JPH01114532A - Drive mode selection controller for four-wheel-drive vehicle - Google Patents

Abstract

PURPOSE:To realize the drive mode suitable for the traveling state at that time point if a drive mode detecting means fails, by installing a drive mode selecting mechanism, drive mode detecting means, flywheel device, flywheel state detecting means, operating means, and a control means. CONSTITUTION:When anomaly exists in the output signal of a drive mode detecting means 37, a control means 88 judges the generation of trouble in the detecting means 37, and operation-controls a drive mode selecting mechanism in the following manner according to the output of a flywheel state detecting means in preference independently of the output signal of an operating means. In other words, if the flywheel state detecting means detects the lock state of a flywheel device 85, the drive mode selecting mechanism is shifted to a four-wheel drive/center differential gear free mode position. While, if the free state of the flywheel device 85 is detected, the drive mode selecting mechanism is shifted to a two-wheel drive mode position. These both positions are at the both edge parts of the shift positions of the selecting mechanism.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is capable of switching the drive state of a vehicle between a two-wheel drive state and a four-wheel drive state, and when in the four-wheel drive state, the front and rear wheels are The center differential, which distributes and transmits power to both sides, can be switched between a locked state and a free state.
When in wheel drive mode, the idle wheel side can be made free 4
The present invention relates to a drive mode switching control device for a wheel drive vehicle.

(Prior Art) Conventionally, in addition to a 2/4 switching mechanism that switches the drive state of a vehicle from a two-wheel drive state to a four-wheel drive state, a transfer system has a center differential switching mechanism that switches a center differential between a locked state and a free state. The installation δ is published in JP-A-60-127.
It has become publicly known as ``Vehicle Power Split Device'' in Publication No. 232@.

That is, to explain this type of transfer device using the above-proposed "vehicle power valve vI device" as an example, as shown in FIG. One output shaft e of the center differential C is formed hollow and is disposed coaxially with the output shaft. A hub portion f is integrally formed on the shaft end of the output shaft e from the center differential C, and a hub portion q is integrally formed on the output shaft from the sub-transmission 11a opposite to the hub portion f. It is formed.

In addition, a power take-off gear i with a chain transmission mechanism is rotatably fitted to the output shaft e from the center differential C to transmit power to either the front wheels or the rear wheels. The gear 1 is integrally formed with a spline piece j that faces a hub portion f provided on the output shaft e of the center differential C.

Then, this spline piece j and the above two hub parts f
, 9 is provided with a coupling sleeve k that is slidably spline-fitted to them, and by slidingly moving the coupling sleeve k in the axial direction, the power transmission state is changed. It is possible to switch between a two-wheel drive state, a four-wheel drive/center differential lock state, and a four-wheel drive/center differential free state.

In other words, coupling sleeve k is connected to two hub parts f and q.
When the two are engaged, the input member d of the center differential C and one output shaft e rotate together, and the rotation of the output shaft of the sub-transmission 11a is transmitted to the other output shaft of the center differential C. At this time, the power take-off gear i of the chain transmission mechanism does not rotate, and the vehicle enters a two-wheel drive state.

Also, when the coupling sleeve k is engaged between the two hub parts r and q and the spline piece j, the sub-shift 1
The rotation of the output shaft 1a is also transmitted to the power tick-off gear i of the chain transmission mechanism, and at this time, the center differential C is in a locked state, and power is transmitted to the front wheels and the rear wheels. In other words, it becomes a four-wheel drive/center differential lock state.

Furthermore, when the coupling sleeve k is engaged between the hub part f of one output shaft e of the center differential C and the power take-off gear i, the rotation of the output shaft of the sub-shift Ila is caused by the rotation of the input member d of the center differential C. Two outputs @e,
The rotation of one output shaft e is transmitted to the power take-off gear i of the chain transmission mechanism, and the four wheels e/center differential are brought into a free state. At this time, since the center differential C is in a free state, torque is distributed to the front and rear wheels according to their respective loads.

Furthermore, in a four-wheel drive vehicle that is equipped with the above-mentioned transfer device and is capable of switching between a two-wheel drive state and a four-wheel drive state, the idle heavy wheel side in the two-wheel drive state is By using a freewheel device as shown in Japanese Patent Publication No. 56-135320, the axle shaft and other power transmission systems are made free, and the section from the 2/4 switching mechanism of the transfer to the freewheel device is It is also well known that the rotation of the power transmission system is stopped, thereby improving fuel efficiency when driving two wheels.

By the way, in a four-wheel drive vehicle equipped with a transfer device and a freewheel device as described above, there are restrictions on the switching procedure when switching the drive state from a two-wheel drive state to a four-wheel drive/center differential free state. occurs.

That is, the power transmission system from the drive mode switching mechanism part (2/4 switching mechanism part) whose rotation is stopped in the two-wheel drive state to the freewheel device is connected to the engine side and the idle wheel side, To transmit engine power to the idle wheels, first set the drive mode switching mechanism of the transfer device to the 4-wheel drive/center differential lock state, then set the freewheel device to the locked state, and then change the drive mode switching mechanism to the 4-wheel drive/center differential lock state. It is necessary to make the center differential free.

In other words, if you set the drive mode switching mechanism to the 4-wheel drive/center differential free state before locking the freewheel device, the load on one output shaft of the center differential will shift from the load on the other output shaft that is constantly transmitting power. Since it is extremely light compared to the load, almost all of the power is distributed to one output shaft side, which has a light load. Then, almost no power is transmitted to the drive wheels on the other output shaft side, making it impossible for the vehicle to maintain its running state.

Further, under such a situation, it becomes impossible to lock the freewheel device due to the strength of the synchronization mechanism section of the freewheel device.

On the other hand, if the freewheel device is set to the locked state before the drive mode switching mechanism is set to the 4-wheel drive/center differential lock state, the front wheels and rear wheels will rotate at the circumferential speed when the vehicle is traveling straight at a constant speed. However, when there is a difference in rotational speed between the front and rear wheels, such as when cornering or acceleration/deceleration, the load applied to the synchronization mechanism when the drive mode switching Akebonohashi is activated becomes As the size increases, the switching operation becomes impossible from the viewpoint of strength.

Therefore, these switching operations can be electrically activated.
If the center differential is configured to be
Generally, switching between the wheel drive state and the wheel drive state is performed by operating the corresponding changeover switch, but when both of these changeover switches are operated, the state changes from the two-wheel drive state to the four-wheel drive/center differential free state. When the drive mode switching mechanism is switched from 2-wheel drive to 4-wheel drive/center differential lock, the drive mode switching mechanism is changed from 2-wheel drive to 4-wheel drive/center differential lock, and then after the freewheel device is locked, the drive mode switching mechanism is switched to 4-wheel drive. The system is configured to shift to a drive/center differential free state.

