JPH055063Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is a drive state switching control for a so-called part-time four-wheel drive vehicle in which a two-wheel drive state or a four-wheel drive state is selected by the driver's switching operation. Regarding equipment.

[Prior art]

The first prior art regarding this type of device is as shown in Japanese Patent Application Laid-Open No. 59-216732,
An operating lever for selectively switching between a two-wheel drive state and a four-wheel drive state, and an operating lever that transmits rotational driving force of the output shaft of the transmission only to the rear wheels when the operating lever selects the two-wheel drive state. It is equipped with a power distribution device that transmits the same rotational driving force to the front wheels and rear wheels when the four-wheel drive mode is selected, and a freewheel hub is provided between the front axle shaft and the front wheels, and the two When the wheel drive state is selected, the rotational drive force of the output shaft of the transmission is transmitted only to the rear wheels, and the freewheel hub is set to the free state so that the rotation of the front wheels as the vehicle travels causes the rotation of the front axle shaft to be transmitted only to the rear wheels. and the front propeller shaft are prevented from being rotationally driven, and when a four-wheel drive state is selected by the operation lever, the rotational driving force of the output shaft of the transmission is transmitted to the rear wheels, and the freewheel hub is locked. There are some that are set so that the same rotational driving force is also transmitted to the front wheels. Further, this device detects the locked state and free state of the freewheel hub based on the relationship between the vehicle speed and the rotational speed of the front propeller shaft, and identifies and displays the two states based on the detection.

On the other hand, as a second prior art related to this type of device, as shown in Japanese Utility Model Application Publication No. 55-13102, there is a self-operating device that selectively switches between a two-wheel drive state and a four-wheel drive state in place of the above-mentioned operating lever. It is equipped with a holding type operation switch (operation knob) and an electric control device that switches and controls the power distribution device according to the switching of the switch, and the vehicle can be set in a two-wheel drive state or a four-wheel drive state according to the switching operation of the operating switch. Some are designed to switch to wheel drive mode. Further, this device includes first and second detection switches that open and close according to the engine speed and the magnitude of the engine intake pipe negative pressure, respectively, to detect the operating characteristics of the engine,
If setting the vehicle to a two-wheel (or four-wheel) drive state by switching the operating switch has an adverse effect on the power transmission system in relation to the operating characteristics of the engine, the first or second The detection switch acts, regardless of the selection of the two-wheel (or four-wheel) drive state by switching the operation switch.
An electric control device sets and controls the vehicle in a four-wheel (or two-wheel) drive state.

[Problem that the invention attempts to solve]

However, in the first conventional device, the two-wheel drive state is selected using the operating lever, the freewheel hub is set to the free state, the vehicle is driven, and the operating lever is operated while the vehicle is running at medium to high speeds. When trying to switch the vehicle to four-wheel drive mode, the front propeller shaft is almost stationary, even though the output shaft of the transmission is rotating at medium and high speeds, so the front propeller shaft and the front propeller shaft are When connected, a large impact force is applied to the power distribution device due to the collision between the rotating and non-rotating parts of the device, and this large impact force may generate loud noises,
There is a problem with this, which may cause some parts of the device to be damaged.

In order to solve the above-mentioned problems, the present inventor first controlled the switching of the power distribution device using a self-holding operation switch and an electric control device like the second conventional device, and also 1
Based on the detection result of the locked state and the free state of the freewheel hub in the conventional device, it is determined whether to allow or prohibit switching of the power distribution device, and based on this determination result, the electric control device is activated as in the second conventional device. devised a device that prohibits the switching of the power distribution device. However, with this device, when the driver tries to change the driving state of the vehicle by switching the operating switch, the state of the freewheel hub causes switching of the power distribution device to be prohibited. If there is, the driving state of the vehicle will not be changed when the operating switch is operated to change the operating switch.
After the prohibition is lifted, the driving state of the vehicle will be changed. In such a case, the driver will not be able to recognize when to change the driving state,
Since this change in the driving state is against the driver's wishes, there is a problem in that the maneuverability of the vehicle deteriorates.

The present invention was devised in view of the above problem, and its purpose is to eliminate the above problem by determining whether switching of the power distribution device is permitted or prohibited, and the purpose of this invention is to solve the above problem by determining whether switching of the power distribution device is permitted or prohibited, and the purpose of this invention is to solve the above problem by determining whether switching of the power distribution device is permitted or prohibited. It is an object of the present invention to provide a drive state switching control device for a four-wheel drive vehicle that does not change on the contrary.

[Means for solving problems]

In order to solve the above problems and achieve the purpose of this invention, the structural features of this invention include first drive wheels 1a, 1a that are constantly driven as shown in FIG.
It has second drive wheels 1b, 1b that are selectively driven, and freewheel hubs 2, 2 that are assembled to the second drive wheels 1b, 1b and that connect and disconnect power to the second drive wheels 1b, 1b. Applicable to 4 wheel drive vehicles,
In the first state, the rotational driving force of the output shaft 3a of the transmission 3 is transmitted only to the first driving wheels 1a, 1a, and in the second state, the rotational driving force is transmitted to the first driving wheels 1a, 1a.
a, 1a and the second driving wheels 1b, 1b;
A drive state switching control device for a four-wheel drive vehicle, which includes a switching device 5 that selectively switches between a state and a second state, and an electric control device 6 that electrically controls the switching by the switching device 5. A reset type operation switch 6a and the operation switch 6a
and an operation detection means 6b for detecting the operation state of the power distribution device 4 when the operation switch 6a is operated in response to the detection by the operation detection means 6b.
determining means 6c for determining whether or not the power distributing device 4 is in a state that allows switching between the first state and the second state; Only when the determination is made, the state of the power distribution device 4 is changed from the first state to the second state.
The electric control device 6 is configured with an output means 6d for outputting a control signal to the switching device 5 for inverting the state or from the second state to the first state.

[Functions and effects of the idea]

In the present invention configured as described above, when the driver operates the operation switch 6a, the operation detection means 6b detects this operation, and in response to this detection, the determination means 6c determines that the power distribution device 4 It is determined whether the state is in a state that allows switching between the state and the second state. In this determination, the determination means 6c
However, if it is determined that the power distribution device 4 is in a state that allows the switching, the output means 6d outputs a control signal for reversing the state of the power distribution device 4 to the switching device 5, and the device 4 The driving state of the vehicle is switched from a two-wheel drive state to a four-wheel drive state, or from a four-wheel drive state to a two-wheel drive state. On the other hand, in the determination, the determination means 6c
If it is determined that the output means 6d is not in a state that allows the switching, the output means 6d does not output the control signal, so the power distribution device 4 is not switched and the driving state of the vehicle is maintained in the previous state. in this way,
Due to the action of the determining means 6c, the power distribution device 4 is switched only when the device 4 allows switching between the first state and the second state, so that no loud noise is generated due to switching of the power distribution device 4. , the above-mentioned problems such as damage to a part of the device 4 are resolved.

