JPH01160731A - Engine control device in four-wheel drive car - Google Patents

Abstract

PURPOSE:To reduce a shock at changing over the state of a center differential gear by reducing an engine output at reversibly changing over the free and locked states of the center differential gear. CONSTITUTION:A control unit U supplies actuators M1, M2, M3 and solenoids SL1-SL4 with an output. The solenoid SL1 is to engage and to disengage a lock up clutch, and the solenoids SL2-SL4 are to perform the speed changing of a main gear shifter MT according to their combined excitation and demagnetization. The actuator M2 is selected to properly regulate an engine output, which is therefore reduced at reversibly changing over the locked and free states of the center differential gear.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is four-wheel drive! This relates to an engine control device in li.

(Prior Art) Recently, there are many four-wheel drive vehicles in which both front wheels and rear wheels are driven. Some of these four-wheel drive vehicles are capable of selectively switching between two-wheel drive and four-wheel drive, and this is achieved by reducing engine output when switching between two-wheel drive and four-wheel drive. There is a device designed to reduce the shock at the time of switching (see, for example, Japanese Utility Model Application Publication No. 147524/1983).

On the other hand, there is a tendency for an increasing number of four-wheel drive RATs to be equipped with a center differential for absorbing the difference in rotation between the front wheels and the rear wheels. Furthermore, in a four-wheel drive vehicle that uses such a center differential, a locking mechanism is provided to lock the center differential, and the center differential is locked when either the front wheels or the rear wheels are spinning. Due to this, there are many models that can effectively transmit power to the other lj wheel that does not spin (for example, Japanese Patent Application Laid-Open No. 1983-1999)
(See Publication No. 70238).

(Problems to be Solved by the Invention) By the way, in a four-wheel drive vehicle equipped with a center differential and a locking mechanism for locking the center differential, when the locking mechanism is switched, that is, the center differential is in a free state and a locked state. When switching between the two, a rather large shock occurs, which is a cause for concern.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an engine control device for a four-wheel drive vehicle that can reduce shock when a center differential is switched between a free state and a locked state.

(Means and operations for solving the problem) In order to achieve the above-mentioned object, in the present invention, the engine output is reduced when the center differential is switched between the free state and the locked state. in particular.

In a four-wheel drive 1F equipped with a locking mechanism for locking a center differential interposed between front wheels and rear wheels, when the locking mechanism switches the center differential between a locked state and a free state, This configuration includes an output reduction means for reducing engine output.

(Example) Examples of the present invention will be described below based on the attached drawings.

In Figure 1, '(, E is an engine, and its output (power) is a torque converter with a lock-up clutch 0,
It is transmitted to the transfer TF via the main transmission M T and the sub-transmission ST. This transfer TF is 2
Equipped with a switching mechanism for selectively switching between wheel drive and four-wheel drive, when four-wheel drive is selected, power is transmitted to the rear wheels via the rear-wheel drive shaft 2, and the front-wheel drive shaft: 3 is transmitted to the rear wheels. power is transmitted to the front wheels through the Further, when selecting two-wheel drive, power is transmitted only to the rear wheels via the rear wheel drive shaft 2.

The details of the sub-transmission device S'" and the transfer I"F section will be explained with reference to FIG. In FIG. 2, 1 is a human power shaft, and the engine output after passing through the main transmission device MT is input to this human power shaft 1. On this human power shaft l and the rear wheel drive shaft 2, there is a sub-transmission ST and a center differential 5, which will be described later, and a first switching mechanism 6 and a second switching mechanism for switching thereon.
A switching mechanism 7 is arranged respectively.

The sub-transmission device S selectively switches the rotation transmitted to the input shaft 1 into two stages, high and low.
It is a device that transmits information to the side, and is composed of a planetary gear mechanism. Specifically, the first ring gear 26 fixed to the casing 28 side, the first sun gear 24 attached to the first intermediate shaft 81 with zero relative rotation ability, and the first ring gear 26 fixed to the casing 28 side.
A first pinion gear 25 is attached to a first carrier 27 fixed to the intermediate shaft 8.