Conversely, when switching from 4-wheel drive/center differential free state to 2-wheel drive state, there will be no problem with the strength of the synchronization mechanism when cutting off the transmission of driving force, so first the drive mode After the switching mechanism has passed from the 4-wheel drive/center differential free state to the 2-wheel drive state through the 4-wheel drive/center differential locked state, the freewheel device is switched to the free state, and the 2-wheel drive state is changed as soon as possible. The system is set to wheel drive mode to reduce the load on the engine and improve fuel efficiency.

Therefore, in such a drive mode switching control device, a detection means to accurately know the actual switching position of the drive mode switching mechanism is essential. etc. are used.

(Problems to be Solved by the Invention) By the way, in the conventional drive mode switching control 1i1, if the switching movement position detecting means fails, appropriate switching of the drive mode cannot be performed.

That is, for example, if the drive mode detection means fails, the switching position of the drive mode switching mechanism cannot be detected and the switching control device cannot perform control.

In this case, as a countermeasure in the event of a failure, it may be possible to fix the drive mode to one (for example, two-wheel drive state) set at the end of the switching stroke. However, if the drive mode is limited to one in the event of a failure, , there is a possibility that the vehicle may not be suitable for the current driving condition.

The present invention has been made in view of the above circumstances, and
The purpose is to provide a drive mode switching control device for a four-wheel drive vehicle that can switch and set a drive mode switching mechanism to a drive mode that is as suitable as possible for the current driving condition when the drive mode detection means fails. It's about doing.

(Means for Solving the Problems) In order to achieve the above object, the present invention changes the drive modes of the transfer device δ having a center differential to two-wheel drive and four-wheel drive/center differential lock.

Clutch gear type drive that switches between 4-wheel drive/center differential free modes, and passes through 4-wheel drive/center differential lock mode when switching between 2-wheel drive mode and 4-wheel drive/center differential free mode. a mode switching mechanism; a drive mode detection means for detecting an actual switching position of the drive mode switching mechanism; and locking an idle wheel side in a two-wheel drive state to a free state with respect to a power transmission system from the transfer device. a freewheel device that is switched to a four-wheel drive state and locked in a four-wheel drive state; a freewheel state detection means that detects a free state and a locked state of the freewheel device; an operation means for selecting the drive mode, and an operation means for controlling the operation of the drive mode switching mechanism and the freewheel device based on output signals from the operation means, the drive mode detection means, and the freewheel state detection means; When an abnormality is detected in the output signal from the mode detection means, the drive mode switching mechanism is switched to the two-wheel drive state position in accordance with the output signal from the freewheel state detection means, giving priority to the output signal from the operation means. or a control means for switching to a four-wheel drive/center differential free state position, and constitutes a drive mode switching control I5A position for a four-wheel drive vehicle.

(Function) According to the present invention having the above configuration, when there is an abnormality in the output signal from the drive mode detection means, the control means considers that the drive mode detection means has failed, and thereafter the output signal from the operation means is Irrespective of this, the operation of the drive mode switching mechanism is controlled as follows in accordance with the output signal from the freewheel state detection means.

That is, if the freewheel state detection means detects the locked state of the freewheel device, the drive mode switching mechanism is moved to the 4-wheel drive/center differential free mode position and the drive state of the vehicle is changed to 4-wheel drive/center differential. Make it free and maintain it. On the other hand, if the freewheel state detection means detects the free state of the freewheel device, the drive mode switching mechanism is moved to the two-wheel drive mode position to change and maintain the drive state of the vehicle in the two-wheel drive state. . At this time, since the two-wheel drive mode position and the four-wheel drive mode position are located at both ends of the movement position of the drive mode switching mechanism, even if the drive mode detection means is out of order,
The drive mode switching mechanism can be reliably positioned at a position as suitable as possible for the current driving condition.

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

FIG. 1 shows a part-time four-wheel drive vehicle according to an embodiment of the present invention, where 1 is the vehicle body, 2 is an engine mounted in a so-called vertical position at the front end of the vehicle body 1, and 3 is the engine 2.
This is a manual transmission that changes the output rotation of the transmission 3, and a transfer device 9 is disposed at the rear of this transmission 3. This transfer device 9 has front wheels 7. Front and rear differential mechanisms 5 each consisting of a bevel gear mechanism for wheels 8 and 8.
．． Drive connection is made via 6.

The transfer device 9 has a transfer case 10 connected to a case 3a of the transmission 3, as shown in detail in FIG. The input @ 11 is arranged on the same axis as the input shaft 11, the front wheel side output shaft 12 is arranged parallel to the side of the input shaft 11, and the input @ 11 is arranged on the same axis behind the input shaft 11 (to the right in the figure). The rear wheel side output shafts 13 are each rotatably supported. At the front end of the input shaft 11, that is, at the end on the transmission 3 side, a speed reduction mechanism 14 is disposed to reduce the rotation transmitted from the engine 2 to the wheels 7.8. The speed reduction mechanism 14 includes a sun gear 15 rotatably supported on the input shaft 11 and a spline connection to the input shaft 11 rearward of the sun gear 15 so as to rotate integrally with the sun gear 15.
A planetary gear vIIIl! which has a binion carrier 17 carrying a plurality of binions 16, 16... that mesh with the binions 16, 16, and a ring gear 18 that meshes with each of the binions 16. The ring gear 18 is fixed to the transfer case 10 in a non-rotatable manner by having a lower part 18a formed on its outer circumferential surface meshing with teeth 10a formed on the inner surface of the transfer case 10.

On the other hand, a sun gear spline tooth portion 15a is formed on the outer periphery of the front end of the sun gear 15, and a spline tooth portion 17a for the binion carrier is formed on the inner periphery of the front end of the binion carrier 17, respectively. Further, a cylindrical member 19 is disposed around the front end of the input shaft 11, and the front end is spline-coupled to the output shaft 3b of the transmission 813 so as to rotate integrally with the cylindrical member 19.
On the outer peripheral surface of the rear end of 9 is the sun 1! A spline tooth portion 19a having the same diameter as the sun gear spline tooth portion 15a is formed, and the spline tooth portion 19a has a sleeve that has an inner peripheral spline tooth portion 20a that can mesh with the sun gear spline tooth portion 15a at its rear end. 20 is spline-coupled so as to be slidable and rotatable, and a spline m portion 20b that can engage with the spline tooth portion 17a for the binion carrier is formed on the outer circumferential surface of the rear end of the sleeve 20. Then, by sliding this sleeve 20 on the cylindrical member 19, the outer spline tooth portion 20b is selected as the spline tooth portion 17a for the binion carrier, or the inner spline tooth portion 20a is selected as the spline tooth portion 15a for the sun gear. By engaging the wheels 7 and 7, the reduction gear mechanism 14 is operated and controlled.
．． 8, and position the sleeve 20 at the front high speed position P■, as shown by the solid line in the figure, and press the outer spline teeth 20.
When b is engaged with the teeth 17a for the nion carrier, the gear is shifted! ! 13 output shaft 3b to the binion carrier 1
The input shaft 1 is directly connected to the rotating body through the transfer shaft 11 through the input shaft 7, and the rotation of the output shaft 3b is directly connected to the input shaft 1 without decelerating the rotation of the output shaft 3b.
1, the power transmission ratio is brought to a high speed state, while the sleeve 20 is moved to the rear side at a low speed position g? as shown by the imaginary line. Positioned at PL, its inner circumferential spline tooth portion 20
a is meshed with the sun gear tooth portion 15a, the transmission output @3b is transferred to the transfer human power shaft 11 via the sun gear 15, each pinion 16, and the pinion carrier 17.
The H/L switching mechanism 21 is configured to set the power transmission ratio to a low speed state by transmitting power to the engine and decelerating its rotation.

