JP2578006B2 - Automotive differential limit controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an automobile in which the function of a differential mechanism incorporated in a drive system of the automobile is restricted to improve escape performance on rough roads or rough terrain. And a control device of the differential limiting mechanism.

<Prior Art> When one driving wheel of an automobile fits on a low friction road surface such as a muddy road or a snowy road, the ground resistance (transmitted torque) of the driving wheel becomes small. Then, only a similar small torque can be transmitted to the opposite drive wheel by the differential action by the differential mechanism, so that the drive torque of the entire vehicle is reduced and escape becomes difficult.

In order to solve such a problem, a clutch mechanism is provided inside the differential mechanism, and various types of operation limiting devices that prevent a decrease in driving torque by operating the clutch mechanism have been proposed and put into practical use. Has been

In other words, in the conventional differential limiter, for example, pages 1-31 to 1-32 of the 5th edition of "Automotive Engineering Handbook" (Nov.
On March 26, issued by the Society of Automotive Engineers of Japan), etc., torque proportional differential limiting device, preload differential limiting device, torque proportional preload differential limiting device, mechanical By incorporating a differential limiting device or a ZF differential lock mechanism, it was possible to prevent the steering wheel from being taken off by one wheel slip and to improve the escape performance from low friction road surfaces.

<Problems to be Solved by the Invention> However, in the conventional differential limiting device, since the differential function is not limited unless the rotational difference between the left and right drive wheels is sufficiently high, the low friction road surface The problem is that the differential function cannot be limited in advance when it is predicted that the vehicle will enter the vehicle, or that the differential limiting mechanism cannot be activated during straight running to increase the straight running stability of the vehicle. There was a point.

In order to solve such a problem, there is also a device in which the differential limiting mechanism can be artificially turned on and off. The grip force of the wheel becomes so small that it causes a so-called swinging phenomenon. In particular, if one of the drive wheels slips during turning and the differential limiting mechanism is activated, the steering characteristics are accordingly increased. May change in the understeer direction to make it difficult to turn, or the left and right drive wheels may slip and spin.

The present invention has been made to solve such a conventional problem, and it is necessary to limit the differential function, or to rotate when it is more convenient to perform the differential limiting function. By exerting a differential limiting function based on an external signal such as an output signal of a sensor, it is possible to improve running stability when traveling straight without reducing the escape performance on a low friction road surface, Moreover, it is an object of the present invention to provide a differential limiting device for an automobile which can secure stability during turning.

<Means for Solving the Problems> In order to achieve the above object, according to the present invention, in a vehicle including a differential limiting mechanism and an actuator for controlling the differential limiting force of the differential limiting mechanism to increase or decrease, the steering angle is reduced. A steering angle sensor for outputting a response signal, a vehicle speed sensor for outputting a signal in response to the vehicle speed, and a rotation sensor for detecting a rotation difference between the left and right driving wheels and a rotation difference between the front and rear wheels are provided according to the vehicle speed and the steering angle. Storage means for storing in advance a signal corresponding to the optimum differential limiting force.
The control means for supplying a signal read from the storage means to the actuator as a control signal; and the storage means when it detects that only one of the right and left drive wheels has slipped based on the output of the rotation sensor. A correction means is provided for gradually increasing and correcting the signal read from the controller and supplying the corrected signal to the control means. When the steering angle detected based on the output of the steering angle sensor is larger than a predetermined value and when it is detected that both the left and right drive wheels have slipped based on the output of the rotation sensor, a release signal is sent to the actuator. A release limiting means is provided to constitute a differential limiting control device for an automobile.

<Operation> With such a configuration, when the rotation difference between the left and right driving wheels is smaller than a predetermined value, it is determined that the vehicle is in a normal running state without slip, and the signal read from the storage unit is used as it is. Is supplied to the actuator as a control signal. Therefore, in this case, the optimum limiting force according to the vehicle speed and the steering angle at that time is obtained, so that the steering characteristics of the vehicle are secured.

On the other hand, when the rotation difference between the left and right drive wheels becomes larger than a predetermined value, that is, when it is detected that one of the drive wheels has slipped, the correction means functions based on the output of the rotation sensor. Then, since the signal read from the storage means and supplied to the actuator is gradually increased and corrected, the differential limiting force of the differential limiting mechanism is gradually increased, and the rotational difference between the left and right driving wheels is reduced. Decrease gradually. Therefore, the rotation difference between the left and right driving wheels is eliminated, and the escape performance is improved. However, even if one of the drive wheels is slipping, if the steering angle is larger than the predetermined value, the release means operates to return the operation limiting mechanism to the inoperative state. Changing and avoiding slippage of the drive wheels on both sides are avoided, so that turning stability is guaranteed. When the correction means stops along with the elimination of the slip, the degree of the increase correction of the signal read from the storage means gradually decreases, and the differential limiting force is reduced to a standard value determined by the vehicle speed and the steering angle at that time. Will be returned.

Further, when the rotation difference between the front and rear wheels becomes larger than a predetermined value, that is, when both the left and right driving wheels are slipping, the grip force in the lateral direction becomes extremely small, which is dangerous. However, when both the left and right drive wheels slip, the release signal of the actuator is supplied based on the output of the rotation sensor, so that the differential limiting mechanism does not function at all. Then, even if one of the driving wheels slips, the other driving wheel does not slip, so that the grip force in the lateral direction is not lost, and safety is ensured. If both the left and right drive wheels slip, the driver's vehicle may be notified (warned).

<Example> Hereinafter, an example of the present invention will be described in detail.

FIG. 1 is a schematic configuration diagram showing an embodiment of a differential limiting control device for an automobile according to the present invention. A pair of left and right side gears 3 are axially mounted on a differential case 2 accommodated in a Teff carrier 1 and fixed to the differential case 2. By pinning the pinion 5 to the spider 4, the two side gears 3 are linked via the pinion 5. Reference numeral 6 denotes a ring gear fixed to the differential case 2, and reference numeral 7 denotes a drive pinion for driving the ring gear 6. Driving wheels are respectively connected to tips of an axle shaft (not shown) spline-fitted to the side gear 3. The configuration of such a differential mechanism is substantially the same as the conventional one.

A sleeve 8 spline-fitted to a drive shaft (not shown) is provided together with the side gear 3 located on the right side in the drawing, of the pair of left and right side gears 3, and is fitted to the differential case 2 so as to be movable in the axial direction. A plurality of friction disks engaged with and held in the sleeve 8 so as to be movable only in the axial direction, and the differential case 2
A plurality of friction plates engaged and held so as to be movable only in the axial direction are alternately overlapped and sandwiched between the left side surface of the pressure plate 9 and the clutch surface formed in the differential case 2 so as to sandwich the pressure plate. When the pressure of the chamber 10 formed between the right side surface of the differential case 9 and the differential case 2 is increased or decreased to bring the pressure plate 9 into or out of contact with the clutch surface, the relative rotation between the right side gear 3 and the differential case 2 in the drawing is increased. It constitutes a friction clutch mechanism that is restricted or allowed.

Also, an air passage from the air tank 11 to the chamber 10
An air supply valve 13 is interposed in the air passage 12, and the air passage 12 and the atmosphere are connected via an exhaust valve 14.The air supply valve 13 and the exhaust valve 14 are respectively opened and closed based on the output of a controller 15. By doing so, the chamber 10 is
And the atmosphere so that the internal pressure can be increased or decreased.

The controller 15 is connected with rotation sensors 16 that output signals corresponding to the rotation speeds of the left and right front wheels and the left and right rear wheels (drive wheels), for example, based on the rotation difference between the left and right front wheels. The steering angle is determined, and the vehicle speed is calculated based on the average rotational speed of the left and right front wheels.
Further, the controller 15 determines whether one of the drive wheels is slipping based on the rotational speed of the left and right rear wheels (drive wheels), and furthermore, based on the rotational difference between the front and rear wheels, Are slipping together. Further, while supplying output signals of the brake sensor 17 and the manual switch 18 to the controller 15 and providing storage means (not shown), correction means, release means, and control means (not shown), the rotation sensor 16, the brake sensor 17, the manual switch 18
By changing the time ratio (duty) of the ON of the pulse (control) signal supplied to the supply valve 13 and the exhaust valve 14 based on the output of the supply valve 13 and the exhaust valve 14, the opening of the supply valve 13 and the exhaust valve 14 The degree is variably controlled.

Incidentally, a signal corresponding to the optimum differential limiting force according to the vehicle speed and the steering angle is stored in advance in the storage means, and the signal read from the storage means is supplied to the control means via the correction means. ing. Here, the control means variably controls the control signals (pulse signals) supplied to the air supply valve 13 and the exhaust valve 14 in accordance with the supplied signals, and the correction means is read from the storage means and transmitted to the control means. It has a function to gradually increase the supplied signal as needed, or to gradually reduce the degree of increase correction. The release means is read from the storage means when detecting that the steering angle is larger than a predetermined value based on the output of the rotation sensor 16 and when determining that both the left and right drive wheels are slipping. A non-operation signal (a signal with zero duty) is output from the control means regardless of the magnitude of the signal.

In the vehicle differential limiting control device configured as described above, when the vehicle is used for traveling, the vehicle speed and the steering angle at that time are detected (calculated) based on the output of the rotation sensor 16, and the vehicle speed and the steering angle are detected. Is read out from the storage means. When the rotation difference between the left and right driving wheels (rear wheels) is smaller than a predetermined value, that is, when the vehicle is being used for normal traveling, the signal read from the storage unit is supplied to the control unit as it is. Therefore, a control signal responsive to this signal is supplied to the supply valve 13 and the exhaust valve 14. Therefore, during such normal traveling, the differential limiting force is optimally controlled in accordance with the vehicle speed and the steering angle, so that high-speed straightness and the like can be secured without impairing the turning performance of the automobile.

