JP2762419B2 - Center differential lock switching control device for four-wheel drive vehicle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a four-wheel drive vehicle having a center differential, and more particularly to a center of a four-wheel drive vehicle in which the center differential can be switched to a free state or a locked state by an actuator. The present invention relates to a differential lock switching control device.

(Prior Art) In a four-wheel drive vehicle in which the front wheels and the rear wheels are driven by the engine output, the front wheel at the time of cornering,
In order to absorb the difference in rotational speed between the rear wheels and realize smooth cornering traveling, one input element to which engine output is input and the input to this input element are divided and output to the front and rear wheel sides, respectively. There is a case where a differential device called a center differential including two output elements is provided.

In addition, when such a center differential is provided, when one of the front wheel and the rear wheel slips, the driving force is not transmitted to the other, so that the differential operation of the two output elements is prevented to prevent the front and rear wheels from moving. In some cases, the center differential can be locked so as to transmit the driving force evenly to the wheels. In this case, a switching mechanism for switching the center differential between a free state and a locked state is provided.

Further, there is a case where transmission of the driving force from one output element of the center differential to the front wheel or the rear wheel can be interrupted to switch to the two-wheel drive state. In this case, the four-wheel drive state and the two-wheel drive state are provided. A state switching mechanism is provided.

Such a center differential free, lock switching and 2
As a switching mechanism for switching between wheel drive and four-wheel drive, for example, there is a mechanism disclosed in Japanese Utility Model Laid-Open No. 60-127232. This means that the sleeve that is slid in the axial direction is provided with a two-wheel drive position for interrupting the transmission of driving force from one output element of the center differential to the front wheel or the rear wheel, and a differential operation of the two output elements of the center differential. It is configured to be able to take three positions of a four-wheel drive device of a center differential lock for blocking and a four-wheel drive position of a center differential free for allowing a differential operation between the output elements. In order to improve the operability of the switching operation, there has been known an operation in which the sleeve is operated by an actuator in accordance with a driver's selection.

(Problems to be Solved by the Invention) By the way, in the case where the sleeve of the switching mechanism is operated by the actuator as described above, the switching mechanism may not operate smoothly for some reason, so that the actuator may be overloaded. Therefore, it is possible to protect the actuator by providing an operation force setting means for setting the operation force by the actuator and stopping the operation of the actuator when a load exceeding the operation force set by the means is applied. It is considered. However, in this case, when the sleeve is operated to slide to the position at the stroke end, the actuator continues to operate by inertia even though the sleeve has reached this position, and the operation of the actuator is When the force, that is, the load, exceeds the value set by the operating force setting means, and as a result, the operation of the actuator is stopped, and then the sleeve is operated in the opposite direction from the position at the end of the stroke, And the operation becomes impossible.

On the other hand, the operation force set by the operation force setting means is set to a relatively small value so that an overload due to inertia force does not act on the actuator at the stroke end position at the time of operation to the position. However, in such a case, there is a possibility that the operation force is insufficient at the time of the operation in the opposite direction from the position of the stroke end, so that reliable and quick operation cannot be performed.

Therefore, an operating force varying means capable of changing the operating force of the actuator is provided, and when the sleeve is operated to the stroke end position, the operating force is reduced to a small value, and when the sleeve is operated from the position in the opposite direction, the operating force is increased. It could be set to a value,
Even in this case, when operating from the stroke end position to another position, particularly when the other position is a position for locking the center differential, the operation force is large, so the center differential is locked rapidly. This causes a problem that a switching shock occurs.

The present invention addresses the above-described problem in a four-wheel drive vehicle provided with a switching mechanism operated by an actuator. In particular, the present invention relates to locking and free switching operations of a center differential, and performs the switching operation reliably and quickly. It is another object of the present invention to suppress the occurrence of the switching shock.

(Means for Solving the Problems) In order to solve the above problems, the present invention is characterized in that it is configured as follows.