On the other hand, there is a free play f#l' on the rear end of the transfer input shaft 11! A center differential 22 of the type is arranged. The sun gear 23 of this center differential 22 is rotatably supported on the input shaft 11, and when supporting each binion 24, the nion carrier 25 is rotatably splined to the input shaft 11 on the rear side of the sun gear 23, and the ring gear 26 is connected to the input shaft 11 on the rear side of the sun gear 23. It is rotatably coupled to the wheel side output @13.

Further, a drive sprocket 27 is rotatably supported on the input shaft 11 on the front side of the center differential 22, and between the sprocket 27 and a driven sprocket 28 rotatably coupled to the front wheel side output shaft 12. is chain 29
The chain 29 is used to transmit the rotation of the input shaft 11 to the front output shaft 12.

Further, the sun gear 23 and ring gear 26 of the center differential 22 are each extended forward, and a clutch hub 30 having spline teeth 30a on the outer peripheral surface is rotatably coupled to the front end of the extended portion of the sun gear 23. On the other hand, the extension part of the ring gear 26 is supported on the outer periphery of the extension part of the sun gear 23 so as to be relatively rotatable, and the spline tooth part 26 having the same diameter as the spline tooth part 30a on the outer periphery of the clutch hub 30 is provided on the outer periphery of the extension part. It is formed. Further, the driving sprocket 27 is extended rearward, and the spline tooth portion 30 on the outer periphery of the clutch hub 30 is provided on the outer periphery of the extended portion.
A spline tooth portion 27a having the same diameter as a is formed. Furthermore, a sleeve 31 is slidably spline-coupled to each of the spline tooth portions 30a, 26a, and 27a of the clutch hub 30, the ring gear 26 of the center differential 22, and the drive sprocket 27 at its inner peripheral spline tooth portion 31a. Then, by sliding the sleeve 31 in the front-rear direction, the center differential 22 is switched to a free state or a locked state, and the drive state is switched to a two-wheel drive state or a four-wheel drive state, respectively, and the sleeve 31 is moved as shown by the imaginary line in the figure. When the front end is positioned at the four-wheel drive/center differential free position P4F, the clutch hub 30 and the drive sprocket 27 are rotationally connected to form a four-wheel drive state, and the ring gear 26 of the center differential 22 and the sun gear 23
The center differential 22 is brought into a free state by being disconnected from the center differential 22. Furthermore, when positioned at the front/rear intermediate 4-wheel drive/center differential lock position P4L, the clutch hub 30 and the drive sprocket 27 are rotatably connected to each other in the same manner as described above to establish a 4-wheel drive state, and the ring gear of the center differential 22 is 26 and the sun gear 23 to connect the center differential 2.
2 is in the locked state. Furthermore, when the sleeve 31 is positioned at the rear end two-wheel drive position ffP2 as shown by the solid line in the figure, the ring gear 26 of the center differential 22 and the sun gear 23 are connected to lock the center differential 22, and the clutch hub A drive mode switching device that disconnects the drive sprocket 30 from the drive sprocket 27 and switches to a two-wheel drive state! ! 1132 is configured. Therefore, in this embodiment, this drive mode switching mechanism 32 allows
A first switching mechanism and a second switching mechanism are configured.

Furthermore, as shown in FIG. 2, a shift rod 33 for switching and controlling the drive mode switching mechanism 32 is slidably supported on the transfer case 10, and a drive mode switch is provided on the shift rod 33. A shifting fork 34 that engages with and slides the sleeve 31 of the switching mechanism 32 is fixed. Further, a cam is connected to the shift rod 33 in the transfer case 10 on the side of the shift rod 33, and the rod 33 is connected to the shift rod 33 by rotation.
A camshaft 35 for driving the camshaft 35 is rotatably supported, and this camshaft 35 is drivingly connected to an ff1fjl motor 36 mounted outside the case 10, and the operation of the motor 36 controls the operation of the drive mode switching mechanism 32. By rotating the motor 36 in one direction (CCW direction), the sleeve 31 is slid forward (to the left in the figure), and by rotating in the other direction (CW force direction), the sleeve 31 is slid backward (to the right in the figure). The center differential 22 is configured to be switched between a free state, a locked state, and a two-wheel drive state or a four-wheel drive state.

In addition, as shown in FIG. 2, the transfer case 1
0 is provided with mode detection means 37 for detecting the actual switching movement position of the drive mode switching mechanism 32 based on the movement position of the shift rod 33. In the illustrated example, this mode detection means 37 is composed of three microswitches A, B, and C. When the drive mode switching mechanism 32 is in the two-wheel drive mode IP2, switch A is turned on.
Switch B is turned on when the four-wheel drive/center differential lock mode is at 11p4L, and switch C is turned on when the four-wheel drive/center differential free mode is at 1iffP4F. When the drive mode switching mechanism 32 is moved, it switches between two-wheel drive mode 2nd and four-wheel drive/center differential lock mode 4H.
If the switches A and B are located between the
N, 4-wheel drive/center differential lock mode 4HL and 4
When located between the wheel drive/center differential free mode 4HF, switches B and C are both turned on, making it possible to detect five positions.

In other words, the ON signals of the switches A, B, and C outputted from the drive mode detection means 32 sequentially change in the order of 80AB←B→BC→C as the drive mode switching mechanism moves.

On the side of the transfer manual shaft 11, there is an H/L shift rod 3 for switching and controlling the H/L switching mechanism 21.
8 is slidably supported in the same direction as the input shaft 11.

