JPH01115733A - Switchover device for four-wheel-drive vehicle - Google Patents

Abstract

PURPOSE:To contrive to simplify switchover operations, to prevent switchover from being unsatisfied and to reduce shock and the like in switchover by letting the switchover between a two-wheel drive and a four-wheel drive configuration be made by an actuator through a synchronized meshing method, and concurrently providing a waiting mechanism making use of an elastic body. CONSTITUTION:An electromagnetic actuator M is fixed onto the casing C of a power transmitting device, the switchover force of it is transmitted to a switchover mechanism 7 via a switchover force transmitting mechanism T. Namely, a cam follower 63 is moved to the left via a cam shaft 62 by, for example, normally rotating the actuator M, and concurrently, a sleeve gear 34 is pressed to the direction via a shift fork 66 in such a way as to be meshed with a switchover gear 33. In this case, a spring 64 is pressed by the cam follower 65 by a specified quantity of stroke. And when the quantity of relative rotation of the switchover gear 53 is changed to a position at which it can be meshed with the sleeve gear 34, both of them 35 and 34 are meshed with each other by the energizing force of the spring 64.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a four-wheel drive system capable of switching between two-wheel drive and four-wheel drive.
This invention relates to a switching device for a wheel drive vehicle.

(Prior Art) Many recent automobiles are designed to selectively switch between two-wheel drive and four-wheel drive. The switching device for this purpose is generally of the mesh selection type so that a large amount of power (torque) can be transmitted, and when the gear is engaged, it is set to four-wheel drive, and when it is disengaged, it is set to two-wheel drive.

In such meshing type switching devices, the meshing mechanism is operated manually or by an electromagnetic seven-wheel drive unit, but since it does not have a synchronizer, switching operations such as selecting four-wheel drive are not performed. In such cases, if there is a difference in rotation, the meshing relationship may not go well. For this reason, a waiting mechanism using a so-called spring is provided, and when engagement is not possible, the switching force is stored as compression force of the -H spring at the engagement standby position, and when engagement becomes possible, the switching force is stored as compression force of the -H spring. It is also possible to complete the meshing state using the biasing force of the compressed spring.
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(Problems to be Solved by the Invention) Recently, there has been a strong desire to be able to switch between two-wheel drive and four-wheel drive as easily, smoothly, and reliably as possible. Particularly recently, many passenger car-type vehicles are capable of switching between 2-wheel drive and 4-wheel drive. Some devices are equipped with a synchronizing device and are switched using an actuator. However, in this case, since there is a limit to the switching speed by the actuator, there is a possibility that synchronization failure may occur. In other words, when the synchronizer ring of the synchronizer and the connected gear are synchronized, the sleeve pushes the synchronizer ring apart and engages the connected gear.During the stroke, the synchronizer that was previously acting on the sleeve - Even though the force pressing the ring disappears, the sleeve and gear are not engaged for a certain period of time (the time required for the actuator to move the above stroke at a constant speed). - This is because the ring (sleeve) will rotate relative to each other again.

Therefore, an object of the present invention is to provide a switching device for a four-wheel drive vehicle that allows switching between two-wheel drive and four-wheel drive to be performed more easily, smoothly and reliably without synchronization failure in a switching mechanism having a synchronizer. It's about doing.

