JPH08108768A - Four-wheel drive apparatus of automobile - Google Patents

Abstract

PURPOSE: To smoothly change over the drive condition from 2-wheel to 4-wheel drive condition when such change-over is obtained on the basis of intake negative pressure of an engine that even if the intake negative pressure gets lower than 'predetermined pressure' for a certain short time. CONSTITUTION: A differential lock engaging element 23 for engaging a differential case 11 of a center differential 9 separably with a first or second differential side gear 13 or 14 is provided. A power transmitting means 15 is interposed between front wheels and the first differential side gear 13. A synchronous meshing device 21 operated connectively by the intake negative pressure of an engine is interposed between the first differential side gear 13 and the power transmitting means 15. A free wheel clutch operated connectively by the intake negative pressure is interposed between the front wheels and the power transmitting means 15. A connection blocking means 68 is provided which blocks the connecting operation (4WD) of the synchronous meshing device 21 when the intake negative pressure is lower than predetermined pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-wheel drive system for an automobile capable of switching between a two-wheel drive state and a four-wheel drive state.

[0002]

2. Description of the Related Art Conventionally, some automobiles are constructed as follows.

That is, the engine side and the input part of the center differential are connected, and one of the output parts of the center differential is connected to the front wheel, while the other output part and the rear wheel are connected. It is connected. A diff lock engaging element is provided which is connected and disconnected so as to engage and disengage the input part and the output part of the center differential.

Power transmission means is interposed between the front wheel and the one output portion. Also, a synchronous meshing device that is connected by the negative pressure of the intake air of the engine is interposed between the one output portion and the power transmission means, and the diff lock engaging element is interlocked with the connecting operation of the synchronous meshing device through a spring. Then, it is designed to be divided. Further, the same as above, a free wheel clutch that is connected by an intake negative pressure is interposed between the front wheel and the power transmission means, and the free wheel clutch is connected by interlocking with the initial operation of the connecting operation of the synchronous meshing device. It is like this.

In the above structure, if the synchronous meshing device is divided and the diff lock engaging element is connected, the two-wheel drive state by only the rear wheels can be obtained.

When the vehicle is running in the two-wheel drive state, the undriven front wheels roll on the road surface in an idling manner, but at this time, if the free wheel clutch remains engaged. The power transmission means is interlocked with the idle front wheel, resulting in unnecessary power loss.

Therefore, in the two-wheel drive state, the power transmission means and the front wheels are separated by the disengagement operation of the free wheel clutch.
In the two-wheel drive state, the power transmission means is prevented from interlocking with the idle front wheel, and unnecessary power loss is prevented.

On the other hand, when the above-mentioned two-wheel drive state is to be switched to the four-wheel drive state, first, the synchronous meshing device is brought into the connecting operation by the intake negative pressure. Then, the diff-lock engaging element interlocks with the connecting operation of the synchronous meshing device via the spring, and in parallel with this, the free wheel clutch operates in parallel with the initial operation of the connecting operation of the synchronous meshing device. Are connected by the intake negative pressure, and a four-wheel drive state is obtained.

[0009]

By the way, the above-mentioned 2
When the wheel drive state is switched to the four-wheel drive state, the intake negative pressure is a pressure sufficient to immediately engage the synchronous meshing device and the free wheel clutch (hereinafter, this is referred to as a pressure exceeding "predetermined pressure"). If the synchronous meshing device is connected by the intake negative pressure, the free wheel clutch is immediately connected by the intake negative pressure in conjunction with the initial operation of the connecting operation.

Immediately after the connection operation of the free wheel clutch, the connection operation of the synchronous meshing device is not completed, that is, since the meshing operation is not performed, the disengagement operation of the diff lock engaging element which is linked to this is also completed. Therefore, the input and output parts of the center differential are still connected, and at this time, the center differential does not exert the differential function, and in this state, the four-wheel drive state is established. Then, as the connecting operation of the synchronous meshing device progresses immediately after this state, the diff-lock engaging element mechanically interlocks with this connecting operation via a spring to perform a dividing operation. Then, as a result, a desired (full-time) four-wheel drive state in which the center differential exerts a differential function is obtained.

That is, as described above, the connecting operation of the synchronous meshing device, the connecting operation of the free wheel clutch, and the disconnecting operation of the differential lock engaging element are performed in this order (hereinafter, referred to as "predetermined operation order"). By doing so, the switching from the two-wheel drive state to the four-wheel drive state can be smoothly performed without any trouble.

[0012] However, in the above-mentioned conventional structure, since the structure is not guaranteed to secure the above-mentioned "predetermined operation sequence", the following problems may occur.

That is, when the negative pressure of the intake air is insufficient and is equal to or less than the "predetermined pressure", such as immediately after the engine is started, and the vehicle is started from the stopped state, the four wheels are driven from the two-wheel drive state. If the synchronous meshing device is operated to connect in an attempt to switch to the drive state, the free wheel clutch connecting operation interlocked with the initial operation of this connecting operation tends to be delayed due to the shortage of the intake negative pressure. Then, the disconnecting operation of the diff lock engaging element mechanically interlocked with the connecting operation of the synchronous meshing device by a spring may be faster than the connecting operation of the free wheel clutch.

In this case, the center differential is brought into a state capable of exerting a differential function, while the free wheel clutch is kept in the disengagement operation, and the power transmission means is separated from the front wheels to be freely rotatable. Has become.

Therefore, the power transmitted from the engine to the center differential is simply made idle by the power transmission means via the synchronous meshing device after the initial operation of the connecting operation by the differential function of the center differential, while the rear wheels are rotated. Will not be transmitted to. Therefore, until the free wheel clutch is connected after this, the vehicle cannot start.

Moreover, as described above, once the power transmission means starts idling before the free wheel clutch is connected, when the free wheel clutch is subsequently connected, the power transmission means is in a stopped state. With the above front wheels,
Due to the large "speed difference" between the idling power transmission means, the power transmission means exerts a large impact on the free wheel clutch, which is high in terms of strength of the free wheel clutch and noise. Not preferable.

That is, when the intake negative pressure of the engine is equal to or lower than the "predetermined pressure", the above-mentioned "predetermined operation sequence" may not be obtained. This causes a problem that the switching to the wheel drive state cannot be performed smoothly.

[0018]

SUMMARY OF THE INVENTION The present invention has been made by paying attention to the above circumstances, and in the case where the switching from the two-wheel drive state to the four-wheel drive state is obtained based on the intake negative pressure of the engine. Then, even if the magnitude of the intake negative pressure becomes equal to or lower than the "predetermined pressure" in a short time, it is an object of the present invention to smoothly perform the above switching.

[0019]

[Means for Solving the Problems] The present invention for achieving the above object is as follows.

Incidentally, this "means for solving the problem"
In the section, the terms in parentheses below correspond to the terms in the claims.