As shown in enlarged detail in FIG. 5, the H/L shift rod 38, by sliding in its axial direction, sequentially moves from the front to three switching mode positions of a switching lever 62 in a transfer switching operating device 61, which will be described later. In other words, 2 wheel drive/high speed mode position 2nd (4 wheel drive/high speed/center differential free mode position 48F), 4 width side e/high speed/center differential lock mode position 4HL, and 4 wheel drive/low speed/center differential lock mode position 14LL They are provided so that they can take three corresponding positions.

On this )-1/L shift rod 38, a fork 39 that engages with and slides the sleeve 20 of the above-mentioned) 1/L switching mechanism 21 is slidably supported by its boss portion 39a. A sliding surface 39b is formed on the boss portion 39a of the fork 39 at a portion facing the inner surface of the transfer case 10. Further, a bottle insertion hole 40 is formed in the boss portion 39a of the fork 39 and extends radially inward from the sliding surface 39b in a direction perpendicular to the axis.
A locking pin 41 is slidably inserted into the bottle insertion hole 40, and the tip of the locking pin 41 is formed on the outer peripheral surface of the 1/L shift rod 38 so as to extend in the sliding direction thereof. It is provided so as to be engageable with the engagement groove 38a having a predetermined length. Further, a sliding contact plate 42 that is in sliding contact with the sliding contact surface 39b on the outer periphery of the boss portion 39a of the fork 39 is fixed to the inner surface of the transfer case 10 by bolts 43, 43, and the sliding contact plate 42 or the outer case 10 A spring housing hole 44 is formed at a predetermined position, and a ball 45 that can suppress the back surface of the locking pin 41 and a spring 46 that biases the ball 45 toward the fork 39 are installed in the spring housing hole 44. This spring 46 allows
When the bottle insertion hole 40 of the boss portion 39a matches the spring accommodation hole 44 as the fork 39 moves, the locking pin 41 in the bottle insertion hole 40 is inserted into the engagement groove of the shift rod 38 with its tip end. A pressing force f=J is applied via the ball 45 so as to engage the ball 38a.

Further, on the outer periphery of the shift rod 38, a ring-shaped connecting member 47 capable of pressing the boss portion 39a in the axial direction is provided at a predetermined portion on the front side (on the left side in FIG. 5) of the boss portion 39a of the fork 39. 48, they are movably coupled together. Further, the front road end position of the fork 39 is regulated by a regulating member 49 protruding from the sliding contact plate 42, and the H/L
The shift rod 38 is in two positions on the front side, i.e. two-wheel drive/
High speed mode! When moving between 2H and 4-wheel drive/high speed/center differential lock mode 1f4HL,
The locking bottle 41 is pushed out from the engagement R38a of the shift rod 38 against the biasing force of the spring 46, and the locking bottle 41 is inserted into the bottle insertion hole 4.
0, the fork 39 stops moving even if the shift rod 38 slides, and the switching operation of the H/L switching mechanism 21 is prohibited.
4 wheel drive/low speed/center differential lock mode at the rear end! When the H/L shift rod 38 is slid on the F4LL, the locking pin 41 biased by the spring 46 is slid within the engagement groove 38a of the shift rod 38 by the connecting member 47 integrated with the shift rod 38. The fork 39 is moved integrally with the shift rod 38, and the H
A missed swing mechanism 50 is configured to switch the /L switching mechanism 21 to the low speed position PL. In addition, in FIG. 5, 51 is a ball 5 biased by a spring 52.
3 is the engagement recess 39c on the outer periphery of the boss portion 39a of the fork 39.
, 39d to determine the stop position of the fork 39.

Roughly, as shown in FIG. 6, the connecting member 47 integrally connected to the H/L shift rod 38 is integrally formed with a connecting portion 47a having an engagement hole 47b. The connecting arm 5 is provided in the engagement hole 47b of the connecting portion 47a.
The ball-shaped locking portion 54a at the end of the connecting arm 54 is fitted and engaged with the H/L shift rod 38.
It is movably fixed to a control rod 55 that is supported parallel to the transfer case 10 on the side.

Three engagement recesses 55a to 55C are formed at equal intervals in the axial direction on one side of the outer periphery of the rear end (right end in the figure) of the control rod 55. A spring housing hole 56 is formed in the transfer case 10 facing the mating recesses 55a to 55c, and the spring housing hole 56 accommodates each of the engaging recesses 55.
A ball 57 that engages with a to 55c and a spring 58 that biases the ball 57 in the engagement direction are fitted,
By engaging the balls 57 with the respective engagement recesses 55a to 55c, the control rod 55 is moved to the two-wheel drive/high-speed mode position 15N2H, the four-wheel drive/high-speed/center differential lock mode position 4HL, and The positioning 811I459 is configured to be positioned at three positions: 4-wheel drive/low speed/center differential lock mode position 41L.

Further, the front end of the control rod 55 is connected to the negative end of a push-pull type control cable 60. The other end of this cable 60 is connected to the H/L switching mechanism 21 and the drive mode switching mechanism 21 as shown in FIG. il
! It is mechanically linked to a transfer switching operating device 61 for controlling the operation of the mechanism 32. The transfer switching operation device 61 has a column-operated mode switching lever 62 as shown in FIG.
Reference numeral 2 denotes an arm member fixed to the upper end of a support shaft 63 rotatably arranged and supported substantially parallel to a steering V-shift 65 for supporting the steering wheel 64, for example, an arm member rotatably fixed to the support shaft 63. The other end of the cable 60 is connected to the tip (not shown) of the cable 60, and the cable 60 is moved by rotation of the support shaft 63 in response to the switching operation of the switching lever 62. By rotating the switching lever 62 about its support shaft 63, the switching lever 62 is moved from the top to the two-wheel drive/high-speed mode.
12H (4 wheel drive/high speed, /center differential free mode position 48F), 4 wheel drive/high speed/center differential lock mode position 1!4HL and 4 wheel drive/low speed/center differential lock mode position V! 14LL located in three switching positions.

Further, at the upper end of the support shaft 63 of the switching lever 62, the switching lever 62 has a low speed position of 4 wheel drive/low speed/center differential lock mode position 41m and a high speed position of 4 wheel drive/high speed/center differential lock mode position. Mode position a48
A center differential changeover switch 66 serving as a first switch means that is operated to maintain the state when the changeover operation is made from L to a changeover position other than these, that is, the two-wheel drive/high-speed mode position ff12H. is installed. That is, as shown in FIGS. 9 and 10, the center differential changeover switch 66 includes a switch body 66a disposed close to the support shaft 63, and a switch body 66a attached to the switch body 66a so as to protrude toward the support shaft 63. and a limit switch having an actuating pin 66b that is supported by a force such that the tip end of the actuating pin 66b is in sliding contact with the outer circumferential cam surface of a substantially cylindrical cam 67 that is rotatably attached to the support shaft 63. It is located. The cam 67 is formed in a two-stage structure with a large diameter portion 67a and a small diameter portion 67b continuous to the large diameter portion 67a in the circumferential direction.
is in the two-wheel drive/high-speed mode position 2H, the large diameter portion 67a of the cam 67 causes the center differential changeover switch 66 to
The operating bottle 66b is pushed into the main body 66a to keep the switch 66 in the OFF state, while the small diameter portion 67b closes the switch 66 when the switch 66 is in the mode position 4H1 or 41L other than the two-wheel drive/high-speed mode position 2nd. The switch 66 is configured to be kept in the ON state by causing the activation bottle 66b to protrude from the inside of the main body 66a.