That is, the center differential lock switching control device for a four-wheel drive vehicle according to the present invention has one input element and two output elements, and divides the input from the engine and outputs it to the front wheel side and the rear wheel side, respectively. A center differential, switching means for switching the center differential between a free state permitting the differential operation between the two output elements and a locked state preventing the differential operation, an actuator for switching the switching means, and the actuator In the four-wheel drive vehicle having an operating force varying means for changing the switching operating force of the center differential, the free position of the center differential is set at the stroke end of the switching means, the lock position is set on the opposite side, and the center differential is When switching from the locked state to the free state, the operating force by the actuator is set to a small value, The switching to, increase its initial operating force, then to reduce the operating force, characterized in that a control means for actuating the operating force variation means.

(Operation) According to the above configuration, when the center differential free position is provided at the stroke end of the switching means, the operation force is set to a small value at the time of the switching operation from the center differential lock position to the free position. When the actuator is moved to the free position, an overload due to inertial force is prevented from acting on the actuator. On the other hand, at the time of the switching operation from the center differential free position at the stroke end to the lock position, the operation force is set to a large value in the initial stage of the switching, so that this operation is performed reliably and quickly, and thereafter the operation force is reduced. Since the value is changed to a small value, switching to the center differential lock position is performed smoothly, and switching shock is suppressed.

(Examples) Hereinafter, examples of the present invention will be described.

First, a schematic configuration of a four-wheel drive vehicle according to the present embodiment and a control system thereof will be described with reference to FIG.

The four-wheel drive vehicle is provided with a transfer device 10 to which an engine output is input via a transmission (not shown). The transfer device 10 has a first output shaft 11 protruding forward and a protruding rearward. A second output shaft 12 is provided. The first output shaft 11 includes a propeller shaft 13 and a front wheel differential device 14.
The vehicle also reaches the front wheels via left and right front axles 15 and 16, and, though not shown, the second output shaft 12 also reaches the rear wheels via a propeller shaft, a rear wheel differential, and left and right rear axles.

As will be described later, the transfer device 10 includes, as main components, an auxiliary transmission 20, a center differential 30, and a switching device 40 (see FIGS. 2 and 3). The transfer device 10 includes a two-wheel drive state in which the power from the auxiliary transmission 20 is transmitted only from the second output shaft 12 to the rear wheel side, and a two-wheel drive state in which the first and second output shafts 11 and 12 It is possible to switch between a four-wheel drive state that outputs to the rear wheel side.
In the wheel drive state, the center differential 30 is differentially operated to allow a difference in rotational speed between the front and rear wheels to be allowed. Switching to a center differential lock state in which driving is performed uniformly can be performed, and these switchings are performed by the switching device 40.

Further, the front wheel differential device 14 is provided with a freewheel device 50 for connecting and disconnecting the transmission of power to one of the front axles 16, and is provided with a negative pressure type actuator 51 for driving the device 50. The actuator 51 includes first and second actuators.
By opening and closing the control valves 52 and 53, a negative pressure is introduced from one of the first and second negative pressure passages 54 and 55 to connect or disconnect the freewheel device 50.

The four-wheel drive vehicle includes the transfer device
A controller 60 for controlling the operation of the switching device 40 and the freewheel device 50 in 10 is provided.
Reference numeral 60 designates a signal a from a switch (2-4 changeover switch) 61 for switching between two-wheel drive and four-wheel drive, which is operated by the driver, and a switch for switching between locking and free of the center differential (center differential switch). Signal b from 62
And a signal c from a position switch or a limit switch for detecting the state of the switching device 40, and a signal d from a sensor 63 for detecting the state of the freewheel device 50. Control signals e, f, and g are output to the actuator of the switching device 40 and the first and second control valves 52 and 53 that drive the actuator 51 of the wheel device 50, respectively.

Next, the structure of the transfer device 10 will be described with reference to FIGS.

As described above, the transfer device 10 includes the sub-transmission 20 that is input after the engine output is reduced by the transmission according to the shift speed, and outputs the output of the sub-transmission 20 to the front wheel side and the rear wheel side. And a center differential 30 that is divided into

Of these, the auxiliary transmission 20 has a transmission output shaft 21 connected to a sun gear by a switching sleeve 22 as schematically shown in FIG.
23 or a planetary gear mechanism selectively connected to the pinion carrier 24. Since the ring gear 25 of the planetary gear mechanism is fixed and the pinion carrier 24 is connected to the intermediate shaft 26 that transmits power to the center differential 30, the transmission output shaft 21 is connected to the pinion carrier as shown by the solid line. When connected to 24, the rotation of the shaft 21 is transmitted to the intermediate shaft 26 as it is,
When the transmission output shaft 21 is connected to the sun gear 23, the rotation of the shaft 21 is reduced and transmitted to the intermediate shaft 26.

