JP2691999B2 - 2-4 switching control device for four-wheel drive vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a four-wheel system in which a four-wheel drive state and a two-wheel drive state are switched by an actuator, and the operating force of the switching operation by the actuator is variable. The present invention relates to a 2-4 switching control device for a driving vehicle.

(Prior Art) As a four-wheel drive vehicle in which front wheels and rear wheels are driven by engine output, for example, as disclosed in Japanese Utility Model Publication No. 63-28646, front wheels and rear wheels are selected by a driver. It is possible to switch between a four-wheel drive state in which the vehicle is driven and a two-wheel drive state in which only one of the front wheel and the rear wheel is driven, and the operation is performed by an actuator in order to improve the switching operability. It is known to have been made. This is because a switching mechanism is provided on a power transmission path to either one of the front wheels or the rear wheels to disconnect or connect the driving side member and the driven side member by separating or connecting the driving side member and the driven side member. The actuator is configured to be operated by an actuator, but in this case, the actuator may be overloaded due to some abnormality.
Therefore, in order to protect the actuator from overload, an operating force limiting mechanism for limiting the operating force to a certain limit is required, but the limit value of the operating force by this mechanism is different for each switching operation. It has been considered that the value can be set to a value to suppress the occurrence of shock at the time of switching or to shorten the switching operation time as much as possible to improve the operability. Specifically, when the drive side member and the driven side member of the switching mechanism are connected at the time of switching from the two-wheel drive state to the four-wheel drive state, it is necessary to synchronize them, and the operating force by the actuator is set to a large value. In addition to setting, when switching from the four-wheel drive state to the two-wheel drive state, the operating force by the actuator is changed in order to prevent a switching shock due to a sudden interruption of the transmission of the driving force to one wheel. It is considered to set it to a small value.

(Problems to be Solved by the Invention) By the way, as described above, while operating the switching mechanism between the two-wheel drive state and the four-wheel drive state by the actuator,
An operating force varying means for changing the operating force is provided to set the operating force to a small value in order to suppress the switching shock when switching from the four-wheel drive state to the two-wheel drive state. In the following cases, the switching operation time is unnecessarily lengthened.

In other words, the switching shock as described above is transmitted from the state in which the engine output is divided and transmitted to both the front wheels and the rear wheels to the state in which the engine output is transmitted to only one of the front wheels and the rear wheels. This is caused by a sudden change, but when the engine output that is the source of this shock is small, a large shock does not occur even if the power transmission state changes. Therefore, in such a case, if the switching operation force from the four-wheel drive state to the two-wheel drive state is reduced, this switching operation is performed unnecessarily slowly, and the operation time is lengthened. is there.

The present invention has the above-mentioned disadvantages in a four-wheel drive vehicle provided with an actuator for operating a switching mechanism between a two-wheel drive state and a four-wheel drive state, and an operation force varying means for changing an operation force by the actuator. To deal with
At the time of switching from the four-wheel drive state to the two-wheel drive state, the switching operation force is changed according to the magnitude of the engine output, that is, the engine load, so that the switching shock is prevented from occurring and the switching time is shortened as much as possible. This is an issue.

(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 2-4 switching control device for a four-wheel drive vehicle according to the present invention switches between a two-wheel drive state in which only one of the front wheels or the rear wheels is driven and a four-wheel drive state in which the front and rear wheels are driven. In a four-wheel drive vehicle having switching means for performing the above-mentioned operation, an actuator for operating the switching means, and operating force varying means for changing the operating force by the actuator, engine load detecting means for detecting the engine load is provided, and When switching from the two-wheel drive state to the two-wheel drive state, the operation force by the actuator is set to a small value if the engine load detected by the detection means is large, and the operation force is set to a large value if the engine load is small. A force setting means is provided.

(Operation) According to the above configuration, when a switching shock occurs when the transmission of the driving force to one wheel is interrupted because the engine load is large at the time of switching from the four-wheel drive state to the two-wheel drive state. In this case, the switching shock is suppressed by setting the operating force of the actuator to a small value and performing the switching operation gently. Also,
When the switching shock does not cause a problem because the engine load is small, the operating force by the actuator is set to a large value, and the switching operation from the four-wheel drive state to the two-wheel drive state is performed quickly.

