JPH03217333A - Transmission for four-wheel drive car - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a transmission for a four-wheel drive vehicle.

(Prior Art) A four-wheel drive (4WD) vehicle, in which all four front and rear tires of the vehicle have driving force, has a running ability that is incomparable to a two-wheel drive vehicle. Such four-wheel drive vehicles have traditionally been used for cross-country vehicles, but have recently been adopted for passenger cars as well.

There are two types of four-wheel drive: one that is always four-wheel drive (full-time type) and one that applies drive to all four wheels when it is necessary to drive only two wheels (part-time type). There is one that uses a differential (hereinafter referred to as a "center differential") and a viscous coupling as its differential limiting mechanism.

A four-wheel drive system that uses this method is shown in Figure 6.
Transmission 2 connected to the output shaft of engine l
The output (power) is transferred to the front wheel drive shaft 6 by the bevel gear type (4 pinion) center differential 4 of the transfer 3.
, the driving force of the front wheel drive shaft 6 is transmitted to the left and right front wheels 13, 13 via the front differential 7 lateral 8 and the left and right drive shafts 9, 9,
The driving force of the rear wheel drive shaft 7 is transmitted to the left and right rear wheels 14, 14 via the propeller shaft 1O, the rear differential 11, and the left and right drive shafts 12, 12.

The viscous coupling 5 is interposed between the rear wheel drive shafts 6 and 7 in front of the center differential 4, and when a difference in rotational speed occurs between these two shafts, it transmits a large torque corresponding to the difference. to limit the differential of the center differential 4. In other words, the viscous coupling 5 has an appropriate torque transmission characteristic, and the center
While making full use of the advantages of full-time 4WD with four differentials, it limits the differential movement of the center differential under adverse conditions to the extent that tight corner braking phenomena do not occur.

(Problem to be solved by the invention) By the way, in motor sports that involve handbraking, turning, etc., the four wheels are directly connected to each other to produce an extremely powerful driving force at the time of starting, and after that, only the rear wheels are directly connected to the rear wheels, which is rear wheel drive. A very responsive transmission is desirable.

However, with normal four-wheel drive using a viscous coupling, the driving force is insufficient on rough roads compared to direct-coupled four-wheel drive.・Difficulty making turns. In particular, with a transmission that has a compact and dense structure, the front wheel drive shaft quickly disconnects after starting and becomes non-directly connected, and when the accelerator is depressed, it quickly connects (directly connects). It is difficult to put into practical use a transmission suitable for motor sports that can perform handbrakes, turns, etc.

The present invention has been made in view of the above points, and an object of the present invention is to provide a transmission for a four-wheel drive vehicle that is compact and suitable for motor sports vehicles.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a transmission for a four-wheel drive vehicle that includes a transfer that distributes power between the front wheels and the rear wheels. A one-way clutch connects the front wheel drive shaft directly to the rear wheel drive shaft when the rotation is slower than the rear wheel rotation, and does not directly connect the front wheel drive shaft when the front wheel rotation is faster than the rear wheel rotation, and a one-way clutch is provided between the front and rear wheel drive shafts. The structure includes a differential limiting mechanism that is interposed and absorbs the difference in rotational speed between the front and rear wheels when these drive shafts are directly connected.

(Operation) A one-way clutch is used to generate four-wheel drive by directly connecting the front wheel drive shaft to the rear wheel drive shaft when the front wheels rotate slower than the rear wheels, such as when starting suddenly. possible. When the front wheels are not driven, such as during coasting rotation, where the front wheels rotate faster than the rear wheels, the front wheel drive shaft is separated from the rear wheel drive shaft so that they are not directly connected, resulting in rear wheel drive (two-wheel drive). The one-way clutch has extremely fast on/off response, and connects the front wheel drive shaft directly to the rear wheel drive shaft.
Quickly switch non-direct connections. In addition, the differential limiting mechanism is
It absorbs the difference in rotation speed between the front and rear wheels that occurs during four-wheel drive.

(Example) An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

Incidentally, the same elements as those shown in FIG. 6 are given the same reference numerals and detailed explanations will be omitted.