The torque transmission path of this sub-transmission device ST is switched to the axially outward side of this sub-transmission device S'r (toward the human power shaft 1 side)]
The first switching mechanism 6 described above is provided. This first
The switching mechanism 6 is composed of a sleeve gear type switching mechanism, and includes a first switching gear 21 formed on the human power shaft l, a second switching gear 22 spline-engaged with the first carrier 27, and - 1-2 Third sun gear formed on first sun gear 24
It includes a switching gear 23 and a first sleeve gear 29 that selectively meshes with these three switching gears 21, 22, and 23 by being slid in the axial direction of the switching gear 23. According to this first switching mechanism 6, as shown in FIG.
In the state in which it meshes with the switching gear 22, the same rotation of the human power shaft 1 is transmitted as it is to the first carrier 27 without being decelerated, and is outputted from the first carrier 27 to the center differential device 5, which will be described later. In other words, a high speed gear is established (pattern a).

In response, the first sleeve gear 29 moves rightward (toward the sub-transmission device ST side) from the state shown in FIG.
1 and the third switching gear 23, and in the state in which the second switching gear 22 is meshed, the rotation of the input shaft l is as follows.
The signal is transmitted to the first sun gear 24 of the sub-transmission device S'F, and further transmitted from the first sun gear 24 to the first ring gear 26 via the first pinion gear 25. Therefore, the rotation of the human power shaft 1 is decelerated and output from the first gear A/rear 27 to the center differential 5 side. That is, a sun gear human power/carrier output type planetary gear is configured, and thereby a low speed gear is configured (pattern b).

The center differential is for differential operation between the rear wheel drive shaft 2 and the front wheel drive shaft 3, and is constructed of a planetary gear mechanism similar to the sub-transmission device S'F described in . ing. Specifically, a second sun gear 35 formed on the rear wheel drive shaft 2, a second ring gear 37 formed integrally with the first carrier 27 of the second sub-transmission ST, and a third intermediate shaft IO and a second pinion gear 36 fixed to a second carrier 38 integrally formed with the second carrier 38.

Further, on the axially outward side of the center differential 5, there is provided a mechanism for controlling the differential operation between the rear wheel drive shaft 2 and the front wheel drive shaft 3 by switching the torque transmission path of the center differential 5. (hereinafter simply referred to as 2WD) and four-wheel drive (hereinafter simply referred to as 4WD) is provided with the aforementioned second switching mechanism 7. That is, the second switching mechanism 7 includes a fourth switching gear 31 that is spline-engaged with the rear wheel drive shaft 2, a fifth switching gear 32 that is spline-engaged with the third intermediate shaft 10, and the fourth switching gear 31 that is spline-engaged with the rear drive shaft 2; 3 intermediate shaft 10
A sixth switching gear 33 is formed integrally with the fourth intermediate shaft 1N, which is relatively rotatably engaged with the outside of the switching gear 33, and these three switching gears 31, 32 are slidably displaced in the axial direction.
33, and a second sleeve gear 34 that selectively meshes with the second sleeve gear 33. Further, a front side drive gear 41 is formed on the fourth intermediate shaft It, and further, this front side drive gear 41 is connected via a chain 15 to a front side driven gear 42 attached to the L2 front wheel drive shaft 3 side. .

There are three switching patterns of the second switching mechanism 7, Δ, B, and C. First, the pattern Δ is the switching pattern of the fourth switching gear 3 by the second sleeve gear 34 as shown in FIG. and the fifth switching gear 32 are coupled, and the sixth switching gear 33 is in a free state. In this pattern 8, the second of center differential 5
Since the sun gear 35 and the second pinion gear 36 are integrated, the rotation of the second ring gear 37 is directly transmitted only to the rear wheel drive shaft 2 side, thereby realizing a 2WD state.

Pattern B is the second sleeve gear 3 as shown in FIG.
4, the fifth switching gear 32 and the sixth switching gear 33 are coupled, and the fourth switching gear 31 is in a free state. In this pattern B.

