JPS62218233A - Controlling method for four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To prevent the durability of a parking device from deteriorating, by having the number of driving wheels once selected to two wheels at the time of parking shift operation during four-wheel driving, in case of a device which makes each rotation of these driving wheels checkable by doing the parking shift operation. CONSTITUTION:In this transmission 30, an engaged state of gears are selected according to operation of a shift lever, and power according to a driving state is transmitted to a rear-wheel output shaft 31 via a transfer, while it is also transmitted to a front-wheel output shaft 33 via a 4WD 2WD selector mechanism 32. In this case, the selector mechanism 32 is controlled by a controller 34 according to each output of respective car speed sensors 38-40, a shift position sensor 35, a parking lock sensor 36, and a 4WD detector 37 additionally installed in an output shaft of the transmission, the rear-wheel output shaft 31 and the front-wheel output shaft 33 each. And, a controller 34 is installed so as to be capable of doing such control as reducing the number of driving wheels once to two wheels at the time of parking shift operation during car driving by means of four-wheel drive.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method of controlling a part-time four-wheel drive vehicle, that is, a four-wheel drive vehicle that can be switched between four-wheel drive and two-wheel drive, and in particular, relates to a method for controlling a part-time four-wheel drive vehicle, that is, a four-wheel drive vehicle that can be switched between four-wheel drive and two-wheel drive. It concerns a method of controlling the state.

As is well known in the art, four-wheel drive vehicles are equipped with a power distribution device (transfer), which distributes power that is constantly applied to either the front or rear wheels, such as the rear wheels, to the front wheels as needed. This is a drive configuration. This is shown in Figure 7 for a four-wheel drive vehicle with an automatic transmission. This is described in Japanese Patent Application Laid-Open No. 56-39352, in which a power distribution device 3 is provided following an automatic transmission 2 connected to an engine 1. A front export force shaft 5 is provided which receives power from the driven rear export force shaft 4 via a clutch.

The rear export power shaft 4 is connected to a rear axle (wheel bearing axle) 8 via a propeller shaft 6 and a differential gear 7, whereas the front export power shaft 5 is connected to a front axle (a front axle) via a propeller shaft 9 and a differential gear 10. (front wheel axle) 11.

In a vehicle having an automatic transmission configured as described above, the shift lever automatically switches between predetermined gears in the range set, and when the shift lever is set in the parking range, the parking device is activated. It is configured to operate to prevent rotation of the output shaft and maintain the vehicle in a stopped state. 8 and 9 are schematic diagrams showing an example of a conventionally known parking device. At one end of a manual shaft 13 provided in a transmission case 12, a transmission control shaft lever 14 and a wire or A shift lever (not shown) is connected via a link, and a manual valve lever 15 is attached to the other end of the manual shaft 13. One end of a parking lock rod 16 is rotatably connected to an eccentric position of the manual valve lever 15, and the other end of the parking lock rod 16 is connected to a parking lock pole bracket provided inside the transmission case 12. 17 so that it can move back and forth in the axial direction. Roughly, a conical cam collar 18 with a small diameter on the tip side is fitted into the parking lock rod 16 so as to be freely movable forward.
A spring 19 is arranged on the left side of the figure. On the other hand,
A parking lock pawl 20 as a fixed member is disposed in the transmission case 12 in a direction perpendicular to the moving direction of the cam collar 18, and one end of the parking lock pawl 20 is connected to the shaft 2.
1 and a torsion spring 22, and has engaging teeth 23 provided at the lower center portion as shown in FIG.

