JPH02120135A - Four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To make improvements in drivability at time of rectilinear driving by feeding a hydraulic motor for symmetrical wheels with oil discharge in an equal manner, in a device which drives one side of both front and rear wheels through an engine via a transmission and the other through the hydraulic motor, respectively. CONSTITUTION:Front wheels 14 are rotated by motive power taken out of a transmission 11 connected to an output shaft of an engine 10, while rear wheels 15 are constituted so as to be rotated by a hydraulic motor 13 owing to discharge oil of a hydraulic pump 12 being directly driven by the engine 10. This hydraulic pump is formed into a two-throw type of a first pump 12A for combined use of power steering-four-wheel drive and a second pump 12B for 4WD exclusive use, and a selector valve 30 for 2WD and 4WD is installed at the discharge side. Then, a flow control valve 32 and a fluid flow equal distributor 33 are installed side by side in a feed passage 31 feeding the hydraulic motor 13 with pump discharge oil, and a feed flow rate to each hydraulic motor 13 of symmetrical rear wheels 15 is distributed so as to become equal parts.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a four-wheel drive vehicle that can simultaneously drive both rear wheels.

(Prior Art) Conventionally, in a four-wheel drive vehicle, one of the front and rear wheels is mechanically driven from the engine through the transmission, and at the same time, the other wheel is mechanically driven from the transmission through the propeller shaft. A device that is driven by this is now in practical use.

However, in the above-mentioned four-wheel drive vehicles, the propeller shaft must pass through the front and back of the vehicle, so a tunnel must be formed in the floor of the vehicle, which limits the leg space for the passengers and reduces comfort. However, there were many other problems, such as the need to modify the transmission for four-wheel drive. Therefore, as shown in FIG. 5, it forms a pair with a transmission 2 that changes the speed of the driving force of the engine 1 and a hydraulic pump 3 driven by the engine 1, and is operated by receiving oil discharged from the pump 3. Equipped with a pair of hydraulic motors 4.4, one of the front and rear wheels (front wheel) 5.
5 is mechanically driven via the transmission 2, and the other wheel (rear wheel) 6, 6 is driven by the pair of hydraulic motors 4.
, 4 has been proposed (see Japanese Unexamined Patent Publication No. 74222/1983).

(Problem to be Solved by the Invention) In the above four-wheel drive vehicle, the oil discharged from the hydraulic pump 3 is distributed to the pair of hydraulic motors 4.4 by the distributor 8, and a large amount of oil is distributed to the low-load side of the hydraulic motors 4.4. However, since a small amount of oil is distributed to the high-load side, effective differential control can be obtained when the vehicle turns.

In other words, when turning, the load on the inner wheel from the road surface is greater than that on the outer wheel, so a larger amount of hydraulic pressure is supplied to the hydraulic motor on the outer wheel, which has a smaller load, than the inner wheel, which has a higher load, and as a result, the outer wheel receives more power than the inner wheel. rotates quickly and performs differential function.

However, when traveling straight, if one wheel is in a no-load state due to no contact with the ground or an extreme slip, in the above-mentioned equal hydraulic distribution system, most of the discharged oil is supplied to the hydraulic motor of this one wheel, and the other There was a problem with one wheel not being driven, resulting in reduced drive performance.

The present invention has been made in order to solve the above problem, and is a method for distributing discharged oil to the left and right hydraulic motors in a four-wheel drive vehicle in which one of the wheels is driven by a hydraulic motor as described above. The purpose of this is to improve drivability when driving straight.

(Means for Solving the Problems) Therefore, the present invention provides a pair of left and right wheels that operate by receiving oil discharged from a transmission connected to the output shaft of the engine and a hydraulic pump directly driven by the engine. The vehicle is equipped with a hydraulic motor, and one of the rear wheels is mechanically driven via the transmission, the left wheel of the other wheel is driven by a left wheel hydraulic motor, and the right wheel is driven by a right wheel hydraulic motor. In a four-wheel drive vehicle configured to be hydraulically driven by a hydraulic motor, the hydraulic motor for the right wheel is provided with a fluid flow rate distributing means that equally divides and supplies the discharged oil to the right wheel hydraulic motor. It is characterized by:

