JPH036512Y2 - - Google Patents

Description

[Detailed explanation of the invention] Industrial applications Generally, 4WD vehicles use a freewheel hub, and when used in 2WD, the drive wheel is separated from the drive shaft to avoid applying extra load. There is. In a 4WD vehicle with such a freewheel hub, there is a risk of accidental
When 4WD operation was performed, problems such as latching of the freewheel hub and 4WD switching without the freewheel hub being locked occurred.

Therefore, in order to solve these problems, the present invention determines the current situation based on the signals from the changeover switch and the propeller shaft rotation speed detection sensor.
The present invention relates to a 4WD vehicle that has a controller that controls the switching to 4WD appropriately.

Conventional technology In conventional 4WD vehicles, a transmission is connected to the engine, and a bevel gear, etc., which is a transfer device and a change device, such as a clutch for switching between 2WD and 4WD, is additionally installed via a two-stage auxiliary transmission. Ta. and,
A part-time 4WD system was adopted that switched between 2WD and 4WD by operating the transfer wheel. 2WD of this part-time 4WD system
The switching between 4WD and 4WD is done by the 2nd gear 4WDH/L sub-transmission.
A switching lever is provided as a button switch,
By operating the switch, the switching solenoid was energized, the actuator was operated, and the transfer was used to switch between 2WD and 4WD. As with most of these 4WD vehicles, the freewheel hub is attached to the wheel that becomes the driven wheel during 2WD, and when 2WD, this freewheel hub is in the free state and drives the driven wheel during 2WD. This prevents the system from backdriving, reducing fuel consumption and improving handling when in 2WD.

Problems that the invention aims to solve: However, in 4WD vehicles with freewheel hubs, the freewheel hub locks while the vehicle is running, and the auto freewheel hub requires the vehicle to stop and back up in order to release the lock. In a 4WD vehicle equipped with
If the driver accidentally switched to 4WD, the propeller shaft would rotate and rotate the drive shaft of the drive wheel that was not rotating, causing problems such as ratcheting in the auto freewheel hub. In addition, in 4WD vehicles with manual freewheel hubs that require the driver to stop the vehicle and get out of the vehicle to operate the freewheel hub, when the freewheel hub is not in the locked state, the changeover switch There was a problem where the vehicle would not reliably become 4WD even if the vehicle was switched to 4WD.

The ratcheting phenomenon refers to the gear noise that occurs when the slide gear that makes up the freewheel hub and the gear on the housing are not meshed and there is a difference in rotation speed between them, and the difference in rotation speed is approximately 150 rpm. Occurs above.

Means for Solving the Problems Therefore, in order to solve the above-mentioned problems, the four-wheel drive vehicle of the present invention is a part-time four-wheel drive vehicle having a freewheel hub. A propeller shaft rotational speed detection sensor that detects the rotational state of the propeller shaft in which power transmission is connected or disconnected, a mode changeover switch, an actuator that switches the transfer between the 4WD state and the 2WD state, and the propeller shaft rotational speed detection sensor. and the mode changeover switch, and when the mode changeover switch is in the 4WD state and detects that the detected rotational speed of the propeller shaft rotational speed detection sensor is equal to or higher than the reference rotational speed, the actuator switches to 4WD. and a controller that outputs a switching drive signal to the state.

Function Therefore, in the four-wheel drive vehicle of the present invention, the mode changeover switch is activated by signals from the propeller shaft rotation speed detection sensor and the mode changeover switch.
The system detects that the propeller shaft rotation speed detection sensor detects that the propeller shaft rotation speed is equal to or higher than the standard rotation speed, and sends a signal to the actuator to switch to 4WD to switch the transfer.

Embodiment Hereinafter, an embodiment will be explained with reference to the drawings. As shown in FIG. Detect mode.
The rotation speed detected by the propeller shaft rotation speed detection sensor 1 is calculated as a pulse signal by the calculation means 2, and then the propeller shaft rotation speed determination means 3 determines whether it is equal to or higher than the reference rotation speed of the propeller shaft stored in advance. do. The signal determined in this manner and the open/close mode signal of the mode changeover switch 4 having a mode holding function such as a button switch are inputted to the changeover mode signal output determination means 5 which is a gate circuit, and the position of the changeover switch 4 is It has a controller C that sends a signal to energize solenoid 6 so that the transfer can be switched to 4WD when the propeller shaft is in closed 4WD mode and the propeller shaft rotation speed is below the reference rotation speed.
It is a 4WD vehicle.