In the four-wheel drive system for an automobile according to the first aspect of the present invention, the engine 6a side and the differential case (input section) 11 of the center differential 9 are connected to each other, and the first differential side gear (one output section) 13 of the center differential 9 is connected. While connecting the front wheel 2 with the second differential side gear (the other output portion) 14 and the rear wheel 4.
And the center differential 9 is connected to the differential case (input section)
11 is provided with a diff lock engaging element 23 that is connected and disconnected to engage and disengage the output parts 13 and 14, and a power transmission means 15 is provided between the front wheel 2 and the first diff side gear (one output part) 13. Same as above, the synchronous meshing device 21 which is connected by the intake negative pressure of the engine 6a is connected to the first differential side gear (one output portion) 13 and the power transmission means 1.
5, the differential lock engaging element 23 is interlocked with the connecting operation of the synchronous meshing device via the spring 38 to perform a disconnecting operation, and the free wheel clutch 3g is connected by the intake negative pressure. The free wheel clutch 3g intervenes between the front wheel 2 and the power transmission means 15 so as to interlock with the initial operation of the connecting operation of the synchronous meshing device, and the connecting operation of the synchronous meshing device 21. And a dividing operation of the diff lock engaging element 23,
With the connection operation of the free wheel clutch 3g, the above,
In the case where the four-wheel drive state by the rear wheels 2 and 4 is obtained, when the intake negative pressure is equal to or lower than a predetermined pressure, the connection blocking for blocking the meshing operation after the initial operation in the connection operation of the synchronous meshing device 21. The means 68 is provided.

According to a four-wheel drive system for an automobile of a second aspect of the present invention, the front wheel 2 and the rear wheel 4 in the first aspect of the invention are replaced with each other.

[0023]

[Operation] The operation according to the invention of claim 1 is as follows.

In the "action" section, the terms in parentheses below correspond to the terms in the claims.

In particular, in FIGS. 1 and 2, when the synchronous meshing device 21 is to be connected (4WD) by the intake negative pressure to switch from the two-wheel drive state to the four-wheel drive state, the intake negative pressure is increased. Is a pressure exceeding the “predetermined pressure”, when the synchronous engagement device 21 is connected (4WD) by the intake negative pressure, the intake negative pressure is linked to the initial operation of the connection operation (4WD). Immediately, the free wheel clutch 3g is also connected.

Immediately after the connection operation of the free wheel clutch 3g, the connection operation of the synchronous meshing device 21 (4 W
D) has not been completed, that is, since the meshing operation has not been performed, the disconnecting operation (UL) of the differential lock engagement element 23 that is interlocked therewith has not been completed, and therefore, the differential case (input section) of the center differential 9 is not completed. 11 and the first differential side gear (one output portion) 13 and the second differential side gear (the other output portion) 14 are still connected, the center differential 9 does not exhibit the differential function at this time. In this state, the four-wheel drive state is set. Then, as the connecting operation (4WD) of the synchronous meshing device 21 progresses immediately after this state, the diff-lock engagement element 23 mechanically interlocks with this connecting operation (4WD) via the spring 38 to perform the disconnecting operation (UL). . As a result, the desired (full-time) four-wheel drive state in which the center differential 9 exhibits the differential function can be obtained.

That is, as described above, the synchronous meshing device 21
Connection operation (4WD), connection operation of the free wheel clutch 3g, and disconnection operation of the differential lock engagement element 23 (U
By performing L) in this order, that is, in the “predetermined operation order”, the switching from the two-wheel drive state to the four-wheel drive state can be smoothly performed without any trouble.

On the other hand, as immediately after the engine 6a is started,
When the intake negative pressure is equal to or lower than the “predetermined pressure” and the vehicle 1 starts from a stopped state, the synchronous meshing device 21 tries to switch from the two-wheel drive state to the four-wheel drive state.
When the connection operation (4WD) is performed, the connection operation of the free wheel clutch 3g interlocked with the initial operation of the connection operation (4WD) tends to be delayed due to the lack of intake negative pressure. Then, the connecting operation of the synchronous meshing device 21 (4 W
The disconnecting operation (UL) of the diff lock engaging member 23 mechanically interlocked with D) is faster than the connecting operation of the free wheel clutch 3g, that is, the "predetermined operation sequence" is obtained. Sometimes there is not. As a result, there arises a problem that it is not possible to smoothly switch from the two-wheel drive state to the four-wheel drive state.

Therefore, as described above, when the intake negative pressure is equal to or lower than the "predetermined pressure", the connecting operation of the synchronous meshing device 21 (4
Connection blocking means 68 for blocking the meshing operation after the initial operation in WD) is provided.

That is, the connecting operation of the synchronous meshing device 21 (4 W
Free wheel clutch 3g linked to the initial operation of D)
As above, when the intake negative pressure is equal to or lower than the “predetermined pressure”, the meshing operation in the connection operation (4WD) of the synchronous meshing device 21 is performed as described above. Since it is blocked by the blocking means 68,
The spring 38 is connected to the connecting operation (4WD) of the synchronous meshing device 21.
Completion of the disconnection operation (UL) of the diff lock engaging element 23 mechanically interlocked with each other is also prevented.

Therefore, the completion of the connection operation of the free wheel clutch 3g is delayed due to insufficient intake negative pressure, but gradually progresses to the connection operation, and the diff lock engaging element 23 is connected (DL). The connection operation of the free wheel clutch 3g is completed as it is.
Then, the center differential 9 becomes a four-wheel drive state in which the differential function is not exerted.

After that, the intake negative pressure is "predetermined pressure".
As shown in FIGS. 1 to 4, the connection operation of the synchronous meshing device 21 by the connection preventing means 68 (4 W
The blocking operation of the meshing operation in D) is released, the connecting operation (4WD) of the synchronous meshing device 21 is completed by the intake negative pressure, and the diff lock engaging element 23 is springed in the connecting operation (4WD). By mechanically interlocking via 38, the cutting operation (UL) is also completed, which allows the center differential 9 to perform the differential function of the desired (full time) 4
A wheel drive state is obtained. That is, the switching from the two-wheel drive state to the four-wheel drive state is performed in the "predetermined operation sequence".

The operation according to the invention of claim 2 can be read by replacing the front wheel 2 and the rear wheel 4 with each other in the operation according to the invention of claim 1.

[0034]

Embodiments of the present invention will be described below with reference to the drawings.

(Example 1)

1 to 7 show a first embodiment.

In FIG. 2, reference numeral 1 denotes an automobile, which is an arrow Fr.
Indicates the front of the automobile 1. The right and left described below means the vehicle width direction toward the front.

The automobile 1 is provided with a pair of left and right front wheels 2 and 2 at a front portion thereof and a front differential 3 provided between the front wheels 2 and 2. Each of the front wheels 2 is connected to the front differential by an axle 2a. It is connected to 3.

The front diff 3 is rotatably supported by a diff carrier 3a fixed to the body frame side, which is the stationary side of the vehicle body, and in the diff carrier 3a, rotatably about an axis extending in the vehicle width direction on the diff carrier 3a. Differential case 3b
It has and. The differential case 3b includes an outer case 3c and an inner case 3d housed in the outer case 3c. The outer case 3c and the inner case 3d are relatively rotatable about the axis. ing.

In the inner case 3d, a differential pinion 3e is rotatably supported by the inner case 3d, and a pair of left and right differential side gears 3f, 3f are provided which mesh with the differential pinion 3e and rotate about the same axis. There is.
The front wheels 2 are connected to the respective diff side gears 3f, 3f via the axles 2a as described above.

Outer case 3c and inner case 3d
A free wheel clutch 3g for connecting and disconnecting is provided. The free wheel clutch 3g is composed of splines formed on the outer case 3c and the inner case 3d, and an engaging element 3h which is slidably fitted on the splines only in the axial direction.