(Operations and Effects of the Invention) The present invention is configured to supply an equal amount of oil to each of the hydraulic motors of the left and right wheels using the fluid flow equal distribution means, so that the hydraulic motors of the left and right wheels can be driven by a pair of hydraulic motors. Even if one of the wheels is in a no-load state, the same amount of oil is supplied to the hydraulic motor of this one wheel and the hydraulic motor of the other wheel, so the discharge amount will be reduced. There is no fear that almost the entire amount will be supplied to one wheel, and the other wheel can be reliably driven, so even in the above case, driveability can be ensured.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, a four-wheel drive vehicle has a transmission 11 connected to the output shaft of an engine 10, a hydraulic pump 12 directly driven by the engine 10, and operates by receiving oil discharged from the pump 12. A pair of hydraulic motors 1
3 and 13, the front wheels 14.14 are mechanically driven via the transmission 11, and the left and right rear wheels 15.1
5 are hydraulically driven via the respective hydraulic motors I3.13.

A power steering cylinder 17 is connected to the front wheels 14, 14, and the cylinder 17 is provided with a control valve 18. The control valve 18 is connected to the hydraulic pump 12 to discharge oil from the hydraulic pump 12. As a result, the cylinder 17 is actuated, and the operating force of the handle 19 is reduced.

The hydraulic pump 12 is connected to the output pulley 10 of the engine IO.
a and the input pulley 12a of the hydraulic pump 12 are connected to the belt 20.
It is directly connected to the engine 10 and driven by the engine 10. In other words, it is not driven via the transmission 11.

The hydraulic pump 12 includes a first pump 12A for both power steering and four-wheel drive, and a second pump 1 for four-wheel drive.
2B is configured in two series.

2 for the above hydraulic pump 12 (+2A, 12B)
A switching valve 30 between wheel drive and four-wheel drive is provided.

When switching to four-wheel drive (4WD) as shown in FIG. The fluid flow is equally distributed to the rear wheel 15, 15 side by the distributor 33.
．． By equally distributing the flow to each of the 15 hydraulic motors 13, 13, each hydraulic motor I3.13 rotates the left and right rear wheels 15.15.

Although not specifically shown, the fluid flow rate equal distribution divider 33 also applies to the hydraulic motor 13 of this single wheel even if one of the left and right rear wheels 15 and 15 is in a no-load state when traveling straight. It has a known configuration that has the characteristic of supplying the same amount of oil to the other single-wheel hydraulic motor.

Each of the hydraulic motors 13, 13 is provided with a reducer 34, 34 including a one-way clutch. A planetary gear type reducer 34 is provided between the hydraulic motor 13 and the rear wheel 15.
Sun gear 4 integrally provided on the outer periphery of casing 44 of
5, and a plurality of binions 46 that mesh with the sun gear 45 and perform planetary rotation. ..., 46, and the pinion 46. ..., output pinion 4 that rotates integrally with 46
A ring gear 48 is meshed with 7, . . . , 47,
A one-way clutch 50 is interposed between the ring gear 48 and the axle 49 of the rear wheel 15.

This one-way clutch 50 transmits the rotational force of the ring gear 48 to the axle 49, and also transmits the rotational force of the ring gear 48 to the axle 49.
This is a known configuration that allows the rear wheel I5 to rotate freely when the rear wheel I5 rotates faster than the ring gear 48.

To explain more specifically, in the structure of the present invention which equally distributes the amount of oil to the left and right hydraulic motors 13, 13, the left and right rear wheels normally rotate at a constant speed, but for example, when turning As in time, the loads on the left and right rear wheels 15.15 are different, and the outer wheel rotates faster than the inner wheel.

In such a case, the one-way clutch 50 allows the outer ring to rotate freely and ensure turning performance.

As shown in FIG. 4, the reducer 34 is arranged in the wheel space, and the brake 55 (brake drum 56, brake shoe 57, piston 58) is attached to the output shaft 59 of the hydraulic motor 13. It becomes possible to downsize and shorten the axial dimension.

The discharge oil supplied to each of the above hydraulic motors 3.13 is:
It is returned to the reserve tank 36 through the return passage 35.

When the steering wheel 19 is operated during this four-wheel drive, discharge oil is supplied from the branch passage 37 of the flow control valve 32 to the power steering cylinder 17 via the check valve 38 and the control valve 18, and the operation of the cylinder 17 causes the steering wheel to move. ! 9's operating force is reduced. Note that 39 is a reserve tank for power steering.

In addition, FIG. 2 shows the switching valve 30 in two-wheel drive (2WD) mode.
) side.