(Means and operations for solving the problem) In order to achieve the above-mentioned object, the present invention first uses a synchronous mesh type switching mechanism for switching between two-wheel drive and four-wheel drive, and this meshing, that is, two This is to allow for smoother switching from wheel drive to four-wheel drive. Second, in the present invention, the switching sleeve gear in the switching mechanism is operated by an electromagnetic seven actuator, thereby simplifying the switching operation by the driver as much as possible. Thirdly, by interposing a waiting mechanism using an elastic body in the switching force transmission line for four-wheel drive selection between the actuator and the switching sleeve gear, situations such as synchronization failure of the synchronized mesh switching device can be avoided. This is to reliably avoid this and also to prevent undue force from being applied to the actuator. Also,
By providing this waiting mechanism, the elastic body buffers the sudden operation of the actuator, causing a feeling of anxiety that tends to occur when switching to four-wheel drive (a type of torque that occurs when the two wheels that were previously driven are changed to the driving wheels). shock) is reduced. Specifically, the present invention has the following configuration. That is, a switching mechanism for switching between two-wheel drive and four-wheel drive that is a synchronous mesh type and is set so that four-wheel drive is selected when meshing, and an electromagnetic mechanism for driving a switching sleeve gear in the switching mechanism. a switching sleeve gear interposed in a switching force transmission path for four-wheel drive selection between the actuator and the sleeve gear, and required for at least the switching mechanism to change from a synchronized state to an engaged state; and an elastic body that can be compressed and deformed by the stroke.

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

In FIG. 1, l is an input shaft, 2 is a rear wheel drive shaft arranged coaxially with the input shaft 1, and 3 is arranged parallel to the rear wheel drive shaft 2 and spaced apart from each other. The input shaft 1 receives power from an engine output shaft (not shown). A sub-transmission device 4, a center differential device 5, and a first switching mechanism 6 and a second switching mechanism 7, which will be described later, are arranged on the input shaft l and the rear wheel drive shaft 2, respectively.

The sub-transmission device 4 is for selectively switching the rotation transmitted to the input shaft l into two stages, high and low, and transmitting it to a center differential device 5, which will be described later, and is composed of a planetary gear mechanism. has been done. Specifically, a first ring gear 26 fixed to the casing 28 side and a first sun gear 24 mounted on the first intermediate shaft 8 so as to be relatively rotatable.
and a first pinion gear 25 attached to a first carrier 27 fixed to the first intermediate shaft 8.

On the axially outward side of this sub-transmission device 4 (on the input shaft 1 side),
The above-mentioned first switching mechanism 6 for switching the torque transmission closed path of the sub-transmission device 4 is provided. This first switching mechanism 6
is composed of a sleeve gear type switching mechanism, and includes a first switching gear 21 formed on the input shaft l, a second switching gear 22 spline-engaged with the first carrier 27, and the first switching gear 22. 1 third switching gear 23 formed on sun gear 24
and a first sleeve gear 29 that selectively meshes with these three switching gears 21, 22, and 23 by being slidably displaced in the axial direction. and,
According to this first switching mechanism 6, the first sleeve gear 29 is connected to the first switching gear 21 and the second switching gear 22 as shown in FIG.
In the state in which the input shaft 1 is engaged with the input shaft 1, the rotation of the input shaft 1 is transmitted as it is to the first carrier 27 without being decelerated, and from the first carrier 27 the rotation of the input shaft 1 is transmitted to the center differential device 5, which will be described later.
The output is unevenly distributed. In other words, a high speed gear is configured (
Pattern a).

In response, the first sleeve gear 29 moves rightward (toward the sub-transmission device 4 side) from the state of 111M, and the first switching gear 29
1 and the third switching gear 23, and the second switching gear 22.
In the state where the input shaft 1 is in mesh with the input shaft 1, the rotation of the input shaft 1 is transmitted to the first sun gear 24 of the sub-transmission device 4, and is further transmitted from the first sun gear 24 to the first ring gear 26 via the first pinion gear 25. transmitted to. Therefore, input shaft 1
The rotation of is reduced and the center differential equipment is installed from the first carrier 27! It is output in 5 parts. That is, a planetary gear of the sun gear human power/carrier output type is configured, and a low speed gear is configured (pattern b).
.

The center differential device 5 includes the rear wheel drive shaft 2
This is for performing a differential operation between the front wheel drive shaft 3 and the front wheel drive shaft 3, and is constructed of a planetary gear mechanism like the sub-transmission device 4 described above. 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 sub-transmission device 4,
Second carrier 38 integrally formed with third intermediate shaft lO
It has a second pinion gear 36 fixed to.

