JPH0537701Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field of the Invention) The present invention relates to a differential control device, and more particularly, to a differential control device in a vehicle in which front or rear left and right wheels are driven by a differential device having a differential limiting mechanism. The present invention relates to a device for controlling the differential of a motor.

(Prior art) When driving on so-called straddle roads, where one of the left and right drive wheels of a vehicle is on a road surface with a low coefficient of friction and the other is on a road surface with a normal coefficient of friction, the wheels are on a road surface with a low coefficient of friction. The drive wheels may spin, or spin. When this wheel spin occurs, no driving force is generated at the other drive wheel, so it is necessary to limit the differential to ensure traction.

A control device that limits or cancels the differential of a differential device according to the difference in rotational speed between the left and right drive wheels (for example, Japanese Patent Application Laid-Open No. 133920/1982,
According to Japanese Patent Publication No. 54630), the above problem can be addressed.
On the other hand, at the same time as the differential is restricted, the difference in rotational speed between the left and right sides decreases or becomes zero, so if the differential restriction is canceled and the difference in rotational speed becomes larger than a predetermined value due to this release, the differential will be activated again. be in a restricted state,
In this way, the differential is repeatedly restricted and released, resulting in inefficiency, and the differential restriction and release of the differential device becomes more frequent, which deteriorates the durability of the differential limiting mechanism. In view of this, a separate control device was proposed (Patent Application No. 62-64300).

The control device according to this proposal is a device for controlling the differential of a differential device in a vehicle in which front left and right wheels or rear left and right wheels are driven by a differential device having a differential limiting mechanism. The controller includes means for detecting the rotational speed of the left and right wheels and rear left and right wheels, a controller that receives a signal from the detection means, and a means for operating the differential limiting mechanism. The difference in rotation speed between the left and right wheels driven by the differential gear is calculated, the calculated rotation speed difference is compared with a first reference value, and when the calculated rotation speed difference is greater than or equal to the first reference value, the differential The controller also calculates a rotational speed difference between the front and rear wheels, and compares the calculated rotational speed difference between the front and rear wheels with a second reference value. The difference in rotation speed between the front and rear wheels is the second
is below the reference value, the operating means is controlled to release the differential restriction of the differential device.

(Problem to be solved by the invention) In the control device according to the above proposal, when the inner wheel enters a wheel spin state during a turn and the differential of the differential gear is restricted, the differential restriction is released until the end of the turn. There is a risk that it will continue without being implemented. this is,
The rotational speed of the front and rear wheels during a turn is rarely the same due to the difference in the turning radius, and therefore the difference in the rotational speed of the front and rear wheels is never smaller than the second reference value. by. This problem can be resolved by setting the second reference value to a large value, but doing so makes it difficult to ensure traction by limiting the differential when traveling straight.

If the drive force is increased while maintaining the limited differential state during a turn, the left and right drive wheels tend to spin, reducing the cornering force of the tires. As a result, in rear-wheel drive vehicles, tailing occurs at the rear of the vehicle body, and in front-wheel drive vehicles, severe understeer occurs and the turning radius increases, making it difficult to turn.

SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a differential control device capable of increasing traction and improving vehicle stability both when traveling straight and when cornering.

(Means for Solving the Problems) The present invention is a device for controlling the differential of a differential device in a vehicle in which front left and right wheels or rear left and right wheels are driven by a differential device having a differential limiting mechanism. means for detecting the rotational speed of each of the front left and right wheels, a means for detecting the rotational speed of each of the rear left and right wheels, a means for detecting a steering angle, and a controller that receives signals from each of the detection means; means for operating the differential limiting mechanism; the controller calculates a rotational speed difference between the left and right wheels driven by the differential, and uses the calculated rotational speed difference as a first reference value. One of the left and right wheels driven by the differential device is compared with a first reference value for determining whether or not one of the left and right wheels is in a wheel spin state, and the calculated rotational speed difference is determined by the first When the reference value is exceeded, it is determined that the one wheel is in a wheel spin state, and the controller is configured to control the operating means to start limiting the differential of the differential device, and the controller also controls the rotation speed difference between the front and rear wheels. At the same time, the calculated rotational speed difference between the front and rear wheels is used as a second reference value, which determines whether one of the left and right wheels driven by the differential device is in a wheel spin state when traveling straight. In addition, the rotation of the front and rear wheels calculated by comparing it with a second reference value for determining whether or not the left and right wheels driven by the differential device will be in a wheel spin state during a turn. It is determined that the one wheel is not in a wheel spin state when the difference in number of rotations is less than the second reference value when driving straight, or when the calculated difference in the number of rotations between the front and rear wheels becomes larger than the second reference value when turning. It is determined that the wheels are in a spin state, and the operating means is controlled to release the differential restriction of the differential gear.