In this state, the supply passage 31 to the rear wheel side is connected to the first and second supply passages.
Pumps +2A and 12B are shut off, and the second pump 1
The oil discharged from the pump 2B is returned to the reserve tank 36, while the oil discharged from the first pump 12A is sent from the branch passage 40 to the power steering cylinder 17 via the control valve 18.
is supplied to the cylinder 1, and when the handle 19 is operated, the cylinder 1
7, the operating force of the handle 19 is reduced.

On the other hand, controller (in-vehicle microcomputer) 4
2 is provided, and the controller 42 has engine speed NE, steering angle, vehicle speed, 4WD/2
By inputting input information such as a drive selection signal, it is possible to switch the switching valve 30 between the 4-wheel drive position and the 2-wheel drive position, and to control the amount of oil discharged from the flow control valve 32 to the rear wheels 15 and 15 ( control of flow rate) is executed.

The flow rate control valve 32 is controlled by the controller 4 when traveling straight.
Calculate the front wheel rotation speed (NF) and rear wheel rotation speed (NR) from the various manual input information in step 2, and calculate these front and rear wheel rotation speeds N.
Based on F and NR, the flow rate is controlled so that the front and rear wheels 14.15 rotate synchronously.

The first method for detecting the front wheel rotation speed (NF) and rear wheel rotation speed (NR) is to install rotation sensors on the front wheels 14 and rear wheels 15 and directly detect the front wheel rotation speed (NF). Rear wheel rotation speed (NR) using speedometer signal
The second method uses the engine rotational speed (NE) signal to detect, the front wheel rotational speed (NF) is detected using a speedometer, and the rear wheel rotational speed (NR) is detected using the rear wheels! There is a third method using a flow rate signal to 5, etc.

In addition, to explain the second method a little further, when q: pump-specific discharge amount, qM: motor-specific discharge amount, α: constant, rear wheel rotation speed NR is NR due to the oil amount relationship. =
Since it is expressed as qp/QM-NB·α, the rear wheel rotation speed (NR) can be calculated by detecting the engine rotation speed NE.

In addition, when turning, the flow rate control valve 32 is controlled based on the steering angle of the steering wheel 19 and vehicle speed signals that are input to the controller 42, and the front and rear wheel rotational speeds NF and NR that are directly input or calculated. , the flow rate is controlled to differentially rotate the front and rear wheels 14,15.

With the above configuration, the equal amount of oil is supplied to each hydraulic motor I3.13 of the left and right rear wheels 15°15 by the fluid flow rate equalizer 33, so when traveling straight, one wheel is Even in a no-load state, this single-wheel hydraulic motor 13
Since the same amount of oil is also supplied to the hydraulic motor 13 of the other one wheel, an accident in which the other one wheel is no longer driven does not occur.

Therefore, drivability when traveling straight is improved.

Furthermore, when turning, the outer wheels of the left and right rear wheels 15.15 rotate faster than the inner wheels, but since the one-way clutch 50 allows the outer wheels to rotate freely, the rotation is differentially controlled, and turning stability is also improved. .

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a four-wheel drive vehicle according to the present invention when the vehicle is in four-wheel drive mode, FIG. 2 is a configuration diagram when it is in two-wheel drive mode, FIG. 3 is a front view of the main parts of FIG. Vertical cross-sectional view of the hydraulic motor and reducer, No. 5
The figure is a configuration diagram of a conventional four-wheel drive vehicle. IO...Engine, 11...Transmission, I
2...Hydraulic pump, 13...Hydraulic motor, I4...
・Front wheel, I5... Rear wheel, 20... Belt, 30...
・Switching valve, 33...Distributor (fluid flow rate distribution means), 34...Reducer, 45...Sun gear, 46
...Pinion, 48...Ring gear, 49...Axle, 50...One-way clutch. Figure 5 Patent applicant Mazda Motor Corporation

Claims (1)

[Claims] (1) Equipped with a transmission connected to the output shaft of the engine and a pair of hydraulic motors for left and right wheels that operate by receiving oil discharged from a hydraulic pump directly driven by the engine, one of the front and rear wheels. The four wheels are configured to mechanically drive the wheels of the other wheel through the transmission, and the left wheel of the other wheel is hydraulically driven through the left wheel hydraulic motor, and the right wheel is hydraulically driven through the right wheel hydraulic motor. A four-wheel drive vehicle, characterized in that the left and right wheel hydraulic motors are provided with fluid flow rate distribution means that equally divides and supplies the amount of discharged oil.