As shown in FIG. 2, if the engaging element 3h is spline-fitted across both splines, the outer case 3c and the inner case 3 are connected by the engaging element 3h.
d is connected, that is, the free wheel clutch 3g is connected. On the other hand, when the engagement element 3h is slid on one of the splines, the outer case 3c and the inner case 3d are separated,
In other words, the free wheel clutch 3g is disengaged.

When the free wheel clutch 3g is engaged as described above, the outer case 3c and the inner case 3d are integrally rotated, and the power applied to the outer case 3c is changed by the normal differential action. It is transmitted to each front wheel 2, 2 via the axle 2a. On the other hand, when the free wheel clutch 3g is disengaged, the outer case 3c and the inner case 3d are disengaged, that is, the outer case 3c.
And the power transmission between the front wheels 2 and 2 and the respective axles 2a is cut off.

The vehicle 1 has a pair of left and right rear wheels 4 and 4 at its rear portion, and a rear differential 5 provided between the rear wheels 4 and 4.
And each rear wheel 4 is connected to the rear differential 5 by an axle 4a.

The rear differential 5 includes a differential carrier 5a fixed to the vehicle body frame side, and a differential case 5b rotatably supported in the differential carrier 5a by the differential carrier 5a about an axis extending in the vehicle width direction. I have it.
Further, in the differential case 5b, a differential pinion 5c is rotatably supported by the differential case 5b, and a pair of left and right differential side gears 5d, 5d that mesh with the differential pinion 5c and rotate about the same axial center are provided. The rear wheels 4 are connected to the respective diff side gears 5d and 5d via the axles 4a as described above.

The automobile 1 has a drive unit 6.
The drive device 6 is composed of an engine 6a, which is an internal combustion engine, and a transmission device 6b which inputs power from the engine 6a, changes the speed of the power, and outputs the speed. Further, the same as above, the automobile 1 outputs the output of the transmission 6b to the front differential 3
And a transfer 7 for transmitting to the rear differential 5, respectively.

The transfer 7 will be described with reference to FIGS. 1 to 3.
Will be described.

The transfer 7 is provided with a transfer case 8 fixed to the vehicle body frame side, which is the stationary side of the vehicle body, and a center differential 9 contained in the transfer case 8. The center differential 9 has a differential case 11 as an input portion, and the differential case 11 is rotatable around the axis of the output shaft 10 of the transfer 7 and is rotationally driven by the output shaft 10. The differential pinion 12 is rotatably supported by the differential case 11 in the differential case 11, and meshes with the differential pinion 12 to rotate on the output shaft 10 about the axial center of the output shaft 10. And a second differential side gear 14 which is an output part of the.

The second differential side gear 14 is connected to the front end of a rear wheel drive shaft 16 provided coaxially with the output shaft 10 by spline fitting, and the rear end side of the rear wheel drive shaft 16 is the rear differential. 5 is connected to the differential case 5b, which is the input side.

The front wheel drive shaft 1 is parallel to the rear wheel drive shaft 16.
7 is supported by the transfer case 8. A drive chain 18 is rotatably supported on the rear wheel drive shaft 16, while the driven chain 1 is mounted on the rear end of the front wheel drive shaft 17.
9 is rotatably supported, and a transmission chain 20 is wound around the drive chain wheel 18 and the driven chain wheel 19. The front end side of the front wheel drive shaft 17 is connected to the outer case 3c which is the input side of the front differential 3.

The outer case 3c of the front differential 3,
The front wheel drive shaft 17, the drive chain wheel 18, the driven chain wheel 19, and the transmission chain 20 are the front wheel 2 which is either one of the front wheels and the rear wheels 2 and 4, and the center differential 9 which is the engine 6a side. And a power transmission means 15 interposed between the first differential side gear 13 and the first differential side gear 13.

First differential side gear 1 of the center differential 9
3 and the drive chain 18 of the power transmission means 15 are provided with a synchronous meshing device 21. The synchronous meshing device 21 includes a drive gear 13a that rotates integrally with the first differential side gear 13 of the center differential 9 and a power transmission means 15.
The driven gear 18a formed on the drive chain wheel 18 and the synchronizer ring 2 that can be frictionally joined to the drive chain wheel 18 side.
1a, a power connecting / disconnecting engagement element 22 slidably fitted (engaged) in the axial direction across the drive gear 13a, the driven gear 18a, and the synchronizer ring 21a.
And have.

As shown by the solid line in FIG. 1 and FIG. 2, the power connecting / disconnecting engagement element 22 is connected to the drive gear 13a and the driven gear 18.
a and the spline fitting over the synchronizer ring 21a, the first differential side gear 13 of the center differential 9 and the drive chain 18 of the power transmission means 15 are connected by the power connecting / disconnecting engagement element 22, that is, The synchronous meshing device 21 is connected (4WD). on the other hand,
If the power connecting / disconnecting engagement member 22 is slid to be spline-fitted only to the drive gear 13a, the first differential of the center differential 9 can be obtained.
Drive chain 18 of differential side gear 13 and power transmission means 15
Are divided, that is, the synchronous meshing device 21 performs a dividing operation (2WD).

The dividing operation of the synchronous meshing device 21 (2 W
The state from D) to the completion of the connecting operation (4WD) will be described. In the operation after the initial operation in the connecting operation (4WD) of the synchromesh device 21, the power connecting / disconnecting engagement element 22 is splined to the synchronizer ring 21a. At the time of fitting, the synchronizer ring 21a is frictionally joined to the drive chain wheel 18 side, and the power connecting / disconnecting engagement element 22 is attached.
And the speed difference of rotation of the driven gear 18a on the side of the drive chain wheel 18 are reduced, whereby the power connecting / disconnecting engagement element 22 and the driven gear 18a on the side of the drive chain wheel 18 are "synchronized".
The spline fitting, which is the meshing operation of the power connecting / disconnecting engagement element 22 to the driven gear 18a on the drive chain wheel 18 side thereafter, is smoothly performed without any impact. That is, the meshing operation in the connecting operation (4WD) of the synchronous meshing device 21 is smoothly performed by the action of the “synchronization”.

First differential side gear 1 of the center differential 9
A diff lock engagement element 23 is spline-fitted on the third side so as to be slidable only in the axial direction. This diff lock engaging element 2
Reference numeral 3 denotes a connecting operation (DL) by the sliding, which enables the first differential side gear 13 and the differential case 11 to be connected,
By the connecting operation (DL) of the diff lock engaging element 23, the center diff 9 is brought into a diff lock state. To be

On the other hand, the first differential side gear 13 and the differential case 11 can be separated by the dividing operation (UL) by sliding the diff lock engaging member 23 opposite to the above, and the separating action of the diff lock engaging member 23 is performed. (UL) brings the center differential 9 into the unlocked state, and in this case, the center differential 9 exerts a differential function so that the first differential side gear 13 and the second differential side gear 14 output the same torque.