Moreover, after the driver releases the operation of the operating switch 6a, the switch 6a automatically returns to the state before the operation. In this case, the operation detection means 6b does not detect the operation of the operation switch 6a, and accordingly, the determination means 6c also does not make a determination, and the output means 6
d also does not output a control signal, so the switching device 5 does not change the state of the power distribution device 4. In this way, after the operation switch 6a is released, the state of the power distribution device 4 is changed and the drive state of the vehicle is not changed, so the drive state is not changed against the driver's will. Not,
The maneuverability of the vehicle is improved. Furthermore, since a self-resetting type switch is adopted as the operation switch 6a, the operation switch can be mounted on four wheels ( or 2
It is possible to avoid discrepancies in which the vehicle is in a two-wheel (or four-wheel) drive state even though the vehicle is in a two-wheel (or four-wheel) drive state.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 schematically shows a four-wheel drive vehicle according to the present invention.

This four-wheel drive vehicle has an engine 21, and driving force from the engine 21 is transmitted to a power distribution device 24 via a clutch device 22 and a transmission 23.

The power distribution device 24, as shown in detail in FIG. 3, has a rear wheel drive shaft 24a for transmitting driving force to the left and right rear wheels RWa, RWb. This rear wheel drive shaft 24a is rotatably supported by the housing 24b, and rotates integrally with the output shaft 23a of the transmission 23. A drive sprocket 24c is attached to the outer periphery of the rear wheel drive shaft 24a so as to be rotatable with respect to the drive shaft 24a, and a spline portion 24c1 is integrally formed on the sprocket 24c. Further, a clutch hub 24d is attached to the rear wheel drive shaft 24a so as to rotate integrally with the rear wheel drive shaft 24a, and a clutch sleeve 24e is spline-coupled to the outer periphery of the hub 24d. This clutch sleeve 24e is driven by a diaphragm type cylinder 37, which will be described later, to be displaced in the front-rear direction (corresponding to the vertical direction in FIG. 3), and in its first state (solid line in FIG. 3), it is coupled only to the clutch hub 24d. The hub 24d and the spline portion 24c1 are separated and the second state (third state) is performed.
The clutch hub 24d is connected to the clutch hub 24d (broken line in the figure) and also splined to the spline portion 24c1 to connect the hub 24d and the spline portion 24c1. In addition, the power distribution device 24 is connected to the left and right front wheels.
It has a front wheel drive shaft 24f for transmitting driving force to FWa and FWb. This front wheel drive shaft 24f is rotatably supported by the housing 24b, and a driven sprocket 24g is assembled to the drive shaft 24f so as to rotate integrally with the drive shaft 24f. This driven sprocket 24g is connected to a drive sprocket 24c by a chain 24h, and rotates in conjunction with the rotation of the drive sprocket 24c.

The rear end of the rear-wheel drive shaft 24a is connected to the front end of a rear propeller shaft 26 via a hook joint 25, and the rear end of the shaft 26 is connected to an input shaft 28a of a differential device 28 via a hook joint 27. The differential device 28 distributes the driving force transmitted from the rear-wheel drive shaft 24a to the input shaft 28a via the rear propeller shaft 26, and transmits it to the left and right rear wheels RWa, RWb via left and right rear axle shafts 29a, 29b.

The front end of the front wheel drive shaft 24f is connected to the rear end of the front propeller shaft 32 via a hook joint 31, and the front end of the shaft 32 is connected to the input shaft 34a of the differential gear 34 via a hook joint 33. It is connected to the. The differential device 34 connects the front propeller shaft 3 from the front wheel drive shaft 24f.
2, the driving force transmitted to the input shaft 34a is distributed to the left and right front axle shafts 35a, 3.
5b to the left and right front wheels FWa and FWb.
Freewheel hubs 36a, 36b are provided between the left and right front axle shafts 35a, 35b and the left and right front wheels FWa, FWb, respectively. These freewheel hubs 36a, 36b are in a locked state and are connected to the left and right front axle shafts 35a, 36b.
35b and the left and right front wheels FWa and FWb are connected respectively,
and releases the connection in a free state,
This freewheel hub may be a known manual freewheel hub that switches between a locked state and a free state by manual operation, or a known automatic freewheel hub that automatically switches between a locked state and a free state. can be used.

As shown in FIGS. 2 and 3, the power distribution device 24 is equipped with a diaphragm-type cylinder 37 that drives the clutch sleeve 24e, and the cylinder 37 has immediate chambers 37b and 37c partitioned by a diaphragm 37a. has. A rod 37d is fixed to the diaphragm 37a, and by displacement of the diaphragm 37a in the immediate direction, the rod 37d is fixed to the diaphragm 37a.
7d is displaced in the immediate direction and the clutch sleeve 24
e in the first state (solid line in Figure 3) or the second state (third state)
(Dotted line in the figure).

Immediately after the diaphragm cylinder 37, the chamber 37b,
Vacuum switching valves 38, 39 (VSV1, VSV1,
VSV2) are connected to each other. As shown in FIGS. 2 and 3, the vacuum switching valve 38 includes a switching valve 38a and an electromagnetic solenoid 3.
8b. The switching valve 38a is set to the first state by de-energizing the electromagnetic solenoid 38b, allowing communication between the boat 38c opened to the atmosphere and the boat 38d connected to the conduit P1,
The second state is set by energizing the electromagnetic solenoid 38b, allowing communication between the boats 38b and 38e. The vacuum switching valve 39 includes a switching valve 39a and an electromagnetic solenoid 39b.
It is made up of. The switching valve 39a is set to the first state by de-energizing the electromagnetic solenoid 39b, and the boat 39c opened to the atmosphere and the conduit P2 are connected to each other.
The board 39d is set to the second state by excitation of the electromagnetic solenoid 39b, allowing communication between the board 39d and the boat 39e. Each boat 38e, 39e of these valves 38, 39 is connected to one end of a conduit P3, and the other end of the conduit P3 is connected to the intake pipe of the engine 21, and when the engine 21 starts, each boat 38e, The pressure at 39e is set to negative pressure. Also, the tank 41 is in the conduit P3.
and a check valve 42 are interposed, and the conduit P3
The pressure inside the conduit P3 does not fluctuate, and the air flow inside the conduit P3 does not flow backwards.

Further, this four-wheel drive vehicle has an electric control circuit 50 that controls switching of drive states.
As shown in FIGS. 2 and 3, it is equipped with a detection switch 51, rotational speed sensors 52, 53, an operation switch 54, and a microcomputer 55.

