JP2861573B2 - Vehicle drive wheel switching control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive wheel switching control method for a vehicle such as a tractor or a specially equipped vehicle, the drive wheels of which can be switched to all wheels or only rear wheels.

[0002]

2. Description of the Related Art For example, some large semi-trailer tractors have two rear wheels on the left and right sides and can transmit driving force from an engine to each of a front wheel and a rear wheel via a transfer. , This type of transfer
It has a built-in precursor clutch that interrupts transmission of driving force to the front wheels. Therefore, in this type of tractor, when the precursor clutch is switched on,
The driving force from the engine is transmitted to all the front and rear wheels, and all the wheels become driving wheels. On the other hand, when the precursor clutch is switched off, the driving force from the engine is transmitted only to the rear wheels. As a result, the front wheels become driven wheels.

In recent years, this kind of tractor has been equipped with an anti-skid brake system, which can prevent the skid of each wheel during braking and perform the braking safely. The distance can be shortened. However, in a tractor of the type described above, if all the wheels are running as drive wheels, the vehicle speed cannot be accurately calculated, so that anti-skid brake control cannot be performed stably. For this reason, in this type of tractor, when the anti-skid brake control is started, the above-described precursor clutch is automatically turned off, and the front wheel is set as a driven wheel. Based on the calculated vehicle speed, the anti-skid brake control is performed stably, that is, the brake pressure of each wheel is optimally controlled.

[0004]

By the way, in the tractor described above, when the anti-skid brake control ends, the precursor clutch is switched back to the original state, that is, automatically turned on again. When the driver depresses the accelerator pedal to accelerate rapidly, the speed deviation between the rear wheel speed and the front wheel speed becomes large. Such a speed deviation is seen on the front wheel side and the rear wheel side,
Since a large relative speed difference is generated before and after the pre-clutch, there is a problem that the on-operation of the pre-clutch, specifically, the engagement of the dog gear in the pre-clutch is not performed smoothly.

The present invention has been made in view of the above-mentioned circumstances, and has as its object to change the driving wheels of a vehicle so that the on-return of the precursor clutch can be smoothly performed after the end of the anti-skid brake control. It is to provide a control method.

[0006]

According to the present invention, in a vehicle of the type described above, a method for controlling driving wheel switching of a vehicle according to the present invention comprises the steps of providing a speed deviation between a wheel speed of a rear wheel and a wheel speed of a front wheel. If the speed deviation is larger than a predetermined value, engine output control is performed to reduce the engine output so that the speed deviation falls within the predetermined value.
Under execution of the engine output control, when the anti-skid brake control is started, the precursor clutch is switched off to make the front wheel the driven wheel, and thereafter, when the anti-skid brake control ends, the precursor clutch is switched on. the switching control of the clutch are the real Hodokosuru so.

[0007]

According to the vehicle drive wheel switching control method described above, since the engine output control is always performed, the speed deviation between the front wheels and the rear wheels is kept within a range smaller than a predetermined value. . Therefore, in such a situation, by starting the front wheel and the anti-skid brake control, the precursor clutch is switched off, and when the anti-skid brake control ends, the precursor clutch is switched from off to on. However, since the speed difference between before and after the precursor clutch is within a predetermined range, switching of the precursor clutch from off to on is performed smoothly.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a large semi-trailer tractor is schematically shown, comprising a front axle 1, front and rear rear axles, ie, a front rear axle 2 and a rear rear axle 3.
And Front wheels FW are mounted on the left and right sides of the front axle 1, and rear wheels RW are also mounted on the left and right sides of the rear axles 2 and 3, respectively. Each rear wheel RW is a double wheel.

The driving force from the engine 4 of the tractor is transmitted through the transmission clutch 5, transmission 6, first propeller shaft 7, transfer 8, second propeller shaft 9, center differential, so-called inter differential 10, third propeller shaft 11, and rear axle differential 12. The driving force is transmitted to the rear axle 3 via the inter differential 10 to the inner rear axle 2. INTERDEF 10
Has a built-in differential lock that stops the function as needed.