Further, on the outside of the center differential device 5 in the axial direction, there is provided two devices that simultaneously control the differential operation between the rear wheel drive shaft 2 and the front wheel drive shaft 3 by switching the torque transmission circuit of the center differential device 5. The second switching mechanism 7 described above is provided to switch between wheel drive (hereinafter simply referred to as 2WD) and four-wheel drive (hereinafter simply referred to as 4WD). 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 IO, and a fourth switching gear 31 that is spline-engaged with the rear wheel drive shaft 2; The sixth intermediate shaft 11 is integrally formed with the fourth intermediate shaft 11 and is relatively rotatably engaged with the outside of the intermediate shaft IO.
It has a switching gear 33 and a second sleeve gear 34 that selectively meshes with these three switching gears 31, 32, and 33 by sliding displacement in the axial direction. Further, a front side drive gear 41 is formed on the fourth intermediate shaft 11,
Further, this front side drive gear 41 is connected via a chain 15 to a front side driven gear 42 attached to the front wheel drive shaft 3 side.

There are three switching patterns of this second switching mechanism 7, A, B, and C. Firstly, in pattern A, as shown in FIG. 1, the fourth switching gear 31 and the fifth switching gear 32 are coupled by the second sleeve gear 34. In this state, the sixth switching gear 33 is free. In this pattern A, the second sun gear 35 and the second pinion gear 36 of the center differential device 5
Since these are integrated, the rotation of the second ring gear 37 is directly transmitted only to the rear wheel drive shaft 2 side, and a 2WD state is realized.

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, the fourth intermediate shaft 11 and the third intermediate shaft IO are coupled, so that a 4WD condition is realized. Also,
At the same time, the center differential device 5 is in a free state, and 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, since the fourth intermediate shaft and the 883 intermediate shaft 10 are coupled, a 4WD condition is realized, and at the same time, the center The differential device 5 is in a locked state and no differential operation is performed between the rear wheel drive shaft 2 and the front wheel drive shaft 3.

In the power transmission device Z thus constructed, four operation patterns as shown in the following table can be obtained by selecting the switching patterns of the first switching mechanism 6 and the second switching mechanism 7.

Although not shown in the drawings, a remote freewheel is provided on the front wheel drive shaft to prevent rotation of the drive train path on the driven wheel (front wheel) side when in the 2WD state.

(The following is a blank space.) FIG. 4 shows the second switching mechanism 7 and an electromagnetic actuator (for example, a step motor, D
A switching force transmission mechanism T for transmitting the switching force from the actuator M to the switching mechanism 7 is shown.

The second switching mechanism 7 is of a synchronous mesh type, particularly as shown in FIG. That is, the second switching mechanism 7 includes, in addition to the switching sleeve gear 34, a synchronizer key 51, a synchronizer ring 52, and a cone portion 53 formed on the sixth switching gear 33 for selecting four-wheel drive. Such a synchronized mesh type second switching mechanism 7 is shown in FIGS. 4 and 5.
When the sleeve gear 34 is moved to the left in the figure from the two-wheel drive selection state shown in the figure (see Figure 6 ■), the key 51 presses the ring 52 against the cone portion 53 (frictional engagement), and
The sloped end surface of the sleeve gear 34 comes into contact with the sloped surface of the ring 52 (synchronization complete - see Figure 6 ■) - 0 Further leftward movement of the sleeve gear 34 brings the sleeve gear 34 into contact with the end surface of the sixth switching gear 33. (see Fig. 6 (■)), and eventually reaches a position where it can engage with the sixth switching gear 33 (see Fig. 6 (■)), and finally the engagement is completed (4-wheel drive selection completed - see Fig. 6 (■)). In addition, in the case of switching by an electromagnetic actuator such as a motor, there is a limit to the operating speed, and as the above-mentioned synchronized state does not shift instantaneously to the engaged position, it may cause future synchronization failure. In this case, a waiting mechanism, which will be described later, ensures that the engagement is completed.