The center differential 30 is also formed of a planetary gear mechanism, the intermediate shaft 26 is connected to the pinion carrier 31 of the planetary gear mechanism, and the ring gear 32 is connected to the second output shaft 12 that outputs power to the rear wheels. Have been. The sun gear 33 of the planetary gear mechanism is provided with a clutch mechanism 41 constituting the switching device 40 and the intermediate shaft 26.
The first output shaft 11 is connected to the first output shaft 11 via a driving sprocket 71, a chain 72, and a driven sprocket 73 that constitute a chain type transmission mechanism provided between the first output shaft 11 and the first output shaft 11. ing.

On the other hand, the switching device 40 includes the above-described clutch mechanism 41, an operation mechanism 42 for operating the clutch mechanism 41, a motor 43 as an actuator, and an operation force setting mechanism 44 for setting an operation force by the motor 43. .

Of these, the clutch mechanism 41 is connected to the center differential 30.
Clutch hub connected to the extension of sun gear 33 at
81, a first clutch gear 82 provided integrally with the ring gear 32, and a second clutch gear 83 provided integrally with the driving sprocket 71 of the chain type transmission mechanism. And a switching sleeve 84 fitted with splines. In this embodiment,
A synchronizer ring 85 for synchronizing the rotation between the clutch hub 81 and the second clutch gear 83 is provided.
Is interposed.

Here, the switching sleeve 84 in the clutch mechanism 41
First, when the sleeve 84 is located at the left stroke end in the drawing, the center hub is connected to the clutch hub 81 and the second clutch gear 83 when the sleeve 84 is located at the left stroke end in the drawing. The thirty sun gears 33 are connected to the driving sprocket 71 of the transmission mechanism. This allows
The center differential 30 has a sun gear 33 which is one of the output elements.
Are connected to the front wheels from the first output shaft 11 and the ring gear 32, which is the other output element, to the rear wheels from the second output shaft 12, respectively, to transmit the power input from the pinion carrier 31 to the front and rear wheels, respectively. In addition to the four-wheel drive state, in this case, the relative rotation between the sun gear 33 and the ring gear 32 is allowed, and a center differential free four-wheel drive state in which a rotational speed difference between the front and rear wheels can be generated ( Hereinafter, written as 4WF).

Further, from this state, at the stroke intermediate position where the sleeve 84 has been slid to the right by a predetermined amount in the drawing, the sleeve 84 allows the clutch hub 81 and the first and second clutch gears 82 and 83 on both sides thereof to be moved. Are coupled to each other, the power input to the pinion carrier 31 of the center differential 30 is output from the sun gear 33 to the front wheel side, and from the ring gear 32 to the rear wheel side, as in the case described above.
In this case, the front and rear wheels are driven in a four-wheel drive state. In this case, the sun gear 33 and the ring gear 32 are coupled to each other, so that their differential operation is prevented, and the front and rear wheels are evenly distributed. Center differential lock driven 4 wheel drive state (hereinafter 4W
L).

Further, from this state, when the sleeve 84 slides to the right in the drawing and is positioned at the right stroke end as shown by the solid line in FIGS. 2 and 3, the sleeve 84 is moved to the clutch hub 81 and the first clutch gear 82. The clutch hub 81 and the second clutch gear 83 are disengaged from each other. Therefore, the transmission of power from the center differential 30 to the first output shaft 11 or the front wheel side is cut off while the center differential 30 is locked, whereby the two-wheel drive in which power is transmitted only to the rear wheel side. State (hereinafter referred to as 2W).

