JPH03200424A - Diff-lock device of vehicle - Google Patents

Abstract

PURPOSE:To improve operativity and safety by constituting the diff-lock system of the vehicle to output a lock command signal by way of providing a switch means to instruct changeover of lock-unlock of the diff-lock system and by supplying electric source to a control circuit only when this switch means instructs diff-lock. CONSTITUTION:A four wheel drive vehicle has a front wheel diff 5 and a rear wheel diff 7, and the front wheel diff 5 and the rear wheel diff 7 are connected to each other with a propeller shaft connecting a front shaft 2-1 and a rear shaft 2-2 to each other with a center diff 11. In this case, each of the diffs 5, 7, 11 is constituted to nullify differential function when a gear to allow differential action by an actuator 13 is fixed, and the actuator 13 is controlled by a controlcircuit 15 to input output signals of a car speed sensor 10, a center diff-lock SW 14a, a front and a rear wheel diff-lock SWs 14b, 14c. Then, electric source is supplied to this control circuit 15 only when diff-lock is instructed so that a lock instruction signal is output.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a differential lock device for locking and unlocking a differential provided between the left and right wheels of a vehicle, and particularly for use in four-wheel drive vehicles. It is suitable.

(Conventional technology) Conventionally, for example, in a four-wheel drive vehicle, when there is a difference in the trajectory of the left and right wheels or the front and rear wheels due to curves, etc., a differential device (hereinafter abbreviated as differential) is used to absorb this difference as a difference in rotation. A front differential that adjusts the rotation difference between the left and right front wheels, a rear differential that adjusts the rotation difference between the left and right rear wheels, and a center differential that adjusts the rotation difference between the front and rear wheels caused by the difference between the inner wheels. These allow the vehicle to run stably and smoothly, whether going straight or turning.

[Problem to be solved by the invention]

3. Detailed description of the invention However, in the above vehicle, if one wheel comes off the wheel while driving on a rough road, pressing the accelerator pedal will only cause the off wheel to spin, and the driving force will be absorbed by the differential. There is a problem that the signal is not transmitted to other wheels. For this reason, some vehicles are equipped with a locking mechanism on the center differential or rear differential, and by mechanically fixing these differentials, the driving force is transmitted to the other wheels. be. This conventional locking mechanism transmits the driver's operating force via a mechanical transmission system such as a link to drive a member that fixes the differential. Therefore, a great deal of force is required to operate the differential, and it also takes time to fix the differential due to factors such as gear engagement, which is a burden on the driver.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a differential lock device for a vehicle that takes safety measures into account while improving operability during differential locking.

[Means to solve the problem]

In order to achieve the above object, a differential lock device according to the present invention includes: a differential provided between left and right wheels of a vehicle; an actuator that locks the differential in order to prevent generation of a rotational speed difference between the left and right wheels; and the differential. and an output means to which power is supplied when the switch means instructs locking and unlocking of the differential, and output means outputs a lock command signal to the actuator.

[Effect]

In the vehicle differential lock device configured as described above, when the operator instructs locking of the differential using the switch means, the actuator is driven in response to this instruction and the differential is locked. That is, in order to lock the differential, the operator only needs to operate the switch means, which can significantly reduce the burden on the operator.

Further, the output means for outputting a lock command signal to the actuator is supplied with power only when locking of the differential is instructed by the switch means. Therefore, even if a failure such as a short circuit occurs in the output means, the differential will not be locked by mistake, which is excellent in terms of safety.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a case where a differential lock device according to the present invention is applied to a four-wheel drive vehicle.

In FIG. 1, the front wheels 1-1.1-2 are connected by left and right axles 31.3-2, which are provided with a front wheel differential 5 at the joint, and the rear wheels 1-3.1-4 are connected The left and right axles 3-3 are provided with a rear wheel differential 7 at the portion thereof. 3-4.

