JPH01168553A - Four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To keep off repetition of on-off operation on a clutch as well as to improve the extent of accelerating performance by disengaging the clutch of a connecting shaft in an all-wheel driving system at the tie of antiskid braking, and making the clutch in a low speed state resettable to its engaged state at the time of braking release. CONSTITUTION:A clutch 4 is installed in a propeller shaft 3 connecting both front and rear driving systems connected to a power unit P, an antiskid control part 2 is installed in a brake driving part 1, and when this antiskid control part 2 is operated, the clutch 4 is disengaged by an actuator 5, whereby mutual intervention between front and rear wheels at the time of antiskid braking is prevented from occurring. If braking is released, the clutch 4 is made resettable to an engaged state only in its low speed state. A vehicle is made into a 4WD state after braking at low speed and improvement in the extent of accelerating performance is promoted, while a repetition of on-off operation on the clutch is prevented from occurring, smooth running is made attainable.

Description

Detailed Description of the Invention A9 Purpose of the Invention (1) Industrial Application Field The present invention is directed to a drive system that connects front and rear wheels, and which is interposed in the middle of a drive system that connects front and rear wheels. a clutch that can switch between the front and rear wheels; a braking force control means that can control the operating mode of the brakes installed on the front and rear wheels differently for the front and rear wheels; The present invention relates to a four-wheel drive vehicle including a control means for controlling the vehicle.

(2) Conventional technology Conventionally, such four-wheel drive vehicles have been developed, for example, in
It is known from the publication No. 5132.

(3) Problems to be Solved by the Invention In such a four-wheel drive vehicle, the clutch is placed in a two-wheel drive state in a disconnected state to avoid mutual interference between the front wheels and rear wheels when a braking force control means such as anti-lock control is activated. In the conventional system described above, when the anti-lock control state ends, the clutch is connected to return to the four-wheel drive state. However, when the anti-lock control state occurs intermittently by applying light brakes, the clutch is repeatedly engaged and disengaged, and this repeated engagement and disengagement causes problems with noise, vibration, and durability. arise. On the other hand, in a low vehicle speed state, the accelerator may be suddenly pressed to accelerate from the brake state, and in such a case, it is preferable to improve the acceleration performance by setting the vehicle to a four-wheel drive state.

The present invention has been made in view of the above circumstances, and provides a four-wheel drive vehicle that solves the above problems by setting vehicle speed or low vehicle speed as at least one of the conditions for returning the clutch to the connected state. The purpose is to

B0 Structure of the Invention (1) Means for Solving the Problems According to the present invention, the control means is configured to be able to switch the clutch from a disengaged state to a connected state only in a low vehicle speed state.

(2) Effect According to the above configuration, after the clutch is in the disconnected state, it does not return to the connected state at high vehicle speeds, and the clutch is prevented from frequently repeating the connected state and the disconnected state at high vehicle speeds. Furthermore, since the connected state can be restored only at low vehicle speeds, acceleration performance is improved during sudden acceleration operations after braking at low vehicle speeds.

(3) Embodiment Hereinafter, an embodiment of the present invention will be explained with reference to the drawings. First, in FIG. It is suspended, and both front axles Wf! ,W
Brake Bf for fr and both rear wheels Wrffi, Wrr
f, Bfr; Brf, Brr are respectively equipped, and these brakes Bff, Bfr, Bri! , Br.
In addition, the hydraulic control circuit l that constitutes the brake device B includes front wheels Wfl, Wfr side brakes BfI! ,,Bfr
and rear wheel Wrffi, Wrr side brake Brj! ,Br
An anti-lock control means 2 is attached as a braking force control means that can control the brakes and r by differentiating their operating modes.

This anti-lock control means 2 controls, for example, the left front wheel Wrl.
brake Bff of the front right wheel Wfr, brake Bfr of the right front wheel Wfr, and both rear wheels Wrffi.

Wrr brake Brj! , Brr can be individually controlled, and the brake oil pressure is reduced when anti-lock control is activated.

Both front axles Wrj! , Wfr and both rear wheels Wrj2. Wrr
is connected to a power unit P via a drive system A.