As shown by the solid line in FIG. 1 and FIG. 2, the power connecting / disconnecting engagement element 22 of the synchronous meshing device 21 is slid to move the first
The differential side gear 13 and the drive chain 18 are connected, that is, the synchronous meshing device 21 is connected (4WD), and the free wheel clutch 3g is connected as shown in FIG. Then, a part of the power of the drive device 6 causes the first differential side gear 13 of the center differential 9, the power connecting / disconnecting engagement element 22, the drive chain wheel 18, the transmission chain 20, and the driven chain wheel 1 to travel.
It is transmitted to the front wheels 2 and 2 which is one of the front wheels and the rear wheels 2 and 4 through the front wheel drive shaft 17 and the front wheel drive shaft 17. On the other hand, the other parts of the power of the drive device 6 are the second differential side gear 14 of the center differential 9, the rear wheel drive shaft 16,
And the rear wheels 4, 4 which are the other wheels via the rear differential 5.
Conveyed to.

At this time, as shown by the solid line in FIGS. 1 and 2, the differential lock engagement element 23 is moved rearward to separate the first differential side gear 13 and the differential case 11, that is, the differential lock engagement element 23 is separated. The center differential 9 is unlocked by operating (UL). Then, the center differential 9 exerts a differential function, whereby a full-time four-wheel drive state is obtained.

On the other hand, as shown by the phantom line in FIG. 1, the diff lock engaging member 23 is moved forward from the above state to move the first
The differential side gear 13 and the differential case 11 are coupled, that is, the differential lock engagement element 23 is connected (DL) to bring the center differential 9 into the differential lock state. As a result, a part-time four-wheel drive state is obtained.

From the above-described full-time four-wheel drive state,
As indicated by a phantom line in FIG. 1, the power connecting / disconnecting engagement element 22 of the synchronous meshing device 21 is moved forward to separate the first differential side gear 13 from the drive chain 18, that is, the synchronous meshing device. When 21 is divided (2WD), the driving force of the drive device 6 is the second differential side gear 1 of the center differential 9.
4, transmitted to only the rear wheels 4, 4 via the rear wheel drive shaft 16 and the rear differential 5. Then, as a result, the two-wheel drive state of only the rear wheels 4 and 4 is obtained.

By the way, in the above state, the first differential side gear 13 remains in the idling state, and the drive device 6
The motive power of the above is merely idling the first differential side gear 13, and this motive power is not transmitted to the rear wheels 4 and 4, so that the vehicle cannot run.

Therefore, when the above-described two-wheel drive state is set, the differential lock engagement element 23 is moved forward as shown by the phantom line in FIG. 1 to perform the connecting operation (DL), and the first differential side gear 13 and the differential case 11 are connected. Engage. That is, the center differential 9 is set in the differential lock state, and the drive device 6
The power of is transmitted to the rear wheels 4 and 4.

Further, in the above state, when the automobile 1 is running, the power transmission means 15 is interlocked with the front wheels 2 and 2 rolling on the road surface, resulting in unnecessary power loss.

Therefore, if the free wheel clutch 3g is disengaged, the interlocking of the power transmission means 15 is prevented, that is, the unnecessary power loss is prevented.

1 to 3, the power connecting / disconnecting engagement element 22 and the diff lock engagement element 2 of the synchronous meshing device 21 are referred to.
An operation device 25 is provided as an operation device for connecting or disconnecting the three. This operating device 2
5 is engaged with the power connecting / disconnecting engagement element 22 to engage the synchronous engagement device 2
Connect 1 (4WD) or disconnect (2WD)
The power connecting / disconnecting operator 26 to be engaged with the diff lock engaging element 23 is connected to connect the diff lock engaging element 23 (D
L) or a differential lock operation element 27 for performing a dividing operation (UL).

An operating shaft 28, which is a stationary member, is installed in parallel with the output shaft 10 on the transfer case 8, and is fixed to the transfer case 8 by a fixing pin 29. An operating cylinder 31 is externally fitted to the middle of the operating shaft 28 so as to be slidable back and forth in the axial direction, and a circlip 32 is externally fitted and fixed between the front and rear sides of the operating cylinder 31. .

The power connection / disconnection operator 26 is the operation cylinder 3
The operation cylinder body 3 is fitted on the rear side of the body 1 so as to be slidable back and forth.
An engagement body 33 is externally fitted and fixed to the rear end of the first unit. A spring 34 is provided between the power connecting / disconnecting operator 26 and the engaging body 33. The spring 34 is the same as the power connecting / disconnecting operator 2 until the power connecting / disconnecting operator 26 contacts the circlip 32.
6 is biased forward.

The diff lock operator 27 is externally fitted on the front side of the operating cylinder 31 so as to be slidable forward and backward, and a boss 36 is externally fitted and fixed to the front end of the operating cylinder 31 by a fixing pin 37. A spring 38 is interposed between the diff lock operator 27 and the boss 36. The spring 38 urges the diff lock operator 27 rearward until the diff lock operator 27 contacts the circlip 32. ing.
In the above case, a notch 39 is formed at the front end of the operating shaft 28, and the fixing pin 37 is fitted in the notch 39 so as to be slidable back and forth, whereby the operating cylinder 3
1 is slidable only back and forth with respect to the operating shaft 28, and is not rotatable around its axis.

In the above case, the power connecting / disconnecting operator 26, the diff lock operator 27, the operating cylinder 31, the engaging body 33, and the boss 36 constitute a movable member with respect to the operating shaft 28.

A switching lever 41 is engaged with the engaging body 33, and when the switching lever 41 rotates back and forth, the operating cylinder body 31 slides back and forth on the operating shaft 28 together with the engaging body 33. It has become.

Then, as shown by the solid line in FIGS. 1 to 4, when the operating cylinder 31 is moved rearward by operating the switching lever 41, the circlip 32 pushes the power connecting / disconnecting operator 26 rearward, Along with this, the power connecting / disconnecting engagement element 22 moves rearward, and the synchronous meshing device 21 is connected (4WD). Further, the boss 36 mechanically pushes the diff lock operator 27 rearward through the spring 38 along with the operation cylinder 31, and accordingly, the diff lock engaging element 23 moves rearward to cause a dividing operation (UL). To be

In this case, the diff case 11 and the first diff side gear 13 which are connected to each other while the automobile 1 is in the steering etc.
When torque is transmitted between the differential cylinder 11 and the operating cylinder 31, the differential lock engaging member 23 is moved by the frictional force only by the compression of the spring 38 by the corresponding amount. The state in which the first differential side gear 13 is kept connected is maintained. Then, after that, when the automobile 1 goes straight ahead,
When the torque transmission with the differential side gear 13 is reduced and the frictional force is reduced, the differential lock operating element 27 is moved backward by the biasing force of the spring 38. That is, by the spring 38, the differential case 1
The 1 and the first differential side gear 13 are to be separated from each other without difficulty.

In FIG. 1, the diff lock operator 27 is shown.
An engaging body 42 is integrally molded with the engaging member 42, and a manual diff lock lever 43 is engaged with the engaging member 42. When the diff lock lever 43 is rotated, the diff lock operator 27 can be moved forward and backward while the spring 38 is expanded and contracted while the operation cylinder 31 remains stationary with respect to the operation shaft 28. ing. The diff lock operator 23 is connected (DL) with the forward movement of the diff lock operator 27.

In the phantom line in FIG. 1, FIG. 5 and FIG. 6, when the operating cylinder 31 moves forward by the rotation of the switching lever 41, the engaging body 33 moves the power connecting / disconnecting operator 26 forward through the spring 34. The power connecting / disconnecting engaging element 22 moves forward, and the synchronous meshing device 21 is moved as indicated by a phantom line in the figure.
Is divided (2WD). The function of the spring 34 in this case is similar to that of the spring 38 described above. Along with this, the circlip 32 pushes the diff lock operating element 27 forward, and accordingly, the diff lock engaging element 23.
Moves forward and performs a connecting operation (DL), and the center differential 9 is brought into a differential lock state.