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

First, referring to FIG. 1, a schematic configuration of a four-wheel drive vehicle and a control system therefor according to the present embodiment will be described. An engine output is input to this four-wheel drive vehicle via a transmission (not shown). The transfer device 10 is provided with a first output shaft 11 projecting forward and a second output shaft 12 projecting rearward. The first output shaft 11 includes the propeller shaft 13, the front wheel differential device 14, and the left and right front wheels.
It reaches the front wheel through 15,16, and the second wheel
The output shaft 12 also reaches the rear wheel through the propeller shaft, the rear wheel differential device, and the left and right rear wheels.

As described later, the transfer device 10 has an auxiliary transmission 20, a center differential 30, and a switching device 40 as main components (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, and the center differential 30 is prevented from being differentially operated. It is possible to switch to the center differential lock state by evenly driving the
It is supposed to be done by 40.

Further, the front wheel differential device 14 is provided with a free wheel device 50 for connecting / disconnecting power transmission to one front wheel 16, and a negative pressure type actuator 51 for driving the device 50. This actuator 51 has a first and a second
The negative pressure passages 52 and 53 are connected, and the freewheel connecting solenoid 54 and the disconnecting solenoid 55 are arranged in the negative pressure passages 52 and 53, respectively, and the connecting solenoid 54 is turned on and the disconnecting solenoid 55 is connected. When it is OFF, the freewheel device 50 is connected and the connecting solenoid 54 is OF
F, the freewheel device 50 is disconnected when the disconnecting solenoid 55 is ON.

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.
The signal a from the switch (center differential switch) 61 for switching the center differential 30 between locked and free,
A signal b from a switch (2-4 changeover switch) 62 for switching between two-wheel drive and four-wheel drive, a signal c from a position switch or a limit switch for detecting the state of the changeover device 40, and the freewheel. A signal d from a sensor 63 for detecting the state of the device 50 and a signal e from a throttle sensor 64 for detecting a throttle opening in an engine (not shown) are input, and the controller 60 drives the actuator of the switching device 40. The control signals f, g, h are output to the connecting and disconnecting solenoids 54, 55 for driving the actuator 51 of the freewheel 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 auxiliary transmission 20 to which the engine output is decelerated by the transmission according to the gear stage and the input, and the output of the auxiliary transmission 20 to the front wheel side and the rear wheel side. And a sensor differential 30 which 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 this 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, as shown by the solid line, the transmission output shaft 21 is connected to the pinion carrier. When connected to 24, the rotation of the shaft 21 is directly transmitted to the intermediate shaft 26,
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 composed of a planetary gear mechanism, the intermediate shaft 26 is connected to the pinion gear 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 wheel side. ing.
The sun gear 33 of the planetary gear mechanism includes a clutch mechanism 41 that constitutes the switching device 40 and a drive side sprocket 71 that constitutes a chain type transmission mechanism provided between the intermediate shaft 26 and the first output shaft 11. , The chain 72 and the driven sprocket 73, and is connected to the first output shaft 11.

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.

Here, the switching sleeve 84 in the clutch mechanism 41
First, when the sleeve 84 is located at the stroke end on the left side in the drawing, the clutch hub 81 and the second clutch gear 83 are coupled to each other, so that the center differential described above is described. The sun gear 33 of 30 is coupled to the drive side sprocket 71 of the chain type transmission mechanism. As a result, in the center differential 30, the sun gear 33, which is one output element, is connected to the front wheel from the first output shaft 11, and the ring gear 32, which is the other output element, is connected to the rear wheel from the second output shaft 12, respectively. The power input from the carrier 31 is transmitted to the front and rear wheels, respectively, and a four-wheel drive state is established. In this case, relative rotation between the sun gear 33 and the ring gear 32 is allowed, and rotation between the front and rear wheels is allowed. This is a center differential free four-wheel drive state (hereinafter referred to as 4WF) in which a speed difference can be generated.