Furthermore, the front wheel differential 5 and the rear wheel differential 7 are connected to the front axle 2-
1 and the rear shaft 2-2 are mutually connected by a propeller shaft connected by a center differential 11. This center differential 11 transmits driving force transmitted from an engine (not shown) through a transmission 9 to a front wheel differential 5.
and the rear wheel differential 7. These diff 5
, 7, and 11 are configured such that the differential function is disabled when the gear that allows differential operation is fixed by the actuator 13. Furthermore, each differential 5,
At 7.11, a defroster detection sensor 6.8.12 is installed to detect whether or not the differential operation is functioning, and its detection signal is input to the control circuit 15. The transmission 9 is also provided with a vehicle speed sensor 10, and this detection signal is also input to the control circuit 15 in the same way as the differential lock detection signal. Furthermore, inside the vehicle, there is a center float switch (SW) 14a.

Front wheel differential lock 5W14b and rear wheel differential lock SW 1
4c are installed, and these switches instruct the locking/unlocking of the respective differentials 5, 7, and 11.

The control circuit 15 includes an input port 15a for inputting signals from each sensor and switch, a CPU 15d and a ROM 1 connected to the input port 15a via a common bus 15c.
Actuator 1 is activated by signals output from 5e, RAM 15f, output boat 15g, and output boat 15g.
and a drive circuit 15h that outputs a drive signal for driving 3.

The operation of the above configuration will be explained using FIG. 2.

FIG. 2 is a flowchart showing the flow of control executed by the CPU 15d of the control circuit 15. Note that this flowchart shows the control for the rear wheel differential 7, and the details of the control for the other differentials 5 and 11 are almost the same, so a description thereof will be omitted.

In FIG. 2, in step 210, the detection signal output from each differential lock detection sensor 6.8.12, the vehicle speed signal output from the vehicle speed sensor 10, and each differential lock 5W
The switching signals from 14a, 14b, and 14c are taken in. In step 220, it is determined whether the value of a flag F indicating that the rear wheel differential 7 is fixed (locked) is 1 or not. At this time, if the rear wheel differential 7 is not locked and the value of the flag F is zero, the process proceeds to step 230, and the detected vehicle speed ■,
and a predetermined reference vehicle speed ■o. Step 230
As a result of the comparison, if the set vehicle speed V is smaller than the reference vehicle speed v0, the process proceeds to step 240, and rear wheel differential lock 5 is set.
It is determined whether W14c is turned on and locking of the rear wheel differential 7 is instructed. At this time, rear wheel differential lock 5
If W14c is turned on, the process advances to step 250;
Based on the detection signal of the center differential lock detection sensor 12, it is determined whether the center differential 11 is locked. At this time, if the center differential 11 is locked, the process proceeds to step 260, and a control signal is output to the drive circuit 15h to lock the rear wheel differential 7. Step 270
Now, the value of the flag F is set to 1 and the control is ended. Therefore, once the rear wheel differential 7 is locked, the flag determination process in step 220 omits the overlap determination process in step 230. In this multiplex determination process, the detected vehicle speed ■ is the predetermined reference vehicle speed ■. (for example, 8 km/h) or more, the process proceeds to step 280, where the rear wheel differential 7 is unlocked (turned off). This is because when the rear wheel differential 7 is locked, the differential operation on the rear wheels does not function, making it difficult for the vehicle to turn, and when the vehicle is running at high speeds, it significantly impairs the running stability of the vehicle. This is to do so. Further, in step 240, rear wheel differential lock 5WI4c
Even if it is off, the process proceeds to step 280 and the rear wheel differential 7 is unlocked. In other words, the fact that the rear wheel differential lock 5W14c installed inside the vehicle is off means that the vehicle is in a situation where the rear wheel differential 7 should be locked (for example, one of the rear wheels has come off and is spinning. This is because it can be determined that there is no such situation. Furthermore, when it is determined in step 250 that the center differential 11 is not locked, the process proceeds to step 280 and the rear wheel differential 7 is unlocked. This means that even if you lock the rear wheel differential 7 when the rear right wheel is idling due to the wheel coming off, if the center differential 11 is not locked, sufficient driving force will not be transmitted to the front wheels. This is because only the rear left wheel generates force, making the vehicle unstable. Even if the rear right wheel is spinning,
If both the rear wheel differential 7 and the center differential 11 are locked, driving force is generated in three wheels except the rear right wheel, and the vehicle can stably escape. When the rear wheel differential 7 is unlocked in step 280, step 290
Then, the value of the flag F is set to zero and the control is terminated.

In the above flowchart, differential lock control is shown for the rear wheel differential 7, but the front wheel differential 5 may be controlled in exactly the same manner as described above. Also, center differential 11
, step 250 of the above flowchart is omitted and the detected vehicle speed V is determined.