In a preferred embodiment, the first reference value and the second reference value are set based on at least one of vehicle speed and steering angle.

In a preferred embodiment, the second reference value is set based on at least one of vehicle speed and steering angle.

Among the front left and right wheels and the rear left and right wheels, the left and right wheels that are not driven by a differential device that has a differential limiting mechanism are either non-driven or are driven by a differential that does not have a differential limiting mechanism. driven by the device.

The first reference value and the second reference value can be determined experimentally.

(Operation and Effect) The controller calculates the rotational speed difference between the left and right wheels driven by the differential device having the differential limiting mechanism, and when the calculated rotational speed difference is equal to or greater than the first reference value, It is determined that one of the left and right wheels is in a wheel spin state, and the operating means is operated to start limiting the differential. As a result, the differential movement between the left and right wheels is restricted, making it impossible to freely differentially move the wheels.
Drive force is now transmitted to the wheels that are not experiencing wheel spin. This ensures traction.

The controller calculates the rotational speed difference between the front wheels and the rear wheels, and when the calculated rotational speed difference is less than or equal to a second reference value when traveling straight, the controller determines whether the one wheel is not in a wheel spin state, that is, whether the wheel spin has been resolved. Or, determine that it is not occurring and release the differential restriction. Alternatively, when the calculated rotational speed difference between the front and rear wheels becomes larger than the second reference value during a turn, both wheels enter a wheel spin state, such as tail drift in a rear-wheel drive vehicle or understeer tendency in a front-wheel drive vehicle. Since the system determines that there is a risk of the vehicle becoming unstable and lifts the restriction on the differential, it is possible to improve driving stability while ensuring suitable traction. Note that when the calculated rotational speed difference is larger than the second reference value when traveling straight,
Since centrifugal force and other forces are not acting on the vehicle and it is less likely to be adversely affected by wheel spin, differentials are still restricted to ensure traction.

According to a preferred embodiment, the first reference value and the second reference value are set based on at least one of the vehicle speed and the steering angle, and change together with the other, thereby making it possible to more accurately discriminate between wheelspin and turning. It can be carried out.

(Embodiment) The differential control device 10 controls the differential of the differential device 14 in a vehicle in which front or rear left and right wheels (not shown) are driven by a differential device 14 having a differential limiting mechanism 12. Control. For example, when the rear left and right wheels are driven by the differential device 14, the front left and right wheels are not driven or are driven by a differential device that does not include a differential limiting mechanism.

The differential control device 10 includes means 16 for detecting the rotation speed of the front left wheel, means 18 for detecting the rotation speed of the front right wheel, means 20 for detecting the rotation speed of the rear left wheel, and means 20 for detecting the rotation speed of the rear left wheel. Means 2 for detecting the rotation speed of the wheel
2, a means 24 for detecting a steering angle, a controller 26, and a means 28 for operating the differential limiting mechanism 12.

Any differential device can be used as long as it has a differential limiting mechanism. Illustrated differential 14
Here, one of the shafts 36 each connected to a pair of side gears 34 (one of which is shown in the figure) that meshes with a plurality of pinions 32 arranged in the differential case 30, and the differential case 30 and the differential limiting mechanism 1
2 is provided.

The differential limiting mechanism 12 includes a plurality of first friction plates 40 that engage one shaft 36 via a spacer 38, and a plurality of second friction plates 40 that engage the differential case 30 via a transmission member 42. friction plate 44
Equipped with. The first friction plate 40 is the spacer 38
It is supported non-rotatably but movably in the axial direction of the shaft 36. On the other hand, a second friction plate 44 is supported by the enlarged diameter portion of the transmission member 42 so as to be non-rotatable and movable in the axial direction. The first friction plates 40 and the second friction plates 44 are arranged alternately.