Because the fourth intermediate shaft II and the third intermediate shaft 10 are combined,
WD state is realized. At the same time, the center differential 5 is in a free state.

A differential operation is performed between the rear wheel drive shaft 2 and the front wheel drive shaft 3.

Pattern C is the second sleeve gear 3 as shown in FIG.
4, the fourth switching gear 31, the fifth switching gear 32 and the sixth switching gear
This is a state in which the main parts of the switching gears 33 are integrally connected.

In this pattern C, the fourth intermediate axis and the third intermediate axis 1
0 is coupled, a 4WD state is realized, and at the same time, the center differential 5 is locked from the point where the rear wheel drive shaft 2 and the third intermediate shaft 10 are coupled, and the rear wheel drive shaft 2 and the front wheel drive are coupled. No differential operation is performed between the shaft 3 and the shaft 3.

In the power transmission device Z configured in this manner, four operating patterns as shown in the robe can be obtained by selecting the switching patterns of the first switching mechanism 6 and the second switching mechanism 7 described above.

Although not shown, a remote freewheel is provided on the front wheel drive shaft for controlling the rotation of the drive path on the driven wheel (front wheel) side by 1τl in the 2WD state.

(The following is a blank space) FIG. 5 shows the second switching mechanism 7 1111 and an electromagnetic actuator (for example, a step motor, a DC motor, etc.) M+ for driving the second switching mechanism 7.

In this FIG. 5, 61 is a screw shaft rotated by the actuator Ml, and a threaded portion 61a of this screw shaft 61.
A threaded sleeve 62 is screwed onto the sleeve. A shift fork f32a is protruded from this threaded sleeve 62, and this shift fork 62a is engaged with the 1111 sleeve gear 34 so as not to move in its axial direction. In accordance with the rotation of the actuator Ml, the locking sleeve 62 is moved left and right in the figure, and the four operating patterns shown in the table mentioned above, first to fourth, can be selected.

Then, the current position of the pattern is detected by a sensor SNI that detects the rotational position of the rotation shaft 61. In FIG. 5, in order to smoothly engage gears 31 and 33 via sleeve gear 34, synchronizer key 51. Engagement amount with 52 exclusive synchronizer rings! A g1 device is provided.

Again in FIG. 1, reference numeral [) is a control unit configured by, for example, a microcomputer, and this control unit U receives signals from the sensors or switches SNI to SN4 and SWI in addition to the output signals from the sensor SN, 1. is input. The mud sensors SN2 to SN4 are used for speed change control (lock-up control), SNI is for detecting [II speed], SN3 is for detecting accelerator opening, and SN4 is for detecting the main transmission. This detects the current gear position of the MT. In addition, switch SW1
is for manually selecting the four operation patterns No. 1 to No. 4 in the table described above.

On the other hand, from the control unit U, the actuator M1
In addition to being output to solenoid S Ll-3L4 and actuators M2 and M3. Solenoid S L 1 turns the lock-up clutch ON and OFF.
In addition, SL2 to SL4 are used to control the transmission MT according to the combination of excitation and demagnetization.
It is used to change gears. Of course, these nodes SL, 1 to S14 are incorporated in the shifting (lockup) hydraulic circuit of the L transmission MT including the torque converter C, and are connected to the hydraulic friction elements for shifting (lockup). This is for switching the operation. Furthermore, the actuator M2 described in (h) is for adjusting, particularly reducing, the engine output, and an appropriate actuator for adjusting the engine output may be selected. For example, intake air (throttle actuator, which drives the throttle valve that adjusts ii in the closing direction, and igniter, which adjusts the ignition timing)
It is said that Of course, in order to reduce the engine output, other appropriate methods such as reducing the fuel supply capacity may be adopted.

Although not shown in the figure, II + of the sub-shift adjustment S'r.

1. Regarding the actuator for OW switching (for operating the first switching mechanism 6), for example, the one shown in Fig. 5 (M
2.61.62 etc.), and the actuator for this is designated by the symbol St M in Fig. 1.
It is shown as 3.