Further, a parking gear 24 as a rotating member with which the engaging teeth 23 mesh is arranged corresponding to the parking lock pawl 20. This parking gear 24 is substantially directly connected to the drive wheels, and by setting the shift lever to the parking range, the manual shaft 13 and the manual valve lever 15 are rotated.
Accordingly, the parking lock rod 16 moves forward, and the cam collar 18 fitted therewith is pushed forward by the spring 19, and its cam action pushes the parking lock pole 20 downward in FIG. 9. As a result, the engaging teeth 23 are configured to mesh with the parking gear 24 to prevent rotation of the drive wheels. Note that when the vehicle is traveling at a predetermined speed or higher, even if a parking shift operation is performed, the parking lock pole 20 will not engage with the parking gear 24 and will be flipped up, and the cam collar 18 will resist the spring 19 and return to its original position. The parking system does not function. In other words, the spring 19, together with the height of the teeth of the parking gear 24 and the strength of the torsion spring 22, determines the vehicle speed at which the parking device functions.

Problems to be Solved by the Invention As mentioned above, with conventionally commonly used parking devices, when shifting to the parking range while driving,
If the vehicle speed is below the set speed, the parking lock pole 20 engages the parking gear 24 to lock the drive wheels, and at the same time, in the automatic transmission, transmission of power to the output shaft is released. This situation is the same even when driving in four-wheel drive, so if you operate the parking shift in four-wheel drive, all four wheels will be locked and the braking action will stop the vehicle from moving due to inertial force. occurs on all four wheels, and the resulting load is applied to the parking device. As a result, the durability of the parking system is reduced because the load is larger than that of a two-wheel drive vehicle, and in order to avoid such inconveniences, it is necessary to increase the size and strength of the components and supporting members of the parking system. For example, a problem arises in that the weight increases.

This invention has been made in view of the above circumstances, and it is an object of the present invention to provide a control method for a four-wheel drive vehicle that can reduce the load applied to the parking device when the parking shift is operated while driving. be.

Means for Solving the Problems In order to achieve the above object, the present invention is capable of switching the number of driving wheels between four wheels and two wheels, and that a fixed member is fixed to a rotating member by operating a parking shift. In a four-wheel drive vehicle that can be engaged to prevent rotation of the drive wheels, the control method is characterized in that the number of drive wheels is temporarily reduced to two when a parking shift is operated while driving in four-wheel drive. be.

Flowcharts 1 to 1 including control according to the present invention can be shown as shown in FIG. Since the control method of the present invention is based on the premise that the drive wheels are locked based on the parking shift operation while the vehicle is traveling in four-wheel drive, it is first determined whether or not the vehicle is traveling in four-wheel drive. In the case of four-wheel drive driving, the system makes a judgment as to whether the vehicle speed is above the set vehicle speed or not.
A determination is made as to whether the vehicle speed is lower than another set vehicle speed. 2 like this
Generally speaking, if the vehicle speed is at or above a certain level, the fixed member and rotating member will not engage (the parking device will not function) even if the parking shift is performed, so the vehicle speed is determined in four-wheel drive mode. This is because there is no need to eliminate the problem, and in the case of a slow vehicle speed that is close to a stopped state, it is considered that there is no particular problem even if all wheels are locked while remaining in the four-wheel drive state. If the vehicle speed is within the set speed range or above, and a parking shift operation is performed in that state, the number of driven wheels will be reduced from four to two. In this way, the front or rear wheels are left in a free state, and the two-wheel drive state is forced until a predetermined condition is met, for example, the fixed member and the rotating member engage (the parking device functions). Then, after the fixed member and the rotating member are engaged to lock the two driving wheels, the two-wheel drive is returned to the four-wheel drive.

Function: Therefore, according to the control method of the present invention, when the fixed member and the rotating member engage, the two-wheel drive state is always established.
As a result, the braking force that stops the vehicle from moving due to inertia is
This is caused by the two wheels that are the driving wheels, and the other two wheels are in a free rotation state. Therefore, the impact load acting on the fixed member and rotating member that engage with each other is only the load from the two driving wheels, which is reduced by half compared to when all four wheels are locked. Note that by returning to four-wheel drive after the fact, the stopped state can be ensured. The vehicle may be moving at a very slow speed when returning to four-wheel drive, but in that case, the stationary member and rotating member are already engaged, and the vehicle speed is extremely slow, so these members There is no problem with the load being applied to it.