This drive system A has both front axles Wf! ! ,, a front differential device Df that connects Wfr and power unit l-P, a rear differential device Dr that connects both rear wheels Wrf and Wrr, and a connection between power unit) P and rear left drive device Dr. In the middle of this propulsion shaft 3, both front shafts Wfj
2. Wfr and both rear wheels Wrj2. A dog clutch 4 that can switch between a connected state and a disconnected state between rr is interposed, and an actuator 5 such as a cylinder for driving this dog clutch 4 is controlled by a control means 6.

In FIG. 2, which shows the configuration of the main parts of the control means 6, signals indicating that the anti-lock control state is in place are inputted from the adjuster lock control means 2 to input terminals 7, 8, and 9, respectively. That is, a high level signal is input to the input terminal 7 when the brake Bfj2 of the left front wheel Wfffi is in the anti-lock control state, and a high level signal is input to the input terminal 8 when the brake Bfr of the right front wheel Wfr is in the anti-lock control state. A signal of level 1 is input to input terminal 9, and both rear wheels W are input to input terminal 9.
ri! .

Wrr brake Brj! , Brr are in the anti-lock control state, a high level signal is input. These input terminals 7, 8.9 are connected in parallel to an OR circuit 10, and therefore, the OR circuit 10 outputs a high level signal when the anti-lock control means 6 is in the anti-lock control state.

An output terminal of the OR circuit 10 is connected to one input terminal of an AND circuit 11, and an input terminal 12 is connected to the other input terminal of the AND circuit 11. An accelerator switch (not shown) is connected to the input terminal 12, and a high-level signal is input when the foot is released from the accelerator pedal. Therefore, the AND circuit 11 outputs a high-level signal when the anti-lock control means 6 is performing anti-lock control and the foot is released from the accelerator pedal. It is input to the set input terminal S.

The signal input to the input terminal 12 is inverted by the inverting circuit 14 and then input to one input terminal of the OR circuit 15 .

Further, the signal output from the AND circuit 11 is
After being inverted at step 6, the signal is input to one input terminal of an AND circuit 17. Furthermore, the signal input to the input terminal I8 is inverted and input to the other input terminal of the AND circuit 17.
A signal that becomes high level when the value is 0 or more is manually input. Therefore, the output of the AND circuit 17 is that the vehicle speed ■ is a constant value ■. When the output of the AND circuit 11 is at a low level, that is, when anti-lock control by the anti-lock control means 6 is not being performed or when the accelerator pedal is being depressed, a high-level signal is output. The output is input to the other input terminal of the OR circuit 15.

By the way, the constant value ■ of the vehicle speed ■. Even if you press the accelerator pedal while applying the brake, the dog clutch 4 will not engage.
The speed is set at a speed that does not cause two-wheel wheel spin that affects cutting control, for example, 30kn+/H.
stipulated in

The output of the OR circuit 15 is input to one input terminal of the AND circuit 19, and the signal from the input terminal 20 is input to the other input terminal of the AND circuit 19.

This input terminal 20 is connected to -B when the rotation speed difference between the front and rear axles is within a certain range, that is, the difference ΔW between the sum of the speeds of both front axles wrz and wrr and the sum of the speeds of both rear wheels WrQ and Wrr.
(For example -10km/H) ≦ΔW≦C (For example 10km/H)
A signal that is at a high level when the voltage is (kIl/H) is input. The output of this AND circuit 19 is input to the reset input terminal R of the flip-flop 13.

Here, the signal input to the reset input terminal R of the flip-flop 13 becomes high level because -B≦ΔW≦C
, and the vehicle speed V
is less than the constant value ■6.

An output terminal Q of the flip-flop 13 is connected to an output terminal 22 via an inverting circuit 21. This output terminal 22 is
It is for controlling the operation of the actuator 5 that drives the dog clutch 4, and when the signal output from the output terminal 22 is at a high level, the actuator 5 operates to disconnect the dog clutch 4.

Next, the operation of this embodiment will be explained with reference to FIGS. 3 and 4. First, the dog clutch 4 is in a connected state, and both front axles Wfffi, Wfr and both rear wheels Wrj2
．． When the vehicle is in a four-wheel drive state with Wrr connected, the operation of the actuator 5 is controlled according to the procedure shown in FIG. 1
It is determined whether the signal input to 2 is at a high level. When the foot is off the accelerator pedal, it is determined in the next second step S2 whether anti-lock control is being performed by the anti-lock control means 6, and in the case of anti-lock control, the actuator 5 controls the dog clutch 4 in a third step S3. Activate the cutoff.