Next, the control contents of the control unit U will be explained with reference to the flowchart shown in FIG. Note that in the following explanation, [) indicates a step.

First, at l' I, each sensor or switch S
W1. After the output signals from SNI to SN4 are read,
1-) In step 2, shift (lockup) control is performed. This shift (lockup) control is performed in a known manner based on shift characteristics (lockup characteristics) created using heavy speed and accelerator opening as parameters.

After P2, it is determined through the determination processes I)3 to P5 which of the first to fourth operation patterns the driver has selected using the switch SWt. If all of the determinations in [13 to l)5 are NO, it means that the first to third operation patterns are not selected, and the fourth operation pattern is selected after all. At this time, in P6, it is determined by checking the output of the sensor SNI whether or not the fourth operation pattern is currently set. With this P6 determination, Y I′:, S
When , the operation pattern requested by the driver and the current (actual) operation pattern match, so
It will be returned as is. On the other hand, when the determination in l)6 is NO, the engine output is reduced in P7, and a switching signal is output to the actuator M1 in P8, thereby realizing the fourth operation pattern.

When the determination in 1)5 is YES, the processing from F)9 onwards is obtained. This I) Processing after 9, that is, P9, r'
The meaning of lo and pH is 1t1 mentioned 1)6~
1) Since it is the same as 8, the duplicate explanation will be omitted.

This corresponds to 1) 1 when NO is determined in P4.
The same is true for the processes after 2 (PI3, P 1:3, PI3), and the processes after 1] 15 (PI3, PI3.P2O) when the determination is NO in P3. When the engine is switched, the engine output is reduced during this switching to prevent shock associated with the switching.

Below 1. Although one embodiment has been described, the present invention is not limited to this, and includes, for example, the following case.

(1) The vehicle in four-wheel drive may be a so-called full-time four-wheel drive vehicle in which two-wheel drive cannot be selected. In addition, if it is possible to select between two-wheel drive and four-wheel drive, the vehicle may be of a type in which only the front wheels are driven during two-wheel drive.

■The center differential is not limited to the planetary gear type, but may also be one using a viscous coupling or any other appropriate type.

■Among the four operating patterns 1st to 4th, only when switching between the free state and locked state of the center differential is performed, especially in the case where the switching is most likely to occur frequently. The engine output may be reduced only between the second and third operating patterns.

■When the auxiliary transmission ST can be used in any way. (Effect of the invention) As will be clear from the description hereinafter, the present invention is as follows.

The shock caused when the center differential is switched between the free state and the locked state can be reduced, and this switching can be performed smoothly.

[Brief explanation of the drawing]

FIG. 1 is an overall system diagram showing one embodiment of the present invention. Fig. 2 is a skeleton diagram showing an example of a power transmission system for a four-wheel drive 11. Figs. 3 and 4 show switching between two-wheel drive and four-wheel drive, and switching between a free state and a locked state of the center differential. A skeleton diagram of the main parts showing the different operating states of the switching mechanism. Figure 5 shows a specific example of the switching mechanism that switches between 2-wheel drive and 4-wheel drive and switches between the free state and locked state of the center differential, and shows the actuator for its operation. 6 is a flowchart showing a control example of the present invention. EN: Engine C: Torque converter MT: l:, Transmission S i': Sub-transmission TF: Transfer 1: Input shaft 2: Rear wheel Drive shaft: 3 Two front wheel drive shafts 5: Center differential 6: First switching mechanism (for sub-shift) 7: Second switching mechanism (for 2-wheel drive/4-wheel drive and lock/free state switching) 31.32, ;33: Switching gear 34 Ni sleeve gear 61: Rotating shaft 61a: Threaded portion 62: Threaded sleeve 62a: Shift fork Ml: Actuator SWI: Changeover switch

Claims (1)

[Claims] (1) In a four-wheel drive vehicle equipped with a locking mechanism for locking a center differential interposed between front wheels and rear wheels, when the locking mechanism switches the center differential between a locked state and a free state, An engine control device for a four-wheel drive vehicle, comprising: an output reduction means for reducing engine output.