JP2722150B2 - Control device for differential limiting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a differential limiting device mounted on a vehicle, and more particularly, to steering stability (straight running stability) by appropriately performing differential limiting even in middle and high vehicle speed ranges. The present invention relates to a control device for a differential limiting device that obtains the following.

[0002]

2. Description of the Related Art A differential limiting device used for improving an escape from a rough road or the like can also be used for improving the steering stability at the time of high-speed running on a general road. Therefore, Japanese Unexamined Patent Application Publication No.
In Japanese Patent Application Laid-Open No. 9, the differential limiting force of the differential limiting device is controlled in accordance with the vehicle speed. However, the differential limiting force of the differential limiting device and the friction coefficient of the traveling road surface are irrelevant.

[0003]

Even when traveling on a snowy road, the differential limiting force of the differential limiting device is increased in a high vehicle speed range,
Steering stability can be obtained, but on snowy roads as low-friction roads, it is necessary to prioritize escape from rough roads rather than steering stability. The vehicle speed at which the increase starts must be higher than when traveling on a general road. In Japanese Patent Application Laid-Open No. 61-67629, the differential limiting force of the differential limiter is determined regardless of whether the vehicle is traveling on a general road or on a snowy road. When the differential limiting force of the device is adjusted, there is a problem that the other becomes inappropriate.

In view of the above, the present applicant has filed a patent application filed on June 12, 1991 with a general road map designating a differential limiting force suitable for driving on general roads and a road map suitable for driving on snowy roads. Prepare two types of maps, a snowy road map specifying the differential limiting force, and detect whether the vehicle is running on a general road or in a snowy road mode from the slip ratio and the like. A control device of the differential limiter that selects automatically is proposed.

On the other hand, when the foot brake is depressed, it is necessary to release the differential limit of the differential limiter. In a general road map designating the differential limit force of the differential limiter when driving on a general road. When the differential limiting force is set so that the differential limiting is also performed by the differential limiting device even in a low vehicle speed range,
In response to frequent activation and deactivation of the foot brake in a low vehicle speed range when driving on a general road, the differential limiting force of the differential limiting device frequently fluctuates between zero and a set value on a general road map. In a general control device of a differential limiting device, the differential limiting force is controlled through control of the air pressure of the differential limiting device by an electromagnetic switching valve. The switching frequency of the electromagnetic switching valve is increased to make the control unstable.

Further, automatic switching between the general road map and the snow road map is performed based on the detection of a slip ratio and the like.
When a vehicle moves from a general road to a snowy road, it will actually switch to the snowy road, change the slip rate, etc., and switch to the snowy road map. The control of the differential limiting force of the differential limiting device is performed on the basis of the above, which is inappropriate.

An object of the present invention is to provide a control device for a differential limiting device capable of improving the stability of control in a low vehicle speed range when traveling on a general road. Claim 2
SUMMARY OF THE INVENTION It is an object of the present invention to provide a control device of a differential limiting device capable of quickly switching to a snow road map when a vehicle moves from a general road to a snow road.

[0008]

The present invention will be described with reference to the drawings corresponding to the embodiments. In the differential limiting device (10) which is the premise of claim 1, the differential limiting force is adjustable, and the differential limit is released when the foot brake is operated. The control device (1) of the differential limiting device (10) of claim 1
2) is based on the general road map (76) and the general road map (76) that specifies zero differential limiting force in low vehicle speed ranges and specifies differential limiting force suitable for driving on ordinary roads in middle and high vehicle speed ranges. And control means (50) for controlling the differential limiting force of the differential limiting device (10).

In the differential limiting device (10) based on the premise of claim 2, the differential limiting force is adjustable. The control device (12) of the differential limiting device (10) according to the second aspect includes a general road map (76) designating a differential limiting force suitable for traveling on a general road, and a general road map (76) for driving on a snowy road. Snow road map (78) specifying suitable differential limiting force
Mode switching that switches between an automatic mode (90) in which a general road map (76) and a snow road map (78) are automatically switched and a snow road mode (92) in which only the snow road map (78) is selected. means
(94) and the differential limiting force of the differential limiting device (10) based on the general road map (76) or the snow road map (78) selected according to the mode switched by the mode switching means (94). And control means (50) for controlling.

[0010]

In the control device (12) of the differential limiting device (10) according to the first aspect, the control means (50) reduces the differential limiting force of the differential limiting device (10) based on the general road map (76). Control. In the low vehicle speed range, the differential limiting force of the differential limiting device (10) is zero, that is, the differential limiting by the differential limiting device (10) is in the released state.