Further, from this state, at the stroke intermediate position where the sleeve 84 is slid to the right by a certain amount in the drawing, the sleeve 84 causes the clutch hub 81 and the first and second clutch gears 82 and 83 on both sides of the clutch hub 81 to move in the three positions. As a result of being connected, 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, respectively.
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 side in the drawings and is located at the stroke end on the right side as shown in FIGS. 2 and 3, the sleeve 84 is attached only 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 by being engaged with 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).

When the switching sleeve 84 slides from the 2W position to the 4WL position shown in the drawing and meshes with the second clutch gear 83, it is necessary to synchronize the rotations of the clutch hub 81 and the second clutch gear 83. 81 and second clutch gear
The synchronizer ring 85 provided between the synchronizer ring 85 and the synchronizer ring 85 is connected to the second synchronizer ring 85 by the operating force of the sleeve 84.
The second clutch gear 83 is pressed against the clutch gear 83 side.
There is provided a synchronization mechanism including a key 86 for synchronizing the rotation of the sleeve 84 with the rotation of the sleeve 84.

In addition, the operating mechanism 42 for operating the clutch mechanism 41
Is 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 in the cam 91, and fixed to the shift rod 93. And the shift fork 94 engaged with the switching sleeve 84 in the clutch mechanism 41. 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 rotating shaft 91b of the cylindrical cam 91 through 03, 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. A pair of pins 106a and 106a are also provided on the surface of the driven gear 106 facing the driven gear 102 so as to abut against the leg portions 108a and 108a of the coil spring 108, respectively. When the coil spring 108 is rotated, one leg portion 108a of the coil spring 108 pushes one pin 106a of the driven gear 106 side, so that the coil spring 108
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.
While a and 109b are attached, as shown in FIG. 6, on the surface of the driven gear 106 facing the drive gear 102,
A conductive plate 110 that constitutes a limit switch together with the brushes 109a and 109b is attached. The thin plate 110 is provided with the brush 109 when there is no relative rotation between the gears 102 and 106.
A narrow first notch 110a corresponding to the first brush 109a on the outer side in the radial direction centered on the neutral position where a and 109b are located.
And a wide second notch 110b corresponding to the second brush 109b on the inner side in the radial direction centered on the neutral position, and the conducting plate 110 has a predetermined potential (positive potential of the power source). Or negative potential). As a result, the first set value, which is constituted by the first brush 109a and the first cutout 110a, and in which the operating force by the motor 43 corresponding to the relative rotation between the drive gear 102 and the driven gear 106 is relatively small.
The first limit switch that conducts at P ₁ (eg 40 kg) or more
111, the second brush 109b, and the second cutout portion 110b, and the second set value P ₂ (for example, 80 kg) having a large operation force is provided.
The second limit switch 112 that conducts the above 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. These position switches 116 to 118 are, depending on the combination of ON and OFF, as shown in FIG. 7, the 2W position of the right stroke end of the sleeve 84, the 4WL position of the stroke center, and the left stroke end. It is possible to detect three positions of the 4WF position and a total of five positions of the first and second intermediate positions α and β between these positions.

The center differential changeover switch 61 shown in FIG. 1 is constituted by a changeover lever provided near the steering wheel in the driver's seat as shown in FIG. 8, and the 2-4 changeover switch 62 is provided on the lever. It is composed of a switching button. Then, when the switching lever 61 is at the intermediate position shown by the solid line, the center differential 30 is locked in the four-wheel drive state (4WL), and the switching button 62 is operated while the switching lever 61 is at the upper position shown by the chain line. Center differential free four-wheel drive state (4WF) and two-wheel drive state (2
W) is to be switched. Further, by operating the switching lever 61 to the lower position shown by the chain line, the auxiliary transmission 20 is operated to the low gear stage side in the 4WL state.

Next, the operation of the present embodiment will be described with reference to the flow charts of FIG. 9 and thereafter showing the switching control operation by the controller 60.