Further, an operating mechanism 42 for operating the clutch mechanism 41,
A cylindrical cam 91 rotated by the motor 43 via the operating force setting mechanism 44, a shift rod 93 having a follower 92 engaged with a cam groove 91a of the cam 91, and a shift rod 93 fixed to the shift rod 93. The clutch mechanism 41 includes a shift fork 94 engaged with a switching sleeve 84. The rotation of the cylindrical cam 91 by the motor 43 causes the switching sleeve 84 to slide between the left and right stroke ends and the intermediate position via the shift rod 93 and the shift fork 94 as described above.

Next, the operation force setting mechanism 44 in the switching device 40 will be described with reference to FIGS.

The operating force setting mechanism 44 includes a drive gear 102 made of an insulator meshed with a gear 101 on a rotating shaft of the motor 43, and a reduction gear 1 which is arranged coaxially with the gear 102 and opposed to each other.
The gear 105 on the rotation shaft 91b of the cylindrical cam 91 via the gears 03 and 104
And a driven gear 106, which is also made of an insulator, is wound around a common shaft 107 of the driving gear 102 and the driven gear 106, and legs 108a, 108a at both ends of the driven gear
A coil spring 108 is engaged with a pair of pins 102a, 102a protruding from a surface facing the coil 106. Also, a pair of pins 106a, 106a is protrudingly provided on the surface of the driven gear 106 facing the drive gear 102, and is in contact with the legs 108a, 108a of the coil spring 108, respectively. When rotated, one of the legs 108a of the coil spring 108 pushes one of the pins 106a on the driven gear 106 side, so that the coil spring
The rotation is transmitted to the driven gear 106 via the elastic force of 108. At this time, the coil spring 108 bends according to the load on the driven gear 106 side, so that the driving gear 102 and the driven gear 106 rotate relative to each other by an amount corresponding to the load.

The first and second brushes 109 are provided on the surface of the drive gear 102 facing the driven gear 106 at different positions in the radial direction.
As shown in FIG. 6, a guide plate 110 which forms a limit switch with the brushes 109a and 109b is attached to an opposing surface of the driven gear 106, as shown in FIG. The guide plate 110 has a first cut having a small width corresponding to the radially outer first brush 109a around a neutral position where the brushes 109a and 109b are located when there is no relative rotation between the gears 102 and 106. A notch 110a and a wide second notch 110b centered on the neutral position and corresponding to the second brush 109b radially inward are provided, and the conductive plate 110 has a predetermined potential (power supply). (Positive potential or negative potential). Thereby, the first brush 10
9a and the first notch 110a, the operating force of the motor 43 corresponding to the relative rotation between the drive gear 102 and the driven gear 106 is not less than a first predetermined value P ₁ (for example, 40 kg). Conductive first limit switch 111 and second brush 1
09b and the second notch 110b, the second of which the operating force is larger than the second predetermined value P ₂ (for example, 80 kg) or more.
A limit switch 112 is configured.

Further, as shown in FIG. 4, a disk 113 made of an insulator is fixed to the rotating shaft 91b of the cylindrical cam 91, and the disk
3, three arcuate conductive plates 114a, 114b, 114c are adhered concentrically, and three brushes 115a, 115b, 115c are provided corresponding to these conductive plates, respectively. , That is, first to third position switches 116, 117, and 118 for detecting the position of the sleeve 84 in the clutch mechanism. As shown in FIG. 7, these position switches 116 to 118 are, depending on the combination of ON and OFF, at the 2W position at the right stroke end of the sleeve 84, the 4WL position at the stroke center, and the 4WF position at the left stroke end. It is possible to detect a total of five positions including three positions and first and second intermediate positions α and β between these positions.

The 2-4 changeover switch 61 shown in FIG. 1 is operated by a lever 120 provided near the steering wheel in the driver's seat as shown in FIG. 8, and the center differential changeover switch 62 is operated by the lever 120. Push button 12
1 is provided. Also, by operating the lever 120,
In the four-wheel drive state, the shift speed of the auxiliary transmission 20 is also switched.

Next, the switching control operation by the controller 60 shown in FIG. 1 will be described with reference to the flowcharts in FIG.