Further, as shown in FIG. 7, the mode switching lever 6
2 is equipped with a 2/4 changeover switch 68 as a second switch means that is directly operated by the driver. As shown in enlarged detail in FIG. 8, the 2/4 changeover switch 68 is a momentary type bushing switch that outputs a signal only while the driver operates the bushing. Therefore, for example, if the button is operated when the vehicle is in a two-wheel drive state, a command signal is issued to switch from the two-wheel drive state to the four-wheel drive/center differential free state.

When the button is operated while the vehicle is in the four-wheel drive/center differential free state, a command signal for switching from the four-wheel drive/center differential free state to the two-wheel drive state is alternately output.

That is, by rotating the switching lever 62 and pushing the 2/4 changeover switch 68, the drive modes can be set to 2-wheel drive/high-speed mode 2H, 4-wheel drive/high-speed/center differential free mode 48F, 4-wheel drive/high-speed/ When the drive modes are respectively switched to center differential lock mode 4HL and 4-wheel drive/low speed/center differential lock mode 4LL, and at this time, when the switching lever 62 is positioned at the central 4-wheel drive/high speed/center differential lock mode position 4HL, the vehicle Switch the drive mode to 4-wheel drive/high speed/center differential lock mode, and move the switching lever 62 to the lower 4-wheel drive/low speed/center differential lock mode. When positioned at 141L, the drive mode of the vehicle is switched to 4-wheel drive/low speed/center differential lock mode, and the switching lever 62 is moved to the upper 2-wheel drive/high-speed mode 2H (4-wheel drive/high speed/center differential free mode position). 1ff48F), it is configured to switch to a two-wheel drive mode or a four-wheel drive/high speed/center differential free mode in accordance with the switching operation of the 2/4 changeover switch 68.

Front wheel side and rear wheel side output of the above transfer device 9 @1
2.13 are connected to the front and rear differential mechanisms 5.6 through propeller shafts (not shown), respectively. As shown in enlarged detail in FIG. 3, the front differential mechanism 5 includes a housing 69 and a transfer mechanism M9 supported by the housing 69.
It has an input shaft 70 connected to the front wheel side output shaft 12 of the , and axle shafts 71.71 as output shafts connected to the left and right front wheels 7.7, for example, the right side (upper side in the figure).
The axle shaft 71 is located on the outer extension line of the axle shaft 71.
A joint shaft 72 connecting the front wheel 7 and the right front wheel 7 is arranged concentrically. Axle of this joint shaft 72 @
A small-diameter portion 72 having a smaller diameter than other portions is provided opposite to 71.
a is formed, while the outer end of the axle shaft 71 (
A large-diameter portion 71a having a larger diameter than other portions is formed in the right end portion), and a fitting recess 71bIfi into which the tip of the small-diameter portion 72a of the joint shaft 72 is relatively rotatably fitted is formed on the end surface of the large-diameter portion 71a. It is provided. In addition, the axle shaft 7
A spline southern portion 71G is formed on the outer periphery of the large diameter portion 71a of the joint shaft 72, while a spline tooth portion 73a corresponding to the spline tooth portion 71G of the axle shaft 71 is formed on the outer periphery of the small diameter portion 72a of the joint shaft 72. A spline member 73 is fixed to rotate integrally. Further, a sleeve 74 is spline-coupled to the outer peripheral spline tooth portion 73a of the spline member 73 and the spline tooth portion 71b of the axle shaft 71 so as to be able to slide between the spline portions 71b and 73a. By switching the spline member 73 and the spline tooth portions 73a, 71b of the axle shaft 71 into a meshing state or a non-meshing state, the differential mechanism 5 and the front wheels 7.7 are connected to enable power transmission or the power transmission is interrupted. It is done like this.

A fork 75 is movably locked to the sleeve 74, and the fork 75 is fixed to one end (left end) of a shift rod 76 that is slidable in the same direction (left and right) as the sleeve 74. , the other end of the shift iron door 6 (
Right end) is the diaphragm device 77 as an actuator.
is connected to. This diaphragm device 77 includes a diaphragm 78 connected to the shift rod 76, and first and second diaphragms defined by the diaphragm 78.
As shown in FIG. ), and the intake negative pressure is introduced therein. Further, a 7-way solenoid valve 83 and a lock solenoid valve 84 with a normal R leap are disposed in the negative pressure passages 81 and 82, respectively, and the axle shaft 71 is controlled by opening/closing control of these solenoid valves 83 and 84.
and the joint shaft 72, and when the free solenoid valve 83 is opened, the free solenoid valve 83 is connected to the right axle shaft 71 connected to the front differential mechanism 5 and the right front wheel 7. The connection with the joint shaft 72 is cut off, and the front wheel 7.7 (idling wheel)
By rotating only the side gears and binions (none of which are shown) of the differential mechanism 5 when the front wheels 7 and 7 rotate, the rotation of the front wheels 7 and 7 is prevented from being transmitted to the transfer device 9, thereby creating a free state. (unlocked state), and conversely, lock solenoid pulp 8
4, a freewheel device 85 is constructed in which the axle shaft 71 and the joint shaft 72 are rotationally connected and locked.

In addition, in FIG. 3, 86a is the freewheel device 85.
A freewheel lock detection switch 86b similarly detects that the freewheel device 85 is in a free state (unlocked state) based on the movement position of the shift rod 76. This is a freewheel free detection switch, and these two switches constitute freewheel state detection means 87. Although not shown, two freewheel lock detection switches 86a are provided.

1 for controlling the drive mode switching mechanism 32! dynamic motor 36
and freewheel device 851. Both solenoid pulps 83 and 84 for IJ use are operated by a controller 88 having a built-in CPU as shown in FIG.

This controller 88 includes the three types of detection switches 3 mentioned above.
7.86.87 and the transfer switching operation device 6
The respective output signals from the center differential changeover switch 66 and the 2/4 changeover switch 68 are input.