The control device (1) for the differential limiting device (10) according to claim 2 is provided.
In 2), the driver operates the mode switching means (94) to switch between the automatic mode (90) and the snowy road mode (92).
When the automatic mode (90) is selected, it is automatically determined whether the vehicle is traveling on a general road or a snowy road from detection data such as a slip ratio,
The general road map (76) or the snow road map (78) is selected based on the discrimination result, and the control means (50) is based on the selected one of the general road map (76) and the snow road map (78). The differential limiting force of the differential limiting device (10) is controlled. When the snow road mode (92) is selected, the control means (50) controls the differential limiting force of the differential limiting device (10) based on the snow road map (78).

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 4 is a configuration diagram of the differential limiting device 10 and the control device 12 thereof. In the differential limiting device 10, the input shaft 14 extends in the front-rear direction of the vehicle, is rotatably supported by the carrier case 16, and has a pinion 18 at the tip. Drive shaft 20a, 20b
Are horizontally protruded from the left and right sides of the carrier case 16 in the left-right direction of the vehicle, and drive wheels (not shown)
The differential case 22 surrounds the ends of the drive shafts 20a and 20b. The ring gear 24 rotates integrally with the differential case 22 and meshes with the pinion 18. Spider 26
It penetrates between the ends of the drive shafts 20a and 20b, is fixed to the differential case 22 at both ends, and rotates integrally with the differential case 22. The pinions 28a, 28b are rotatably supported by the spider 26, and the side gears 30a, 30b are spline-fitted to the ends of the drive shafts 20a, 20b, respectively, and are simultaneously engaged with the pinions 28a, 28b. The multi-plate clutch 32 controls connection between the differential case 22 and a sleeve 34 that is spline-fitted to the drive shaft 20b on the inner peripheral side, and includes a cylinder 36 that slidably accommodates a piston 38 therein. By the supply of pressurized air into the cylinder 36, the pressing force of the piston 38 increases, and the engaging force of the multi-plate clutch 32 increases. Multi-plate clutch
As the engagement force of 32 increases, the rotational speed of drive shaft 20b approaches the rotational speed of ring gear 24, and the differential limiting force of differential limiting device 10 increases. The air pipe 40 is connected to the joint ring 42
, And extends inside the carrier case 16.

In the control device 12, the first electromagnetic switching valve 44
Controls the connection between the air tank 46 for storing pressurized air and the air pipe 40, and the second electromagnetic switching valve 48 controls discharge of pressurized air from the air pipe 40. The CPU 50 includes a pressure sensor 52 that detects a pressure in the cylinder 36 of the multi-plate clutch 32,
Based on detection data from a vehicle speed sensor 54 for detecting the vehicle speed, a wheel speed sensor 56 for detecting the rotational speed of the driving wheels, and a brake sensor 58 for detecting the operation and non-operation of a foot brake (not shown), Electromagnetic switching valve 44 and the second
The control signal is sent to the electromagnetic switching valve 48. First electromagnetic switching valve 44
When the second electromagnetic switching valve 48 is opened and closed, the pressurized air in the air tank 46 is introduced into the cylinder 36 of the multi-plate clutch 32, and the differential limiting force of the differential limiting device 10 increases. . When the first electromagnetic switching valve 44 and the second electromagnetic switching valve 48 are closed and open, respectively, pressurized air is discharged from the cylinder 36 of the multi-plate clutch 32 and the differential limiting force of the differential limiting device 10 is reduced. Decrease.

FIG. 1 shows a vehicle speed and a differential limiting device specified in a general road map 76 and a snow road map 78 as an example.
9 is a graph showing a relationship between the differential limiting force of No. 10 and the differential limiting force. In the general road map 76, the differential limiting force is 0 to 30 corresponding to the low vehicle speed range.
As it becomes zero at km / h, it rises to a predetermined value at 30 km / h and falls within the middle vehicle speed range from 30 to 70 km / h.
In the range of 70 km / h or more, which corresponds to a high vehicle speed range, the vehicle is in a complete, that is, 100% differential limiting state. On the other hand, in the snowy road map 78, the differential limiting force of the differential limiting device 10 is used in order to secure the escape of the vehicle from the rough road, in the range of 0 to 70km / h, which is a low / medium vehicle speed range. It is held at the value at 30 km / h on the map 76 and 70
In the high vehicle speed range of ~ 140km / h, it is 100 from the value of 70km / h.
It is specified to increase gradually to%. Note that the above numerical values are merely examples, and the present invention is not limited thereto. The above numerical values can be arbitrarily changed depending on the vehicle or as needed.