Example Next, the present invention will be explained based on examples.

First, an example of a system for implementing the method of the present invention is shown. In FIG. 2, reference numeral 30 indicates a transmission including an automatic transmission and a four-wheel drive transfer 1. Manual shift lever provided
(not shown), parking range (P), reverse range (R), neutral range (N), forward range (
D) is set to each range such as the deceleration/forward range (L), and the gears are switched to the meshing state corresponding to each range, and the power corresponding to the running state is transmitted to the rear export force shaft 31 via the transfer, Roughly speaking, when the four-wheel drive-two-wheel drive switching mechanism (hereinafter simply referred to as the switching mechanism) 32 is operating, the power is transmitted to the front export power shaft 33 together with the rear export power shaft 31. . Here, in addition to the switching operation by the driver, the switching device @ 32 has a configuration that performs switching operation with priority over the switching operation, or determines the driving state, based on an output signal from a control device 34 mainly composed of a microcomputer, for example. In this configuration, the control device 34 automatically performs the switching operation. The following signals are input to the control device 34 as data for controlling the switching mechanism 32. First, among the signals outputted by the shift position sensor 35 linked to the manual shift lever, there is a parking shift signal especially when the parking range is set, and a parking gear engagement signal from the parking lock sensor 36 which detects the completion of operation of the parking device. A signal is input to the control device 34. Additionally, a four-wheel drive state signal and a vehicle speed signal are input to the control device 34 in order to determine whether or not it is necessary to forcibly switch from four-wheel drive to two-wheel drive. Among these, the four-wheel drive status signal is generated by a four-wheel drive detector 37 that is built into the transfer or a control mechanism that controls the transfer and outputs a signal when power is distributed to the front export power shaft 33. The signal may be used. Also, as a vehicle speed signal, a vehicle speed sensor 38 attached to the output shaft of the automatic transmission device
, output signals from a vehicle speed sensor 39 attached to the rear export force shaft 31 and a vehicle speed sensor 40 attached to the front export force shaft 33 are used. In this way, by picking up vehicle speeds from a small number of locations and using them as control data, highly reliable control becomes possible.

To further specifically illustrate the main parts of the above-mentioned configuration, FIG. 3 is a schematic diagram showing a gear train of a four-wheel drive transfer.
It has the same configuration as that proposed in No.-101525, and is provided with an auxiliary transmission so that it can be converted into three modes: high-speed two-wheel drive H2, high-speed four-wheel drive H4, and deceleration four-wheel drive. That is, the input shaft 41 of the sub-transmission is directly connected to the sun gear 43 of the planetary gear mechanism 42, while the input shaft 41 is connected to the carrier 44 via the clutch C3.
is connected to. Further, a brake B4 that stops the rotation of the ring gear 46 is provided between the ring gear 46 with which the pinion 45 is engaged and a fixed part 47 such as a casing. , the rear export force IFllI31 is the carrier 4
A power transmission mechanism 48 is connected to the carrier 44 via a clutch C4 for switching between two-wheel drive and four-wheel drive. The power transmission mechanism 48 is for transmitting power to the front export force shaft 33, and is composed of, for example, a pair of sprockets and a chain wound around the sprockets.

Therefore, if the clutch C3 of the auxiliary transmission is connected (engaged) and the brake B4 and the clutch C4 of the power distribution device are released, the input shaft 41 and the rear export power shaft 31 are directly connected, and the high-speed two-wheel drive H2 is activated. . If the clutch C4 is connected (engaged) from this state, power is transmitted to the front export power shaft 33 via the power transmission mechanism 48, resulting in high-speed four-wheel drive H4. If the clutch C3 of the auxiliary transmission is roughly disengaged (released) and the brake B4 and clutch C4 are engaged, the input shaft 41 decelerates the pinion 45 via the sun gear 43 and causes it to revolve.
The rotation of the input shaft 41 is transmitted at a reduced speed to the rear export force shaft 31 and the front export force shaft 33, which are integrated with the input shaft 4, resulting in a decelerated four-wheel drive L4.