A restricting means 45 is provided for restricting the connecting operation and the disconnecting operation of the power connecting / disconnecting engagement member 22 and the diff lock engaging member 23.

According to the restricting means 45, as shown in FIGS.
As shown by the solid line, when the power connecting / disconnecting engagement element 22 is connected (4WD) and is in the four-wheel drive state, the connection operation (DL operation of the diff lock engaging element 23 by the operation of the diff lock operator 27) is performed. ), The dividing operation (UL) is enabled. Further, as shown by the phantom line in FIG. 1 and FIG. 5, the above-mentioned synchronous meshing device 21 is made to perform a dividing operation (2WD),
In the case of the two-wheel drive state, the diff-lock engagement element 23 is held in the connecting operation (DL) as it is, that is, the disconnection operation (UL) of the diff-lock engagement element 23 by the manual operation on the diff-lock operation element 27 cannot be performed. It is said that

The regulating means 45 will be described in more detail with reference to FIGS. 1 and 3 to 6.

The regulating means 45 has a swing arm 46. A rear end of the swing arm 46 is pivotally supported by an inner wall of the transfer case 8 by a pivot shaft 47, and a swing end 48 of the pivot shaft 47 is vertically swingable. A cam groove 50 is formed in the middle of the swing arm 46, while a cam shaft 51 that engages with the cam groove 50 is provided on the side surface of the power connecting / disconnecting operator 26. Then, the rocking arm 46 is rocked up and down by cam-engaging the movement of the power connecting / disconnecting operator 26.

On the other hand, the diff lock operator 27 has an engaging projection 52 on its side portion, and the engaging projection 52 is located in front of the swing arm 46.

As shown by the solid line in FIGS. 1 to 4, the power connecting / disconnecting operator 26 connects the synchronous meshing device 21 (4 W).
When the rearward movement is performed so as to cause D), the rearwardly moving cam shaft 51 slides to the rear end of the cam groove 50 together with the power connecting / disconnecting operator 26, and the swinging arm 46 swings upward in one direction. The diff lock operator 27
The engaging projection 52 is disengaged upward from the front-back movement locus.

Therefore, in this case, both the connecting operation (DL) and the disconnecting operation (UL) of the differential lock engagement element 23 by the operation of the differential lock operation element 27 are possible.

As shown in FIG. 1 and a phantom line in FIG. 3, when the power connecting / disconnecting operator 26 moves forward so as to cause the synchronous meshing device 21 to perform the disengagement operation (2WD), as shown in FIGS. As shown by, the cam shaft 51 moving forward together with the power connecting / disconnecting operator 26 slides to the front end of the cam groove 50, and the swing arm 46 swings downward in the other direction. 48 connects the diff lock engaging element 23 (D
L) The engaging projection 5 of the diff lock operator 27
It will be located near the rear of 2.

For this reason, in this case, the rearward movement of the differential lock operating element 27, which attempts to cause the differential lock engagement element 23 to perform the disconnecting operation (UL), is blocked by the swinging end 48 of the swinging arm 46. That is, in the two-wheel drive state, the center differential 9 is held in the diff-lock state, which prevents the traveling in the two-wheel drive state from being disabled.

If it is attempted to move the power connecting / disconnecting operator 26 rearward in an attempt to bring the differential lock engagement element 23 into the two-wheel drive state from the state in which the disconnection operation (UL) is performed, this The swinging end 48 side of the swinging arm 46, which is cam-engaged with the power connecting / disconnecting operator 26 and rotates downward, comes into contact with the engaging protrusion 52 of the diff lock operator 27, and further power connecting / disconnecting operation is performed. Rearward movement of the child 26 is prevented.

Therefore, according to the restricting means 45, in the two-wheel drive state, the center differential 9 is held in the diff-locked state and the traveling is maintained in the two-wheel drive state.

In FIG. 2, the operating device 25 is interlocked with the synchronous meshing device 21 and the free wheel clutch 3g.
Drive means 5 for connecting or disconnecting the
Have five.

The driving means 55 has a diaphragm valve type first actuator 56, and the switching lever 41 is connected to the first actuator 56. The first
The actuator 56 includes an intake manifold 58 of the engine 6a via a valve device 57 including a plurality of solenoid valves.
The intake negative pressure can be supplied from the valve, and the valve device 5
It is possible to communicate with the atmosphere via 7 and the air cleaner 59.

The drive means 55 has a diaphragm valve type second actuator 61, and the second actuator 61 is provided with an engaging element 3 of the free wheel clutch 3g.
h is connected. The intake manifold 58 is also connected to the second actuator 61 via the valve device 57.
It is possible to supply the intake negative pressure from the above, and it is possible to communicate with the atmosphere through the valve device 57 and the air cleaner 59.

A change-over switch 62 is provided for electrically controlling the valve device 57 so that the valve device 57 can be switched between a two-wheel drive state and a four-wheel drive state. That is, when the changeover switch 62 is operated, the voltage from the battery 63 is given to a predetermined electromagnetic valve in the valve device 57. Further, a parallel circuit of a 4WD detection switch 65 and an indicator lamp 66 is electrically connected in series with the changeover switch 62, and the 4WD detection switch 65 is connected to the changeover lever 4
It is provided corresponding to the operation of 1.

When the four-wheel drive state shown in FIGS. 1 and 2 is to be obtained from the two-wheel drive state shown by the phantom line in FIG. 1 and FIG. 5, the changeover switch 62 is operated as shown in FIG. , A voltage is applied from the battery 63 to a predetermined electromagnetic valve in the valve device 57, and these perform a predetermined opening / closing operation,
As a result, the intake negative pressure of the intake manifold 58 is transmitted to one of the two chambers partitioned in the first actuator 56, and the atmospheric pressure is transmitted to the other chamber, whereby the first actuator is 56 starts the forward movement of the forward movement and the backward movement, that is, the synchronous meshing device 21 performs the connecting operation (4 W
Perform the initial operation of D). Then, the switching lever 41 is interlocked with the first actuator 56, and accordingly, the power connecting / disconnecting operator 26 starts to move backward, and the spring 3
The diff lock operator 27 starts to mechanically interlock via 8.

Then, at the initial stage of the interlocking of the switching lever 41 with the first actuator 56, that is, at the initial operation of the connecting operation (4WD) of the synchronous meshing device 21, the switching lever 41 causes the 4WD detection switch 65 to move. Turn on.
Then, the indicator light 66 is turned on, and when the four-wheel drive detection switch 65 is turned on, a voltage is applied from the battery 63 to a predetermined electromagnetic valve in the valve device 57 to open and close them, whereby the intake manifold 58 of the intake manifold 58 is opened. The intake negative pressure is transmitted to one of the two chambers partitioned in the second actuator 61, and the atmospheric pressure is transmitted to the other chamber so that the second actuator 61 moves forward and backward. Move forward. Then, the engagement member 3h of the free wheel clutch 3g is interlocked with the second actuator 61, and as shown in FIG.
Are connected.