It is only necessary to perform lock/unlock control based only on the and center differential lock SW. At this time, the detected vehicle speed V
, the reference vehicle speed V to be compared with, for example, 15 km/h
Note that in this embodiment, the front wheel differential 5 and the rear wheel differential 7
The detection signal from the differential lock detection sensor 6.8 provided in the differential lock detection sensor 6.8 is used for fail-safe operation to confirm whether or not it corresponds accurately to the drive signal output from the drive circuit 15h.

That is, for example, if a detection signal indicating the unlocked state of the rear wheel differential 7 is output from the differential lock detection sensor 8 even though a drive signal for locking the rear wheel differential 7 is output, the actuator 13 or Assuming that some abnormality has occurred in the drive circuit 15h or the like, a lamp (not shown) is flashed to alert the driver.

FIG. 3 is a detailed circuit configuration diagram of the control circuit 15 and actuator 13. In addition, in Fig. 3, the front wheel differential 5. Typical examples are shown as drive circuits and actuators for the rear wheel differential 7 and center differential 11, and therefore the differential lock 5WI4, signal path, actuator 13
etc. are shown for only one system. .

In FIG. 3, when a differential lock switch 14 is turned on when an ignition switch (not shown) is turned on, power is supplied to the collector terminal of the transistor 31 via the differential lock switch 14. At this time, if the conditions shown in the flowchart of FIG. 2 are satisfied, the EC
U (input port 15a, CPU 15d in FIG.
, ROM 15e, RAM 15f, output port 15g) to the base terminal of the transistor 31 for a predetermined period of time (for example, 5 seconds). transistor 3
1 is made conductive by this Hi-level signal, and a current flows through the relay coil 33a of the relay 33 via the differential lock switch 14 and the transistor 31. By energizing this relay coil 33a, the relay contact 33b switches, and the power source → relay 33 → motor 35 → relay 34 →
Current flows through the motor 35 through a path called arc, and differential lock is performed. In addition, 36 is a limit switch,
When the rotation angle of the motor 36 reaches a predetermined angle, the contacts are switched to cut off the power supply to the motor 35.

Thereafter, when the conditions for turning off the differential lock are met, the ECU outputs a Hi level signal to the base terminal of the transistor 32 for a predetermined period of time. As a result, the transistor 32 becomes conductive, and current flows through the transistor 32 to the relay coil 34a of the relay 34. Therefore, the relay contact 34b of the relay 34 is switched, and the motor 35 is connected to the motor 35 via the power supply → relay 34 → motor 35 → relay 33 → ground.
A current flows through the differential lock, and the differential lock is released.

Here, since the collector terminal of the transistor 31 that controls the differential lock is connected to the power supply via the differential lock switch 14, even if a short-circuit failure occurs between the collector terminal and the emitter terminal in the transistor 31, for example, the differential lock switch 14 is not turned on, no current flows through the relay coil 33a and differential lock is not performed. Therefore, it is possible to prevent the differential lock from being performed irrespective of the driver's intention, which is extremely superior in terms of safety.

〔Effect of the invention〕

As described above, according to the present invention, when locking the differential, it is only necessary to instruct the locking of the differential by the switch means (and the output means for outputting the lock command signal is supplied with power only when the differential lock is instructed by the switch means). Therefore, it is possible to provide a vehicle defroster device that is extremely superior in terms of operability and safety.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention, FIG. 2 is a flowchart showing a control procedure executed by the CPU shown in FIG. 1, and FIG. 3 is a control circuit and actuator shown in FIG. 1. FIG. 5...Front wheel differential, 7...Rear wheel differential, 11...Center differential, 6,8.12...Differential lock detection sensor,
9... Transmission, 10... Vehicle speed sensor,
13... Actuator, 15... Control circuit.

Claims (1)

[Scope of Claims] A differential provided between left and right wheels of a vehicle; an actuator that locks the differential in order to prevent a rotation speed difference between the left and right wheels; and a switch that locks and unlocks the differential. A differential locking device for a vehicle, comprising: a switch means for instructing to lock the differential; and an output means to which power is supplied when locking of the differential is instructed by the switch means and outputs a lock command signal to the actuator.