In FIG. 1, the transfer 30 is interposed between the output shaft 21 of the transmission 2, the front wheel drive shaft 6, and the rear wheel drive shaft 7, and the front wheel drive shaft 6 has a front side as shown in FIG. It is pivotally supported by the casing 20 of the transmission 2 by bearings l5, l5. The casing 3l of the transfer 30 is fitted onto the front wheel drive shaft 6, and the outer peripheral surface at both ends thereof is connected to the casing 20 by bearings 32, 32, and the inner peripheral surface is connected to the rear outer periphery of the front wheel drive shaft 6 by bearings 33, 33. It is pivoted on a surface. The rear wheel drive shaft 7 passes through the front wheel drive shaft 6 and the inside of the casing 3l of the transfer 30, and its approximate center is pivotally supported by one end of the front wheel drive shaft 6 via a bearing l6, and its rear end is attached to the rear end of the casing 3l. 31a is spline-fitted.

As a result, the casing 31 of the transfer shaft 30 is connected to the casing 20 of the front wheel drive shaft 6 and the transmission 2.
The rear wheel drive shaft 7 is rotatably supported by the front wheel drive shaft 6 and rotatable integrally with the casing 3l of the transfer 30. The driving force of the front wheel drive shaft 6 is transmitted to the front differential 8 (Fig. 1) via the gear 6a provided at the front end, and the driving force of the rear wheel drive shaft 7 is transmitted to the front differential 8 (FIG. 1) via the gear 6a provided at the front end. It is transmitted to the rear differential 11 via the propeller shaft IO.

A four-wheel drive high-speed range gear 34 is externally fitted and fixed to the front end of the outer peripheral surface of the casing 3l of the transfer 30, and a four-wheel drive low-speed range gear 35 is externally fitted and fixed to the rear end, and a sleeve 36 is spline-fitted to the center of the gear. It is possible to selectively engage with either 34 or 35. Gya 34, 3
5 meshes with drive gears 22 and 23 fixed to the output shaft 2l of the transmission 2. Further, the sleeve 36 is connected to a transfer lever (not shown).

The transfer 30 includes two one-way clutches 37 and 38
and a differential limiting mechanism 39, the one-way clutch 37 is externally fitted and fixed to the inner ring 37a (FIG. 3) or the front wheel drive shaft 6, and the outer ring 37b is fixed to the casing 3 of the transfer 30.
It is fixed inside the l. Similarly to the one-way clutch 37, the one-way clutch 38 has an inner ring externally fitted and fixed to the front wheel drive shaft 6, and an outer ring internally fitted and fixed to the casing 31. These one-way clutches 37 and 38 directly connect the front wheel drive shaft 6 and the casing 3l (clutch-on) when the front wheels l3 and l3 rotate slower than the rear wheels 14 and l4, and when the front wheels rotate faster and are not driven. Drive shaft 6 and casing 3l
It is installed so that it is not directly connected (clutch off). Incidentally, the one-way clutches 37 and 38 are arranged in pairs in order to obtain a large torque capacity.

The differential limiting mechanism 39 is composed of, for example, a friction plate containing a disc spring. The annular friction plates 40 and 41 are arranged alternately, and the inner peripheral surface of each friction plate 40 is aligned with the front wheel drive shaft 6.
The front wheel drive shaft 6 is fitted onto the front wheel drive shaft 6 with a slight gap between the outer circumferential surface and the outer circumferential surface of the casing 3l, and the outer circumferential surface is spline-fitted to the inner circumferential surface of the casing 3l.

Further, each friction plate 4l has an outer circumferential surface fitted into the casing 31 with a slight gap between the outer circumferential surface and the inner circumferential surface of the casing 31, and an inner circumferential surface spline-fitted to the outer circumferential surface of the front wheel drive shaft 6. ing.

A plurality of annular disc springs 43 are compressed between an annular pressing member 44 that contacts the friction plate 40 on one side and a stopper 45 that is disposed between the front wheel drive shaft 6 and the casing 3l. , the front wheel drive shaft 6 and the rear wheel drive shaft 7 are always connected by pressing the friction plates 40 and 41 together with a predetermined spring force.

The action will be explained below.