Further, connected to the controller 88 are a buzzer device M89 that notifies the driver of the switching of the drive mode by sounding, and a lighting display device 190 that indicates by lighting a lamp. The lighting display device 90 is, for example, a four-wheel drive display lamp 91 disposed on the instrument panel.
(4WD lamp), center differential display lamp 92 (C/D
lamp).

The deceleration mechanism 14 has a high/low speed indicator lamp 93 (H/1 lamp), and the four-wheel drive indicator lamp 91 lights up in four-wheel drive mode and turns off in two-wheel drive mode, and also has a center differential indicator lamp. 92 is set to be lit in the center differential lock mode and turned off in the free mode, and a high/low speed indicator lamp 93 is set to be lit in the low speed mode and turned off in the high speed mode.

The controller 88 constitutes a control means in the present invention, and the operation control procedure for the motor 36, solenoid valves 83, 84, buzzer device 89, and lighting display device 90 will be described below in FIGS. 11 to 16. This will be explained using a flowchart.

Figure 11 shows the main routine. Immediately after the ignition switch is turned on, the step SO
Initial setting is performed in this section. That is, when the ignition switch is turned on, the output signal from the center differential changeover switch 66, the output signal from the freewheel lock detection switch 86, and the output signal from the freewheel free detection switch 87 are read out in step S1. Next, in step S2, it is determined whether or not the center differential changeover switch 66 is in the ON state, and if YES, the transition is made to a subroutine for switching from the two-wheel drive mode to the four-wheel drive/center differential lock mode shown in steps 821 to S25, which will be described later. After this is executed and the driving state of the vehicle is changed to a four-wheel drive/center defroster state, the process proceeds to step 81G.

On the other hand, if the determination in step $2 is No, it is determined in the next step S3 whether or not the freewheel device 85 is in a free state. If this determination is YES, in the next step S4, the motor 36 is energized to rotate in a direction (direction that moves the sleeve 31 of the CW force direction drive mode switching mechanism 32 forward), and in the next step S5 In step S6, the output signal from the mode detection switch 37 is read out, and in step S6, it is determined whether the sleeve 31 of the drive mode switching device 32 has been switched to the two-wheel drive mode position P2. After repeating steps 84 to S6 and setting the vehicle drive state to two-wheel drive state 2H, the process proceeds to step 81G.

Further, if the determination in step S3 is NO, the process moves to step S7, and the motor 36 is instructed to rotate in the CCW direction (the direction in which the sleeve 31 of the drive mode switching mechanism 32 is moved clockwise). Power is applied, and in the next step S8, the output signal from the mode detection switch 37 is read out, and in step S9, the sleeve 31 of the drive mode switching mechanism 32 is set to the four-wheel drive/center differential free position 1ip4F.
After repeating steps 87 to S9 until the determination becomes YES and setting the vehicle drive state to the four-wheel drive/center differential free state 48F,
Proceed to the next step 810.

In this step S10, the four-wheel drive indicator lamp 91 (4WD lamp), the center differential indicator lamp 92 (C/D lamp), and the altitude indicator lamp 93 of the lighting display device 90 are
(H/L lamps) are lit as shown in Table 1 below to display the current drive mode to the driver.

When the initial setting is completed in this way, in step 811, the center differential changeover switch 66
and each output signal of the 2/4 changeover switch 68,
Next, in step 812, the drive mode to which the current drive mode is to be changed is determined from the operating states of these switches 66, 68 based on Table 2 below, and then step 813
The process moves to each switching subroutine shown in 337 to 337.

(Left below) Table 1 Table 2 Each of the above subroutines will be explained. FIG. 12 shows the flow of the switching subroutine when switching from the two-wheel drive mode 2nd to the center differential free four-wheel drive/high-speed mode 4HF. In this flow, first step 8
In step 13, the buzzer device 89 is made to sound for, for example, 100 m seconds, and in the next step 314, the four-wheel drive indicator lamp 91 in the lighting indicator bag @90 is blinked. This blinking is performed, for example, in a blinking mode in which the ratio of the lighting time is greater than the turn-off time, and this blinking mode indicates to the driver that the mode is in the middle of switching from the two-wheel drive mode to the four-wheel drive mode. After this, proceed to step S15,
The motor 36 is operated in the CCW direction (drive mode switching mechanism 32
The sleeve 31 is energized to rotate in the forward movement direction), and the drive mode switching mechanism 32 is switched from the rear two-wheel drive position P2 to the front and rear intermediate four width sides! Fill/center differential lock position P4L to lock center differential 22. After that, in step 816, the drive mode switching mechanism 3
Steps 315 and 316 are repeated until the determination becomes YES. . If the determination is YES, in step S11, an ON signal is output to the lock solenoid valve 84 to lock the freewheel device 85. After that, in step 818, the freewheel device 85 is activated based on the output signal of the freewheel lock detection switch 86.
It is determined whether or not the is actually in the locked state, and steps 317 and 318 are repeated until this determination becomes YES. If the determination is YES, in step 819, the motor 36 is energized again to rotate in the CCW direction, and the drive mode switching mechanism 32 is switched from the 4-wheel drive/center differential lock position fiP4L to the front 4-wheel drive/ The center differential is switched to the free position P4F, and the center differential 22 is placed in a free state. After that, in step 820, the drive mode switching mechanism 32 actually changes the four-wheel drive center differential free position P4 based on the output signal of the mode detection switch 37.
It is determined whether or not the drive mode has become 4-wheel drive/high speed/center differential free mode 48F, and steps 819 and 820 are performed until this determination becomes YES.
is repeated, and when the determination becomes YES, the process ends.

FIG. 13 shows the flow of the switching subroutine when switching from the two-wheel drive mode 2nd to the four-wheel drive mode 48L with center differential lock. In this flow, first, in a first step 321, the four-wheel drive indicator lamp 91 and the center differential indicator lamp 9 are located at the lighting display position 90.
2 blinks in the same manner as above, and then steps 822 to 825 similar to steps 815 to 818 in the subroutine described above are executed. That is, step 822
In step 823, the motor 36 is energized to rotate in the CCW direction to lock the center differential 22. Next, in step 823, based on the output signal of the mode detection switch 37, the drive mode is set to 4-wheel drive/ It is determined whether the high speed/center differential lock mode 4HL is reached, and steps 822 and 823 are repeated until this determination becomes YES. If the determination is YES, an ON signal is output to the lock solenoid valve 84 in step S24 to lock the freewheel device 85, and then step S24 is performed.
25, based on the output signal of the freewheel lock detection switch 86, it is determined whether the freewheel device 85 is actually in the locked state, and this determination is YE.
While repeating steps 824 and 825 until S,
When the determination becomes YES, the control is ended.