Referring again to FIG. 4, the actuator M is fixed to the casing C of the power transmission device Z, and the driving force of the actuator M is transmitted to the sleeve gear 34 via the switching force transmission mechanism T. This transmission mechanism T includes a speed reduction mechanism 61, a camshaft 62, a cam follower 63, a spring 64 as an elastic body, a spring seat 65, and a shift lever 66. The camshaft 62 is connected to the rear wheel drive shaft 2. The actuator M is rotatably held in the casing C in parallel.
is rotated forward or reversed via the deceleration mechanism 61.

Further, a holding shaft 67 is fixedly held in parallel with the camshaft 61,
The cam follower 63 and the spring seat 6
5. The shift fork 66 is slidably fitted.

The cam follower 63 is attached to a holding shaft 67 as shown in FIG.
a cylindrical portion 63a that is slidably fitted into the cylindrical portion 63a; an arm portion 63b that integrally extends from the cylindrical portion 63a;
A follower part 63c consisting of a roller rotatably held at the tip of the camshaft 62 is fitted into a cam groove 62a formed on the outer peripheral surface of the camshaft 62. The cam follower 63 has a cylindrical portion 63a.
A fork portion 63d having a forked tip and extending integrally with the camshaft 62 is fitted onto the outer periphery of the camshaft 62. As a result, when the camshaft 62 rotates forward or reverse, it is stopped by the fork portion 63d and the cam follower 63 is displaced leftward or rightward in FIG.

The shift fork 66 has first and second cylindrical portions 66a and 66b spaced apart in the axial direction,
The two cylindrical portions 66a and 66b are slidably fitted onto the holding shaft 67. A shift fork portion 66c is integrally extended from the first cylindrical portion 66a, and the tip of the shift fork portion 66c is fitted into the engagement groove 34a formed on the outer periphery of the sleeve gear 34. This first. A cylindrical spring seat 65 is slidably fitted to the holding shaft 67 between the second cylindrical parts 66a and 66b, and between the spring seat 65 and the cylindrical part 63a of the cam follower 63. , a coil spring 64 is interposed. In the state shown in FIG. 4 in which the two-wheel drive is selected, the spring 64 causes the cylindrical portion 63a of the cam follower 63 and the first cylindrical portion 66a of the shift fork 66 to come into slight contact.

With the above configuration, the actuator M is rotated forward, for example, in order to switch from two-wheel drive to four-wheel drive. As a result, the camshaft 62 is rotated in the forward direction as shown by the arrow in FIG.
is moved to the left in Figure 4. As a result, the shift fork 6
6 receives a force to the left in FIG. 4, and moves the sleeve gear 34 to the fourth
The left side of the figure, that is, the sleeve gear 34 is the sixth switching gear 33
Press in the direction of engagement. Although the actuator M itself is driven all at once to a predetermined stroke before the four-wheel drive selection position, the sleeve gear 34 is stopped at the synchronization completion position shown in FIG. The cam follower 63 compresses the spring 64 and is displaced by the stroke amount corresponding to the rotation of the actuator M toward the four-wheel drive selection position, and the compression of the spring 64 applies a load of more than a predetermined value to the actuator M. By this, the output of the load detection sensor of the actuator itself can
This stop position is set a predetermined stroke before the four-wheel drive selection position (the shift fork 66 is set when the sleeve gear 34 is in the synchronization completion position). When the relative rotational position of the sixth switching gear 33 changes to a position where the sleeve gear 34 is in the meshing position while the spring 64 is being compressed, the compressed spring 64 is The shift fork 66 and therefore the sleeve gear 34 are displaced by the biasing force, and the engagement is completed (four-wheel drive selection).Of course, the range in which the spring 64 can be compressed and deformed is at least from the synchronization completion position to the sixth position in FIG. Sleeve gear 34 up to the meshing position shown in Figure ■
is set to a value equal to or greater than the stroke of .

When the 7-wheel drive motor M is reversed from the above four-wheel drive selection state, the camshaft 62 is reversed, and as a result, the cam follower 63
is moved to the left in Figure 4. As a result, shift fork 6
The first cylindrical portion 68a of the cam follower 63 is pushed to the right by the cylindrical portion 63a of the cam follower 63, and the shift fork 66 and therefore the sleeve gear 24 move leftward in FIG. This switches to two-wheel drive selection.