FIG. 9 shows a main routine of this switching control operation. The controller 60 first performs a predetermined system initialization in step S ₁ and then, in steps S ₂ and S ₃ , first to third positions. The signals from the switches 116 to 118 are input, and the ON / OFF combination indicated by these signals is compared with the ON / OFF combination for each preset position shown in FIG. Then, when the actual combination does not correspond to any of the set combinations, the position switch
It is determined that a failure has occurred in any of 116 to 118, and the position switch failure mode control in step S ₄ is executed.

Also, 2-4 when switching of on the basis of a signal from the changeover switch 62 from the two-wheel drive state to the four-wheel drive state is detected, the clutch hub 81 in the clutch mechanism 41 in step S ₅ the second clutch gear When the synchronization state with 83 is detected and it is determined that this synchronization operation is not normally performed, steps S ₆ to S ₇ are executed to control the synchronization failure mode.

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

This normal switching control is performed according to the flow chart of FIG. 10. First, in step S ₁₁ , the position switch 1
A target for realizing the drive mode selected by the driver by the signals from ₁₆ to 118 to determine the current position of the switching sleeve 84, and by the signals from the center differential switching switch 61 and the 2-4 switching switch 62 in step S12. Determine 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 procedure is as follows according to the flowchart of FIG.

First, it is determined whether or not it is immediately after the ignition switch of the engine has been turned ON in step S _21, the first in the next step S _22, S ₂₃ if immediately after, the second limit switch 11
Determine whether 1,112 is in the ON state. Then, if any of the limit switches also OFF, the 1 execution flag F ₀ in step S _24, is one of the limit switches
If it is ON, the flag F ₀ is set to 0 in step S ₂₅ .

Next, determining the value of the execution flag F ₀ in step S _26, performs the steps S ₂₇ following the rotating direction of the motor of the setting operation if F ₀ = 1.

That is, in steps S ₂₇ and S ₂₈ , it is determined again whether or not the first and second limit switches 111 and 112 are in the ON state. If both limit switches are OFF, in step S ₂₉ the rotation allowance flag F in the X direction is set. Rotation allowance flag F in _AX and Y directions
_{All AYs} are reset to 0. Here, the X direction is a direction in which the sleeve 84 in the clutch mechanism 41 shown in FIG. 2 slides from the right side to the left side in the drawing, that is, the 2W → 4WL → 4WF direction, and the Y direction is the sleeve 84. It is the direction of sliding in the opposite direction.

On the other hand, when at least one of the first and second limit switches 111 and 112 is in the ON state, the above step S ₂₇ or step S ₂₈ to step S ₃₀ is executed and Y of the motor 43 is changed.
The value of the Y-direction rotation flag F _Y indicating the rotation in the direction is determined.
When F _Y = 1 (that is, when the motor 43 is rotating in the Y direction), it is confirmed in step S ₃₁ that the Y direction rotation allowance flag F _AY is 0, and then step S
_{At 32} , the rotation permission flag F _AX in the X direction is set to 1. When the Y direction rotation flag F _Y = 0, the value of the X direction rotation flag F _X indicating the rotation of the motor 43 in the X direction is determined in step S ₃₃ , and when F _X = 1, that is, the motor 43 when rotating in the X direction, set on at step S ₃₄ the rotation permission flag F _AX of the X-direction was calculated as follows: 0, the rotation permission flag F _AY in the Y direction to 1 in step S ₃₅ To do.
In this way, while the motor 43 is rotating in the X direction or the Y direction, the first and second limit switches 111, 112
When at least one of the two turns ON, the rotation permission flag F _AY or F _AY for the rotation in the opposite direction is provided, provided that the rotation permission flag F _AX or F _AY for the current rotation direction is reset to 0. Set F _AX to 1. This allows the motor 43 to rotate in the direction in which the limit switches 111, 112 are turned off, and 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 equal to or ON, the case turned ON, the both operation force limitation flag F _IX, F
Hold _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 signal from the second limit switch 112 stops the energization of the motor, and the motor 42 may be overloaded. To 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, also the first limit switch 111 when OFF, the ie operation of the motor 43 If the force is less than the first set value P ₁ (40Kg), step S ₄₄
Then, both the X-direction and Y-direction operation force limit flags F _IX and F _IY are reset to zero. As a result, when both limit switches 111 and 112 are OFF, these switches 111 and 112 are
The motor 43 is allowed to be energized in the X and Y directions regardless of the signal from the.