First, the main routine of this switching control operation will be described with reference to the flowchart of FIG.
In Step S ₁ after performing predetermined system initialization, in step S _2, S _3, the first to third position switch 116-118
, And compares the combination of ON and OFF indicated by these signals with the combination of ON and OFF for each preset position shown in FIG. Then, when none of the combinations actual combination is set, a fault in any of the position switch 116 to 118 is determined as occurring, the control of the position switch failure mode in step S ₄ Run.

Furthermore, the case shown that the signal from the 2-4 changeover switch 61 is switched from two-wheel drive state to the four-wheel drive state is performed, the clutch hub 81 in the clutch mechanism 41 in step S ₅ second Detects the state of synchronization with clutch gear 83,
When the synchronous operation is determined to have not been performed normally, executing the control of the synchronous failure mode from step S ₆ in step S _7.

When the failure and poor synchronization of position switch described above does not occur, performs normal switching control in step S _8.

The normal switching control is performed according to the flowchart of FIG. 10, first, the position switch 1 at step S ₁₁
Determines the current position of the switching sleeve 84 by a signal from 16 to 118, also a signal from 2-4 changeover switch 61 and the center differential changeover switch 62 in step S _12, the target to achieve the operation mode selected by the driver Judge the position.

Then, it sets the rotation direction and the operation force of the motor 43 in the switching device 40 in step S _13, S _14, step
In S _15, controls the driving of the motor 43 so that the resulting direction and the operating force by these setting operation.

Setting the rotational direction of the motor by the step S ₁₃ is first
The operation is performed as follows according to the flowchart of FIG.

First, immediately after power ON, it is determined whether or not at step S _21, the first in the next step S _22, S ₂₃ if immediately determines whether the second limit switch 111 is in the ON state. And if both limit switches are OFF,
Step S to 1 execution flag F _O at _24, if either one of the limit switches is ON, the setting the flag F _O 0 in step S _25.

Next, determining the value of the execution flag F _O in step S _26, performs the steps S ₂₇ following the rotating direction of the motor of the setting operation if F _O = 1.

That is, first in step S _27, S _28, whether the second limit switch 111 is in the ON state is determined again, the rotation permission flag F in step S ₂₉ in the case of OFF both limit switches in the X direction _AX and Y direction rotation permission flag F
Set both _AY to 0. Here, the X direction is the second direction.
The sleeve 84 in the clutch mechanism 41 shown in FIG.
This is a method of sliding from the right side to the left side, that is, in the direction of 2W → 4WL → 4WF, and the Y direction is the direction in which the sleeve 84 slides in the opposite direction.

Meanwhile, first, when at least one of the second limit switch 111 is in the ON state, performs the steps S ₃₀ from the step S ₂₇ or step S _28, the motor 43 is Y
The value of the Y-direction rotation flag F _Y indicating that the rotation is in the direction is determined. When F _Y = 1, that is, when the motor 43
1 when but that actually rotated in the Y direction, after confirming that the Y-direction of the rotary permission flag F _AY is 0 in step S _31, the rotation permission flag F _AX in the X-direction in the step S ₃₂
Set to. Further, when the Y-direction rotation flag F _Y = 0, to determine the value of the X-direction rotation flag F _X to indicate that the motor 43 is rotating in the X direction in step S _33, when the F _X = 1, that is, when the motor 43 is currently rotating in the X direction, the rotation permission flag F _AX of the X-direction at the step S ₃₄ 0
After confirming that it is set to 1 the rotation permission flag F _AY in the Y direction in step S _35. In this way,
With the motor 43 rotating in the X or Y direction,
When at least one of the first and second limit switches 111 and 112 is turned on, the rotation permission flag F _AX or F _AY for the direction currently rotating is reset to 0, on the condition that the direction is opposite. The rotation permission flag F _AY or F _AX for rotation is set to 1. This enables the rotation of the motor 43 in a direction in which the limit switches 111 and 112 are turned off, and also prevents the rotation in both directions from being permitted at the same time.