Also, Figure 14 shows four-wheel drive mode 4 with center differential lock.
The flow of the switching subroutine when switching from HL to center differential free four-wheel drive mode 48F is shown. In this flow, first, in the first step 826, the center differential display lamp 92 is blinked, and then the process proceeds to step 827, in which the motor 36 is energized to rotate in the CCW direction, and the drive mode switching mechanism 32 is turned on and off. 4
Switch from wheel drive/center differential lock position 11P4L to four-wheel drive/center differential free position 4P4F on the front side,
The center differential 22 is set in a free state. Then, in step 828, it is determined whether the drive mode is 4 wheel drive/high speed/center differential free mode 48F, and steps 827 and 328 are repeated until the determination becomes YES, and the process ends when the determination becomes YES. .

Further, FIG. 15 shows the flow of a switching subroutine when switching from the center differential free four-wheel drive mode 48F to the center differential lock four-wheel drive mode 48L, contrary to the above. In this flow, the first step 829
, the center differential display lamp 92 is blinked,
In the next step S30, the motor 36 is energized to rotate in the direction in which the sleeve 31 of the CW force direction drive mode switching mechanism 32 moves backward), and the drive mode switching mechanism 32 is switched to the 4-width side! II/ 4 width side 1 behind center differential free position p4F! ! l/center differential lock position P
Switch to 4L and lock the center differential 22.

Then, in step 831, it is determined whether the drive mode is 4 wheel drive/'B speed/center differential lock mode 4HL, and step 831 continues until this determination becomes YES.
30 and 331 are repeated, and when the determination becomes YES, the process ends.

Also, Figure 16 shows center differential free four-wheel drive mode 4.
The flow of a switching subroutine when switching from 8F to two-wheel drive mode 2H is shown. In this flow, in the first step 332, the buzzer device 89 is
After blowing for 00 m seconds, in the next step 833,
Four-wheel drive indicator lamp 91 at the lighting display position 90
flash. This blinking is performed in the opposite manner from the above-mentioned 2-wheel drive mode to 4-wheel drive mode, for example, in a blinking form in which the ratio of the off time is greater than the on time.
Displays to the driver that the mode is being switched from wheel drive mode to two-wheel drive mode. After that, in step S34, the motor 36 is energized to rotate in the CW force direction, and the drive mode switching mechanism 32 is switched from the front end 4-wheel drive/center differential free position P4F to the intermediate 4-wheel drive/center differential lock position P4L. After that, the rear end two-wheel drive position P? move it towards.

Then, in step 335, the drive mode switching mechanism 32 is actually switched to the two-wheel drive position P2 based on the output signal of the mode detection switch 37, and the drive mode is changed to two-wheel drive/high speed mode 2H. Determine whether the
Step 83 until this determination becomes YES.
Repeat steps 4 to 835. If the determination is YES, an ON signal is output to the free solenoid pulse 83 in step 836 to set the freewheel device 85 in a free state. Thereafter, in step 837, it is determined whether or not the freewheel device 85 is actually in the °free state based on the output signal of the freewheel lock detection switch 86, and until this determination becomes YES, step 837 is performed.
36. Repeat 837. When this determination becomes YES, the control ends.

By the way, the feature of the present invention is that when the mode detection means 37 fails, the controller 88 detects this and thereafter changes the drive mode switching mechanism 32 to the first
The purpose is to control the operation according to the mode detection means failure subroutine shown in FIG.

At this time, the controller 88 detects a failure in the mode detection means 37 based on an abnormality in the output signal outputted from the mode detection means 37. That is, as mentioned above, if the three switches A, B, and C are normal, the output signal from the mode detection means 37 is always the ON output signal from them A→ABHB←
It is designed to change sequentially between BC←C. Therefore, if ON output signals of combinations other than these are output, or if the ON output signals do not change in the above order, the controller 88 can thereby detect that a failure has occurred in the mode detection means 37. When this failure is detected, the controller 88 immediately executes the following mode detection means failure subroutine regardless of the output signal from the switching device 61.

When control first flows to this subroutine, in the first step 338, it is determined whether or not the freewheel device 85 is in the locked state based on the output signal from the freewheel state detection means 87.

If this determination is YES, the next step S39
Then, the motor 36 is energized and rotated in the CCW direction, thereby moving the mode switching mechanism 32 toward the four-wheel drive/center differential free mode position P4F. Then, in the next step 349, the limit switch provided in the motor 36 (this limit switch is turned on when the load resistance of the motor 36 becomes excessive and its rotation is stopped) is turned on. Determine whether it is turned on,
Steps 839 and 840 are repeated until this becomes YES.

After this, when the determination in step S40 becomes YES, the timer is reset to T=O in the next step 341 to start measuring time, and the motor 36 is further continued to rotate in the CCW direction in the next step S42. Thereafter, in the next step 843, it is determined whether the limit switch is turned on.

If this determination is No, that is, if the motor 36 has started rotating again, the drive mode switching mechanism 32 has not been moved to the end of its movement position, so the control is returned to step 839 and thereafter Step 839
-343 are repeated.

Furthermore, if the determination in step 343 is YES,
That is, if the rotation of the motor 36 remains stopped, it is determined in the next step S44 whether or not the measured time T has passed a predetermined time 1, for example, 30 seconds.

If the determination in step S44 is No, the control returns to step 842 and steps 842 to 344
repeat. On the other hand, the determination at step 844 is Y.
When ES is reached, that is, the motor 36 is stopped rotating even though it is energized for a predetermined period of time (30
seconds), it is determined that the drive mode switching mechanism 32 has been moved to the end of its movement position and positioned at the 4-wheel drive/center differential free mode position P4F, and in the next step 845 the 4-wheel drive indicator lamp 91 is turned on. It blinks and continues to maintain this state from now on.

Therefore, when a failure of the mode detection means 37 is detected, the freewheel device 85
is in the locked state, the drive mode switching mechanism 32
Forces 4-wheel drive center differential free mode fip4
The vehicle is moved to F, and the vehicle drive state continues to be maintained in the four-wheel drive/center differential free state, and at this time, the four-wheel drive display lamp 91 continues to flash to notify the driver that a wandering problem has occurred. It turns out.

On the other hand, if the determination in step 838 is NO, that is, if the freewheel device 85 is in the free state when the failure of the mode detection means 37 is detected, the control is transferred to step 346 and the steps 839 to 839 described above are performed. Almost the same control as the control up to S44 is performed from step 34B to step 350. Note that this step 3
The control from 46 to 850 is the same as steps 39 to 344 above.
What is different from the previous control is step 846 and step 8.
48 and B, the direction of energization to the motor 36 is reversed, and the drive mode switching mechanism 32 is set to the two-wheel drive mode position P2.
Since the only point is that the switch is switched and moved toward , a detailed explanation thereof will be omitted.