Further, when the second limit switch 112 is OFF and the first limit switch 111 is ON, that is, the operating force of the motor 43 is in the range from the first set value P ₁ to the second set value P ₂ (40 to 80).
When in Kg), in step S ₄₅ the current position is the Y-direction side of the 4WL position of the switching sleeve 84, that is, whether or not either of 2W position or the first intermediate position alpha, at these locations If there is, the operation force limit flag F _IX in the X direction is reset to 0 in step S ₄₆ , and based on the signal from the throttle sensor 64 in step S ₄₇ ,
It is determined whether the engine throttle opening is larger than a predetermined value θ ₀ . And, when this predetermined value θ _{0 is} greater than,
That is, when the engine is in a high load state, the operation force limit flag F _IY in the Y direction set in step S ₄₁ is maintained at 1 as it is, and the throttle opening is set to the predetermined value θ.
_{When it is 0} or less, that is, when the engine is in a low load state, in step _S48 , the operation force limit flag F in the Y direction is
Reset _IY to 0. Also, when the current position of the switching sleeve 84 can if not Y direction side of the 4WL position described above, the current position is equal to or a 4WF position in step S _49, in this 4WF position, step S ₅₀ Resets the Y-direction operation force limit flag F _IY to zero.

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
At the WF position, the ON signal from the first limit switch 111 is ignored, and at these positions, the operating force of the motor 43 causes the second limit switch 112 to turn ON. The second set value P ₂ (80K
g) is allowed, and in other positions (marked with ○ in Fig. 13), the first limit switch 11
The operation force is limited by the first set value P ₁ (40Kg) where 1 is ON. Then, particularly when the current position of the sleeve 84 is located on the Y direction side of 4WL, when the sleeve 84 slides in the Y direction, the operating force is high when the engine is under heavy load, as indicated by a triangle mark in FIG. First set value P ₁
Therefore, when the engine load is low, the second set value P _{2 is} allowed. In that case, when the engine load is low, the first limit switch 111 is turned on even at the 4WL position.
The signal may be ignored, and the operating force in the Y direction from that position may be allowed up to the second set value P ₂ .

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
It 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 of the switching sleeve 84 matches the target position, and if they match, X is determined in step _S52 .
The rotation flags F _X and F _Y in the Y and Y directions are reset to 0. That is, in this case, the motor 43 is not rotated.

On the other hand, if the current position of the switching sleeve 84 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 it is on the X direction side, that is, when it is desired to operate in the Y direction, the rotation flag F _X in the X direction is reset to 0 in step S ₅₄ and then the rotation allowance flag F _AY in the Y direction is set in step S ₅₅
Is 1 or not. 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. If F _AY = 0, the value of the Y direction operating force limit flag F _IY is determined in step S ₅₇ , and if F _IY = 0, the Y direction rotation flag F _{Y is set} to 1 in step S _56. And F _IY = 1
Sets the rotation flag F _Y in the Y-direction to 0 in step S ₅₈ if. That is, at the time of operation in the Y direction, if the rotation of the motor 43 in that direction is allowed, the motor 43 is driven in that direction, and if not allowed, the state of the first and second limit switches 111, 112 is set. The motor 43 is driven or stopped accordingly.

Further, if the current position of the switching sleeve 84 is not in the X direction side of the target position, if you want to manipulate i.e. in the X direction, the freewheel device 5 shown in FIG. 1 in step S ₅₉
It determines disconnection state of 0, when in the disengaged state, the switching sleeve 84 further in step S ₆₀ determines whether the current position is the Y-direction side of the 4WL position. When the 4WL position is on the Y direction side, that is, the 2W position or the first intermediate position α, the steps S _{54 to} S ₅₈ are executed to prohibit the operation in the X direction from the current position, and Depending on the state of the flags F _AY and F _IY , the motor 43 may move in the opposite Y direction.
Drive. This is to prevent switching from two-wheel drive to four-wheel drive while the freewheel device 50 is disconnected.