The detection switch 51 is a switch assembly 51a.
Consists of a normally open switch built into the
The assembly 51a is assembled to the housing 24b so as to face the clutch sleeve 24e. When the clutch sleeve 24e is in the first state (solid line in FIG. 3), the switch 51 is opened and the sleeve 24e is in the first state. When the switch 51 is in the 2nd state (broken line in FIG. 3), the switch 51 moves the protrusion 2 of the sleeve 24e.
4e1 to close the gate. The movable contact side of this detection switch 51 is grounded, and the fixed contact side is connected to the power supply +V via a diode Di and a lamp 56. The lamp 56 is built into a display 62 disposed below the speedometer 61 on the front panel section 60, and when the lamp 56 is turned on, the display 62 displays "4WD". Note that while the lamp 56 is off, the display 62 does not display anything. In addition, the detection switch 51
The fixed contact side of the switch 51 is connected to the microcomputer 55 via a resistor r1, and a high level (hereinafter referred to as "1") or low level (hereinafter referred to as "0") status signal representing the opening/closing of the switch 51 is output. The data is supplied to the same computer 55. The collector of a switching transistor 57 whose emitter is grounded is connected to the connection point between the resistor r1 and the microcomputer 55, and the base of the transistor 57 is controlled by the microcomputer 55 to turn the transistor 57 on or off. The signal is now being supplied. Note that the resistor r2 provided in parallel with the lamp 56 and the diode Di is for supplying voltage to the fixed contact side of the detection switch 51 even when the lamp 56 is disconnected.

The rotation speed sensor 52 includes a pick-up coil L1, and the coil L1 is connected to the sensor assembly 5.
It is incorporated into 2a. This sensor assembly 5
2a is assembled to the housing 24b at a position facing a rotating disk 24i with a permanent magnet that rotates integrally with the rear wheel drive shaft 24a, and the sensor 52 rotates as the disk 24i rotates. Coil L1
A voltage signal induced by the disk 24i, that is, a pickup signal having a frequency proportional to the rotational speed of the disk 24i is generated. This rotation speed sensor 52 has a waveform shaper 52.
The shaper 52b shapes the pickup signal into a rectangular wave signal and supplies it to the microcomputer 55.

The rotation speed sensor 53 includes a pick-up coil L2, and the coil L2 is connected to the sensor assembly 5.
It is incorporated in 3a. This sensor assembly 53
a is at a position facing a rotating disk 24j with a permanent magnet that rotates integrally with the front wheel drive shaft 24f,
The sensor 53 is assembled in the housing 24b, and generates a voltage signal induced in the coil L1 as the disc 24j rotates, that is, a pickup signal with a frequency proportional to the rotational speed of the disc 24j. This rotation speed sensor 53 has a waveform shaper 53b.
The shaper 53b shapes the pickup signal into a rectangular wave signal and supplies it to the microcomputer 55.

The operating switch 54 controls the reversal of the driving state of the vehicle, and is composed of a self-resetting normally open switch driven by an operating element 63 provided on the front panel section 60. When the operating element 63 is pressed, only closed. One fixed contact of this operation switch 54 is connected to the power supply +V, and the other contact is grounded through a resistor r3 and connected to the microcomputer 55. "1" indicates whether the switch 54 is open or closed. Alternatively, a status signal of "0" is supplied to the computer 55. A series circuit including a lamp 58, a resistor r4, and a switching transistor 59 is provided in parallel with the operating switch 54 and the resistor r3. The lamp 58 is built into a display 64 disposed above the operator 63 of the front panel section 60, and the indicator 64 turns on or off when the lamp 58 turns on or off.
4) Distinguish and display the driving state of the vehicle, which is reversed every time the operation is performed. A control signal is supplied from the microcomputer 55 to the base of the transistor 59, and the transistor 59 is turned on or off by the control signal.

The microcomputer 55 is composed of a read-only memory (hereinafter referred to as ROM) 55a, a central processing unit (hereinafter referred to as CPU) 55b, a writable memory (hereinafter referred to as RAM) 55c, and an input/output interface (hereinafter referred to as I/O) 55d. These ROM55a, CPU55b,
RAM 55c and I/O 55d are commonly connected by bus 55e. The ROM 55a stores programs corresponding to the flowcharts shown in FIGS. 4 to 6. The CPU 55b repeatedly executes the program in response to the closing of an ignition switch 65, which will be described later, to control the driving state of the vehicle and the display corresponding to the driving state. RAM5
5c temporarily stores data and flags necessary for executing the program. The main data and flags will be listed below.

Detection switch data DTSW…Detection switch 5
This data represents the state of 1, and "0" represents the on state of the switch 51, and "1" represents the off state of the switch 51.

New operation switch data OPSWnew...Data representing the current state of the operation switch 54,
"0" indicates the off state of the switch 54,
And "1" indicates the on state of the switch 54.

Old operation switch data OPSWold...Data representing the previous state of the operation switch 54,
"0" indicates the off state of the switch 54,
And "1" indicates the on state of the switch 54.

Rear rotation speed data Nr...Data representing the rotation speed of the rear wheel drive shaft 24a and the rear propeller shaft 26.

Front rotation speed data Nf…Front wheel drive shaft 24f
and data representing the rotation speed of the front propeller shaft 32.

First lamp flag LPFLG1...Lamp 56, 5
This flag represents the state of lamp 8, and "0" represents the continued lighting or extinguishing state of lamps 56, 58, and "1" represents the blinking state of lamps 56, 58.

Second lamp flag LPFLG2...Flag indicating the repeated state of turning off and lighting up the lamps 56 and 58 which are blinking (LPFLG1="1"), and "0" indicates the off state, and "1"
indicates the lighting state.

First timer data TIME1...Lamps 56, 58 in a blinking state (LPFLG1="1")
Data representing the time from the start of turning off or turning on the light, when the light is off (LPFLG2="0")
It takes a value corresponding to 0 to 1.5 seconds at , and takes a value corresponding to 0 to 0.5 seconds when lit (LPFLG2="1").

Second timer data TIME2...Lamps 56, 58 in a blinking state (LPFLG1="1")
This data represents the time since the start of blinking, and takes a value corresponding to 0 to 20 seconds.

The I/O 55d sends and receives signals (data) to and from an external circuit, and includes a data format converter 55d1, a register 55d2, and the like. This I/O 55d has excitation control circuits 38f and 39f.
are connected to each other, and the same control circuits 38f and 39
f controls the excitation or de-excitation of the excitation solenoids 38b and 39b by controlling the power supply from the power supply +V to the excitation solenoids 38b and 39b, respectively, according to the control data stored in the register 55d2.

Further, a battery 66 is connected to this electric control circuit 50 via an ignition switch 65, and each circuit in the electric control circuit 50 including the microcomputer 55 is connected to a battery 66 when the ignition switch 65 is closed. A voltage (+V) from a battery 66 is supplied.