Then, if the determination in step S50 is YES, that is, even though the motor 36 is energized to rotate in the CW force direction, its rotation has been stopped for a predetermined time (30 seconds). Then, the controller 88 determines that the drive mode switching mechanism 32 has been moved to the end of its movement position and is positioned at the two-wheel drive position P2, and in the next step S52, the drive mode switching mechanism 32 is switched based on the output signal from the center differential switch 66. It is determined whether the lever 62 is in the four-wheel drive/low speed/center differential lock mode position 411. If YES, the buzzer device 89 is sounded in the next step S53 to warn the driver with a caution sound, and the process returns to step 353.Even if the answer is NO, the process returns to step S53, and from this point on, the switching lever 62 is set to 4. Wheel drive/
A caution sound is emitted as soon as the mode is switched to low speed/center differential lock mode position 4LL. Note that the caution sound is generated when the vehicle is erroneously switched to the low-speed mode while the vehicle continues to be in the two-wheel drive state regardless of the switching position of the switching lever 62. This is because the torque transmitted to the power transmission system on the side of the rear wheels 8, which is constantly being driven, becomes excessive and may cause damage to the power transmission system.

Therefore, when a failure of the mode detection means 37 is detected, the freewheel device 85
is in the free state, the drive mode switching mechanism 32
is forcibly moved to the two-wheel drive mode 1iffP2, and the vehicle continues to be driven in the two-wheel drive state, and when the switching lever 62 is switched to the low speed mode at this time, the vehicle is driven with a caution sound. The person will be notified.

Note that when the drive mode switching mechanism 32 is forcibly switched to the 2-wheel drive mode position iP2 and to the 4-wheel drive/sender differential free mode position P4F, the rotation of the motor 36 must be stopped for a long time of 30 seconds or more. The purpose of detecting and confirming this is to take into account the possibility that the drive mode switching mechanism 32 may temporarily stop moving during its movement due to some reason, such as a temporary drop in motor voltage. It is something.

Furthermore, as described above, two freewheel lock detection switches 86a are provided, and unless the output signals from these switches are both in the ON state, switching from the two-wheel drive state to the four-wheel drive state will not be accepted. In this way, the certainty of safety is increased.

(Effects) In summary, according to the present invention, when the drive mode detection means fails, the control means detects the output signal of the freewheel state detection means other than the output signal from the drive mode detection means. From this point on, the drive mode switching mechanism is forced to the two-wheel drive mode position or the four-wheel drive/center differential free mode position, regardless of the output signal from the operating means, depending on the free state or locked state of the freewheel device. Since the drive mode of the vehicle is continuously maintained in the two-wheel drive state or the four-wheel drive/center differential free state by the switching operation, the drive mode switching mechanism can be appropriately switched even if the drive mode detection means fails. be able to.

[Brief explanation of the drawing]

Figures 1 to 17 show embodiments of the present invention. Figure 1 is a schematic side view of a four-wheel drive vehicle, Figure 2 is a schematic diagram showing the overall configuration of the control device, and Figure 3 is a free wheel drive vehicle. 4 is a sectional view of the transfer device, FIG. 5 is a sectional view of the missing swing mechanism, FIG. 6 is a sectional view of the control rond positioning mechanism, and FIG. 7 is the arrangement of the transfer switching operation system. A front view showing the state, FIG. 8 is an enlarged view of the 2/4 changeover switch mounting part, FIG. 9 is a sectional view of the center differential switching detection device, FIG. 10 is a sectional view taken along the line X-X in FIG. 9, and FIG. Figure 12 is a flowchart showing the main routine of the controller, Figure 12 is a flowchart showing the subroutine for switching from two-wheel drive mode to four-wheel drive mode with center differential free, and Figure 13 is a flowchart showing the subroutine for switching from two-wheel drive mode to four-wheel drive mode with center differential lock. FIG. 14 is a flowchart showing a subroutine for switching to wheel drive mode; FIG. 14 is a flowchart showing a subroutine for switching from center differential lock 4-wheel drive mode to center differential free mode; FIG. 15 is center differential free 4-wheel drive mode A flowchart diagram showing a subroutine for switching from the drive mode to the center differential lock mode, Figure 16 is a flowchart diagram showing a subroutine for switching from the center differential free four-wheel drive mode to the two-wheel drive mode, and Figure 17 is a flowchart diagram showing the subroutine for switching from the center differential free four-wheel drive mode to the two-wheel drive mode. FIG. 18 is a flowchart showing a subroutine at the time of the transfer, and FIG. 18 is a diagram showing a conventional transfer device. 2...Engine 7...Front wheel 8, which is the idle wheel side...Rear wheel 9, which is the constantly driven wheel side...Transfer equipment and 22...Center differential 32...Drive mode switching mechanism 36...・Motor 37...Drive mode detection means 61...Transfer switching operation device 85...Freewheel device 87...Freewheel state detection means 88...Controller as control means Fig. 15 Fig. 816 Old drawing Procedural amendment (method) February 25, 1988 Patent Application No. 271701 2, Title of invention Drive mode switching control device for four-wheel drive vehicle 3, Person making the amendment Relationship to the case Patent applicant residence Address: 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima
Mazda Corporation 4, Agent address: 7th Floor 5, Rokin Shinbashi Building, 2-12-7 Shinbashi, Minato-ku, Tokyo; date of amendment order: January 26, 1988 (dispatch) 6. Subject of amendment ( 1) Drawing 7, contents of amendment (1) As per the engraving and attached sheet of drawing No. 4 originally attached to the application (no change in contents)

Claims (1)

[Claims] The drive mode of a transfer device having a center differential is switched to 2-wheel drive, 4-wheel drive/center differential lock, and 4-wheel drive/center differential free mode.
A clutch gear-type drive mode switching mechanism that passes through the 4-wheel drive/center differential lock mode during switching between wheel drive/center differential free mode and the actual switching position of the drive mode switching mechanism is detected. a drive mode detection means, and a freewheel device that switches an idle wheel side in a two-wheel drive state between a free state and a locked state with respect to a power transmission system from the transfer device, and that switches the idle wheel side in a two-wheel drive state to a locked state in a four-wheel drive state. a freewheel state detection means for detecting a free state and a locked state of the freewheel device; an operating means operated by a driver to select the drive mode; the operating means and the drive mode detection means; The operation of the drive mode switching mechanism and the freewheel device is controlled based on the output signal from the freewheel state detection means, and when an abnormality is detected in the output signal from the drive mode detection means, the operation means control means for switching the drive mode switching mechanism to a two-wheel drive mode position or a four-wheel drive/center differential free mode position in response to an output signal from the freewheel state detection means with priority over an output signal from the freewheel state detection means; A drive mode switching control device for a four-wheel drive vehicle, comprising: