JP5337521B2 - Function inspection method of power transmission device in four-wheel drive vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To certainly inspect whether switch from a four-wheel drive state to a two-wheel drive state is performed normally even in a vehicle where velocity deviation between a driving wheel and a driven wheel hardly occurs during deceleration. <P>SOLUTION: The power transmission device in a four-wheel drive vehicle includes a first hydraulic pump 31 interlocking with the driving wheel 11, a second hydraulic pump 32 interlocking with the driven wheel 12, and a hydraulic clutch 40 that engages with it based on the delivery amount difference between the first and second hydraulic pumps and transmits torque of the driving wheel to the driven wheel when the driving wheel speed exceeds the driven wheel speed. This function inspection method of the power transmission device includes a process S2 of determining whether the deviation &alpha; obtained by subtracting the driven wheel speed from the driving wheel speed during the acceleration is a reference value R1 or lower, a process S7 of determining whether the driving wheel speed is lower than the driven wheel speed during the deceleration, a process S11 of, after the driving wheel speed is lower than it, increasing the deviation &beta; obtained by subtracting the driving wheel speed from the driven wheel speed by applying the external force from the outside of the vehicle to the driving wheel or driven wheel, and a process S14 of determining whether the deviation &beta; is a reference value R2 or higher. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a function inspection method for a power transmission device in a four-wheel drive vehicle. Specifically, the present invention relates to a function inspection method for a power transmission device in a four-wheel drive vehicle including a dual pump system.

Conventionally, a four-wheel drive vehicle equipped with a dual pump system that can switch between a four-wheel drive state and a two-wheel drive state according to the traveling state of the vehicle has been developed (see Patent Document 1).
A four-wheel drive vehicle equipped with a dual pump system includes a first hydraulic pump that rotates in conjunction with drive wheels, a second hydraulic pump that rotates in conjunction with driven wheels, and a hydraulic clutch.

The hydraulic clutch engages with the hydraulic pressure generated based on the discharge amount difference between the first hydraulic pump and the second hydraulic pump when the speed of the driving wheel exceeds the speed of the driven wheel during acceleration of the vehicle. Torque is transmitted to the driven wheel to make it a four-wheel drive state.
Further, when the speed of the driving wheel is lower than the speed of the driven wheel when the vehicle is decelerated, the hydraulic clutch is disengaged by the disappearance of the hydraulic pressure to enter the two-wheel driving state.

Conventionally, a method for inspecting whether or not switching between a four-wheel drive state and a two-wheel drive state is normally performed in a four-wheel drive vehicle has been proposed (see Patent Document 1).
In this method, when the vehicle decelerates, it is detected that the speed deviation between the driving wheel and the driven wheel exceeds a predetermined value, and the switching from the four-wheel driving state to the two-wheel driving state is normally performed. Confirm.

Japanese Patent No. 3382315

However, since the hydraulic clutch for transmitting the drive is filled with viscous oil, a certain amount of power is transmitted by the viscosity of the oil even when the hydraulic clutch is disconnected. Therefore, there may be a case where the speed deviation between the driving wheel and the driven wheel is difficult to occur when the vehicle is decelerated, and an appropriate inspection cannot be performed depending on the vehicle type.
Further, even when the speed deviation between the driving wheel and the driven wheel exceeds a predetermined value when the vehicle decelerates, for example, dust is caught in the hydraulic clutch or the hydraulic clutch is not filled with oil. There was a case where a defect could not be detected.

  The present invention has been made in view of the above-described problems, and even when the vehicle is unlikely to cause a speed deviation between the driving wheel and the driven wheel when the vehicle is decelerated, the switching from the four-wheel driving state to the two-wheel driving state is normal. It is an object of the present invention to provide a function inspection method for a power transmission device in a four-wheel drive vehicle capable of reliably inspecting whether or not the operation is being performed.

  The function inspection method for a power transmission device in a four-wheel drive vehicle according to the present invention includes a first hydraulic pump (for example, a first hydraulic pump 31 described later) that rotates in conjunction with a drive wheel (for example, a drive wheel 11 described later). When the speed of the second hydraulic pump (for example, the second hydraulic pump 32 to be described later) that rotates in conjunction with the driven wheel (for example, the following driven wheel 12 to be described later) and the speed of the driving wheel exceeds the speed of the driven wheel. And a hydraulic clutch (for example, a hydraulic clutch 40 to be described later) that engages with a hydraulic pressure generated based on a discharge amount difference between the first hydraulic pump and the second hydraulic pump and transmits torque of the driving wheel to the driven wheel. ) In a four-wheel drive vehicle (for example, a four-wheel drive vehicle 10 to be described later), a first method in which the driven wheel speed is subtracted from the drive wheel speed when the vehicle is accelerated. Deviation (for example, A first step (for example, step S2 to be described later) for determining whether or not the deviation α) is equal to or less than a first reference value (for example, a first reference value R1 to be described later); A second step of determining whether or not the wheel speed is lower than the driven wheel speed (for example, step S7 described later), and after the driving wheel speed falls below the driven wheel speed, the driving wheel or the driven wheel A third step (for example, step S11 described later) for increasing a second deviation (for example, deviation β described later) obtained by subtracting the drive wheel speed from the driven wheel speed by applying an external force to the vehicle from the outside. And a fourth step (for example, step S14 to be described later) for determining whether or not the second deviation is greater than or equal to a second reference value (for example, a second reference value R2 to be described later). To do.

According to this invention, the second deviation obtained by subtracting the driving wheel speed from the driven wheel speed is increased by applying an external force from the outside of the vehicle to the driving wheel or the driven wheel.
As a result, even in the case of a vehicle in which the speed deviation between the driving wheel and the driven wheel is unlikely to occur when the vehicle is decelerated, it is surely checked whether the switching from the four-wheel driving state to the two-wheel driving state is normally performed. Can do.

  The function inspection method for a power transmission device in a four-wheel drive vehicle according to the present invention includes a first hydraulic pump that rotates in conjunction with a drive wheel, a second hydraulic pump that rotates in conjunction with a driven wheel, and the speed of the drive wheel. When the speed of the driven wheel exceeds the speed of the driven wheel, engagement is performed with a hydraulic pressure generated based on a difference in discharge amount between the first hydraulic pump and the second hydraulic pump, and torque of the driving wheel is transmitted to the driven wheel. A function inspection method for a power transmission device in a four-wheel drive vehicle including a hydraulic clutch, wherein a first deviation obtained by subtracting the driven wheel speed from the drive wheel speed during acceleration of the vehicle is equal to or less than a first reference value A first step for determining whether or not (for example, step S42 described later) and a second step for determining whether or not the driving wheel speed is lower than the driven wheel speed during deceleration of the vehicle (for example, step to be described later) S47) and the drive After the speed falls below the driven wheel speed, a third deviation is increased by subtracting the driving wheel speed from the driven wheel speed by applying an external force from outside the vehicle to the driving wheel or the driven wheel. A step (for example, step S51 described later), a fourth step for determining whether the second deviation is between a predetermined lower limit value and a predetermined upper limit value (for example, step S52 described later), And a fifth step (for example, step S54 described later) for determining whether or not the second deviation is equal to or greater than a second reference value.

  According to the present invention, there are effects similar to those described above.

  According to the present invention, the second deviation obtained by subtracting the driving wheel speed from the driven wheel speed is increased by applying an external force to the driving wheel or the driven wheel from the outside of the vehicle. As a result, even in the case of a vehicle in which the speed deviation between the driving wheel and the driven wheel is unlikely to occur when the vehicle decelerates, it is surely inspected whether the switching from the four-wheel driving state to the two-wheel driving state is normally performed. Can do.

1 is a schematic configuration diagram of a four-wheel drive vehicle to which a function inspection method for a power transmission device according to the present invention is applied. It is a schematic explanatory drawing of the function test | inspection apparatus of the power transmission device which implements the function test | inspection method of the power transmission device which concerns on this invention. It is a flowchart in 1st Embodiment of the function test | inspection method of the power transmission device which concerns on this invention. 5 is a timing chart showing an example of a case where the inspection result is normal in the function inspection method for the power transmission device according to the embodiment. In the function inspection method of the power transmission device concerning the above-mentioned embodiment, it is a timing chart which shows an example when a test result is abnormal. It is a flowchart in 2nd Embodiment of the function inspection method of the power transmission device which concerns on this invention. It is a flowchart in 3rd Embodiment of the function inspection method of the power transmission device which concerns on this invention. It is a graph which shows an example of the upper limit of a speed deviation, and a lower limit. It is a graph which shows the example which deviates from an upper limit or a lower limit in the graph of FIG. It is a flowchart in 4th Embodiment of the function test | inspection method of the power transmission device which concerns on this invention. It is a flowchart in 5th Embodiment of the function test | inspection method of the power transmission device which concerns on this invention. It is a flowchart in 6th Embodiment of the function test | inspection method of the power transmission device which concerns on this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram of a four-wheel drive vehicle 10 to which a function inspection method for a power transmission device according to the present invention is applied.

A four-wheel drive vehicle 10 shown in FIG. 1 is a four-wheel drive vehicle including a dual pump system, and includes left and right drive wheels 11 and left and right driven wheels 12. For example, the front wheels are configured as drive wheels 11 and the rear wheels are configured as driven wheels 12.
The four-wheel drive vehicle 10 includes an engine 20 mounted on the front portion of the vehicle, a differential 22 on the front axle, a power transmission device 30, and a differential 26 on the rear axle.

The output of the engine 20 is input to the differential 22 on the front axle side via the transmission 21. The output of the differential device 22 is transmitted to the left and right drive wheels 11 via the drive shaft 23.
The output of the engine 20 input to the differential device 22 is input to the power transmission device 30 via the bevel gear device 24. The output of the power transmission device 30 is transmitted to the differential device 26 on the rear axle side via the bevel gear device 25. The output of the differential device 26 is transmitted to the left and right driven wheels 12 via the drive shaft 27.

  The power transmission device 30 includes a first hydraulic pump 31 driven by an input shaft 28 connected to the bevel gear device 24, a second hydraulic pump 32 driven by an output shaft 29 connected to the bevel gear device 25, and an input shaft. And a multi-plate hydraulic clutch 40 that controls transmission and disconnection of the driving force between the output shaft 29 and a hydraulic control circuit (not shown) that controls the hydraulic clutch 40.

The first hydraulic pump 31 is a trochoid pump, and has a first port 33 serving as a suction port and a second port 34 serving as a discharge port when the vehicle moves forward.
The second hydraulic pump 32 is a trochoid pump, and has a third port 35 serving as a discharge port and a fourth port 36 serving as a suction port when the vehicle moves forward.
The first port 33 and the third port 35 are connected via a first connecting oil passage 37. The second port 34 and the fourth port 36 are connected via a second connecting oil passage 38. The first connection oil passage 37 and the second connection oil passage 38 constitute a closed oil passage through which oil can circulate.

The first connecting oil passage 37 is directly connected to the oil tank 39.
The second connecting oil passage 38 is connected to the oil tank 39 via a relief valve 42 and an orifice 43 arranged in parallel. The second connecting oil passage 38 is connected to the working hydraulic chamber 41 of the hydraulic clutch 40.

When the four-wheel drive vehicle 10 configured as described above is accelerated, the rotation speed of the first hydraulic pump 31 connected to the drive wheel 11 directly driven by the engine 20 is the second hydraulic pressure connected to the driven wheel 12. The rotational speed of the pump 32 is exceeded.
Then, the discharge amount of the first hydraulic pump 31 exceeds the suction amount of the second hydraulic pump 32. Therefore, the oil discharged from the second port 34 of the first hydraulic pump 31 to the second connecting oil passage 38 cannot be completely sucked into the fourth port 36 of the second hydraulic pump 32, and the hydraulic pressure due to excess oil is reduced by the hydraulic clutch 40. Acting on the hydraulic pressure chamber 41.
As a result, the hydraulic clutch 40 is engaged, and the torque of the drive wheel 11 is transmitted to the driven wheel 12 to realize the four-wheel drive state.

When the engine brake is applied while the vehicle 10 is traveling, the braking force is applied only to the drive wheel 11, so the speed Vf of the drive wheel 11 is lower than the speed Vr of the driven wheel 12.
Then, the suction amount of the second hydraulic pump 32 connected to the driven wheel 12 exceeds the discharge amount of the first hydraulic pump 31 connected to the drive wheel 11. Therefore, the oil in the second connecting oil passage 38 is reduced, and the hydraulic pressure acting on the hydraulic pressure chamber 41 of the hydraulic clutch 40 disappears.
As a result, the engagement of the hydraulic clutch 40 is released, the transmission of torque from the drive wheel 11 to the driven wheel 12 is interrupted, and the two-wheel drive state is realized.

The relief valve 42 restricts the transmission torque of the hydraulic clutch 40 by restricting the upper limit of the hydraulic pressure generated in the second connecting oil passage 38.
The orifice 43 is for generating a hydraulic pressure in the second connecting oil passage 38 that is proportional to the square of the discharge amount difference between the first hydraulic pump 31 and the second hydraulic pump 32.

  FIG. 2 is a schematic explanatory view of the power transmission device function inspection device 1 for performing the power transmission device function inspection method according to the present invention.

As shown in FIG. 2, the function inspection device 1 for a power transmission device includes a freely rotatable roller 2 that supports a drive wheel 11 of a vehicle 10 and a freely rotatable roller 3 that supports a driven wheel 12.
The function inspection apparatus 1 includes a driving wheel speed sensor 4 that detects a driving wheel speed Vf from the rotation speed of the roller 2 and a driven wheel speed sensor 5 that detects a driven wheel speed Vr from the rotation speed of the roller 3.

The function inspection apparatus 1 includes a motor 6 that applies a driving force to the roller 3 or a brake 7 that applies a braking force to the roller 2.
The driving wheel speed sensor 4, the driven wheel speed sensor 5, the motor 6 and the brake 7 are connected to the control device 8. The control device 8 is connected to a display 9 for displaying the inspection result.

FIG. 3 is a flowchart showing a first embodiment of a function inspection method for a power transmission device according to the present invention.
A function inspection procedure in the first embodiment will be described with reference to the flowchart of FIG.

