is transmitted to the rear wheels 16.
It becomes a wheel drive state. As a result, 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, by controlling the discharge pressure in the four-wheel drive drive coupling device 13 using the relief valve 33 so that it does not exceed a certain value, when a four-wheel drive state is required in a conventional part-time four-wheel drive vehicle, What used to require operation by the driver now automatically switches between 4-wheel drive and 2-wheel drive, and now a 4-wheel drive state is created with driving force that corresponds to the difference in rotational speed between the front and rear wheels. It will be done. In addition, it can be made smaller and more compact than the center differential that is always installed in full-time four-wheel drive vehicles, and it also reduces weight and costs.

Next, when adjusting the opening pressure of the relief valve 33 by duty-controlling the hydraulic pressure acting on the lower end side of the piston 36, the vane pump 20
The discharge pressure of the engine can be adjusted and controlled, and the driving force to the rear wheels 16 can be adjusted.

Therefore, as the load on the engine 1 increases, if this is detected by the throttle opening signal and the discharge pressure of the vane pump 20 is controlled to increase, the amount of driving force transmitted to the rear wheels 16 in the four-wheel drive state can be reduced. It can be made to run by increasing the .

In addition, the front wheels 9 and rear wheels 16 are prevented from locking up by controlling the discharge pressure of the vane pump 20 to be increased when the brake operation detection switch detects the operating state of the foot brake and turns ON. It is possible to shorten the braking distance and obtain stable braking conditions.

Furthermore, by detecting the steering angle and controlling the discharge pressure so that the larger the steering angle becomes, the lower the discharge pressure becomes, it becomes possible to avoid the tight corner braking phenomenon and smoothly turn the vehicle. Also,
It is also possible to adjust and control the discharge pressure of the vane pump 20 according to the engine rotational speed and vehicle speed using each detection signal input to the computer to achieve a stable running condition.

Next, an embodiment in which the hydraulic control circuit 21 is different will be described based on FIG. 4.

In the four-wheel drive drive coupling device 13 of this embodiment,
The configuration of the hydraulic pump 20 is the same as that already explained, and the first oil passage 26 and the second oil passage of the hydraulic control circuit 21 are connected to each other.
A spool-type switching valve 4 is installed in place of the two check valves 31 and 32 (see FIGS. 3a and b) that are provided between the oil passage 27 and only allow outflow from each of them.
0 is set. The oil passages at both ends of this switching valve 40 communicate with the first oil passage 26 or the second oil passage 27, respectively, and also communicate with the oil reservoir 30 via check valves 28 and 29, respectively, and are switched by a spool. A discharge oil passage 41 is communicated with the intermediate portion.

In addition, a hydraulic control valve 42 may be used instead of the relief valve 33.
A spool 42 is provided with two lands.
A discharge oil passage 41 communicates between the lands of a, and a pressure regulating oil passage 43 communicates with the oil reservoir 30. The biasing force of a spring 42b acts on the left end of the spool 42a, and the orifice 3
7 and a solenoid valve 38 act on hydraulic pressure that is duty-controlled. Therefore,
Pressure regulating oil is delivered to the pressure regulating oil passage 43 and returned to the suction side due to the balance of the oil pressure from the discharge oil passage 41 due to the area difference between the two lands of the spool 42a with respect to the spring 42b and the duty-controlled oil pressure.

According to such a hydraulic control circuit 21, when the rotational speed of the first rotating shaft 11 is relatively high, if the rotor 20a rotates clockwise as explained in FIG. The first oil passage 26 is on the discharge side, and the second oil passage 27 is on the suction side. As a result, in the hydraulic control circuit 21 of FIG. 4, the discharge pressure acts on the left end face of the switching valve 40, so the spool switches to the right end, and the first oil passage 26 communicates with the discharge oil passage 41.
The discharged oil is guided to the hydraulic control valve 42, and the pressure-regulated oil is sent to the suction side via the check valve 29 and circulated.

Further, when the rotational speed of the second rotating shaft 14 is relatively high, the cam ring 20b rotates clockwise as explained in FIG. 3b, and the second oil passage 27 becomes the discharge side. The first oil passage 26 is on the suction side.

As a result, in the hydraulic control circuit shown in FIG. 4, the discharge pressure acts on the right end face of the switching valve 40, so the spool is switched to the left end, and the second oil passage 27 is connected to the discharge oil passage 41.
The discharge oil is guided to the hydraulic control valve 42,
Pressure regulating oil is sent to the suction side via the check valve 28 and circulated.

In this way, regardless of the relative rotational direction between the first rotating shaft 11 and the second rotating shaft 14, the discharge pressure is always guided to the discharge oil passage 41, and the duty control solenoid valve 38 controls the spool 42a. By adjusting the pressure, the discharge pressure of the hydraulic pump 20 can be controlled, and as already explained, it is possible to obtain a driving state according to the operating state.

Next, a four-wheel drive drive coupling device including another hydraulic control circuit 21 shown in FIG. 5 will be described.

In this embodiment, a spool valve 45 controlled by ON/OFF of a solenoid valve 44 is used instead of the switching valve 40, and a first oil passage 26 is connected between each land of a spool 45a having three lands. ,
The second oil passage 27 communicates with the oil reservoir 30 and the pressure regulating oil passage 43 of the oil pressure control valve 42 via check valves 28 and 29, respectively. Also,
The discharge oil passage 4 is opened and closed by an intermediate land.
1 is in communication with the hydraulic control valve 42.
This spool valve 45 has a spring 4 on the left end side.
5b, a solenoid valve 44 which is ON-OFF controlled is provided on the right end side upstream of the orifice 46, and a computer 39 is connected to the solenoid valve 44.