As shown in FIG. 2, this four-wheel drive vehicle controls and outputs the mode signals of the propeller shaft rotation speed detection sensor 1 and the mode changeover switch 4 by the controller C, and the output is controlled by the excitation of the solenoid 6. The actuator 7 is actuated to drive the transfer 8 such as the 4WD switching clutch, and the driving torque from the engine 9 is transferred to the sub-driver which switches between H/L using the transmission 10 and the H/L switching lever 11 of the mode switching switch. If the transfer is switched to the 4WD side via the transmission 12, the transmission is configured to be transmitted to the rear wheels via the propeller shaft 14 and rear differential 15.

Note that 13 is a front differential that transmits drive torque to the front wheels.

Next, to explain the action of controller C based on the flowchart in Fig. 3, it detects the rotation speed of the propeller shaft, and when the rotation speed reaches the reference value.
If the speed is 500 rpm or more, a control signal is output to change the switching mode of the changeover switch to 2WD or 4WD.

An example of a specific control circuit will be described with reference to FIG. 4A. The rotational speed of the propeller shaft, which transmits the driving torque by switching the transfer, is detected as a pulse signal by a rotational speed detection sensor, which is noise-absorbed, waveform-shaped by a comparator, passed through a filter, and latched by a flip-flop. The rotation speed is the standard value.
A propeller shaft rotation speed detection circuit is provided that recognizes the rotation speed as "rotation" when the rotation speed is 500 rpm or more and sends a voltage L, and recognizes the rotation speed as "stopped" when the rotation speed is below a reference value, that is, 500 rpm or less, and sends out a voltage H. . On the other hand, the voltage H is transmitted by setting the changeover switch to 2WD.
A switch circuit is provided that transmits voltage L with the closed position set to 4WD. Then, the signals from these circuits are input to the OR circuit, and the signal is output as L only when the input from the propeller shaft rotation speed detection circuit and the switch circuit is L, and the solenoid is energized to operate the actuator and the transfer is activated.
Switch to 4WD.

Therefore, in the above-mentioned four-wheel drive vehicle, switching from 2WD to 4WD while driving can only be performed when the propeller shaft is at or above the reference rotation speed (the freewheel hub is locked). Therefore, regardless of whether a 4WD vehicle is equipped with an auto freewheel hub or a manual freewheel hub, 2WD
If the freewheel hub is not securely locked while driving, the propeller shaft will not rotate due to backdrive and therefore cannot be switched while driving, which will prevent the occurrence of the ratcheting phenomenon and ensure that switching to 4WD is not possible. It is possible to solve the problems of conventional methods that were said to be impossible.

Effects of the invention As a result of the above, in a part-time 4WD vehicle with a freewheel hub, even if the changeover switch is accidentally switched to the 4WD side while driving in 2WD, the rotation speed of the propeller shaft will be detected and no problems will occur. Since the transfer is switched after it is determined that the freewheel hub is locked, in other words, after confirming that the freewheel hub is locked, it is easier to prevent the ratcheting phenomenon in the case of an automatic freewheel hub, and in the case of a manual freewheel hub. In the case of a hub, it is possible to prevent switching to 4WD when the vehicle is not locked, reducing fuel consumption and improving maneuverability.

[Brief explanation of the drawing]

Figure 1 shows the freewheel hub of this invention.
FIG. 2 is a block diagram of a configuration realizing the functions of a controller in a 4WD vehicle; FIG. 2 is an overall diagram of a 4WD vehicle switched by the controller; and FIG. 3 is a flowchart showing the software of the controller. FIG. 4A is a circuit diagram of the controller, and FIG. 4B is an OR circuit truth table. 1...Propeller shaft rotation speed detection sensor, 3
. . . Propeller shaft rotation speed determination means, 4 . . . Mode switching switch, 5 . . . Switching mode signal output determination means, 6 . 14...Propeller shaft.

Claims (1)

[Scope of utility model registration request] In a part-time four-wheel drive vehicle having a freewheel hub, a propeller shaft rotation speed detection sensor that detects a rotational state of a propeller shaft in which transmission of driving force is disconnected or disconnected depending on a transfer state, and a mode changeover switch; An actuator that switches the transfer between the 4WD state and the 2WD state receives detection signals from the propeller shaft rotational speed detection sensor and the mode switching switch, and when the mode switching switch is in the 4WD state, the propeller shaft rotational speed is changed. A four-wheel drive vehicle, comprising: a controller that outputs a drive signal for switching to a 4WD state to the actuator when it detects that a rotation speed detected by a detection sensor is equal to or higher than a reference rotation speed.