Now, the vehicle is stopped, and the transfer lever is operated in the four-wheel drive high-speed range (4), and the sleeve 36 of the transfer 30 shown in FIG.
Suppose that it meshes with When the accelerator is depressed to start the vehicle, the output of the engine l is transferred from the gear 22 of the output shaft 21 of the transmission 2 to the case song 3l.
is transmitted to. The driving force transmitted to the casing 31 is directly transmitted to the rear wheel drive shaft 7. Also, when starting, the front wheel I
The rotational speed N, of the wheels 3 and 13 is in a driving state that is slower than the rotational speed N, of the rear wheels (Nr<N.), and the one-way clutch 37,
38, the clutch is rapidly turned on to a high torque state as shown in FIG. That is, the front wheel drive shaft 6 is directly connected to the rear wheel drive shaft 7 immediately upon starting, and the driving force is also transmitted to the front wheel drive shaft 6. As a result, the vehicle becomes four-wheel drive, providing powerful driving force.

After starting, the difference in rotation between the front wheel 13 and the rear wheel l4 decreases (
As N r″=.Nu), the one-way clutches 37, 38
As shown in FIG. 5, the casing 3l, that is, the rear wheel drive shaft 7 and the front wheel drive shaft 6 are directly connected in a light torque state.

When the front wheel l3 rotates faster than the rear wheel l4, such as during coasting rotation (NF > Nl), the one-way clutches 37 and 38 are not directly connected (clutch off), and only the rear wheels 14 and l4 are engaged. It is rear-wheel drive. This makes it easier to perform handbrake turns, increase brake distribution to the rear wheels 14 and I4, brake turns, etc., and is suitable for motor sports.

If the road becomes extremely rough while driving in the four-wheel drive high-speed range, when the transfer lever is switched to the four-wheel drive low-speed range, the sleeve 39 of the transfer 30 moves to the right in FIG. 35 to obtain stronger driving force.

(Effects of the Invention) As explained above, according to the present invention, in a transmission for a four-wheel drive vehicle equipped with a transfer that distributes power between the front wheels and the rear wheels, the transfer has the advantage that the rotation of the front wheels is the rotation of the rear wheels. A one-way clutch that connects the front wheel drive shaft directly to the rear wheel drive shaft when the front wheel rotation is faster than the rear wheel rotation, and not directly connects the front wheel drive shaft when the front wheel rotation is faster than the rear wheel rotation; The structure is equipped with a differential limiting mechanism that absorbs the difference in rotation speed between the front and rear wheels when the front and rear wheels are directly connected, so it is possible to obtain strong driving force as a four-wheel drive when starting, etc., and after starting. The transmission can be rear-wheel drive, making it possible to configure a four-wheel drive transmission suitable for motor sports, etc., and improving power performance. Moreover, it has excellent effects such as being able to be incorporated into a conventional compact and high-density four-wheel drive transmission.

4.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a power transmission system of a four-wheel drive vehicle to which a four-wheel drive vehicle transmission according to the present invention is applied, and FIG. 2 is a diagram showing a power transmission system according to the present invention incorporated in the transmission of FIG. FIG. 3 is an enlarged view of the main parts of the one-way clutch shown in FIG. 2, FIGS. 4 and 5 are views showing the action of the one-way clutch shown in FIG. 3, FIG. 6 is a diagram showing a power transmission system of a four-wheel drive vehicle using a conventional transmission. l...Engine, 2...Transmission, 6.
...Front wheel drive shaft, 7...Rear wheel drive shaft, 8...Front differential, 1l...Rear differential, l3...Front wheel, l4...
...Rear wheel, 20, 3l...Casing, 30...Transfer, 34, 35...Gear, 36...Sleeve, 37, 38...One-way clutch, 39...Differential restriction Mechanism, 40, 4l...friction plate, 43...disc spring.

Claims (1)

[Claims] In a transmission for a four-wheel drive vehicle equipped with a transfer that distributes power between front wheels and rear wheels, the transfer directly connects the front wheel drive shaft to the rear wheel drive shaft when the rotation of the front wheels is slower than the rotation of the rear wheels; A one-way clutch that disconnects directly when the front wheels rotate faster than the rear wheels,
A transmission for a four-wheel drive vehicle, comprising a differential limiting mechanism that is interposed between the drive shafts of the front and rear wheels and absorbs a difference in rotational speed between the front and rear wheels when these drive shafts are directly connected.