Each of the clutches C3, C4a and brake B4 is operated by a hydraulic servo consisting of a cylinder and a piston disposed inside the cylinder, and the hydraulic circuit therefor is shown in FIG. Note that in the following explanation, 1 "vertical direction" refers to the vertical direction (as shown in the figure).

Transfer manual valve 50 as gear selection means
has a spool 51 connected to a shift lever (not shown) provided at the driver's seat, and when high-speed two-wheel drive H2 is selected, a line is sent from the main hydraulic control device P via an oil path 60. When hydraulic pressure is supplied to the oil passage 62 and high-speed four-wheel drive H4 is selected, line oil pressure is supplied to the oil passage 62 and oil passage 63, and when deceleration four-wheel drive is selected and 4 is selected, It is configured to supply line hydraulic pressure only to the oil passage 63. An oil passage 63 to which line hydraulic pressure is supplied when four-wheel drive is selected is connected to an inlet port 71 of a timing valve 70, and an outlet port 72 of the timing valve 70 is connected to the two-wheel drive four-wheel drive switch. The hydraulic pump C-4 operates the clutch C4.

That is, the timing valve 70 has a configuration in which a spring 74 is disposed at one end of a spool 73 and an oil chamber 75 is provided at the other end, and when the spool 73 is pushed back by the spring 74, the inlet port 71 is closed. At the same time, the outlet route 72 communicates with the drain port 76, so that the hydraulic pressure for the hydraulic servo C-4 is discharged, and by applying line hydraulic pressure to the oil chamber 75, the spool 73 compresses the spring 74 and moves toward one end. As a result, the inlet port 71 and outlet port 72 communicate with each other, and hydraulic pressure is applied to the hydraulic servo C-4. A solenoid valve $5, which is controlled on and off by the aforementioned control device 34, is interposed in the middle of the oil path to the oil chamber 75, and the oil pressure to the oil chamber 75 is controlled by energizing and energizing the coil. It is configured such that hydraulic pressure can be supplied to the oil chamber 75 by discharging the pressure and demagnetizing it. Therefore, the solenoid valve S
5 is energized, the pressure in the oil chamber 75 is exhausted and the spool 73 is pushed back by the spring 74. As a result, the inlet port 71 is closed and no hydraulic pressure is applied to the hydraulic servo C-4. These timing valve 70 and electromagnetic valve S5 constitute the switching mechanism 32 described above.

The oil passage 62 from the transfer manual valve 50 is
It is connected to a relay valve 80 via an oil strainer ST6. The relay valve 80 has a spool 81 and a spool 81.
By applying line hydraulic pressure to the lower side of the plunger 83 in the illustrated state via the oil passage 61 passing through the oil strainer ST5 and the solenoid valve S4, The plunger 83 pushes up the spool 81 so that the inlet port 84 and the outlet port 85 communicate with each other, and the outlet port 85 communicates with the oil chamber 86 below the spool 81 to apply feedback pressure.
1 is held at the upper end against the spring 82, and the solenoid valve S
When the pressure is exhausted by step 4, only the plunger 83 descends. In addition, by switching the transfer manual valve 50 and discharging the line hydraulic pressure from the oil passage 62, the spool 81 is pushed down by the spring 82, so that the inlet port 84 is closed and the outlet port 85 is communicated with the drain port 87. It is configured.

An outlet port 85 of the relay valve 80 is connected to an oil chamber below a plunger 91 of an inhibitor valve 90 for switching engagement of the clutch C3 and brake B4 during sub-shifting.