A piston chamber 48 is provided in the differential carrier 46 and a first piston 50 is movably and non-rotatably disposed within the piston chamber 48 . A second piston 52 is spaced apart from the first piston 50;
2 is supported by the spacer 38 so as to be non-rotatable and movable in the axial direction. A thrust bearing 54 connects the first piston 50 and the second piston 52
placed between.

When pressure fluid is introduced into the piston chamber 48 from the outside, the first piston 50 engages the thrust bearing 5
4 against the second piston 52,
Between the first friction plate 40 and the second friction plate 44,
A frictional force proportional to the pressing force is generated. This frictional force limits the differential movement of the differential device 14. At this time, the reaction force generated in the transmission member 42 is transmitted to the thrust washer 56 disposed on the differential carrier 46, the thrust washer 58 disposed on the transmission member 42, and the thrust bearing 60 disposed between both washers. It is received by the Farencial Carrier 46.

Means for detecting rotational speed 16, 18, 20, 22
The means 24 for detecting the steering angle is a detector known per se.

The controller 26 is a CPU or a computer, and includes means 16, 1 for detecting the rotation speed.
Signals are input from 8, 20, 22 and a means 24 for detecting the steering angle, and calculations and control as described below are performed.

The operating means 28 includes a liquid pump 64 , an unload relief valve 66 , an accumulator 68 , a current-controlled pressure reducing valve 70 , and a check valve 72 .

A tube 74 extends from pump 64 to differential limiting mechanism 12 and communicates with piston chamber 48 . An unload relief valve 66 is incorporated into the pipe 74;
Current control pressure reducing valve 70 is unload relief valve 66
The differential limiting mechanism 12 is incorporated in the portion extending from the differential limiting mechanism 12 to the differential limiting mechanism 12. Further, an accumulator 68 is connected between the unload relief valve 66 and the current-controlled pressure reducing valve 70, and a check valve 72 is connected between the unload relief valve 66 and the current-controlled pressure reducing valve 70.
6 and an accumulator 68.
Check valve 72 only allows liquid flow or pressure transmission from unload relief valve 66 to accumulator 68 .

When pressurized liquid is supplied from the pump 64, the unload seat of the unload relief valve 66 is closed and the check valve 72 is opened. As a result, pump 64
The pressurized liquid from is led via pipe 74 to the accumulator 68, where the liquid pressure is increased. When the pressure of the accumulator 68 reaches the adjustment pressure of the unload relief valve 66, the unload relief valve 66 instantly opens, the pressurized liquid from the pump 64 flows back to the reservoir tank 76, and the check valve 72 closes. Thus,
A constant pressure is stored in the accumulator 68.

The current-controlled pressure reducing valve 70 has a DC solenoid installed in its pilot section, and controls the pressure continuously and steplessly by controlling the input current to the solenoid. The control pressure in this case is then substantially proportional to the input current. Therefore, if the current applied to the current-controlled pressure reducing valve 70 is controlled by the controller 24, an appropriate pressure can be obtained.

The controller 26 performs calculations and controls shown in FIG. Initialize to 100 and set the differential control signal to
Set OFF to 101, set flag to zero 10
2. The flag F is 1 when the differential of the differential gear is restricted, and is 0 when the restriction of the differential of the differential gear is released.

In the embodiment, it is assumed that the rear left and right wheels are driven by the differential device 14, the rotation speed ω ₁ of the rear left wheel is read 103, and the rotation speed ω ₂ of the rear right wheel is read.
is read (104), and it is determined (105) whether the flag F is zero. If F=0, the absolute value ω of the left and right rotation speed difference is calculated 106, and the calculated rotation speed difference ω is compared with a reference value ω ₀ (107).

When the calculated rotational speed difference ω is greater than or equal to the reference value ω ₀ , the differential control signal is set to ON 108, the flag is set to 1 109, and the differential control signal is output 11
0. In this case, the calculated rotational speed difference ω is the reference value ω ₀
In this case, in order to always give a constant differential limiting amount to the differential limiting mechanism 12, in addition to determining the current value output to the current control pressure reducing valve 70, the pressure P and the current I
and the relationship between the value Δ obtained by subtracting the reference value ω ₀ from the rotational speed difference ω and the pressure P are stored in advance as a map in the controller 26, and a current is output according to the magnitude of Δ. You can also do that.