At this time, the forward movement of the first actuator 56 further progresses, and the power lock / disconnect operator 26 and the diff lock operator 27 are further interlocked with this by the forward / disconnect operator 26, whereby the first actuator 56 and the second actuator shown in FIGS. As shown in FIG.
The connection operation (4WD) is performed, and the differential lock engagement element 23 is disconnected (UL).

Then, the above free wheel clutch 3
As described above, by the connection operation of g and the synchromesh device 21 and the disconnecting operation (UL) of the differential lock engagement element 23, as described above.
A wheel drive state is obtained.

When the changeover switch 62 is operated in order to obtain the two-wheel drive state from the four-wheel drive state, a voltage is applied from the battery 63 to another predetermined electromagnetic valve in the valve device 57 to open and close them. Works and this allows
The intake negative pressure of the intake manifold 58 is transmitted to the other chamber in the first actuator 56, and the atmospheric pressure is transmitted to the one chamber, so that the first actuator 56 moves back. Then, the switching lever 41, the power connecting / disconnecting operator 26, and the diff lock operator 27 are interlocked with the first actuator 56 to cause the synchronous meshing device 21 to perform a disconnecting operation (2WD), and the diff lock engaging element 23 to connect. (DL).

Further, the switching lever 41 interlocked with the first actuator 56 turns off the 4WD detection switch 65. Then, the indicator light 66 is turned off and the voltage from the battery 63 to the valve device 57 is stopped by turning off the 4WD detection switch 65. As a result, the intake negative pressure of the intake manifold 58 is transmitted to the other chamber in the second actuator 61, and the atmospheric pressure is transmitted to the one chamber, so that the second actuator 61 moves back. Then, the engagement element 3h of the free wheel clutch 3g is interlocked with the second actuator 61, and the free wheel clutch 3g is disengaged.

Then, due to the disconnecting operation of the synchronous meshing device 21 and the free wheel clutch 3g and the connecting operation (DL) of the diff lock engaging member 23, the power transmitting means 15 is interlocked with the front wheel 2, resulting in unnecessary power loss. A two-wheel drive state is obtained while preventing the occurrence of

In the above structure, when the two-wheel drive state is changed to the four-wheel drive state and the intake negative pressure of the intake manifold 58 is equal to or lower than the "predetermined pressure", the initial operation in the connecting operation (4WD) of the synchronous meshing device 21. Connection blocking means 68 is provided for blocking the subsequent meshing operation.

In FIGS. 1 and 2 to 7, the connection preventing means 68 has a sliding surface 69 formed by cutting out the surface of the operating shaft 28 which is the fixed member. 69 is a flat surface extending substantially parallel to the axis of the operating shaft 28.

Further, the connection preventing means 68 has a metallic spherical sliding body 71 which is elastically pressed against the surface of the operating shaft 28 and the sliding surface 69 by a spring 70 which is a biasing means. The spring 70 and the sliding body 71 are connected to the housing hole 7 formed in the engaging body 33 on the side of the operating cylinder 31.
It is housed in 2.

In the phantom line in FIG. 1 and the two-wheel drive state shown in FIGS. 5 and 6, the sliding body 71 is elastically pressed against the sliding surface 69 by the urging force of the spring 70.

When the changeover switch 62 is operated as shown in FIG. 2 in order to obtain the four-wheel drive state from the two-wheel drive state, as described above, the forward engagement of the first actuator 56 starts to cause the synchronous meshing. Connection operation of device 21 (4W
The switching lever 41 starts to operate so as to perform the initial operation of D), and the engaging body 33 interlocked with the switching lever 41 is accompanied by the operating cylinder 31, the spring 38, the power connecting / disconnecting operator 26, and the diff lock operator 27. The operation shaft 28 slides rearward.

Then, along with the engaging body 33, the sliding body 7
1 slides on the sliding surface 69 rearward in the axial direction of the operating shaft 28.

In FIG. 7, in the connecting operation (4WD) of the synchronous meshing device 21 from the initial operation to the meshing operation, as described above, the power connecting / disconnecting engagement element 22 of the synchronous meshing device 21 is synchronized with the synchronizer ring. 21a is spline-fitted so that the power connecting / disconnecting engagement element 22 and the driven gear 18a on the drive chain wheel 18 side are "synchronized" with each other, and at this time, the sliding body 71 is an end portion of the sliding surface 69. Step 7
Reach 3.

In this case, the first actuator 5
If the intake negative pressure of the intake manifold 58 transmitted to 6 exceeds the “predetermined pressure”, the biasing force of the spring 70 is caused by the sliding of the engaging body 33 which is interlocked with the forward movement of the first actuator 56 due to the above-mentioned intake negative pressure. Against this, the sliding body 71 easily gets over the stepped portion 73, and the sliding body 71 reaches the surface of the operation shaft 28. The engaging body 33 is transferred to the transfer case 8
When it abuts against the roller and further sliding is stopped,
To the connecting operation of the synchromesh device 21 (4
WD) is completed.

In the above case, when trying to switch from the two-wheel drive state to the four-wheel drive state and the connecting operation (4WD) of the synchronous meshing device 21 is performed by the intake negative pressure, the intake negative pressure is "predetermined pressure". When the pressure exceeds the limit, the synchronous meshing device 21 is connected (4WD) by the intake negative pressure.
Then, interlocking with the initial operation of the connecting operation (4WD), the free wheel clutch 3g is immediately connected by the intake negative pressure.

When the free wheel clutch 3g is engaged, the diff lock engaging element 23 is engaged (DL).
Therefore, the power of the engine 6a is transmitted to the rear wheel 4 via the center differential 9. Along with this, the power transmission means 15 from the same engine 6a through the same center differential 9 and the synchronous meshing device 21 that operates in synchronization after the initial operation of the connecting operation (4WD).
Power is also transmitted to.

Since the front wheels 2 and the rear wheels 4 both roll on the road surface and have substantially the same rotational speed, the "speed difference" between the front wheels 2 and the power transmission means 15 is small. Therefore, the above-described connecting operation of the free wheel clutch 3g, which is interlocked with the initial operation of the connecting operation (4WD) of the synchronous meshing device 21, is smoothly performed without impact.

Immediately after the connection operation of the free wheel clutch 3g, the connection operation of the synchronous meshing device 21 (4 W
D) has not been completed, that is, since the meshing operation has not been performed, the disconnecting operation (UL) of the differential lock engagement element 23 that is interlocked therewith has not been completed, and therefore, the differential case 11 of the center differential 9 and the Since it is still connected to the 1-diff side gear 13, the center diff 9 is in the four-wheel drive state in such a state that it does not exhibit the differential function. And
Immediately after this state, the connecting operation of the synchromesh device 21 (4
With the progress of WD), the diff-lock engagement element 23 mechanically interlocks with this connection operation (4WD) via the spring 38 to perform the disconnection operation (UL). Then, the center differential 9
Thus, a desired (full-time) four-wheel drive state in which the differential function is exhibited can be obtained.

That is, as described above, the synchronous meshing device 21
Connection operation (4WD), connection operation of the free wheel clutch 3g, and disconnection operation of the differential lock engagement element 23 (U
By performing L) in this order, that is, in the “predetermined operation order”, the switching from the two-wheel drive state to the four-wheel drive state can be smoothly performed without any trouble.

By the differential function of the center diff 9, the power is transmitted to the front wheels 2 and the rear wheels 4 at a predetermined ratio of equal ratio torque.