In the inhibitor valve 90, a spool 93 that is pushed back by a spring 92 is arranged above a plunger 91, line hydraulic pressure is applied from a relay valve 80 to the bottom of the plunger 91, and the spool 93 is pushed up by the plunger 91.
Furthermore, when the line hydraulic pressure from the relay valve 80 is discharged, the line hydraulic pressure applied to the upper side of the plunger 91 through the oil passage 61 causes the plunger 91 to descend, and as a result,
A spool 93 is pushed down by a spring 92. The inhibitor valve 90 communicates the upper oil chamber of the spool 93 with the oil passage 61 via the solenoid valve S4 when the spool 93 is in the lower position, and also connects the line hydraulic oil passage 60 with the hydraulic servo B- for the brake B4. 4, and roughly connect the drain port 94 and the direct connection oil passage 65. In contrast, with the spool 93 located above, the oil chamber on the upper end side of the spool 93 This is connected to the drain port in order to handle the hydraulic pressure from the brake B4, and the deceleration oil passage 64 is connected to the drain port 1 to 94 in order to discharge pressure from the hydraulic servo B-4 for the brake B4. Oil passage 65 and line hydraulic oil passage 60
It is configured to communicate with

In addition, the solenoid valve S installed on the downstream side of the oil strainer ST5
4 is for generating oil pressure related to the gear shift area in the oil passage 61, and the driving condition of the vehicle is the high speed gear (+-1
2. It turns on when the shift is from H4) to low gear (L4), discharging the line oil pressure from the oil passage 61, and shifting from low gear (L4) to high gear (H2, H4). When it is within the range, it is turned off and line oil pressure is generated in the oil passage 61.

In addition, notice number 100 in Figure 1 is an accumulator control valve, 1
10 is a shift timing valve, 115 is an orifice control valve, and 120 and 130 are accumulators, respectively.

In the above-described device, the solenoid valve S5, which constitutes a part of the switching mechanism 32, is normally in a demagnetized state and supplies line hydraulic pressure to the oil supply 75 of the timing valve 7Q. Time is spool 7
3 is pushed upward in the figure, and the inlet port 71 and outlet port 72 communicate with each other. In this state, if either high-speed four-wheel drive H4 or deceleration four-wheel drive 4 is selected using the shift lever, the line oil pressure supply oil passage 60 is connected to the oil passage 63 communicating with the timing valve 70, and as a result, , extraction servo C- for clutch C4
4 is supplied with line oil pressure, the clutch C4 is engaged, and power is transmitted to the front export power shaft 33, resulting in four-wheel drive.

and a four-wheel drive detector 37 that outputs a four-wheel drive status signal.
A pressure switch PSW is connected to the outlet port 72 of the timing valve 70 and the clutch C.
4 hydraulic servo C-4.

To briefly explain a specific example of the parking lock sensor 36, the configuration shown in FIGS. 5 and 6 is a parking lock pole that is a fixed member in the parking device described with reference to FIGS. 8 and 9 above. 20 and the parking gear 24, which is a rotating member, is configured to confirm engagement. That is, a switch 140 whose contactor 141 is pressed by its inclined surface 20a when the parking lock pawl 20 rotates toward the parking gear 24 is disposed inside the transmission case 12 at a position close to the parking lock pawl 20. has been done. As shown in the cross-sectional view in FIG.
A cylindrical plunger 144 with a bottom is placed on one side of the plunger 144, and the probe 141 is housed inside the plunger 144, and the probe 141 is made to protrude from the case 142 by a compression spring 145 provided between the two. Press like this,
Another compression spring 147 is provided between the plunger 144 and the snap ring 146 fitted into the case 142, and a conductive plate 149 that closes a pair of contacts 148 is provided on the other side with the diaphragm 143 roughly in between. 150 so as to be pressed against the diaphragm 143. An example of the mounting position of the switch 140 described above is shown by a broken line in FIG. 8.