If F=0, read the steering angle δ112,
The rotation speed W ₁ of the front left wheel is read 113, and the rotation speed W ₂ of the front right wheel is read 114. and,
The sum of rotation speeds AW of the front left and right wheels is calculated 115, the sum of rotation speeds Aω of the rear left and right wheels is calculated 116, and the absolute value AΔ of the rotation speed difference between the front and rear wheels is calculated 117.
In this way, to find the rotation speed difference between the front and rear wheels, first find the sum of the rotation speeds of the front left and right wheels and the sum of the rotation speeds of the rear left and right wheels, and then use the difference between the two as the rotation speed difference between the front and rear wheels. , the difference becomes larger and it becomes easier to control.

The rotation speed difference AΔ between the front and rear wheels is compared with the reference value Aω ₀ (118). If the rotational speed difference AΔ is less than the reference value Aω ₀ , determine whether the steering angle δ is zero 11
9. Then, if the steering angle δ is not zero, that is, if the vehicle is turning, the differential control signal that has been output up to that point is output 110. Thus differential limiting continues.

Even if the rotational speed difference AΔ is less than the reference value Aω ₀ , if the steering angle δ is zero, that is, the vehicle is traveling straight, the differential control signal is set to OFF (120), the flag is set to zero (121), and the control signal is activated. 110 to output. In this case, the current value to be output to the current control pressure reducing valve 70 can be predetermined in order to give a constant and slight differential restriction amount to the differential limiting mechanism 12, and the current value to be output to the current control pressure reducing valve 70 can be predetermined. You can keep it.

When the rotational speed difference AΔ is larger than the reference value Aω ₀ , it is determined again whether the steering angle δ is zero or not (122).
Then, if the steering angle δ is zero, that is, the vehicle is traveling straight, the differential control signal that has been output up to that point is outputted 110. Thus differential limiting continues. Conversely, if the steering angle δ is not zero, that is, if the vehicle is turning, the differential control is set to OFF1.
20. Set the flag to zero 121.

The first reference value ω ₀ and the second reference value Aω ₀ are fixedly determined in the above embodiment. For example, the vehicle speed U is detected, a three-dimensional graph of the vehicle speed U, the steering angle δ, and the reference value is stored as a map in the controller, and the detected vehicle speed U and steering angle δ are used as a three-dimensional graph. If a reference value corresponding to this is determined, since the reference value changes depending on the vehicle speed and the steering angle, it is possible to more accurately discriminate between wheelspin and turning.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the differential control device, and FIG. 2 is a control flowchart. 10...Differential control device, 12...Differential limiting mechanism, 14...Differential device, 16, 18, 20, 22
... Rotation speed detection means, 24 ... Rudder angle detection means, 2
6...controller, 28...operating means, 70...
...Current-controlled pressure reducing valve.

Claims (1)

[Claims for Utility Model Registration] (1) A device for controlling the differential of a differential device in a vehicle in which the front left and right wheels or the rear left and right wheels are driven by a differential device having a differential limiting mechanism. , a means for detecting the rotational speed of each of the left and right front wheels, a means for detecting the rotational speed of each of the rear left and right wheels, a means for detecting a steering angle, a controller that receives signals from each of the detection means, and means for operating a movement limiting mechanism, the controller calculates a rotational speed difference between the left and right wheels driven by the differential device, and sets the calculated rotational speed difference to a first reference value. is compared with a first reference value for determining whether one of the left and right wheels driven by the differential is in a wheel spin state, and the calculated rotational speed difference is determined by the first reference value. When the value exceeds a reference value, it is determined that the one wheel is in a wheel spin state, and the controller controls the operating means to start limiting the differential of the differential device, and the controller also controls the rotation speed difference between the front and rear wheels. At the same time, the calculated rotational speed difference between the front and rear wheels is used as a second reference value to determine whether or not one of the left and right wheels driven by the differential device is in a wheel spin state when driving straight. At the same time, the calculated rotation of the front and rear wheels is compared with a second reference value for determining whether or not both the left and right wheels driven by the differential device will be in a wheel spin state at the time of rotation. It is determined that the single wheel is not in a wheel spin state when the difference in number of rotations is less than the second reference value when driving straight, or when the calculated difference in the number of rotations between the front and rear wheels becomes larger than the second reference value when turning. A differential control device that determines that both wheels are in a wheel spin state and controls the operating means to release the differential restriction of the differential device. (2) The differential according to claim 1, wherein the first reference value and the second reference value are set based on at least one of vehicle speed and steering angle. Control device.