On the other hand, as immediately after the engine 6a is started,
When the intake negative pressure is equal to or lower than the “predetermined pressure” and the vehicle 1 starts from a stopped state, the synchronous meshing device 21 tries to switch from the two-wheel drive state to the four-wheel drive state.
When the connection operation (4WD) is performed, the connection operation of the free wheel clutch 3g interlocked with the initial operation of the connection operation (4WD) tends to be delayed due to the lack of intake negative pressure. Then, the connecting operation of the synchronous meshing device 21 (4 W
The disconnecting operation (UL) of the diff lock engaging member 23 mechanically interlocked with D) is faster than the connecting operation of the free wheel clutch 3g, that is, the "predetermined operation sequence" is obtained. Sometimes there is not.

In this case, the center differential 9 is brought into a state capable of exerting the differential function, while the free wheel clutch 3g is kept in the disengagement operation, and the power transmission means 15 is provided.
Is separated from the front wheel 2 and can freely rotate.

Therefore, from the engine 6a to the center differential 9
Due to the differential function of the center differential 9, the power transmitted to the “synchronization” is performed after the initial operation of the connecting operation (4WD).
The power transmission means 1 through the synchronized meshing device 21
5 will simply idle, while it will not be transmitted to the rear wheel 4. Therefore, after this, the free wheel clutch 3g
During the time (short time) until the connection operation is performed, the vehicle 1 cannot start.

Moreover, as described above, before the connecting operation of the free wheel clutch 3g, the power transmission means 15 is temporarily
When the free wheel clutch 3g is about to engage after the idling, the large "speed difference" between the front wheel 2 in the stopped state and the idling power transmission means 15 causes The power transmission means 15 may give a large impact to the free wheel clutch 3g.

That is, when the intake negative pressure of the engine 6a is equal to or lower than the "predetermined pressure", the "predetermined operation sequence" may not be obtained, and therefore, the two-wheel drive state to the four-wheel drive state may be obtained. It may not be possible to smoothly switch to.

Therefore, as described above, when the intake negative pressure is equal to or lower than the "predetermined pressure", the connection preventing means 68 for preventing the meshing operation after the initial operation in the connection operation (4WD) of the synchronous meshing device 21 is provided. ing.

That is, the connecting operation of the synchronous meshing device 21 (4 W
Free wheel clutch 3g linked to the initial operation of D)
Same as above, the connection operation is started by the intake negative pressure, but when the intake negative pressure is equal to or lower than the “predetermined pressure”, the engagement operation in the connection operation (4WD) of the synchronous engagement device 21 is as described above, as shown in FIG. Since it is blocked by the connection blocking means 68, the completion of the disconnection operation (UL) of the differential lock engagement element 23 mechanically interlocked with the connection operation (4WD) of the synchronous meshing device 21 via the spring 38 is also blocked.

Therefore, until the connection operation of the free wheel clutch 3g is completed, there is a delay due to the lack of intake negative pressure, but it gradually progresses to the connection operation, and the diff lock engaging element 23 is connected (DL). The connection operation of the free wheel clutch 3g is completed as it is.
Then, the center differential 9 becomes a four-wheel drive state in which the differential function is not exerted.

After that, the intake negative pressure is "predetermined pressure".
As shown in FIGS. 1 to 4, the connection operation of the synchronous meshing device 21 by the connection preventing means 68 (4 W
The blocking operation of the meshing operation in D) is released, the connecting operation (4WD) of the synchronous meshing device 21 is completed by the intake negative pressure, and the diff lock engaging element 23 is springed in the connecting operation (4WD). By mechanically interlocking via 38, the cutting operation (UL) is also completed, which allows the center differential 9 to perform the differential function of the desired (full time) 4
A wheel drive state is obtained. That is, the switching from the two-wheel drive state to the four-wheel drive state is performed in the "predetermined operation sequence".

Although the above is based on the illustrated example, the front wheel 2 and the rear wheel 4 may be provided in reverse in the above figure. Also,
The center differential 9 may use a planetary gear.

(Example 2)

FIG. 8 and FIG. 9 show the second embodiment particularly regarding the connection blocking means 68.

This embodiment has the same structure and operation as the first embodiment except for the connection blocking means 68. Therefore, common parts are designated by the same reference numerals in the drawings and their description is omitted. However, the different points will be mainly described.

In FIG. 8, a sliding shaft 75 extending in a direction substantially orthogonal to the operating shaft 28 is provided. The sliding shaft 75 is supported by the transfer case 8 so as to be slidable only in the axial direction. One end of the sliding shaft 75 is connected to the first actuator 56, and the forward and backward movement of the first actuator 56 causes the sliding shaft 75 to forward and backward in the axial direction.

The transfer case 8 has a pivot shaft 76.
Thus, a middle portion of the rotating arm 77 is pivotally supported, one end of the rotating arm 77 is engaged with the engaging body 33, and the other end of the rotating arm 77 is engaged with the sliding shaft 75.

As shown in FIGS. 8 and 9, if the sliding shaft 75 moves forward with the first actuator 56 (FIG. 8,
The arrow A in FIG. 9) and the rotation of the rotating arm 77 (arrow B in FIGS. 8 and 9) accompanying this, the engaging body 33 is interlocked, the synchronous engagement device 21 is connected, and the four-wheel drive state. Is obtained.

On the other hand, when the sliding shaft 75 is moved back along with the first actuator 56 (in the direction opposite to the arrow A in the same figure), the rotation of the rotating arm 77 (arrow B in the same figure) accordingly. The engaging body 33 is interlocked with each other through the (in the opposite direction), and the synchronous meshing device 21 is disengaged to obtain a two-wheel drive state.

The connection blocking means 68 in this embodiment is the sliding surface 6 formed on the surface of the sliding shaft 75 which is the movable member.
9, a spring 70 provided on the side of the transfer case 8 which is a stationary member, a sliding body 71, a housing hole 72, and a stepped portion 73.

That is, the connection preventing means 68 in each of the above embodiments is basically provided with the first actuator 56 which is a drive source which operates (forward and backward movements) by the intake negative pressure,
The first actuator 56 and the synchronous engagement device 21
An interlocking means including an engaging body 33 for connecting with the operating cylinder 31, the power connecting / disconnecting operator 26, the sliding shaft 75, and the like is provided, and stationary members such as the transfer case 8 and the operating shaft 28, and the interlocking means. A sliding body 71, which has a notch-shaped sliding surface 69 formed on one of the facing surfaces of the facing portions and elastically presses against the sliding surface 69 on the other facing surface side.
Is provided between the initial operation and the meshing operation in the connecting operation (4WD) of the synchronous meshing apparatus 21 by the operation of the first actuator 56, more specifically, the synchronous meshing apparatus 2
1, when the "synchronization" action occurs, the sliding member 7
1 reaches the stepped portion 73 at the end of the sliding surface 69.

Since the connection preventing means 68 of the above embodiment is obtained by the sliding surface 69, the sliding body 71 and the like having a simple shape,
The structure of the connection blocking means 68 is simplified and its molding can be facilitated.