Hereinafter, the operation of the above embodiment will be explained with reference to the flowcharts of FIGS. 4 to 6. Before the ignition switch 65 is closed, no power is supplied to the excitation control circuits 38f and 39f.
Since the electromagnetic solenoids 38 and 39 are not energized, the vacuum switching valves 38 and 3
9 are each set to the first state, and the same valve 3
8 and 39 allow communication between the boats 38c and 38d and between the boats 39c and 39d, respectively. As a result, both the pressures in the front and rear chambers 37b, 37c of the diaphragm type cylinder 37 are maintained at atmospheric pressure, and the diaphragm 37a is not pressed in either the forward direction or the rear direction.
is maintained in the state it was in when the ignition switch 65 was previously opened at the end of driving the vehicle.

In this state, in order to start the engine 21, the ignition switch 65 is closed.
When power begins to be supplied from the battery 66 to the electric control circuit 50, the CPU 55b starts to perform the steps shown in FIG.
Start running the program from 70 and go to step 71
Execute the "Initial Settings" routine process. This "initialization" routine consists of steps 71a-71h, as shown in detail in FIG. CPU55
b starts the processing of the same routine at step 71a, and clears (to "0") all data stored in the register 55d2 and RAM 55c in the I/O 55d at step 71b.
Initialize the I/O 55d and RAM 55c.
With this initial setting of I/O55d, I/O55d
d controls the transistors 57 and 59 to be in an off state, and sets the excitation control circuits 38f and 39f to a non-excitation control state. As a result, the electromagnetic solenoids 38a and 38b are not excited, and the vacuum switching valves 38 and 39 are initially set to the first state.

After the initial setting in step 71b, the CPU 55b takes in a state signal representing the on or off state of the detection switch 51 via the resistor r1 and the I/O 55d in step 71c, and sets the detection switch data DTSW to "0" or "0" based on the signal. Set to “1”. In such a case, almost simultaneously with the closing of the ignition switch 65, the vacuum switching valves 38,
39 is set to the first state by the processing in step 71b, the diaphragm type cylinder 37
The pressures in both the front and rear chambers 37b and 37c continue to be maintained at atmospheric pressure as they were before the ignition switch was closed.
The diaphragm 37a is maintained in the state before the ignition switch 65 is closed. As a result, if the diaphragm 37a was in the first state at the end of the previous operation of the vehicle, the diaphragm 37a and the clutch sleeve 2
4e is also in the first state (solid line in FIG. 3) and the detection switch 51 is open, so the detection switch data DTSW is set to "1".
Furthermore, if the diaphragm 37a is in the second state at the end of the operation of the vehicle,
Diaphragm 37a and clutch sleeve 24e
The current state of is also in the second state (dashed line in Figure 3),
Since the detection switch 51 is closed by the protrusion 24e1, the detection switch data DTSW is "0".
is set to Note that at this time, the transistor 5
7 and 59 are in the off state due to the processing in step 71b.

Next, in step 71d, the CPU 55b determines whether the detection switch data DTSW is "1". In this determination, if the same data DTSW is "1", it is determined as "YES", and the CPU 55b
In step 7e, control data for exciting the electromagnetic solenoid 38b is output to the I/O 55d.
The I/O 55d stores the same control data in the register 55d2.
and outputs it to the excitation control circuit 38f, which excites the electromagnetic solenoid 38b. By energizing the electromagnetic solenoid 38b, the vacuum switching valve 38 is switched to the second state, and the boats 38d and 38e communicate with each other. In this state, when the pressure in the boat 38e becomes negative as the engine 21 is started, the pressure in the front chamber 37b of the diaphragm cylinder 37 also becomes negative. Also, at this time, since the vacuum switching valve 39 is set to the first state by the processing in step 71b, the boats 39c and 39d are in communication, and the rear chamber 37c of the diaphragm cylinder 37 is at atmospheric pressure. is maintained. Therefore, the diaphragm 37a is pressed forward and the clutch sleeve 24e is in the first state (third state).
Since the drive is controlled according to the solid line in the figure, the power distribution device 24
will reproduce the state of the vehicle at the end of its operation. Note that in this state, the detection switch 51 and the transistors 57, 59 are off, so the lamps 56, 58 are not lit.

Further, in the determination at step 71d, if the detection switch data DTSW is "0", the determination is "NO", and the CPU 55b outputs control data for exciting the electromagnetic solenoid 39b to the I/O 55d at step 71f. As a result, contrary to the above case, the vacuum switching valve 39
is switched to the second state, and the vacuum switching valve 38 is maintained in the first state, so the pressure in the front chamber 37b of the diaphragm cylinder 37 is set to atmospheric pressure, and the pressure in the rear chamber 37c is set to atmospheric pressure. Set to negative pressure. Therefore, diaphragm 3
7a is pressed rearward and the clutch sleeve 24e
Since the drive is controlled to the second state (dashed line in Figure 3),
The power distribution device 24 reproduces the state at the end of the vehicle operation. After processing step 71f,
The CPU 55b turns on the transistor 59 at step 71g.
Control data for turning on is output to the I/O 55d. The I/O 55d stores this control data in the register 55d2 and also outputs the transistor 59.
and controls the transistor 59 to be turned on. As a result, the lamp 58 is turned on. In this state, the lamp 56 is turned on by the detection switch 51 being closed.

Through the processing of steps 71e and 71g,
The diaphragm type cylinder 37 and the clutch sleeve 24e are connected to the vacuum switching valve 38,
39, the cylinder 37 and the sleeve 24e are reliably maintained in either the first state or the second state. As a result, even if the power distribution device 24 and the diaphragm cylinder 37 vibrate as the vehicle runs, the cylinder 3
7 and the clutch sleeve 24e are no longer changed.

After processing step 71e or step 71g, the CPU
55b terminates execution of the "initialization" routine at step 71h and advances the program to step 72 (FIG. 4). At step 72, the CPU 55b receives a state signal representing the on or off state of the operating switch 54 via the I/O 55d, and sets new operating switch data OPSWnew to a value corresponding to the state of the operating switch 54 based on the signal. In this case, the ignition switch 65 has just been closed and the operating switch 54 is not turned on, so the status signal becomes "0" and the switch data OPSWnew is set to "0". Next, in step 73, the CPU 55b outputs the old operation switch data OPSWold and the new operation switch data.
By comparing with OPSWnew, the on event (change from off to on) of the operation switch 54 can be detected.
Detect. In this case, the old operation switch data
OPSWold and new operation switch data OPSWnew
respectively in step 71 above (step 71b in Figure 5).
Since it is set to "0" by the processing in step 72, the CPU 55b determines "NO", that is, there is no on event, and the program proceeds to step 74.
Proceed to. The CPU 55b updates the old operation switch data OPSWold with the new operation switch data OPSWnew in step 74, and updates the first operation switch data OPSWnew in step 75.
It is determined whether the lamp flag LPFLG1 is "1". In this determination, the first lamp flag LPFLG1 is set at step 71 (step 71 in FIG. 5).
71b), the CPU 55b determines "NO", returns the program to step 72, and repeats steps 72 to 75 until the operation switch 54 is turned on. continue.