In a four-wheel drive vehicle equipped with the transmission 30 described above, if the vehicle is traveling in four-wheel drive, a signal is input from the four-wheel drive detector 37 to the control device 34 . Specifically, in the hydraulic circuit shown in FIG. 4, line oil pressure is supplied from the oil passage 63 through the timing valve 70 to the hydraulic servo C-4, and as a result, the clutch C4 shown in FIG. Power is transmitted to the export power shaft 33, resulting in four-wheel drive. In that case, the four-wheel drive detector 3 installed in front of the hydraulic servo C-4
A hydraulic switch PSW 7 is turned on in response to the line hydraulic pressure and outputs a signal to the control device 34 .

At the same time, vehicle speed signals are input to the control device 34 from each vehicle speed sensor 3B, 39.40.

When the manual shift lever is set in the parking range in this state, the shift position sensor 35 outputs a parking shift signal to the control device 34, and at the same time the parking lock rod 1 in the parking device shown in FIG.
6 moves forward in the right direction in FIG. Since the parking lock pawl 20 is pushed back against the spring 19, it does not engage the parking gear 24.

On the other hand, if the vehicle speed at the time of the parking shift operation is below the predetermined set speed and above the second set speed, which is slower than the predetermined set speed, the control device 34 operates the switching switch based on the parking shift signal. It outputs a signal to @32 and switches to two-wheel drive mode. Specifically, the electromagnetic valve S provided upstream of the timing valve 70 in the hydraulic circuit shown in FIG.
5 is energized, and accordingly, the hydraulic pressure of the oil 75 that presses the spool 73 against the spring 74 in the timing valve 70 is discharged, so the spool 73 is lowered to the lower side in FIG. 4, and the hydraulic servo is activated. C-4 is depressurized. As a result, the clutch C4 shown in FIG. 3 is released and the vehicle is switched to a two-wheel drive state. On the other hand, in the parking device, when the vehicle speed is slower than the set speed, the cam collar 18 is pushed forward by the spring 19, and the cam collar 18 moves the parking lock pole 20 into the parking gear 24.
The engaging teeth 23 are rotated to the side and the engaging teeth 23 are engaged with the parking gear 24.
is engaged. Therefore, when the parking device acts and locks the drive wheels, it is in a two-wheel drive state, so the load that is applied to the parking device due to the braking of inertial force is the load that acts through the two wheels that are the drive wheels. This is halved compared to the case with four-wheel drive.

When the parking lock pawl 20, which is a fixed member, and the parking gear 24, which is a rotating member, engage, the contact 141 of the switch 140 shown in FIGS. 5 and 6 is pushed by the parking lock pawl 20, and its contact 148 is It is closed by a conductive plate 149. That is, the parking lock sensor 36 outputs a parking gear engagement signal to the control device 34.

The control device 34 switches the switching mechanism 32 again based on the parking gear engagement signal to switch from the two-wheel drive state to the four-wheel drive state. Specifically, the solenoid valve S5 shown in FIG. 4 is demagnetized and line hydraulic pressure is supplied to the oil supply port 75 of the timing valve 70, and as a result, the inlet port 71 and the outlet port 72 communicate with each other, and the hydraulic servo C-4 Since line oil pressure is supplied to the clutch C4, the clutch C4 is engaged. Since the return from two-wheel drive to four-wheel drive is performed in this way, all four wheels are locked when the vehicle is stopped, making it possible to stop the vehicle reliably.

Furthermore, if the vehicle speed is extremely slow, such as when the vehicle is about to stop, and is below the second set speed, the control device 34 will not output a signal to switch the switching mechanism 32 even if the parking shift operation is performed, and therefore the four wheels will The parking device operates while the vehicle is in drive mode, locking all four wheels.