First, in step S1, the engine 20 is gradually accelerated from the idling state by the driver of the vehicle 10.
Then, the drive wheel 11 connected to the engine 20 and the first hydraulic pump 31 connected to the drive wheel 11 rotate. The oil pressure discharged from the first hydraulic pump 31 to the second connecting oil passage 38 acts on the operating hydraulic chamber 41 of the hydraulic clutch 40, and the hydraulic clutch 40 is engaged. As a result, the driven wheel 12 starts rotating slightly behind the driving wheel 11.

In step S2, the controller 8 compares the deviation α obtained by subtracting the driven wheel speed Vr from the drive wheel speed Vf with the first reference value R1, and determines whether the deviation α is smaller than the first reference value R1. judge. That is, it is determined whether or not the driven wheel speed Vr increases substantially in synchronization with the driving wheel speed Vf.
If this determination is NO, the process proceeds to step S3, and if YES, the process proceeds to step S5.

If the determination in step S2 is NO and the process proceeds to step S3, in step S3, the control device 8 determines that there is an abnormality in the four-wheel drive state.
In this case, the deviation α is larger than the first reference value R1. That is, the hydraulic clutch 40 is not normally engaged and torque is not sufficiently transmitted to the driven wheel 12.
The cause of the poor engagement of the hydraulic clutch 40 may be a failure of the first hydraulic pump 31, the second hydraulic pump 32, the hydraulic clutch 40, the first connection oil passage 37, the second connection oil passage 38, or the like.

On the other hand, if the determination in step S2 is YES and the process proceeds to step S4, in step S4, the control device 8 determines whether or not the vehicle speed has reached the 4WD inspection end speed.
If this determination is NO, the process returns to step S2. That is, while the determination in step S2 is YES, the process proceeds to step S4, the determination in step S4 is NO, and the process returns to step S2, the deviation α is smaller than the first reference value R1 by the control device 8. Repeat the determination of whether or not.
If this determination is YES, the process proceeds to step S5.

In step S5, the control device 8 determines that the four-wheel drive state is normal.
In this case, the deviation α is smaller than the first reference value R1 until the vehicle speed reaches the 4WD inspection end speed. That is, the hydraulic clutch 40 is normally engaged and the torque is sufficiently transmitted from the driving wheel 11 to the driven wheel 12.

In step S6, the driver of the vehicle 10 decelerates the engine 20 to an idling state.
Then, the engine wheel acts on the drive wheels 11 connected to the engine 20, and the drive wheel speed Vf quickly decreases. On the other hand, the driven wheel speed Vr of the driven wheel 12 to which the engine brake does not act gradually decreases.

In step S7, the control device 8 determines whether or not the driving wheel speed Vf that has been higher than the driven wheel speed Vr until now is lower than the driven wheel speed Vr.
If this determination is NO, the process proceeds to step S8, and if YES, the process proceeds to step S11.
Note that S10, S12, and S13 are not assigned as step numbers.

When the determination in step S7 is NO and the process proceeds to step S8, in step S8, the control device 8 determines whether or not the vehicle speed has reached the 2WD inspection end speed.
If this determination is NO, the process returns to step S7. That is, while the determination in step S7 is NO, the process proceeds to step S8, the determination in step S8 is NO, and while returning to step S7 is repeated, the drive wheel speed Vf is lower than the driven wheel speed Vr by the control device 8. Repeat the determination of whether or not.
If this determination is YES, the process proceeds to step S9.

In step S9, the control device 8 determines that there is an abnormality in the two-wheel drive state.
In this case, the driving wheel speed Vf continues to exceed the driven wheel speed Vr until the vehicle speed reaches the 2WD inspection end speed. That is, the hydraulic clutch 40 is held in the engaged state, and the braking force by the engine brake also acts on the driven wheel 12.

On the other hand, if the determination in step S 7 is YES and the process proceeds to step S 11, the motor 6 is driven by the control device 8 and the driving force is transmitted to the driven wheel 12 via the roller 3 in step S 11.
Thus, the magnitude of the difference between the drive wheel speed Vf that is lower than the driven wheel speed Vr and the driven wheel speed Vr is increased.

In subsequent step S14, the controller 8 compares the deviation β obtained by subtracting the drive wheel speed Vf from the driven wheel speed Vr with the second reference value R2, and whether or not the deviation β is larger than the second reference value R2. Determine.
If this determination is NO, the process moves to step S15, and if YES, the process moves to step S17.

When the determination in step S14 is NO and the process proceeds to step S15, in step S15, it is determined by the control device 8 whether or not the vehicle speed has reached the 2WD inspection end speed.
If this determination is NO, the process returns to step S14. That is, while the determination in step S14 is NO, the process proceeds to step S15, the determination in step S15 is NO, and the process returns to step S14 is repeated, the deviation β is larger than the second reference value R2 by the control device 8. Repeat the determination of whether or not.
If this determination is YES, the process proceeds to step S16.