When the vehicle is driven in this state, if the diaphragm 37a and the clutch sleeve 24e are in the first state, the rotational driving force from the output shaft 23a of the transmission 23 is transmitted only to the rear wheel drive shaft 24a. This transmitted rotational driving force is transmitted from the rear wheel drive shaft 24a to the left and right rear wheels RWa, RWb via the rear propeller shaft 26, the differential gear 28, and the left and right rear axle shafts 29a, 29b.
Since only RWb is driven, the vehicle runs as a two-wheel drive vehicle. Further, if the diaphragm 37a and the clutch sleeve 24e are in the second state,
The rotational driving force from the output shaft 23a of the transmission 23 is transmitted to the rear wheel drive shaft 24a, and is distributed from the rear wheel drive shaft 24a to the clutch hub 24d,
Clutch sleeve 24e, spline portion 24c
1. Drive sprocket 24c, chain 24
h and is also transmitted to the front wheel drive shaft 24f via the driven sprocket 24g. This transmitted rotational driving force is transmitted from the front wheel drive shaft 24f to the left and right front wheels via the front propeller shaft 32, the differential gear 34, the left and right front axle shafts 35a, 35b, and the freewheel hubs 36a, 36b (assumed to be in the locked state). The power is transmitted to FWa and FWb to drive the same front wheels FWa and FWb. in this case,
Since the left and right rear wheels RWa and RWb are also driven in the same manner as in the above case, the vehicle runs as a four-wheel drive vehicle. This two-wheel drive state or four-wheel drive state is set in the same manner as when the vehicle was last driven and then the same drive was completed by the process of the "initial setting" routine consisting of steps 71a to 71h. , the driver can drive the vehicle with the same feeling as when driving the vehicle last time.

During the circulation processing of steps 72 to 75, when the driver presses the operator 63 to turn on the operation switch 54, the operation switch 54 turns on the I/O.
Since the status signal supplied to O55d becomes "1", the new operation switch data OPSWnew is set to step
It is set to "1" by the process in step 72. After this setting, in step 73, the CPU 55b outputs the new operation switch data OPSWnew and the old operation switch data.
By comparing with OPSWold, an on event of the operation switch 54 is detected in the same manner as in the above case. In this case, the old operation switch data
OPSWold is the previous cycle process (processing of step 74)
Since it remains set to “0” due to
The CPU 55b determines "YES" in step 73, that is, there is an on-event, and in step 76 updates the old operation switch data OPSWold with the new operation switch data OPSWnew, and advances the program to step 77.

The CPU 55b executes the above step 71b in step 77.
Based on the first lamp flag LPFLG1 set to "0" through the process of (Fig. 5), it is determined as "YES", and in step 78, the step 71c (Fig. 5) is determined.
Similarly to the process described above, the detection switch data DTSW is set to a value according to the state of the detection switch 51,
At step 79, the switch data DTSW becomes “1”
Determine whether or not.

Now, assume that the vehicle is set to two-wheel drive. In this case, the diaphragm 37a
Since the clutch sleeve 24e is in the first state and the detection switch 51 is off, the detection switch data set by the process in step 78 above is
DTSW is “1” and CPU55b is in step
A determination of "YES" is made in step 79, and the program advances to step 80. The CPU 55b outputs the waveform shaper 52b and I/O from the rotation speed sensor 52 at step 80.
55d, and based on the signal, calculate the rotational speed Nf of the rear wheel drive shaft 24a, that is, the rear propeller shaft 26. In step 81, this rotational speed Nr is converted into a vehicle speed of 10 mph.
It is determined whether the value is greater than or equal to a value equivalent to kilometers. In this determination, if the rotational speed Nr is less than the above value, that is, if the vehicle is stopped or running at an extremely low speed, the CPU 55b determines "NO" in step 81 and advances the program to step 84. In addition, if the rotation speed Nf is equal to or higher than the above value, that is, if the vehicle is running normally, the CPU 55b
is determined to be ``YES'' in step 81, and in step 82, the waveform shaper 53b is output from the rotation speed sensor 53.
and a pickup signal via the I/O 55d, and based on the signal, calculate the rotation speed Nf of the front wheel drive shaft 24f, that is, the front propeller shaft 32. In step 83, this rotation speed Nf is converted into a vehicle speed of 10 mph. It is determined whether the value is greater than or equal to a value equivalent to kilometers. In this determination, even if the rotational speed Nf is less than the above value, that is, the vehicle is running normally, the freewheel hubs 36a, 3
6b is in a free state and the front axle shafts 35a, 35b, front propeller shaft 32, and front wheel drive shaft 24f are not rotationally driven by the left and right front wheels FWa, FWb that are rotating as the vehicle runs, the CPU 55b is in the same state. step
A determination of "NO" is made in step 83, and the program proceeds to step 87, which will be described later. Also, if the rotational speed Nf is equal to or higher than the above value, that is, the freewheel hubs 36a, 36
b is in the locked state and the front axle shafts 35a, 35b, front propeller shaft 32, and front wheel drive shaft 24f are rotationally driven by the left and right front wheels FWa, FWb, which are rotating as the vehicle travels, the CPU 55b is in the same state. A determination of "YES" is made in step 83, and the program advances to step 84.

At step 84, the CPU 55b outputs control data for de-energizing the electromagnetic solenoid 38b and control data for energizing the electromagnetic solenoid 39b to the I/O 55d. The I/O 55d replaces these control data with previously stored control data and stores them in the register 55d2, and outputs them to the excitation control circuits 38f and 39f, respectively. The excitation control circuit 38f de-energizes the electromagnetic solenoid 38b, and the vacuum switching valve 38
The state is switched to the first state, and the front chamber 37b of the diaphragm cylinder 37 is set to atmospheric pressure. The excitation control circuit 39f is an electromagnetic solenoid 39b.
is excited, the vacuum switching valve 39 is switched from the first state to the second state, and the rear chamber 37c of the diaphragm cylinder 37 is set to negative pressure. As a result, the diaphragm 37a is pushed rearward and the diaphragm type cylinder 37 is switched from the first state (solid line in FIG. 3) to the second state (broken line in FIG. 3), so that the clutch sleeve 24e also moves to the first state.
From the state (solid line in Figure 3) to the second state (broken line in Figure 3)
The vehicle is switched from a two-wheel drive state to a four-wheel drive state as described above. At this time, the detection switch 51 detects the clutch sleeve 24
The lamp 5 is closed by the protrusion 24e1 of e.
6 lights up, and the display 62 displays "4DW".
After processing step 84, the CPU 55b proceeds to step 85.
At step 86, the lamp 58 is turned on by the same process as in step 71g (Fig. 5), and the first lamp is turned on at step 86.
The lamp flag LPFLG is set to “0” and the first lamp flag is set to “0” in step 75.
The determination is "NO" based on LPFLG1, and the program returns to step 72. Next, the CPU 55b
As described above, the on event of the operation switch is detected through the processing in steps 72 and 73, but if the driver continues to press the operator 63, the new operation switch data OPSWnew is set to "1" through the processing in step 72. and the old operation switch data
OPSWold is also set to “1” by the processing in step 76 above.
Therefore, the CPU 55b determines "NO" at step 73, that is, there is no on-event, and advances the program to steps 74 and 75, where it executes the circular process consisting of steps 72 to 75 as described above. continue. In this case, the old operation switch data OPSWold is set to “1” by the process in step 74.
is set to . During this circulation process, when the driver releases the pressure on the operator 63, the new operation switch data OPSWSnew is set to "0" by the process in step 72, but the CPU 55b
73, the new operation switch data OPSWnew and the old operation switch data set to "1"
Based on OPSWold, it is determined as "NO", that is, there is no on event, and steps 72~
A circular process consisting of 75 will continue to be executed.
In this case, the old operation switch data
OPSWold is set to "0" by the processing in step 74.