When the user wants to operate in the X direction, the free wheel device 50 is connected, and the current position of the switching sleeve 84 is the 4WL position (or the X direction side from the position) even when the device 50 is disconnected. In this case, the rotation flag F _Y in the Y direction is reset to 0 in step S ₆₁ , and the value of the rotation allowance flag F _AX in the X direction is determined in step S ₆₂ , and if F _AX = 1 then step S _{At 63} , the rotation flag F _X in the X direction is set to 1. If F _AX = 0, the value of the X-direction operating force limit flag F _IX is determined in step S ₆₄ , and if F _IX = 0, the X-direction rotation flag is determined in step S _63.
If F _{X is set} to 1 and F _IX = 1, the rotation flag is set in step S _65.
Set F _X to 0. As a result, similarly to the operation in the Y direction described above, if the rotation of the motor 43 in the X direction is allowed, the motor 43 is driven in that direction, and if not allowed, the first, second The motor 43 is driven or stopped according to the states 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 that case, as shown in FIG. When switching from the four-wheel drive state to the motor 43 regardless of the engine load.
Is allowed up to the second set value P ₂ (80 kg), and the clutch hub 81 and the second clutch gear in the clutch mechanism 41 are
Synchronization with 83 is performed well with a large operating force, and when switching from the four-wheel drive state to the two-wheel drive state, the switching operation is gently performed with a small operating force when the engine is under high load, and a switching shock occurs. When the engine is under a low load, which is prevented and does not have such a shock problem, the switching operation is quickly performed by a large operating force.

(Effect of the Invention) As described above, according to the present invention, the actuator for operating the switching means for switching between the two-wheel drive state and the four-wheel drive state, and the operating force varying means for changing the operating force by the actuator are provided. In a four-wheel drive vehicle, when the engine load is large at the time of switching from the four-wheel drive state to the two-wheel drive state, the operating force by the actuator is set to a small value, and either one of the front wheels and the rear wheels is set. The switching shock when the transmission of the driving force to the engine is cut off is suppressed, and the operating force is set to a large value when the engine load without the problem of the switching shock is small and the switching operation is performed quickly. To be done. Therefore, the operability of the switching operation in the four-wheel drive vehicle of this type is improved.

[Brief description of the drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a switching control system diagram of a four-wheel drive vehicle, FIG. 2 is a cross-sectional view of a main part of a transfer device in the four-wheel drive vehicle, and FIG. 4 and 5 are perspective views 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, and FIG. 7 is an operation explanatory diagram of a position switch. FIG. 8 is a front view of a driver's seat of the vehicle showing an operation lever, and FIG. 9 is a flowchart showing a main routine of control operation,
FIG. 10 is a flow chart showing the control operation during normal operation.
FIG. 11 is a flow chart showing the rotation direction setting operation of the motor, FIG. 12 is a flow chart showing the operating force setting operation,
FIG. 13 is an explanatory diagram of the operation force set by the operation,
FIG. 14 is a flow chart showing the control operation of the motor.
The figure is an illustration of the operating force showing the operation of this embodiment. 41 …… Switching means (clutch mechanism), 43 …… Actuator (motor), 44 …… Operating force changing means (operating force setting mechanism), 60 …… Operating force setting means (controller), 64 ……
Engine load detection means (throttle sensor).

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Claims (1)

(57) [Claims] 1. A switching means for switching between a two-wheel driving state in which only one of the front wheels and the rear wheels is driven and a four-wheel driving state in which the front wheels and the rear wheels are driven, and an actuator for operating the switching means. 2-4 of a four-wheel drive vehicle having an operation force varying means for changing the operation force by the actuator
In the switching control device, an engine load detecting means for detecting an engine load and an operating force by the actuator when the engine load detected by the detecting means is large when switching from a four-wheel drive state to a two-wheel drive state. A 2-4 switching control device for a four-wheel drive vehicle, comprising: a small value, and an operating force setting means for setting the operating force to a large value if the engine load is small.