By the way, in the above-described embodiment, two-wheel drive is returned to four-wheel drive based on the parking gear engagement signal, but the purpose of such control is to lock all four wheels when the vehicle is completely stopped. The purpose of this is to ensure a reliable stop. Therefore, as long as the control is in accordance with this purpose, the parking gear engagement signal may not necessarily be used, and an alternative signal may be used instead. In other words, the parking device comes into play when the vehicle speed drops below a certain level.
The vehicle may be returned to four-wheel drive on the condition that the vehicle speed is below a certain speed, and the vehicle speed may be directly measured by picking up the rotational speed of the rotating shaft connected to the drive wheels. Then, control for returning to four-wheel drive may be performed on the condition that the rotational speed of the rotating shaft becomes equal to or less than a predetermined value. If you perform a parking shift operation when the vehicle speed is below a predetermined set speed, the parking device will operate and the vehicle speed will slow down over time.
It is also possible to return to four-wheel drive on the condition that a certain period of time elapses.

In addition, in the above-mentioned embodiment, the transfer 1 shown in FIG.
Alternatively, the hydraulic circuit shown in FIG. 4, or the hydraulic circuit shown in FIGS.
Although the explanation has been given by taking as an example a four-wheel drive vehicle equipped with the parking lock sensor shown in the figure and the parking device shown in FIGS. 8 and 9, the method of the present invention applies to both two-wheel drive and four-wheel drive. The target is a so-called part-time four-wheel drive vehicle that can be switched, and the target four-wheel drive vehicle is not limited to the one shown in the above-mentioned embodiment.

As described in detail, according to the control method of the present invention, when a parking shift operation is performed while driving, there are always two drive wheels whose rotation should be stopped by the parking device, so that the vehicle does not run due to inertial force. The load that is applied to the parking device when the vehicle is stopped is a load that is applied only from the two wheels that act as drive wheels. Therefore, even if the vehicle is a four-wheel drive vehicle, its parking device may be of the same level as that used in a normal two-wheel drive vehicle. It is possible to reduce the weight of the vehicle and, by extension, the weight of the vehicle.

[Brief explanation of drawings]

Fig. 1 is a flowchart showing a control method of the present invention, Fig. 2 is a block diagram showing an example of a system for carrying out the method of this invention, and Fig. 3 is an example of a four-wheel drive transfer targeted by the present invention. Skeleton (schematic diagram indicated by -)
Fig. 4 is a diagram showing the control hydraulic circuit, Fig. 5 is a schematic diagram showing an example of a parking lock sensor, Fig. 6 is a sectional view of the switch, Fig. 7 is a schematic diagram of a four-wheel drive vehicle, and Fig. 8 9 is a plan view showing an example of a parking device, and FIG. 9 is an explanatory diagram showing the relationship between a parking lock pole and a parking gear. 20...Parking lock pole. 23... Engagement tooth, 24... Parking gear, 31... Rear export force shaft, 33... Front export force shaft, 34... Control I wave device 35... Shift position sensor, 36 ... Parking lock sensor, 37... Four-wheel drive detector,
38, 39.49... Vehicle speed sensor, 140... Switch, C4... Clutch, S5... Solenoid valve.

Claims (6)

[Claims] (1) A four-wheel drive vehicle in which the number of drive wheels can be switched between four and two wheels, and the rotation of the drive wheels can be prevented by engaging a fixed member with a rotating member by operating a parking shift. A control method for a four-wheel drive vehicle, characterized in that the number of driven wheels is temporarily reduced to two when a parking shift is operated while driving in four-wheel drive. (2) A patent that is characterized by reducing the number of driven wheels to two when operating a parking shift while driving in four-wheel drive, and then reducing the number of driven wheels to four again if certain conditions are met. A method for controlling a four-wheel drive vehicle according to claim 1. (3) Claim 2, wherein the certain condition is completion of engagement between the rotating member and the fixed member.
A method for controlling a four-wheel drive vehicle as described in Section 3. (4) The method for controlling a four-wheel drive vehicle according to claim 2, wherein the certain condition is a preset time. (5) The method for controlling a four-wheel drive vehicle according to claim 2, wherein the certain condition is a vehicle speed that is less than or equal to a preset vehicle speed. (6) The four-wheel drive according to claim 2, wherein the certain condition is that the number of rotations of a rotating shaft connected to a drive wheel is equal to or less than a preset number of rotations. How to control the car.