The operation force of the setting operation by the step S ₁₄ of the flowchart of FIG. 10 is carried out in accordance with the flowchart of Figure 12, first, X direction and Y direction of the operation force limitation flag F _IX in step S _41, the F _IY 1 Set to. Then, in step S _42, the second limit switch 112 is determined whether the ON, in the case of ON, the both operation force limitation flag F _IX,
Hold F _IY at 1. This second limit switch 112
When the operating force of the motor 43 is higher than the second set value P ₂ (80 kg)
Since the power is turned ON, when such a large operating force is generated, the power supply to the motor is stopped by a signal from the second limit switch 112, and an overload may be applied to the motor 43. Will be prevented. Also, if the second limit switch 112 is OFF, the first limit switch 111 is determined whether the ON in step S _43, in the case of OFF first limit switch 111, that is, the motor 43
If the operation force of is less than the first set value P ₁ (40Kg), step
At _S44 , the X and Y operation force restriction flags F _IX , F _IY
Are both reset to 0. Thereby, when both limit switches 111 and 112 are OFF, these switches 111 and 11
The signal from 2 is ignored, and energization of the motor 43 in the X and Y directions is permitted.

Furthermore, in the second limit switch 112 is OFF, if the first limit switch 111 is ON, i.e., the range the operating force of the motor 43 from the first set value P ₁ to a second set value P ₂ (40kg~
If there is to 80kg) is, is the current position in the step S ₄₅ 4WL
Position from the Y direction, i.e. 2W position or to determine whether either of the first intermediate position alpha, the operation force in the X direction in step S ₄₆ in the case of these positions limitation flag F
Reset _IX to 0. Also, the current position is above 4W
If not Y direction side of the L position, the current position is equal to or a 4WF position in step S _48, when in the 4WF position, operation force in the Y direction in step S ₄₉ limitation flag F _IY
Is reset to 0.

As a result, the ON signal from the first limit switch 111 is ignored at the 2W position and the first intermediate position α in the X direction, and 4
In the WF position, the ON signal from the first limit switch 111 is ignored, and in these positions, the operating force of the motor 43 is reduced to the second set value P ₂ (80 k
g) will be acceptable. In other positions, the operating force is limited by the first set value P ₁ (40 kg) at which the first limit switch 111 is turned on.

When the rotation direction and the operation force of the motor 43 as described above is set, the control of the motor in step S ₁₅ of the flowchart of FIG. 10 is performed, the control is first
The operation is performed as follows according to the flowchart of FIG.

In this control, first, in step _S51 , it is determined whether or not the current position matches the target position. If so, in step _S52 , the X-direction and Y-direction rotation flags F _X , F _Y Is reset to 0. That is, in this case, the motor 43 is not rotated.

On the other hand, if the current position does not coincide with the target position, the current position is equal to or in the X direction side of the target position in step S _53, when X-direction side, i.e. want to operate in the Y-direction If so, step S ₅₄
In the rotation flag F _X in the X direction on which is reset to 0, in step S ₅₅ is rotated permission flag F _AY in the Y-direction determines whether or not 1. Then, in the case of F _AY = 1, it is set to 1 the rotation flag F _Y in the Y direction in step S _56. Also, F _AY =
If 0, Y direction of the operation force restriction flag F in step S ₅₇
Determining the value of _IY, if F _IY = 0 in step S ₅₆ Y
1 the rotation flag F _Y directions, if F _IY = 1, is set to 0 the rotation flag F _Y in the Y direction in step S _58. In other words, at the time of operation in the Y direction, if the rotation of the motor 43 in that direction is permitted, the motor 43 is driven in that direction; otherwise, the first and second limit switches 111 and 112 are not permitted.
The motor 43 is driven or stopped in accordance with the state of (1).

If the current position is not on the X direction side of the target position, that is, if it is desired to operate in the X direction, step S
The disengagement state of the free wheel 50 shown in FIG. 1 determined in _59, when in the disconnected state is further present position in step S ₆₀ it is determined whether the Y-direction side of the 4WL position. If it is on the Y direction side of the 4WL position, that is, the 2W position or the first intermediate position α, the above-described step _{S54 is performed.}
Running to S _58, it stops the operation of the X-direction from the current position, the flag F _AY, depending on the state of the F _IY driving the motor 43 in the Y direction on the opposite side. This is to prevent switching from two-wheel drive to four-wheel drive while the freewheel device 50 is disconnected.