On the other hand, even though the answer in step 83 is "NO", that is, the rotation speed Nr is greater than the value equivalent to 10 kilometers per hour, the freewheel hub 3
Since 6a and 36b are in the free state, the rotation speed
If it is determined that Nf is less than the value equivalent to 10 kilometers per hour, the CPU 55b executes step 87.
The first lamp flag LPFLG1 is set to "1" at step 88, and the control data for turning on the transistors 57 and 59 is sent to the I/O 55d.
Output to. The I/O 55d replaces these control data with previously stored control data and stores them in the register 55d2.
7 and 59, respectively, and the transistors 57 and 5
9 is turned on. This causes lamp 5
Current flows through lamps 6 and 58, and the same lamps 56 and 58
lights up. Incidentally, the lighting of these lamps 56 and 58 means the first lighting state in which they will blink from now on.
After the processing in step 88, the CPU 55b sets the second lamp flag LPFLG2 to "1" in step 89, and also sets the first and second timer data.
TIME1 and TIME2 are each set to "0", and the first lamp flag LPFLG1 is set to "1" in step 75.
Determine whether or not. In this judgment,
First lamp flag LPFLG set to “1”
1, and the CPU 55b executes the "lamp blinking process" routine at step 90.

In the “lamp blinking process” routine, the sixth
As shown in the figure, the CPU 55b starts executing the program from step 90a, and determines whether the second lamp flag LPFLG2 is "1" at step 90b. In this determination, the CPU 55b determines "YES" based on the flag LPFLG2, which has been set to "1" by the process in step 89, and in step 90c, the first timer data TIME1 is
Determine whether or not is greater than or equal to a value equivalent to 0.5 seconds. In this determination, the CPU 55b uses the same data set to "0" by the process in step 89 above.
Judgment is “NO” based on TIME1 and step
At 90d, it is determined whether the second timer data TIME2 is equal to or greater than a value corresponding to 20 seconds. In this determination as well, the CPU 55b determines "NO" based on the same data TIME2 set to "0" by the processing in step 89, and in step 90e, the minute time data △ is set to the first and second timer data TIME1 and TIME2. The same data can be obtained by adding each t.
TIME1 and TIME2 are updated, and the process of this "lamp blinking process" routine is ended at step 90f. Note that this minute time data Δt is set approximately to the time required for processing steps 72 to 75 and 90.

After processing this "lamp blinking processing" routine,
The CPU 55b returns the program to step 72 and
The processes in steps 72 to 74 described above are executed, and the above-described determination process in step 75 is executed. In this determination, the determination is ``YES'' based on the first lamp flag LPFLG1 which remains set to ``1'', and the CPU 55b again executes the ``lamp blinking process'' routine at step 90. in this case,
The second lamp flag LPFLG2 remains set to "1", and the first and second timer data
Since TIME1 and TIME2 are each set to minute time data Δt by the processing in step 90e, the CPU 55b starts processing the same routine from step 90a, and selects "YES" in step 90b and "YES" in step 90c. "NO", "NO" at step 90d
In step 90e, in the same way as above,
By adding minute time data Δt to the first and second timer data TIME1 and TIME2, the same data TIME1 and TIME2 are updated. This results in
The same data TIME1 and TIME2 are each set to 2Δt. After the process in step 90e, the CPU 55b finishes the process of this "lamp blinking process" routine in step 90f, returns the program to step 72, and thereafter performs a circular process consisting of steps 72 to 75 and 90 (90a to 90f). continue to run. In this circulation process, the first and second timer data TIME1,
TIME2 increases by minute time data △t each time the process of step 90e is executed, and the minute time data △t increases in steps 72 to 75 as described above.
Since the time required for processing 90 is set, the data values TIME1 and TIME2 indicate the time since they were each set to "0".

During such cyclic processing, the first timer data
When 0.5 seconds have passed since TIME1 was set to "0" by the process in step 89 above, the same data
TIME1 has a value equivalent to 0.5 seconds,
The CPU 55b determines "YES" in step 90c, and sends control data to the I/O 55d to turn off the transistors 57 and 59 in step 90g.
Output to. The I/O 55d replaces these control data with previously stored control data and stores them in the register 55d2.
7 and 59, respectively, and the transistors 57 and 5
9 is turned off. As a result, the lamp 56,
58 goes out. After processing step 90g, CPU5
5b is the second lamp flag at step 90h.
Set LPFLG2 and first timer data TIME1 to "0" and "0", respectively, and perform the step in the same way as above.
The processes of 90d, 90e, and 90f are executed to complete the process of the "lamp blinking process" routine. In this case, the first
The timer data TIME1 indicates a value that increases by minute time data △t from "0" again through the processing of steps 90h and 90e, but the second timer data TIME2 continues to increase by minute time data △t through the processing of step 90e. This indicates the value to be used.

After executing the "lamp blinking process" routine in step 90, the CPU 55b executes the processes in steps 72 to 75, and then starts executing the same routine again from step 90a. In this case, the second lamp flag
LPFLG2 is set to “0” by the process in step 90h above.
CPU 55b is set to
It is judged as "NO" in step 90b, and the first step is determined in step 90i.
It is determined whether the timer data TIME1 is equal to or greater than a value corresponding to 1.5 seconds. In this judgment,
The CPU 55b determines "NO" based on the first timer data TIME1 that was set to "0" by the process of step 90h and updated to minute time data Δt by the process of step 90e, and then proceeds to step 90d similar to the above. Execute the process from ~90f to end the process of the "lamp blinking process" routine. Then, the CPU 55b continues to execute the circular process consisting of steps 72 to 75 and 90 again, but in this case, in the "lamp blinking process" routine of step 90, the process consisting of steps 90a, 90b, 90i, and 90d to 90f is repeated. executed.