In such a hydraulic control circuit 21, the first rotating shaft 1
When the relative rotational speed of rotor 20a is high, rotor 20a
If it rotates clockwise, the first oil passage 26 will be on the discharge side and the second oil passage 27 will be on the suction side, as explained in FIG. 3a.

At this time, the rotational direction (relative rotational direction) of the hydraulic pump 20 is known from the rotational speed of the first rotational shaft 11 and the second rotational shaft 14 inputted to the computer 39, and thereby the solenoid valve 44 is turned on and the upstream of the orifice 46 is detected. With the side open, the spool 45a
The first oil passage 26 and the discharge oil passage 41 are communicated with each other with the spool 45a at the right end position by the spring 45b and the biasing force due to the area difference between the lands of the oil discharged from the first oil passage 26. The oil in this discharge oil passage 41 is
It is circulated in the same way as in the figure.

Conversely, in the case of FIG. 3b where the relative rotational speed of the second rotating shaft 14 increases and the cam ring 20b rotates clockwise, the second oil passage 27 becomes the discharge side and the first oil passage 26 becomes the suction side. Be on the side. In this case, the computer 39 turns the solenoid valve 44 OFF.
When the signal is sent, hydraulic pressure acts on the right end surface of the spool 45a, and the spool 45a moves to the left end position against the spring 45b due to the biasing force due to the area difference between the lands of the oil discharged from the second oil passage 27. By switching, the second oil passage 27 and the discharge oil passage 41 are brought into communication. The oil led to this discharge oil passage 41 is circulated in the same manner as in the case of FIG. 4.

By using the spool valve 45 whose switching is controlled by the solenoid valve 44 in this manner, it is possible to always switch between the suction port and the discharge port regardless of the relative rotational direction of the hydraulic pump 20, and the spool valve is operated reliably. be able to.

In the above embodiment, the four-wheel drive drive coupling device 1
3, a vane pump was used as the hydraulic pump, and it was explained as a balanced type with four suction and discharge ports.
Depending on the amount of driving force transmitted, it is also possible to use an unbalanced vane pump with two suction and discharge ports, and other types of hydraulic pumps, such as internal gear pumps, trochoid pumps, hypocycloid pumps, axial and radial pumps. A plunger pump or the like can also be used, as long as the amount of oil discharged changes depending on the rotational speed difference. Furthermore, the present invention is applicable not only to a type that drives the front wheels in a normal straight-ahead state but also to a type that drives the rear wheels. Furthermore, the transmission may be either manual or automatic, and control of the relief valve is not limited to duty control using hydraulic pressure, but may be mechanically controlled.

As described above in detail with the embodiments, according to the present invention, 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 are rotated according to the rotational speed difference between them. They are connected via a hydraulic pump that is driven according to the rotational speed difference and discharges an amount of oil according to the rotational speed difference, and the driving force is transmitted by the static hydraulic pressure to obtain a four-wheel drive state, and the first rotational shaft and the second rotational shaft are connected. Since the discharge port and suction port are automatically switched according to the relative rotation direction with the shaft, 4-wheel drive can be achieved without any operation, making it suitable for tight corner braking of part-time 4-wheel drive vehicles. It is possible to eliminate problems such as phenomena and the complexity of driving operations, and it can be made smaller and lighter than the center differential conventionally equipped on full-time four-wheel drive vehicles, and the structure is simple and inexpensive.

In addition, the hydraulic control circuit is equipped with a control device that controls the maximum discharge pressure of the hydraulic pump according to the vehicle's driving condition, so the maximum transmission torque capacity of the hydraulic pump can be controlled according to the vehicle's driving condition. Running becomes stable.

[Brief explanation of drawings]

1 to 3 show an embodiment of the four-wheel drive drive coupling device of the present invention, and FIG. 1 is a schematic configuration diagram;
FIG. 2 is a detailed sectional view, FIGS. 3a and 3b are illustrations of oil flow, and FIGS. 4 and 5 are sectional views of other embodiments of the present invention. In the drawing, 9 is a front wheel, 10 is a differential gear for the front wheels,
11 is a first rotating shaft, 13 is a four-wheel drive drive coupling device, 14 is a second rotating shaft, 16 is a rear wheel, 17 is a differential device for the rear wheels, 20 is a vane pump, 20a is a rotor, and 20b is a cam ring. , 21 is a hydraulic control circuit, 22, 23, 24, 25 are suction and discharge ports, 2
6, 27 are the first and second oil passages, 28, 29, 3
1 and 32 are check valves, 30 is an oil reservoir, 33 is a relief valve, 36 is a piston, 37 is an orifice, 38 and 44 are solenoid valves, 39 is a computer, 40 is a switching valve, 41 is a discharge oil path, and 42 is oil pressure The control valve 43 is a pressure regulating oil passage.

Claims (1)

[Claims] 1 A first rotating shaft that transmits driving force to the front wheels and a second rotating shaft that transmits driving force to the rear wheels are driven and rotated by the rotational speed difference between the first rotating shaft and the second rotating shaft. Hydraulic control in which the suction port and the discharge port of the hydraulic pump are switched depending on the relative rotational direction of the first rotating shaft and the second rotating shaft, while being connected via a hydraulic pump that discharges an amount of oil according to the speed difference. A drive connection for four-wheel drive, comprising: a circuit; and a control device that is interposed in the hydraulic control circuit and controls the maximum value of the discharge pressure discharged from the hydraulic pump according to the running condition of the vehicle. Device.