Then, when it is desired to operate in the X direction, if the freewheel device 50 is connected and the current position is at the 4WL position (or the X direction side from the position) even if the device 50 is disconnected, step S ₆₁ together resets the rotation flag F _Y in the Y direction 0, to determine the value of the rotation permission flag F _AX in the X direction in step S _62, X-direction in the step S ₆₃ if F _AX = 1 Of the rotation flag F _X is set to 1. In the case of F _AX = 0, to determine the value of the X direction of the operating force limitation flag F _IX in step S _64, the rotation flag F _X in the X direction in step S ₆₃ if F _IX = 0 to 1 sets the rotation flag F _X to zero in step S ₆₅ if F _IX = 1. Thus, similarly to the operation in the Y direction, X
If the rotation of the motor 43 in the direction is permitted, the motor 43 is driven in the direction. If the rotation is not permitted, the first and second rotations are performed.
The motor 43 is driven or stopped according to the state of the limit switches 111 and 112.

As described above, the motor 43 is driven, and the switching sleeve 84 in the clutch mechanism 41 is slid from the current position to the target position. In this case, particularly, the sleeve 84 is moved to the 4WF at one stroke end. When operated in the Y direction from the position, as described above, this 4WF
In the position, since the ON signal of the first limit switch 111 is ignored, the slide starts with a large operating force exceeding the first set value P ₁ (40 kg), and when the second limit position β is reached, the first limit switch 111 is turned off. by energization of the motor 43 is stopped by the 111 oN signal, so that the operating force is limited to the first less than the set value P ₁ above. Therefore, the sleeve 84 reaches the 4WL position with a relatively small operation force.

(Effects of the Invention) As described above, according to the present invention, the center differential lock,
In a four-wheel drive vehicle in which free switching is performed by an actuator, when the free position of the center differential is provided at the stroke end of the switching means, when switching from the locked state to the free state of the center differential,
By operating the switching means with a relatively small operating force, it is possible to avoid a problem that the actuator is stopped due to an overload due to inertial force acting on the actuator.
On the other hand, when the center differential is switched from the free state to the locked state, the initial operation force is large, and thereafter the operation force is reduced, so that the operation can be performed reliably and quickly, and the center differential is rapidly locked with the large operation force. This prevents the occurrence of a switching shock, and thus improves the operability of the switching operation in this type of four-wheel drive vehicle.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a diagram showing a switching control system for a four-wheel drive vehicle according to the embodiment, and FIG.
Sectional view of main part of transfer device in wheel drive vehicle, third
The figure is a skeleton diagram, FIG. 4 is a perspective view of an operating force setting mechanism,
FIG. 5 is a perspective view of a main part of the mechanism, FIG. 6 is a front view of a driven gear in the mechanism, FIG. 7 is an operation explanatory view of a position switch, and FIG. FIG. 9 is a flowchart showing a main routine of the control operation, FIG. 10 is a flowchart showing a control operation in a normal state, FIG. 11 is a flowchart showing a rotation direction setting operation of the motor, FIG. FIG. 13 is a flowchart showing the operation force setting operation, FIG. 13 is an explanatory diagram of the operation force set by the operation, and FIG. 14 is a flowchart showing the control operation of the motor. 30: Center differential, 41: Switching means (clutch mechanism),
43 ... actuator (motor), 44 ... operating force variable means (operating force setting mechanism), 60 ... control means (controller).

Claims (1)

(57) [Claims] 1. A center differential which has one input element and two output elements and divides an input from an engine and outputs the divided input to a front wheel side and a rear wheel side, respectively.
Switching means for switching between a free state in which the differential operation between the two output elements is permitted and a locked state in which the differential operation is prevented, an actuator for switching the switching means, and an operating force for changing the operating force of the actuator A center differential lock switching control device for a four-wheel drive vehicle having variable means, wherein the free position of the center differential is set at the stroke end of the switching means, and the position of the locked position is set to the opposite side thereof; When the center differential is switched from the locked state to the free state, the operating force by the actuator is set to a small value. When the center differential is switched from the free state to the locked state, the initial operating force is increased, and thereafter the operating force is decreased. And a control means for operating the operating force varying means. Center differential lock switching control apparatus.