JPH0615301B2 - Vehicular differential limiting controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention provides a vehicle differential limiting control device that applies differential resistance force by external fluid pressure and performs differential limiting control according to a predetermined control condition. Regarding

(Prior Art) As a conventional differential device having a differential limiting mechanism, for example, “Volume of Automotive Engineering, Volume 9: Power Transmission Device” (1980
A device is known as shown in FIG. 5.32 on page 324 of Sankaidou Co., Ltd., Jan. 15, 2015.

In this conventional device, a multi-disc friction clutch provided between a differential case and a side gear is used as a differential limiting mechanism, and a differential resistance force is applied to the multi-disc friction clutch by a spring force as an initial engagement pressure. It was a torque proportional preload type differential limiting mechanism that applies a differential resistance force by the thrust force generated by the cam mechanism of the pinion mate shaft portion.

Incidentally, the differential limiting mechanism here means a mechanism that exerts a differential limiting function, and a device called a limited slip differential normally distinguishes both as a differential device having a built-in differential limiting mechanism. When simply described as a differential device (differential means), it refers to an ordinary differential device (conventional differential) having a limiting function.

(Problems to be Solved by the Invention) However, in such a conventional device, the transfer torque characteristic is uniquely determined by the differential resistance force due to the combination of the preload torque component and the torque proportional component. Therefore, during turning braking by engine brake,
If the transfer ratio (torque distribution ratio) is set to a large value so that the tack-in prevention effect can be obtained, when the left and right wheels rotate at different speeds, a larger driving torque is transmitted to the inner wheel side, which is the lower speed side, than the outer wheel, and The understeer tendency was strengthened in the initial stage, and the oversteer tendency was strengthened in the latter half of the turn due to the centrifugal centrifugal force to lift up the inner wheel side, resulting in so-called abrupt reverse steer, resulting in poor steering stability.

Therefore, in the conventional device in which the transfer ratio must be set uniquely, it is not possible to achieve both conflicting tack-in prevention and reverse steer prevention at the same time, and since the transfer ratio is generally set to a small value, there is a problem that the tack-in prevention effect is low. was there.

The tuck-in phenomenon means that the front and rear cornering forces Ff and Fr are changed from the balance state before that due to the load movement due to the vehicle deceleration and the tire ground contact characteristics, as shown in FIG. Is a phenomenon in which the moment ψ about the yaw axis that tends to turn the vehicle toward the center of turning is generated.
When the differential resistance is increased during turning braking to increase the braking torques Bo and Bi by the engine braking, the difference between the outer wheel side braking torque Bo and the inner wheel side braking torque Bi becomes large, and the moment M in the direction of canceling the moment ψ is increased. Although the occurrence of the tuck-in phenomenon can be prevented, when the differential resistance is increased during the turning drive, the driving torques Do and Di become larger than the outer-wheel side driving torque Do as the inner wheel side driving torque Di and the turning radius of curvature increases. Shows some understeer tendency.

(Means for Solving Problems) The present invention has been made for the purpose of solving the above-mentioned problems, and in order to achieve this object, the present invention provides the following solving means. .

The solution means of the present invention will be described with reference to the conceptual diagram of the claims shown in FIG. 1. The differential means 3 for distributing and transmitting the engine driving force to the left and right drive wheels 1 and 2 while allowing differential, and the differential means. 3, a differential limiting mechanism 4 for applying a differential resistance force by an external fluid pressure, and a fluid pressure generating means 6 having an actuator 5 for controlling a fluid pressure supply to the differential limiting mechanism 4. A differential limiting control device for a vehicle, comprising: a control unit 8 that outputs a control signal for imparting a differential resistance force to the actuator 5 when a signal indicating that differential limiting is required is input from the input sensor 7. As the input sensor 7, a deceleration sensor 701 that detects a vehicle deceleration is included. When a signal indicating deceleration is input from the deceleration sensor 701, control for increasing the differential resistance force according to the deceleration degree is performed. Control It was the stage 8.

(Operation) Therefore, in the vehicle differential limiting control device of the present invention, as described above, when the signal indicating the time of deceleration is input, the differential resistance force is increased according to the deceleration rate. During turning braking where vehicle deceleration occurs due to engine braking, etc., the differential resistance increases according to the degree of deceleration to prevent the tuck-in phenomenon. At the time of turning drive where no speed is generated, the differential resistance force is small or there is no differential resistance force, and the understeer tendency in the initial stage of turning can be suppressed.