In step S16, the control device 8 determines that there is an abnormality in the two-wheel drive state.
In this case, the deviation β is smaller than the second reference value R2 until the vehicle speed reaches the 2WD inspection end speed. That is, the hydraulic clutch 40 is not completely disengaged, and a part of the torque of the driving wheel 11 is still transmitted to the driven wheel 12.

On the other hand, when the determination in step S14 is YES and the process proceeds to step S17, in step S17, the control device 8 determines that the two-wheel drive state is normal.
In this case, the deviation β is larger than the second reference value R2. That is, the hydraulic clutch 40 is normally disengaged and torque transmission to the driven wheel 12 is interrupted.

In subsequent step S18, the control device 8 determines that the function of the power transmission device 30 is normal.
That is, it is confirmed that the hydraulic clutch 40 is normally engaged when the vehicle 10 is accelerated and is in a four-wheel drive state, and the hydraulic clutch 40 is normally disengaged when the vehicle 10 is decelerated and is in a two-wheel drive state. The

And the determination result of step S3, S9, S16, S17, S18 is displayed on the indicator 9.
In this way, by separately testing the engagement state of the hydraulic clutch 40 during acceleration and deceleration of the vehicle 10, the function of the dual pump system can be reliably and easily inspected.

FIG. 4 is a timing chart showing the relationship between the elapsed time, the driving wheel speed, and the driven wheel speed when the inspection result is normal in the function inspection method for the power transmission device according to the embodiment.
FIG. 5 is a timing chart showing the relationship between the elapsed time, the driving wheel speed, and the driven wheel speed when the inspection result is abnormal in the function inspection method for the power transmission device according to the embodiment.
4 and 5, the graphs with a triangle symbol indicate the driving wheel speed, and the graphs with a circle symbol indicate the driven wheel speed.

In the case of the graph shown in FIG. 4, determination is made as follows according to the flowchart shown in FIG.
That is, the control device 8 detects the drive wheel speed Vf and the driven wheel speed Vr every unit time.

At time t0 when the vehicle is accelerated and the vehicle speed reaches the 4WD inspection start speed, the driving wheel speed Vf0 and the driven wheel speed Vr0 are detected. The deviation α obtained by subtracting the driven wheel speed Vr0 from the driving wheel speed Vf0 is smaller than the first reference value R1.
At time t1 after the unit time, the driving wheel speed Vf1 and the driven wheel speed Vr1 are detected. Further, at time t2 after unit time, the driving wheel speed Vf2 and the driven wheel speed Vr2 are detected. The deviation α obtained by subtracting the driven wheel speed Vr1 from the driving wheel speed Vf1 and the deviation α obtained by subtracting the driven wheel speed Vr2 from the driving wheel speed Vf2 are both smaller than the first reference value R1.
At time t3 after the unit time, the driving wheel speed Vf3 and the driven wheel speed Vr3 are detected. At this time t3, the vehicle speed reaches the 4WD inspection end speed. Since the deviation α obtained by subtracting the driven wheel speed Vr3 from the driving wheel speed Vf3 is also smaller than the first reference value R1, it is determined that the four-wheel driving state is normal.

  Specifically, the 4WD inspection start speed is 30 km / h, the 4WD inspection end speed is 50 km / h, and the first reference value R1 is 5 km / h. Since the deviation α obtained by subtracting the driven wheel speed Vr from the driving wheel speed Vf is lower than 5 km / h continuously while the vehicle speed reaches from 30 km to 50 km, it is determined that the four-wheel driving state is normal.

  When the vehicle is decelerated, at time t15, the driving wheel speed Vf, which has previously exceeded the driven wheel speed Vr, becomes lower than the driven wheel speed Vr for the first time. That is, Vf15 <Vr15. At this time, the control device 8 drives the motor 6 to transmit the driving force to the driven wheel 12.

At time t16 after the unit time, the driving wheel speed Vf16 and the driven wheel speed Vr16 are detected. A deviation β obtained by subtracting the driving wheel speed Vf16 from the driven wheel speed Vr16 is smaller than the second reference value R2.
At time t17 after the unit time, the driving wheel speed Vf17 and the driven wheel speed Vr17 are detected. Further, at time t18 after unit time, the driving wheel speed Vf18 and the driven wheel speed Vr18 are detected. Further, at time t19 after unit time, the driving wheel speed Vf19 and the driven wheel speed Vr19 are detected. Both the deviation β obtained by subtracting the driving wheel speed Vf17 from the driven wheel speed Vr17, the deviation β obtained by subtracting the driving wheel speed Vf18 from the driven wheel speed Vr18, and the deviation β obtained by subtracting the driving wheel speed Vf19 from the driven wheel speed Vr19. It is smaller than the second reference value R2.
At time t20 after the unit time, the driving wheel speed Vf20 and the driven wheel speed Vr20 are detected. Since the deviation β obtained by subtracting the drive wheel speed Vf20 from the driven wheel speed Vr20 is larger than the second reference value R2, it is determined that the two-wheel drive state is normal.