Through this circular processing, the first timer data
When TIME1 gradually increases through the process in step 90e as described above and reaches a value equivalent to 1.5 seconds or more, the CPU 55b determines "YES" in step 90i, and in step 90j performs the same process as in step 88 above. lights up the lamps 56 and 58, and sets the second lamp flag LPFLG2 to “1” at step 90k.
At the same time, the first timer data TIME1 is set to "0", and the processing of steps 90d to 90f is executed to complete the execution of the "lamp blinking processing" routine. Thereafter, the CPU 55b alternately repeats the above case in which the lamps 56 and 58 are turned on and the above case in which the lamps 56 and 58 are turned off.
The lamps 56 and 58 will blink. In addition,
In this case, the lighting time of the lamps 56 and 58 is 0.5 seconds, and the lighting time of the lamps 56 and 58 is 1.5 seconds. During the circulation process consisting of steps 72, 75, and 90, the lamp 5
When 20 seconds have passed since 6,58 started blinking,
The CPU 55b determines "YES" in step 90d, that is, that the second timer data is equal to or greater than the value corresponding to 20 seconds, and determines that the first lamp flag is set in step 90l.
Set LPFLG1 to "0" and at step 90m, transistors 57 and 5 are connected in the same way as in step 90g above.
By turning off the lamps 56 and 58,
Turn off the light. Incidentally, the processing in step 90m means turning off the lamps 56 and 58, and at the same time means turning off the transistor 57, thereby making it possible to detect the on/off state of the detection switch 51 from now on. This step
After processing 90m, the CPU 55b finishes executing the "lamp blinking processing" routine at step 90f, and
The program returns to step 72, and the same steps 72 to 74 as described above are executed, and the determination process of step 75 is executed. In this determination, since the first lamp flag LPFG1 is set to "0" by the processing in step 90l, the determination is "NO", and from then on, the CPU 55b continues to execute the above-mentioned cyclic processing consisting of steps 72 to 75. .

On the other hand, if the operator 63 is pressed again while the lamps 56 and 58 are blinking, the CPU 55b
During the cyclic process of steps 72 to 75 and 90, an on event of the operation switch 54 is detected in step 73, and after the process of step 76, the determination process of step 77 is executed. In this determination, since the first lamp flag LPFLG1 is set to "1" in the process of step 87 described above, the CPU 55b determines "NO" and skips the program to steps 80 to 83.
Proceed to. In this case, step 81 or step 83
In the determination, if the switching from the two-wheel drive state to the four-wheel drive state is permitted, that is, step 81
If the determination is "NO" in step 83 or "YES" in step 83, the CPU 55b switches the vehicle to the four-wheel drive state and turns on the lamps 56 and 58 through the above processing in steps 84 and 85. After the processing in step 85, the CPU 55b returns the first lamp flag that was previously set to "1" in step 86.
Change the setting of LPFLG1 to “0”. This results in
The CPU 55b thereafter executes the above-mentioned cyclic processing consisting of steps 72-75. In addition, in the judgments in steps 81 and 83, from the 2-wheel drive state to the 4-wheel drive state,
If switching to the wheel drive state is prohibited, that is, if the determination is ``YES'' in step 81 and ``NO'' in step 83, the CPU 55b
After the processing of steps 87 to 89, the circulation processing consisting of steps 72 to 75 and 90 is continued again, and the lamps 56 and 58 are made to blink while the vehicle is maintained in the two-wheel drive state. In this case, the second timer data TIME2 is reset to "0" by the process of step 89, so the lamps 56 and 58 are set to "0" again.
After pressing again, it will blink for another 20 seconds.

In this way, even if the operator 63 of the vehicle set to the two-wheel drive state is pressed, if the freewheel hubs 36a and 36b are in the free state and the vehicle speed is 10 kilometers per hour or more, the clutch hub 24d If the rotational speed difference between the clutch hub 24d and the spline portion 24c1 is large, switching from the two-wheel drive state to the four-wheel drive state is prohibited by the processing in steps 80 to 83. There is no need to worry about the generation of loud noises caused by the connection of the sleeves 24e, the hub 24d, and the spline portions 24c1 due to the connection. Also, when this is prohibited, steps 87 to 89, 90 (90a
~90m), the existing lamps 56, 58
(Indicators 62, 64) are made to blink, so the driver can visually recognize the prohibited state without using a separate device to display the prohibited state, which saves on display devices. Leads to.

In addition, the operation element 63 and the operation switch 54 are each constituted by a self-resetting type operation element and switch,
The operation switch 5 accompanying the operation of this operator 63
4 is detected by the processing in steps 72 to 76, and based on the detection, it is determined whether or not switching from the two-wheel drive state to the four-wheel drive state is prohibited or permitted only once when the operator 63 is pressed. As a result, after the driver performs the switching operation, the switching is allowed due to changes in the driving condition of the vehicle, and the vehicle is not suddenly switched to four-wheel drive mode, so the driver can drive the vehicle with peace of mind. I can drive. In addition, due to the prohibition of the above switching, the lamp 56,
Even if 58 (indicators 62, 64) are blinking, if the operator 63 is pressed, steps 72 to 73 and 77 will process the switching judgment made in steps 80 to 84. However, the driver can switch the vehicle to four-wheel drive at any time, unless such switching is prohibited.

In addition, in cases other than the above, i.e., when the freewheel hubs 36a, 36b are in a locked state and the rotational speeds of the clutch hub 24d and the spline portion 24c1 are approximately equal, or when the vehicle speed is less than 10 kilometers per hour and the hub 24d and the spline portion 24c1 rotate at substantially the same speed.
If the difference in rotation speed with c1 is small, proceed to step 80.
Since the process of steps 1 to 83 allows the driver to switch from two-wheel drive to four-wheel drive while the vehicle is moving, the function of the part-time four-wheel drive vehicle is fully utilized.

Next, assume that the vehicle is set to four-wheel drive. When the operator 63 is pressed in this state, the CPU 55b performs steps 72 to 72.
During the cyclic process consisting of step 75, it is determined in step 73 that it is ``YES'' as described above, that is, there is an on event of the operation switch 54, and after the process of step 76, the first lamp flag LPFLG1 is set to ``0'' in step 77.
Determine whether or not. This first lamp flag
LPFLG1 is a flag indicating that the lamps 56 and 58 are flashing (switching from 2-wheel drive to 4-wheel drive is prohibited), and the vehicle is set to 4-wheel drive. In this case, the CPU 55b determines "YES" in step 77, and sends the detection switch data DTSW to the detection switch 51 in step 78.
In step 79, it is determined whether or not the set detection switch data DTSW is "1". In this case, the diaphragm 37a
Since the clutch sleeve 24e1 is in the second state and the detection switch 51 is on, the detection switch data DTSW set by the process in step 78 is "0", and the detection switch data DTSW is "0" in the CPU 55b step.
Judgment is “NO” at 79 and step the program.
Proceed to 91.