(Examples) Hereinafter, examples of the present invention will be described in detail with reference to the drawings. In describing this embodiment, an automobile differential limiting control device equipped with a multi-plate friction clutch mechanism that is operated by an external hydraulic pressure will be taken as an example.

First, the configuration of the first embodiment will be described.

As shown in FIGS. 2 to 4, the embodiment apparatus includes a differential device (differential means) 10, a multi-plate friction clutch mechanism (differential limiting mechanism) 11, a hydraulic pressure generating device (fluid pressure generating means) 12. , A control unit (control means) 13 and an input sensor 14, each of which will be described below.

The differential device 10 has a differential function of providing a speed difference between the left and right wheels in accordance with the difference in rotation speed in a traveling state in which a difference in rotation speed occurs between the left and right wheels, and the engine driving force is applied to the left and right drive wheels. It is a device having a driving force distribution function that distributes and transmits the distribution.

The differential device 10 is housed in a housing 16 attached to a vehicle body by a stud bolt 15, and includes a ring gear 17, a differential case 18,
A pinion mate shaft 19, a differential pinion 20, and side gears 21 and 21 'are provided.

The differential case 18 includes a housing 16
On the other hand, it is rotatably supported by tapered roller bearings 22 and 22 '.

The ring gear 17 is a differential case 18
The drive pinion 24 is fixed to the drive pinion 24 and is engaged with the drive pinion 24 provided on the propeller shaft 23, and the rotational drive force is input from the drive pinion 24.

The left gear side drive shaft 25 and the right wheel side drive shaft 2 which are drive output shafts are provided on the side gears 21 and 21 '.
6 are provided for each.

The multi-disc friction clutch mechanism 11 is a mechanism that is provided between the drive input unit and the drive output unit of the differential device 10 and applies a differential resistance force by the clutch engagement force by the external hydraulic pressure.

The multi-plate friction clutch mechanism 11 is housed in the housing 16 and the differential case 18, and includes the multi-plate friction clutches 27 and 27 ', pressure rings 28 and 28', reaction plates 29 and 29 ', and thrust bearing 30. , 30 ', spacers 31, 31', push rod 32, hydraulic piston 33, oil chamber 34, and hydraulic port 35.

The multi-plate friction clutches 27, 27 'are fixed in the rotational direction by friction plates 27a, 27'a fixed in the differential case (drive input section) 18 in the rotational direction, and by side gears (drive output sections) 21, 21'. The friction disks 27b and 27'b are provided, and the pressure rings 28 and 28 'are provided on both end surfaces in the axial direction.
And reaction plates 29, 29 'are arranged.

The pressure rings 28, 28 'are provided in a fitted state on the pinion mate shaft 19 as a member for receiving a clutch fastening force, and the fitting portion has a rectangular cross section as shown in FIG. The end portion 19a is fitted with the square grooves 28a and 28'a so that the thrust force due to the rotation difference is not generated like the conventional torque proportional differential limiting mechanism.

The hydraulic piston 33 moves in the axial direction (to the right in the drawing) by the hydraulic pressure supplied to the hydraulic port 35 to engage both multi-plate friction clutches 27, 27 'in accordance with the hydraulic level. In the clutch 27, the fastening force is transmitted to the push rod 32 → the spacer 31 → the thrust bearing 30 → the reaction plate 29, and the pressure ring 2 is transmitted.
8 is fastened as a reaction force receiver, and the other multi-plate friction clutch 27 'is fastened by the fastening reaction force from the housing 16 as a fastening force.

The hydraulic pressure generator 12 is an external device that generates a hydraulic pressure that is a clutch engagement force, and includes a hydraulic pump 40, a pump motor 41, and
Pressure oil passage 42, check valve 43, first drain oil passage 4
4, a relief valve 45, a reserve tank 46, a second drain oil passage 47, a switching valve 48, a valve solenoid (actuator) 49, and a pressure switch 50.

The pump motor 41 is a motor that is activated / deactivated according to an energization signal (i) and an energization release signal (o) from the control unit 13 and is used when traveling and when limiting the differential or differential. When there is a possibility of limitation, the motor is in a rotating state according to the energization signal (i), and when there is no need for differential limitation such as when the vehicle is stopped, the energization release signal (o) is in the motor stopped state.

The pressure oil passage 42 is an oil passage that is connected to a pressure oil pipe 51 that supplies pressurized oil to the hydraulic pressure port 35, and an orifice 52 is provided in the middle to moderate the rise of hydraulic pressure.

The relief valve 45 is a valve that releases the pressurized oil flowing through the pressure oil passage 42 to the reserve tank 46 side for pressure adjustment when the pressure oil is equal to or higher than a predetermined pressure.