  Specifically, the 2WD inspection start speed is 60 km / h, the 2WD inspection end speed is 30 km / h, and the second reference value R2 is 5 km / h. Before the vehicle speed reaches 30 km, the deviation β obtained by subtracting the drive wheel speed Vf from the driven wheel speed Vr exceeds 5 km / h, so it is determined that the two-wheel drive state is normal.

In the case of the graph shown in FIG. 5, the following determination is made according to the flowchart shown in FIG.
Driving time Vf and driven wheel speed every unit time from time t0 when the vehicle is accelerated and vehicle speed reaches 4WD inspection start speed to t1, t2, t3 and further t4 when vehicle speed reaches 4WD inspection end speed Vr is detected. During this time, since the deviation α obtained by subtracting the driven wheel speed Vr from the driving wheel speed Vf is lower than the first reference value R1, it is determined that the four-wheel driving state is normal.

  When the vehicle is decelerated, at time t14, the driving wheel speed Vf, which has previously exceeded the driven wheel speed Vr, becomes lower than the driven wheel speed Vr for the first time. That is, Vf14 <Vr14. At this time, the control device 8 drives the motor 6 to transmit the driving force to the driven wheel 12.

  The driving wheel speed Vf and the driven wheel speed Vr are detected every unit time from time t15 after the unit time to t16, t17, t18, t19, and t20 when the vehicle speed reaches the 2WD inspection end speed. During this time, since the deviation β obtained by subtracting the drive wheel speed Vf from the driven wheel speed Vr does not fall below the second reference value R2, it is determined that the two-wheel drive state is abnormal.

According to this embodiment, there are the following effects.
(1) When the vehicle is decelerated and the driving wheel speed Vf falls below the driven wheel speed Vr, the motor 6 is driven from that time to transmit the driving force to the driven wheel 12 from the outside of the vehicle. Thus, the magnitude of the difference between the drive wheel speed Vf that is lower than the driven wheel speed Vr and the driven wheel speed Vr is increased.
Therefore, even in the case of a vehicle in which the speed deviation between the driving wheel 11 and the driven wheel 12 hardly occurs at the time of deceleration, it is possible to surely check whether or not the switching from the four-wheel driving state to the two-wheel driving state is normally performed. it can.

FIG. 6 is a flowchart showing a second embodiment of the function inspection method for the power transmission device according to the present invention.
With reference to the flowchart of FIG. 6, the procedure of the function inspection in the second embodiment will be described.

  Steps S21 to S29 are the same as steps S1 to S9 in the flowchart shown in FIG.

When the determination in step S27 is YES and the process proceeds to step S30, in step S30, the controller 8 determines whether or not the vehicle speed has reached a predetermined speed.
Specifically, it is determined whether or not the vehicle speed has decreased to, for example, around 55 km / h. This is because the vehicle speed at the time of shifting from acceleration to deceleration varies, so that the accuracy of the inspection is made constant by starting the inspection after removing this variation and reaching a constant reference speed.
If this determination is NO, the process returns to step S30, and if YES, the process proceeds to step S31.

  Steps S31 to S38 are the same as steps S11 to S18 in the flowchart shown in FIG.

According to this embodiment, there are the following effects.
(2) When the vehicle is decelerated and the driving wheel speed Vf falls below the driven wheel speed Vr, the motor 6 is driven from the time when the vehicle speed reaches a predetermined speed thereafter, and the driving force is transmitted from the outside of the vehicle to the driven wheel 12. . Thus, the magnitude of the difference between the drive wheel speed Vf that is lower than the driven wheel speed Vr and the driven wheel speed Vr is increased.
Therefore, even in the case of a vehicle in which the speed deviation between the driving wheel 11 and the driven wheel 12 hardly occurs at the time of deceleration, it is possible to surely check whether or not the switching from the four-wheel driving state to the two-wheel driving state is normally performed. it can.
Moreover, even if there is a variation in the vehicle speed when shifting from acceleration to deceleration, the accuracy of the inspection can be made constant by starting the inspection after eliminating this variation and reaching a constant reference speed.

FIG. 7 is a flowchart showing a third embodiment of the function inspection method for the power transmission device according to the present invention.
A function inspection procedure in the third embodiment will be described with reference to the flowchart of FIG.

  Steps S41 to S51 are the same as steps S21 to S31 in the flowchart shown in FIG.

In step S52 following step S51, it is determined whether or not the deviation β obtained by subtracting the drive wheel speed Vf from the driven wheel speed Vr by the control device 8 is between a predetermined lower limit value and a predetermined upper limit value.
If this determination is NO, the process moves to step S53, and if YES, the process moves to step S54.

  When the determination in step S52 is NO and the process proceeds to step S53, in step S53, the control device 8 determines that there is an abnormality in the two-wheel drive state.