At step 91, the CPU 55b outputs control data for energizing the electromagnetic solenoid 38b and control data for de-energizing the electromagnetic solenoid 39b to the I/O 55d. The I/O 55d stores these control data in the register 55d2 in place of previously stored control data, and outputs them to the excitation control circuits 38f and 39f, respectively. The excitation control circuit 38f is an electromagnetic solenoid 38b.
is excited, the vacuum switching valve 38 is switched from the first state to the second state, and the front chamber 37b of the diaphragm cylinder 37 is set to negative pressure. The excitation control circuit 39f is an electromagnetic solenoid 39b.
De-energize the vacuum switching valve 3.
9 is switched from the second state to the first state, and the rear chamber 37c of the diaphragm cylinder 37 is set to atmospheric pressure. As a result, the diaphragm 37a is pressed forward and the diaphragm cylinder 37
From the state (dashed line in Figure 3) to the first state (solid line in Figure 3)
Therefore, the clutch sleeve 24e is also switched from the second state (broken line in FIG. 3) to the first state (solid line in FIG. 3), and the vehicle is switched from the four-wheel drive state to the two-wheel drive state. At this time, the detection switch 51 detects the protrusion 24 of the clutch sleeve 24e.
Since it is opened by releasing the pressure on e1, the lamp 5
6 goes out and the "4WD" display on the display 62 also goes out. After the processing in step 91, the CPU 55b outputs control data for turning off the transistor 59 to the I/O 55d in step 92. I/
O55d stores this control data in register 55d2 in place of previously stored control data, and outputs it to transistor 59. This turns off the transistor 59 and turns off the lamp 58.
(Indicator 64) goes out.

In this way, whenever the operator 63 of a vehicle set to the four-wheel drive state is pressed, the vehicle is switched to the two-wheel drive state.

When the vehicle thus set to the two-wheel drive state or the four-wheel drive state comes to a stop and the ignition switch 65 is opened, the engine 21 stops operating and the electric control circuit 50 is discharged from the battery. 66 will no longer be supplied with power. As a result, the excitation of the electromagnetic solenoids 38b and 38c by the excitation control circuits 38f and 39f is canceled, and the vacuum switching valves 38 and 39 are set to the first state, so that the diaphragm type cylinder 3
The front and rear chambers 37b and 37c of No. 7 are set to atmospheric pressure,
Diaphragm 37a and clutch sleeve 24e
remains in its previous state. In this state, since the vehicle is stopped, the power distribution device 24 and the diaphragm type cylinder 37b do not vibrate, and the diaphragm 37a and the clutch sleeve 24e are not vibrated like when the vehicle is running. Even if the switching valves 38 and 39 are not actively controlled, the states of the flamm 37a and the sleeve 24e will not be changed.

In the above embodiment, the present invention is applied to a four-wheel drive vehicle that is always rear wheel drive, but the present invention is also applicable to a four wheel drive vehicle that is always front wheel drive. In this case, the power distribution device 24 constantly connects the output shaft 23a of the transmission 23 to the front propeller shaft 32, selectively connects the output shaft 23a to the rear propeller shaft 26, and connects the output shaft 23a of the transmission 23 to the rear propeller shaft 26, thereby connecting the freewheel hubs 36a, 36b. Rear axle shafts 29a, 29b and left and right rear wheels RWa,
Each is provided between RWb and RWb. In addition, in the switching judgment process from the two-wheel drive state to the four-wheel drive state in steps 80 to 83 (Fig. 4), the rotational speed is
It is better to reverse the relationship between Nr and Nf.

[Brief explanation of drawings]

Fig. 1 is a diagram corresponding to the configuration of the present invention described in the claims of the utility model registration, Fig. 2 is an overall schematic diagram of a vehicle showing an embodiment of the present invention, and Fig. 3 is the power distribution of Fig. 2. Diagrams showing details of devices, electrical control devices, etc.
4 to 6 are flowcharts of programs executed by the microcomputer shown in FIG. 3. Explanation of symbols, FWa, FWb...Front wheel, RWa,
RWb...Rear wheel, 21...Engine, 23...Transmission, 23a...Output shaft, 24...Power distribution device, 26...Rear propeller shaft, 29a, 2
9b...Rear axle shaft, 32...Front propeller shaft, 35a, 35b...Front axle shaft, 36a, 36b...Freewheel hub, 37...Diaphragm type cylinder, 38, 39...Vacuum switching valve, 38f , 39f... excitation control circuit, 50...
Electrical control circuit, 51...detection switch, 52,5
3... Rotation sensor, 54... Operation switch, 55
...Microcomputer, 55d...I/O interface, 55d2...Register, 56,5
8...Lamp, 65...Ignition switch, 66...Battery.

Claims (1)

[Claims for Utility Model Registration] (1) A first drive wheel that is constantly driven, a second drive wheel that is selectively driven, and a drive wheel that is assembled to the second drive wheel and drives the second drive wheel. It is applied to a four-wheel drive vehicle having a freewheel hub that intermittents power, and in a first state transmits the rotational driving force of the output shaft of the transmission only to the first drive wheel, and in a second state transmits the rotational driving force of the output shaft of the transmission only to the first drive wheel. a power distribution device that transmits driving force to the first drive wheel and the second drive wheel; a switching device that selectively switches the power distribution device to a first state or a second state; and the switching by the switching device. A drive state switching control device for a four-wheel drive vehicle, comprising: a self-resetting operation switch; an operation detection means for detecting the operation state of the operation switch; and an operation detection means for detecting the operation state of the operation switch; determining means for determining whether or not the power distribution device is in a state that allows switching between the first state and the second state when the operation switch is operated in response to the detection by the means;
Only when the determination means determines that the power distribution device is in a state that allows the switching, the state of the power distribution device is changed from the first state to the second state.
Drive state switching control for a four-wheel drive vehicle, characterized in that the electric control device is configured by an output means for outputting a control signal for inverting the state or from the second state to the first state to the switching device. Device. (2) The power distribution device includes a first drive shaft that constantly connects the output shaft of the transmission and the first drive wheel, and a second drive shaft that connects the second drive wheel;
a clutch mechanism that connects or disconnects the first drive shaft and the second drive shaft, and the determining means includes a first rotation sensor that detects the rotation speed of the first drive shaft. a second rotation sensor that detects the rotational speed of the second drive shaft; a detection switch that detects a coupled state or a disengaged state of the clutch mechanism; and a detection switch that detects the disengaged state of the clutch mechanism; the first rotation sensor and the second rotation sensor;
A state in which the power distribution device determines that the power distribution device is in a state that does not allow the switching when the difference between the rotational speeds detected by the rotation sensors is large, and that the power distribution device determines that the power distribution device is in a state that allows the switching in other cases. A drive state switching control device for a four-wheel drive vehicle as claimed in claim 1, comprising determining means.