The switching valve 48 is a valve for switching between supplying pressurized oil to the hydraulic port 35 side and returning to the reserve tank 46, and the valve solenoid 49 receives a control signal (c) from the control unit 13 to operate. To do.

When the control signal (c) is the energizing signal, the electromagnetic force from the valve solenoid 49 is switched to the side overcoming the valve spring 53 and shutting off the second drain oil passage 47, and the pressurized oil is supplied to the hydraulic port 35. When the control signal (c) is a power interruption signal, the valve spring 53 switches to the side for communicating the second drain oil passage 47, and the pressurized oil is drained.

The pressure switch 50 checks the pressure level of the pressure oil passage 42, outputs a switch signal (s) to the control unit 13 when the pressure level is above a predetermined level, and an input sensor for performing feedback control for lowering the pressure level. Is.

The control unit 13 uses an in-vehicle microcomputer, and has an input circuit 131, a RAM (random access memory) 132, a ROM (read only memory) 133, a CPU (central processing unit) 134, a clock. The circuit 135 and the output circuit 136 are provided.

As the input sensor 14, the throttle opening sensor 14
1, a vehicle speed sensor 142 is provided.

The input circuit 131 is a circuit that converts the input signals (θ) and (v) from the input sensor 14 into digital signals that can be processed by the CPU 134.

The RAM 132 is a writable and readable memory, and is used for writing input signals from the sensors 141, 142, 143 and for writing information during calculation in the CPU 134.

The ROM 133 is a read-only memory,
Information necessary for the arithmetic processing in the CPU 134 is stored in advance and is read out from the CPU 134 as needed.

The CPU 134 is a device that performs arithmetic processing on various input information in accordance with predetermined processing conditions.

The clock circuit 135 is a circuit for setting the arithmetic processing time in the CPU 134.

The output circuit 136 is a circuit that outputs a control signal (c) based on a duty signal to the valve solenoid 49 that is an actuator based on a calculation result signal from the CPU 134.

The throttle opening sensor 141 is a sensor that detects a change in throttle opening due to an accelerator operation, and outputs a throttle opening signal (θ).

The vehicle speed sensor 142 is provided on the transmission output shaft or the like, and is a sensor that detects the rotation speed (proportional to the vehicle speed) of the transmission output shaft, and outputs a vehicle speed signal (v).

The throttle opening sensor 141 is used as a sensor that indirectly obtains the vehicle deceleration by obtaining the time differential value of the throttle opening θ.

Further, the vehicle speed sensor 142 is used as a sensor for obtaining the vehicle speed because the first embodiment apparatus sets the differential resistance setting on the two-dimensional map of the vehicle deceleration and the vehicle speed.

Next, the operation of the first embodiment will be described.

First, the operation of the first embodiment will be described with reference to the flowchart (FIG. 6) showing the operation flow of the differential limiting control.

First, the control operation is step 200 → step 201 →
This is done by proceeding from step 202 to step 203.

In step 200, the throttle opening sensor 141 and the vehicle speed sensor 142, which are the input sensors 14, read the throttle opening signal (θ) and the vehicle speed signal (v).

In step 201, the throttle opening θ is read according to the throttle opening signal (θ) read in step 200.
The differential value n of n is calculated.

The differential value n is calculated from the throttle opening degrees θ _n−1 and θn read at intervals of t seconds by the following arithmetic expression.

n = (θn−θ _n−1 ) / t In step 202, the vehicle speed Vn based on the vehicle speed signal (v) read in step 200 and step 20
Based on the throttle opening differential value n calculated in 1, the relationship between the throttle opening differential value θ and the vehicle speed V and the differential resistance F (command value) stored in advance in the ROM 133 of the control unit 13 is shown. Two-dimensional map (5th
The differential resistance force Fn (command value) is retrieved from the table) by table lookup.

In step 203, the control signal (c) having the duty ratio corresponding to the differential resistance Fn obtained in step 202 is output.

In the two-dimensional map shown in FIG. 5, the magnitude of the differential resistance force F (command value) is increased as the throttle opening differential value indicates a larger vehicle deceleration, and the vehicle speed V is increased. The higher the value, the larger the setting.

As described above, in the first embodiment, the differential resistance is increased according to the deceleration degree by the throttle opening differential value, so that the vehicle is decelerated during the turning braking when the vehicle deceleration is generated by the engine braking or the like. Tuck-in phenomenon can be prevented by increasing the differential resistance force depending on the degree, and the differential resistance force can be reduced when the vehicle deceleration is small even during turning, or when the vehicle is driven to turn without deceleration. Is small and there is no differential resistance, and it is possible to suppress the understeer tendency in the initial stage of turning.