FIG. 3 is a flowchart of the control of the differential limiter 10. In step 60, failure diagnosis and failure display are performed, and subsequently, in step 62, operation display is performed. In step 64, the wheel speed, the steering angle, and the vehicle speed are input, and based on these, in step 66, the slip ratio for each drive wheel is calculated. The slip ratio at the time of starting is stored in step 68 and learned in step 74. In step 72, it is determined whether the slip occurs on both wheels or only one wheel, and if it is a two-wheel slip, the air pressure is reduced in step 82 to reduce the differential limiting force of the differential limiting device 10. If it is a one-wheel slip, the air pressure is increased in step 84 to increase the differential limiting force of the differential limiting device 10. In step 72, it is determined whether the mode is the automatic mode or the snowy road mode. If the mode is the automatic mode, it is determined whether the vehicle is running on a general road or a snowy road based on the learning result in step 74, and the general mode is determined based on the determination result. The road map 76 or the snow road map 78 is automatically selected. In step 80, the air pressure P of the cylinder 36 of the multi-plate clutch 32 detected by the pressure sensor 52 (FIG. 4),
The air pressure P0 calculated based on the general road map 76 or the snowy road map 78 is compared. When P> P0, the air pressure in the cylinder 36 is reduced in step 82, and when P <P0, step 84 is performed. , The air pressure in the cylinder 36 is increased,
When = P0, the air pressure in the cylinder 36 is maintained.

FIG. 2 is a control block diagram of the control device 12. The CPU 50 controls the differential limiting force of the differential limiting device 10 through opening and closing of the first electromagnetic switching valve 44 and the second electromagnetic switching valve 48. The mode switching means 94 is operated by the driver to select one of the automatic mode 90 and the snowy road mode 92. CPU
50, further, various detection data such as vehicle speed, foot brake operation state, etc. are input, and when the automatic mode 90 is selected, whether the vehicle is traveling on a general road or a snowy road is detected from the slip ratio and the like, and The first electromagnetic switching valve 44 and the second electromagnetic switching valve 48 are controlled so that the differential limiting device 10 becomes the differential limiting force based on the general road map 76 and the snow road map 78, and the snow road mode 92 is set. If it is selected, the first electromagnetic switching valve 44 and the second electromagnetic switching valve 48 are controlled so that the differential limiting device 10 becomes the differential limiting force based on the snowy road map 78. In the general road map 76, the differential limiting force of the differential limiting device 10 in the low vehicle speed range is designated as zero as shown in FIG. Since the force is released, the first electromagnetic switching valve 44 and the second electromagnetic switching valve 48 are maintained closed and open, respectively, regardless of whether the foot brake is operated or not, and Frequent switching of the switching valve 44 and the second electromagnetic switching valve 48 is prevented. Also, when the vehicle moves from a general road to a snowy road, the driver operates the mode switching means 94 simultaneously with the shift to switch to the snowy road mode 92. As a result, the differential limiting force of the differential limiting device 10 becomes appropriate.

[0017]

According to the first aspect of the present invention, the general road map is
The differential limiting force of the differential limiter in the low vehicle speed range is specified as zero, which is the same as the release of the restriction on the operation of the differential limiter. With respect to the operation and non-operation of the foot brake, the fluctuation of the differential limiting force of the differential limiting device is suppressed, and the stability of the control can be obtained.

According to the second aspect of the present invention, the mode can be switched between the automatic mode and the snowy road mode by operating the mode switching means according to the driver's judgment. By switching to the snowy road mode almost simultaneously, the differential limiting force of the differential limiting device can be controlled based on the snowy road map from the beginning of running on the snowy road.

[Brief description of the drawings]

FIG. 1 is a graph showing, as an example, a relationship between a vehicle speed specified in a general road map and a snow road map and a differential limiting force of a differential limiting device.

FIG. 2 is a control block diagram of a control device.

FIG. 3 is a flowchart of control of the differential limiting device.

FIG. 4 is a configuration diagram of a differential limiting device and a control device thereof.

[Explanation of symbols]

 Reference Signs List 10 differential limiting device 12 control device 50 CPU (control means) 76 general road map 78 snow road map 90 automatic mode 82 snow road mode 94 mode switching means

Claims (2)

(57) [Claims] A differential limiting device in which a differential limiting force is adjustable and a differential limit is released when a foot brake is operated.
In (10), in the low vehicle speed range, the differential limiting force is set to zero, and in the middle and high vehicle speed range, the general road map (76) that specifies the differential limiting force suitable for traveling on general roads, and the general road map (76) Control means (5) for controlling the differential limiting force of the differential limiting device (10) based on the
0). A control device for a differential limiting device, comprising: 2. A differential limiting device (10) having an adjustable differential limiting force, comprising: a general road map (76) designating a differential limiting force suitable for traveling on a general road; An automatic mode (90) in which the snowy road map (78) specifying the differential limiting force suitable for running, the general road map (76) and the snowy road map (78) are automatically switched, and Mode switching means (9) for switching between the snow road mode (92) where only the snow road map (78) is selected.
4) and the differential limiting of the differential limiting device (10) based on the general road map (76) or the snow road map (78) selected according to the mode switched by the mode switching means (94). A control device for a differential limiting device, comprising: control means (50) for controlling a force.