  Steps S54 to S58 are the same as steps S34 to S38 in the flowchart shown in FIG.

FIG. 8 is a graph showing an example of the upper limit value and the lower limit value of the speed deviation.
In step S52 of the flowchart shown in FIG. 7, the lower limit value and the upper limit value of the deviation β obtained by subtracting the driving wheel speed Vf from the driven wheel speed Vr are set as follows, for example.
That is, first, a time series change in speed deviation of about 100 samples is obtained. Next, the average value and standard deviation of the samples are obtained. Then, (average value + standard deviation + a) is the upper limit value, and (average value−standard deviation−b) is the lower limit value. Alternatively, (average value + standard deviation × 2 + a) is set as the upper limit value, and (average value−standard deviation × 2-b) is set as the lower limit value.

FIG. 9 is a graph showing an example that deviates from the upper limit value or the lower limit value in the graph of FIG. FIG. 9 shows an abnormality 1 that deviates from the lower limit value and an abnormality 2 that deviates from the upper limit value.
As shown in the graph of abnormality 1 in FIG. 9, an abnormality that deviates from the lower limit value occurs, for example, in the following case.
That is, this is a case where dust is initially caught in the clutch 40 and then removed. In this case, the clutch is initially connected by dust, and the speed deviation is unlikely to occur. However, a speed deviation occurs immediately after the dust comes off, and may exceed a lower limit value to reach a predetermined speed deviation. This is a case where it should be determined that there is a problem.

As shown in the graph of abnormality 2 in FIG. 9, an abnormality that deviates from the upper limit value occurs, for example, in the following case.
That is, this is a case where the hydraulic pumps 31 and 32 are not filled with oil. In this case, since there is no drive transmission due to the viscosity of the oil, a speed deviation occurs immediately after the clutch 40 is disengaged, which may reach a predetermined speed deviation and further exceed the upper limit value. This is a case where it should be determined that there is a problem.

  In the graphs shown in FIGS. 8 and 9, time can be taken on the horizontal axis. In this case, the graph shows a time-series change of the deviation β obtained by subtracting the driving wheel speed Vf from the driven wheel speed Vr.

  In the graphs shown in FIGS. 8 and 9, the horizontal axis can take a value obtained by subtracting the driven wheel speed Vr at each time from the driven wheel speed Vr at the start of determination. For example, when the driven wheel speed Vr at the start of determination is 55 km / h and the driven wheel speed Vr at a certain time is 50 km / h, the subtracted value is 5. When the driven wheel speed Vr at another time is 45 km / h, the subtracted value is 10. That is, in this case, the deviation β is obtained by subtracting the driving wheel speed Vf from the driven wheel speed Vr according to the change in the driven wheel speed Vr.

According to the present embodiment, there are the same effects as the above (2), and the following effects.
(3) For example, a case in which dust is initially trapped in the clutch 40 and it is difficult for the speed deviation to occur, so that a speed deviation occurs immediately after the dust comes off and reaches a predetermined speed deviation after falling below the lower limit. It can be determined that there is a problem.
(4) For example, since the hydraulic pumps 31 and 32 are not filled with oil and there is no drive transmission due to the viscosity of the oil, a speed deviation occurs immediately after the clutch 40 is disconnected, resulting in a predetermined speed deviation. Furthermore, when it exceeds the upper limit value, it can be determined that there is a defect.

FIG. 10 is a flowchart showing a fourth embodiment of the function inspection method for the power transmission device according to the present invention.
A function inspection procedure in the fourth embodiment will be described with reference to the flowchart of FIG.

  Steps S61 to S69 are the same as steps S1 to S9 in the flowchart shown in FIG.

In step S <b> 71, the brake 7 is operated by the control device 8, and the braking force is transmitted to the drive wheel 11 via the roller 2.
Thus, the magnitude of the difference between the drive wheel speed Vf that is lower than the driven wheel speed Vr and the driven wheel speed Vr is increased.

  Steps S74 to S78 are the same as steps S14 to S18 in the flowchart shown in FIG.

According to this embodiment, there are the following effects.
(5) When the vehicle is decelerated and the driving wheel speed Vf falls below the driven wheel speed Vr, the brake 7 is operated from that point to transmit the braking force to the driving wheel 11 from the outside of the vehicle. Thus, the magnitude of the difference between the drive wheel speed Vf that is lower than the driven wheel speed Vr and the driven wheel speed Vr is increased.
Therefore, even in the case of a vehicle in which the speed deviation between the driving wheel 11 and the driven wheel 12 hardly occurs at the time of deceleration, it is possible to surely check whether or not the switching from the four-wheel driving state to the two-wheel driving state is normally performed. it can.

FIG. 11 is a flowchart showing a fifth embodiment of the function inspection method for the power transmission device according to the present invention.
With reference to the flowchart of FIG. 11, the function test procedure in the fifth embodiment will be described.