[0131]

According to the invention of claim 1, the engine side and the input part of the center differential are connected, and one output part of both the output parts of the center differential is connected to the front wheel, while the other output is connected. Section and the rear wheel are connected to each other, and a differential lock engagement element is provided which connects and disconnects the input section and the output section of the center diff, and which is provided with a power transmission means between the front wheel and the one output section. An interlocking interlocking device is interposed between the one output portion and the power transmission means, and the differential lock engagement element is connected via a spring to the interlocking operation of the interlocking interlocking device. A free wheel clutch that is interlocked to perform a disengagement operation and that is connected by the intake negative pressure is interposed between the front wheel and the power transmission means, and is used as an initial operation of the connection operation of the synchronous meshing device. The four wheel drive state by the front wheel and the rear wheel by the connection operation of the synchronous meshing device, the disconnection operation of the diff lock engaging element, and the connection operation of the free wheel clutch so that the re-wheel clutch is interlocked for connection operation. In a four-wheel drive system for an automobile, in which
When the intake negative pressure is equal to or lower than the predetermined pressure, the connection blocking means for blocking the meshing operation after the initial operation in the connection operation of the synchronous meshing device is provided.

That is, when the intake negative pressure is equal to or lower than the "predetermined pressure", such as immediately after the engine is started, and the vehicle starts from the stopped state, the two-wheel drive state is switched to the four-wheel drive state. Assuming that the synchronous meshing device is connected, the connection operation of the free wheel clutch linked to the initial operation of this connection operation tends to be delayed due to the lack of intake negative pressure. Then, the disconnecting operation of the diff lock engaging element that is interlocked by the spring with the connecting operation of the synchronous meshing device is faster than the connecting operation of the free wheel clutch, that is, the "predetermined operation sequence" cannot be obtained. There is. As a result, there arises a problem that it is not possible to smoothly switch from the two-wheel drive state to the four-wheel drive state.

Therefore, as described above, when the intake negative pressure is equal to or lower than the "predetermined pressure", the connection preventing means for preventing the meshing operation after the initial operation in the connection operation of the synchronous meshing device is provided.

That is, the free wheel clutch starts the connecting operation by the intake negative pressure in the same manner as the initial operation of the connecting operation of the synchronous meshing device. However, when the intake negative pressure is equal to or lower than the "predetermined pressure", as described above. In addition, since the meshing operation in the connecting operation of the synchronous meshing device is blocked by the connection blocking means, the completion of the disconnecting operation of the diff lock engaging element which is interlocked with the connecting motion of the synchronous meshing device via the spring is also blocked.

Therefore, until the connection operation of the free wheel clutch is completed, there is a delay due to the lack of intake negative pressure, but the connection operation gradually progresses, and the diff lock engaging element remains connected, and The connection operation of the free wheel clutch is completed. Then, the center differential is in a four-wheel drive state in which the differential function is not exerted.

After that, the intake negative pressure is "predetermined pressure".
When it exceeds, the blocking of the meshing operation in the connecting operation of the synchronous meshing device by the connection blocking means is released, the connecting operation of the synchronous meshing device is completed by the intake negative pressure, and in this connecting operation, The differential lock engagement element is interlocked via a spring to complete the disconnection operation thereof, whereby a desired (full-time) four-wheel drive state in which the center differential exerts a differential function is obtained. In other words, switching from the two-wheel drive state to the four-wheel drive state is a "predetermined operation sequence".
Then, it will be done.

Further, the operation and effect of the invention of claim 2 is as follows.
In the description of the invention of claim 1, the front wheel and the rear wheel may be read as being replaced with each other.

As described above, claim 1 and claim 2
According to the invention, even when the magnitude of the intake negative pressure becomes equal to or lower than the "predetermined pressure" in a certain short time period, the "predetermined operation sequence" is ensured, and the two-wheel drive state is changed based on the intake negative pressure. Switching to the four-wheel drive state will be smoothly performed.

[Brief description of drawings]

1 to 7 show a first embodiment, and FIG. 1 is a side sectional view of a transfer in a four-wheel drive state.

FIG. 2 is a schematic plan view of an automobile in a four-wheel drive state.

FIG. 3 is a partial plan view of FIG.

FIG. 4 is a partially enlarged view of FIG.

FIG. 5 is a diagram corresponding to FIG. 3 showing a two-wheel drive state.

6 is a partially enlarged view of FIG.

FIG. 7 is an operation explanatory view corresponding to FIGS. 4 and 6 in the middle of switching from the two-wheel drive state to the four-wheel drive state.

FIG. 8 is a diagram corresponding to FIG. 3 in the second embodiment.

FIG. 9 is a sectional view taken along line 9-9 of FIG. 8;

[Explanation of symbols]

 1 Car 2 Front Wheel 3g Free Wheel Clutch 4 Rear Wheel 6a Engine 9 Center Differential 11 Differential Case (Input Section) 13 First Differential Side Gear (One Output Section) 14 Second Differential Side Gear (Other Output Section) 15 Power Transmission Means 21 Synchronous Engagement Device 23 Diff lock engaging element 25 Operating device 28 Operating shaft 38 Spring 68 Connection blocking means 69 Sliding surface 70 Spring 71 Sliding body 73 Stepped portion 75 Sliding shaft

Claims (2)

[Claims] 1. An engine side and an input part of a center differential are connected, one output part of both output parts of the center differential is connected to a front wheel, and the other output part is connected to a rear wheel, An intake negative pressure of the engine is provided by providing a diff lock engaging element that is connected and disconnected to disengage the input portion and the output portion of the center differential, and has a power transmission means interposed between the front wheel and the one output portion. By interposing a synchronous meshing device that is connected by means of the one output portion and the power transmission means, so that the diff lock engaging element interlocks with the connecting operation of the synchronous meshing device via a spring,
Further, the same as above, a free wheel clutch that is connected by an intake negative pressure is interposed between the front wheel and the power transmission means, and the free wheel clutch is connected by interlocking with the initial operation of the connecting operation of the synchronous meshing device. In this way, the four-wheel drive state of the automobile in which the four-wheel drive state by the front and rear wheels is obtained by the connecting operation of the synchronous meshing device, the disconnecting operation of the diff lock engaging element, and the connecting operation of the free wheel clutch. A four-wheel drive system for an automobile, wherein the drive device is provided with connection blocking means for blocking a meshing operation after an initial operation in the connection operation of the synchronous meshing device when the intake negative pressure is equal to or lower than a predetermined pressure. 2. An engine side and an input part of a center differential are connected to each other, one output part of both output parts of the center differential is connected to a rear wheel, and the other output part is connected to a front wheel, The center differential has an input part and an output part which are connected to each other and disengaged from each other. A differential lock engaging element is provided, and a power transmission means is interposed between the rear wheel and the one output part. A synchronous meshing device that is connected by pressure is interposed between the one output portion and the power transmission means so that the diff lock engaging element is interlocked with a connecting operation of the synchronous meshing device via a spring to perform a disconnecting operation. ,
Further, the same as above, a free wheel clutch that is connected by an intake negative pressure is interposed between the rear wheel and the power transmission means, and the above free wheel clutch is interlocked with the initial operation of the connecting operation of the synchronous meshing device. The four-wheel drive state of the vehicle in which the front and rear wheels are driven by the connecting operation of the synchromesh device, the disconnecting operation of the diff lock engaging element, and the connecting operation of the free wheel clutch. A four-wheel drive system for a vehicle, comprising a connection preventing means for preventing a meshing operation after an initial operation in the connection operation of the synchronous meshing device when the intake negative pressure is equal to or lower than a predetermined pressure.