In this way, during anti-lock control by the anti-lock control means 6, the dog clutch 4 is disconnected and both front axles Wf/2
．． Wfr and both rear wheels Wrj! Since the connection between , Wrr was cut off and a two-wheel drive state was established, the front wheel WfI! ,,Wf
r and rear wheel Wr1. Wrr can be prevented from interfering with each other and a sufficient anti-lock effect can be obtained. Moreover, since the dog clutch 4 is disconnected and operated when the torque transmitted to the dog clutch 4 is at its minimum, the driving force of the actuator 5 is small. .

Next, when returning from the two-wheel drive state to the four-wheel drive state, the control procedure shown in FIG. 4 is followed, and the first step M
In step 1, it is determined whether or not the accelerator pedal is being depressed, and if the accelerator pedal is being depressed, the second step M is executed.
2, it is determined whether -B≦ΔW≦C, and -B
When ≦ΔW≦C, the dog clutch 4 is engaged in the third step M3, and a four-wheel drive state is established.

By connecting and operating the dog clutch 4 when the rotational speed difference between the front and rear axles is within a certain range in this way, it is possible to suppress the generation of noise and vibration caused by the engagement, and it is also advantageous in terms of durability. becomes.

If it is determined in the first step Ml that the accelerator pedal is not depressed, the process proceeds to the fourth step M4,
In step M4, it is determined whether the vehicle speed ■ is less than a constant value ■6. ■≧■.

When this is the case, the disconnected state of the dog clutch 4 is maintained as it is, and it is determined in the fifth step M5 whether or not anti-lock control is being performed, and if the anti-lock control is released, the process proceeds to second step M2 and the dog clutch 4 is closed. 4
connection operation is possible.

In this way, when the vehicle speed ■ exceeds the constant value ■6, the dog clutch 4 remains in the disconnected state, so even if a light brake is applied during high-speed driving and anti-lock control is performed intermittently, the dog clutch 4 remains in the disconnected state. It maintains a
Deterioration of durability can be prevented. Therefore, the vehicle speed■
When is less than the constant value {circle around (6)}, the dog clutch 4 can be engaged, so when accelerating by suddenly stepping on the accelerator from a braking state, the four-wheel drive state can be applied and acceleration performance can be improved.

As another embodiment of the present invention, as shown in FIGS. 5 and 6, a signal from a brake switch that is turned on when in a braking state is used as one of the conditions for determining whether to switch on or off the dog clutch 4. It may also be used as one.

C8 Effects of the Invention As described above, according to the present invention, the control means is configured so that the clutch can be switched from the disengaged state to the engaged state only at low vehicle speeds, so that sudden acceleration after braking at low vehicle speeds is prevented. While improving acceleration during operation, it is possible to prevent the clutch from frequently repeating engagement and disengagement operations, and to prevent the generation of noise and vibration caused by such repetition.
Durability can be improved.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention,
Fig. 1 is a schematic diagram of the drive system, Fig. 2 is a circuit diagram showing the configuration of the main parts of the control means, Fig. 3 is a flowchart showing the control procedure when the clutch is disconnected, and Fig. 4 is the clutch engagement operation. 5 and 6 show other embodiments of the present invention, FIG. 5 is a flowchart corresponding to FIG. 3, and FIG. 6 is a flowchart corresponding to FIG. 4. This is a flowchart. 2... Anti-lock control means as braking force control means, 4... Clutch, 6... Control means, A... Drive system, Bf/! , Bfr, BrCBrr...brake,
Wf1. Wf r, Wr x, Wr r... Wheels Figure 4 Figure 3 Figure 6; Figure 5

Claims (1)

[Claims] a clutch that is interposed in the middle of a drive system that connects the front and rear wheels and can switch between connecting and disconnecting the front and rear wheels;
A braking force control means that can control the operating mode of brakes installed on the front and rear wheels differently for the front and rear wheels, and a control means that disengages the clutch when the braking force control means is activated. A four-wheel drive vehicle, characterized in that the control means is configured to switch the clutch from a disengaged state to a connected state only in a low vehicle speed state.