Further, in the first embodiment, the differential resistance force F is set to increase in accordance with the increase of the vehicle speed V, so that the vehicle speed V that affects the occurrence of the tuck-in phenomenon can be dealt with and the differential speed F can be adjusted in the entire vehicle speed range. The tuck-in phenomenon can be prevented in an orderly manner.

Next, a second embodiment shown in FIGS. 7 and 8 will be described.

In the second embodiment, the vehicle speed sensor 142 is used as a sensor for detecting the vehicle deceleration, and the differential resistance force F is increased according to the deceleration degree by the vehicle speed differential value which is the time differential value of the vehicle speed V. Is.

The configuration of the second embodiment is different only in that the throttle opening sensor 141 of the input sensor 14 in the first embodiment is omitted and that the control unit 13 having slightly different stored information and processing is used. Unlike the first embodiment, the other structure is the same as that of the first embodiment, and therefore illustration and description thereof are omitted.

Here, FIG. 7 is a map showing the relationship between the vehicle speed differential value and the differential resistance force F (command value) stored in advance in the ROM 133 of the control unit 13 of the second embodiment device, and FIG. It is a flowchart figure which shows the flow of control operation | movement in the control unit 13 of 2nd Example.

The control operation in the second embodiment is performed in step 204 →
This is done by proceeding from step 205 → step 206 → step 207.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and the present invention can be applied even if there is a design change or the like within a range not departing from the gist of the present invention. included.

For example, in the embodiments, the throttle opening sensor and the vehicle speed sensor that indirectly detect the vehicle deceleration are shown as the deceleration sensor, but a wheel speed sensor or the like may be used as the sensor that indirectly detects the vehicle deceleration. Alternatively, a vehicle front-rear G sensor may be used as a sensor for directly detecting.

(Effects of the Invention) As described above, in the vehicle differential limiting control device of the present invention, when the signal indicating deceleration is input, the differential resistance is increased according to the deceleration rate. During turning braking where vehicle deceleration occurs due to brakes, etc., the tack resistance can be prevented by increasing the differential resistance force depending on the deceleration rate. When the vehicle is driven without turning, the differential resistance is small or there is no differential resistance, the understeer tendency at the beginning of turning can be suppressed, and it is possible to achieve both tack-in prevention and understeer prevention. .

[Brief description of drawings]

FIG. 1 is a conceptual view of a claim showing a vehicular differential limiting control device of the present invention, FIG. 2 is a sectional view showing a differential device portion of a first embodiment device of the present invention, and FIG. 3 is a Z direction of FIG. FIG. 4 is a view showing an oil pressure generating device and a control device of the first embodiment device,
FIG. 5 is a two-dimensional map showing the relationship between the differential value of the throttle opening and the vehicle speed and the differential resistance force stored in advance in the control unit of the first embodiment device, and FIG. 6 is the difference of the first embodiment device. FIG. 7 is a flow chart showing the flow of the motion limiting control operation, FIG. 7 is a map showing the relationship between the vehicle speed differential value and the differential resistance force stored in advance in the control unit of the second embodiment device, and FIG. FIG. 9 is a flowchart showing the flow of the differential limiting control operation of the embodiment apparatus, and FIG. 9 is an explanatory diagram for explaining the tuck-in phenomenon. 1 ... drive left wheel 2 ... drive right wheel 3 ... differential means 4 ... differential limiting mechanism 5 ... actuator 6 ... fluid pressure generating means 7 ... input sensor 701 ... deceleration sensor 8 ... control means

Claims (2)

[Claims] Claim: What is claimed is: 1. A differential means for distributing and transmitting the engine driving force to the left and right driving wheels while allowing differential, and a differential provided on the differential means for imparting a differential resistance force by an external fluid pressure. A fluid pressure generating means having a motion limiting mechanism, an actuator for controlling fluid pressure supply to the differential limiting mechanism, and a control for applying a differential resistance force when a signal indicating the time when differential limiting is required is input from an input sensor. A control means for outputting a signal to the actuator, comprising: a deceleration sensor for detecting a vehicle deceleration as the input sensor; A differential limiting control device for a vehicle, which is control means for performing control to increase the differential resistance force in accordance with the deceleration degree when a signal indicating is input. 2. The control means for increasing the differential resistance force according to the degree of deceleration and for increasing the differential resistance force as the vehicle speed increases, according to claim 1. Differential limiting control device for vehicle.