Here, in the second switching mechanism 7 of the synchronized mesh type, as shown in FIG. They are biased in the direction of separation. As a result, in the two-wheel drive selection state shown in FIG. 5 in which the mesh is released, a slight gap is formed between the ring 52 and the cone portion 53 to prevent seizure (the oil passage is indicated by reference numeral 73). , spring 64 for the waiting mechanism
In addition to the buffering effect of the spring 71, the shock reduction when four-wheel drive is selected is further improved.

Further, a switch is provided to detect when the actuator M is in the four-wheel drive selection position, and the switch is configured to control the operation of the remote freewheel, so that when the actuator M is in the four-wheel drive selection position, the remote The freewheel is locked, and in this case, even if the synchronizer ring 52 and the cone part 53 become stuck to each other (biting) due to seizure, for example, the rotation of the front wheel will be prevented by the cone part 53. 53
(gear 33), and this fixation is released (4)
A more reliable choice of wheel drive).

Note that the present invention is not limited to the above embodiments, but also applies to two-wheel drive,
The front wheels may be used as driving wheels, while the rear wheels may be used as driven wheels.

(Effects of the Invention) As is clear from the above description, the present invention switches between two-wheel drive and four-wheel drive using an electromagnetic seven-wheel drive unit, which simplifies the effort required for this switching operation.

In addition, the switching mechanism between 2-wheel drive and 4-wheel drive is a synchronized mesh type, so switching to 4-wheel drive can be performed reliably, and a waiting mechanism using an elastic body can be installed to accommodate this. Therefore, switching to four-wheel drive becomes even more reliable without causing synchronization failure even when switching by an actuator.

Furthermore, due to the buffering effect of the elastic body constituting the waiting mechanism, shock at the time of four-wheel drive switching is reduced, and four-wheel drive switching can be performed smoothly.

[Brief explanation of the drawing]

FIG. 1 is a skeleton diagram showing the entire power transmission device for a four-wheel drive vehicle to which the present invention is applied. FIGS. 2 and 3 are skeleton diagrams of main parts showing different operating states of the two-wheel drive/four-wheel drive switching mechanism. FIG. 4 is a sectional view showing a specific example of a two-wheel drive/four-wheel drive switching mechanism and its switching force transmission mechanism. FIG. 5 is an enlarged cross-sectional view of a main part of the two-wheel drive/four-wheel drive switching mechanism shown in FIG. 4. FIG. 6 is a simplified plan view showing the synchronization and meshing action of the switching mechanism between two-wheel drive and four-wheel drive. FIG. 7 is an exploded perspective view of essential parts of the switching force transmission mechanism. l2 input shaft 2: rear wheel drive shaft 3: front wheel drive shaft, 4: auxiliary transmission 5: tinter differential device 6: first switching mechanism (for auxiliary transmission) 7: second switching mechanism (2 wheel drive, 4 (For wheel drive switching) 31.32.33: Switching gear 34 Ni sleeve gear 51: Synchronizer key 52: Synchronizer ring 53: Cone portion 61: Reduction mechanism 62: Cam shaft 63: Cam follower 64 Ni spring (elastic body) 66: Shift fork M :Actuator T:Transmission mechanism C:Casing

Claims (1)

[Claims] (1) A switching mechanism for switching between two-wheel drive and four-wheel drive, which is a synchronous mesh type and is set so that four-wheel drive is selected when meshing, and a switching mechanism for driving a switching sleeve gear in the switching mechanism. an electromagnetic actuator, and a switching sleeve gear that is interposed in a switching force transmission path for four-wheel drive selection between the actuator and the sleeve gear, and that is required for at least the switching mechanism to go from a synchronized state to a meshable state. A switching device for a four-wheel drive vehicle, comprising: an elastic body that can be compressed and deformed by a stroke of the length of the elastic body.