On the other hand, when one of the right and left driving wheels slips, the correction means functions to gradually increase and correct the signal supplied from the storage means to the control means. Then, based on this, the opening of the air supply valve 13 is increased and corrected, so that the air tank 11
, The pressure of the air supplied to the chamber 10 increases. Accordingly, the pressing force of the pressure plate 9 is increased, and the coupling force of the friction clutch mechanism is increased to increase the differential limiting force. Therefore, the slip of the drive wheels is suppressed, and the escape performance is enhanced.

However, when the steering angle detected based on the output of the rotation sensor 16 is larger than a predetermined value, the release means operates and the control means outputs a non-operation signal (duty zero signal). Since the exhaust valve 14 is kept open while the valve is kept closed, the internal pressure of the chamber 10 is returned to the atmospheric pressure. Therefore, at the time of such a turn, the differential limiting mechanism does not function, and a change in the steering characteristic during the turn is prevented, or a slip of the drive wheels on both sides is prevented. When the driving wheels no longer slip, the degree of correction by the correction means gradually decreases, and the differential limiting force returns to the optimum value corresponding to the vehicle speed and the steering angle at that time, so that a shock or the like may occur. Nor.

Further, when it is detected that both the left and right drive wheels are slipping, the release means functions and the air supply valve 13
Is closed and the exhaust valve 14 is opened at the same time. Then, in this state, since the internal pressure of the chamber 10 is maintained at the same level as the atmospheric pressure, the pressing action by the pressure plate 9 is not performed, and the sleeve 8 and the side gear 3 rotate freely with respect to the differential case 2. Since the drive wheels do not slip, the lateral grip force is not impaired.

When the brake is actuated, the release means functions based on the output of the brake sensor 17, and when the manual switch 18 is turned on, the correction means automatically functions if the vehicle speed falls below a predetermined value. Maximize the dynamic limiting force.

In the above embodiment, a friction clutch mechanism is interposed between one side gear 3 and the differential case 2, and the clutch mechanism is controlled by the pressure of air to increase or decrease the differential limiting force. A similar clutch mechanism can be interposed between the side gear and the differential case to reduce the load on the clutch mechanism. Although air is used as the working fluid in the embodiment, the chamber 10 can be downsized by using hydraulic pressure. Further, in the embodiment, the steering angle is detected based on the rotation difference between the front left and right wheels, and the vehicle speed is detected based on the average rotation speed of the front left and right wheels. The configuration is not limited to the embodiment.

<Effects of the Invention> As described above, according to the present invention, since the differential limiting force is increased or decreased in accordance with the vehicle speed and the steering angle, the vehicle normally does not need any special operation. The steering characteristics of the vehicle can be improved. In addition, when the vehicle turns with the steering angle larger than the predetermined value and when both the left and right drive wheels slip, the differential limiting function is released. Therefore, there is no possibility of causing slip of the drive wheels, and safety during turning can be ensured. In addition, simultaneous slippage of both drive wheels, which reduces the lateral grip force, is safe.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a differential limiting control device for an automobile according to the present invention. 1 ... differential carrier 2 ... differential case 3 ... side gear 4 ... spider 5 ... pinion 6 ... ring gear 7 ... drive pinion 8 ... sleeve 9 ... pressure plate 10 ... chamber 11 ... Air tank, 12 ... Air passage 13 ... Air supply valve, 14 ... Exhaust valve 15 ... Controller, 16 ... Rotation sensor 17 ... Brake sensor, 18 ... Manual switch

Claims (1)

(57) [Claims] 1. A vehicle equipped with a differential limiting mechanism and an actuator for controlling the differential limiting force of the differential limiting mechanism to increase or decrease the differential limiting force, a steering angle sensor outputting a signal responsive to a steering angle, and a steering angle sensor responding to a vehicle speed. A vehicle speed sensor that outputs a signal, a rotation sensor that detects a rotation difference between left and right driving wheels and a rotation difference between front and rear wheels, and a signal corresponding to an optimal differential limiting force according to the vehicle speed and the steering angle are stored in advance. A storage unit, a control unit that supplies a signal read from the storage unit to the actuator as a control signal, and a control unit that detects when only one of the right and left drive wheels has slipped based on an output of the rotation sensor. Correction means for gradually increasing and correcting the signal read from the storage means and supplying it to the control means; and a steering angle detected based on an output of the steering angle sensor being larger than a predetermined value. Automotive differential limiting control apparatus comprising a releasing means for supplying a release signal to the actuator when it is detected that the left and right drive wheels based on the output of the rotation sensor as well come slips together.