  Steps S81 to S90 are the same as steps S21 to S30 in the flowchart shown in FIG.

In step S <b> 91, the brake 7 is operated by the control device 8, and the braking force is transmitted to the drive wheel 11 via the roller 2.
Thus, the magnitude of the difference between the drive wheel speed Vf that is lower than the driven wheel speed Vr and the driven wheel speed Vr is increased.

  Steps S94 to S98 are the same as steps S34 to S38 in the flowchart shown in FIG.

According to this embodiment, there are the following effects.
(6) When the vehicle is decelerated and the driving wheel speed Vf falls below the driven wheel speed Vr, the brake 7 is activated from the time when the vehicle speed reaches a predetermined speed thereafter, and the braking force is transmitted from the outside of the vehicle to the driving wheel 11. . Thus, the magnitude of the difference between the drive wheel speed Vf that is lower than the driven wheel speed Vr and the driven wheel speed Vr is increased.
Therefore, even in the case of a vehicle in which the speed deviation between the driving wheel 11 and the driven wheel 12 hardly occurs at the time of deceleration, it is possible to surely check whether or not the switching from the four-wheel driving state to the two-wheel driving state is normally performed. it can.
Moreover, even if there is a variation in the vehicle speed when shifting from acceleration to deceleration, the accuracy of the inspection can be made constant by starting the inspection after eliminating this variation and reaching a constant reference speed.

FIG. 12 is a flowchart showing a sixth embodiment of the function inspection method for the power transmission device according to the present invention.
A function inspection procedure in the sixth embodiment will be described with reference to the flowchart of FIG.

  Steps S101 to S110 are the same as steps S41 to S50 in the flowchart shown in FIG.

In step S <b> 111, the brake 7 is operated by the control device 8, and the braking force is transmitted to the drive wheel 11 via the roller 2.
Thus, the magnitude of the difference between the drive wheel speed Vf that is lower than the driven wheel speed Vr and the driven wheel speed Vr is increased.

  Steps S112 to S118 are the same as steps S52 to S58 in the flowchart shown in FIG.

  According to the present embodiment, there are the same effects as the above-described (3), (4), and (6).

  It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.

DESCRIPTION OF SYMBOLS 1 ... Function inspection apparatus of power transmission device 6 ... Motor 7 ... Brake 10 ... Four-wheel drive vehicle 11 ... Drive wheel 12 ... Driven wheel 31 ... First hydraulic pump 32 ... Second hydraulic pump 40 ... Hydraulic clutch R2 ... Second reference Value Vf: Drive wheel speed Vr: Driven wheel speed

Claims (2)

A first hydraulic pump that rotates in conjunction with a drive wheel; a second hydraulic pump that rotates in conjunction with a driven wheel; and the first hydraulic pump that rotates when the speed of the drive wheel exceeds the speed of the driven wheel; Functional inspection of a power transmission device in a four-wheel drive vehicle including a hydraulic clutch that engages with a hydraulic pressure generated based on a discharge amount difference of the second hydraulic pump and transmits torque of the driving wheel to the driven wheel A method,
A first step of determining whether a first deviation obtained by subtracting the driven wheel speed from the driving wheel speed during acceleration of the vehicle is equal to or less than a first reference value;
A second step of determining whether the driving wheel speed is lower than the driven wheel speed when the vehicle decelerates;
After the driving wheel speed falls below the driven wheel speed, an external force is applied to the driving wheel or the driven wheel from outside the vehicle to increase a second deviation obtained by subtracting the driving wheel speed from the driven wheel speed. A third step;
A fourth step of determining whether or not the second deviation is greater than or equal to a second reference value;
A function inspection method for a power transmission device in a four-wheel drive vehicle. A first hydraulic pump that rotates in conjunction with a drive wheel; a second hydraulic pump that rotates in conjunction with a driven wheel; and the first hydraulic pump that rotates when the speed of the drive wheel exceeds the speed of the driven wheel; Functional inspection of a power transmission device in a four-wheel drive vehicle including a hydraulic clutch that engages with a hydraulic pressure generated based on a discharge amount difference of the second hydraulic pump and transmits torque of the driving wheel to the driven wheel A method,
A first step of determining whether a first deviation obtained by subtracting the driven wheel speed from the driving wheel speed during acceleration of the vehicle is equal to or less than a first reference value;
A second step of determining whether the driving wheel speed is lower than the driven wheel speed when the vehicle decelerates;
After the driving wheel speed falls below the driven wheel speed, an external force is applied to the driving wheel or the driven wheel from outside the vehicle to increase a second deviation obtained by subtracting the driving wheel speed from the driven wheel speed. A third step;
A fourth step of determining whether the second deviation is between a predetermined lower limit value and a predetermined upper limit value;
A fifth step of determining whether the second deviation is greater than or equal to a second reference value;
A function inspection method for a power transmission device in a four-wheel drive vehicle.

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