Further, between the transfer 8 and the front axle differential 13, a fourth propeller shaft 14 and a fifth
The driving force of the engine 4 is thus connected to the fourth and fifth propeller shafts from the transfer 8 when the pre-clutch or F / D clutch of the transfer 8 is switched on. It can also be transmitted to the front axle 1 via 14 and 15. Therefore, in this case, all the wheels of the tractor are drive wheels. On the other hand, when the F / D clutch is switched off, only the rear wheel RW becomes a driving wheel, and in this case, the front wheel FW becomes a driven wheel.

The tractor described above further incorporates an anti-skid brake system (ABS), which is shown schematically in FIG. ABS,
Basically has become a pneumatic braking system, the Burekipeda Le (not shown) is depressed, the brake valve 21, the air tank 22, an air pressure corresponding to the depression amount of the brake pedal via a respective control valve 23 brake transmitted to the chamber 24, thereby, the desired brake pressure is to be generated in each wheel.

The front wheel FW and the rear wheel RW located further rearward are provided with wheel speed sensors 25, and these wheel speed sensors 25 are connected to a controller 26. Therefore, the controller 26 controls the wheel speed sensor 25
Calculate the wheel speed of each wheel based on the sensor signal from
Then, anti-skid brake control, that is, ABS control is performed based on these wheel speeds. Specifically, when the start condition of the ABS control is satisfied after the brake pedal (not shown) is depressed, the F / D of the transfer 8 described above is satisfied.
The clutch is switched off. Therefore, after the ABS control is started, the front wheel FW always becomes the driven wheel, and therefore, the controller 26 controls the wheel speed sensor 25 of the front wheel FW.
The vehicle speed can be accurately calculated based on the sensor signal from the vehicle. Then, the controller 26 compares the calculated vehicle speed with the wheel speed of each wheel, and outputs a control signal to the control valve 23 which forms a pair with the skid-prone wheel. The brake pressure of the wheel is controlled, and the skid tendency of the wheel is eliminated.

Although a specific configuration is not shown, the controller 26 controls the F / F of the transfer 8 described above.
The switching operation of the D clutch can also be controlled. In the case of this embodiment, the ABS described above is an anti-spin regulator system (ASR system) for the rear wheel RW.
Is also included. With the ASR system, when spin occurs in the rear wheel RW that is the driving wheel,
This system is for regulating the spin of the rear wheel RW, and is provided with an ASR valve 27. The ASR valve 27 is connected to the air tank 2 on one side.
2 is connected to another air tank 28, and on the other side is also connected to the control valve 23 on the rear wheel RW side. Here, the above-described brake valve 21 side with respect to the control valve 23 on the rear wheel RW. The connection on the ASR valve 27 side is made via a double check valve 30. The air tanks 22 and 28 are connected via a pressure reducing valve 29.

Further, the ASR valve 27 is connected to the above-described controller 26, and is opened and closed based on a control signal from the controller 26. Specifically, when the wheel speed of one of the left and right rear wheels RW is higher than the other wheel speed by a predetermined value or more, the controller 26 determines that spin is occurring on one side of the rear wheel RW, And the ASR valve 27
, And the ASR valve 27 is opened. As a result, the ASR valve 27 and the control valve 2
The air pressure is supplied to the brake chamber 24 of the rear wheel RW in the spin state via 3, and as a result, the brake pressure of the wheel is increased and the spin is regulated.

Further, the ASR system can regulate not only the spin on one side of the rear wheel RW by increasing the brake pressure but also by reducing the output of the engine 4 itself. That is, the fuel injection pump 31 of the engine 4, that is, the metering lever 32 of the mechanical governor is connected to the output lever 34 of the servo motor 33 via a wire.
Reference numeral 3 is electrically connected to the controller 26 described above. The adjusting lever 32 is connected not only to the servo motor 33 but also to an accelerator pedal 36 via a wire and a cancel spring 35.

According to the above-described ASR system, for example, when a spin occurs in both rear wheels RW, the servo motor 33 receives a command from the controller 26 and receives a command from the controller 26.
Is rotated, whereby the rotation angle of the metering lever, that is, the injection amount of the fuel supplied to the engine 4 is reduced independently of the depression of the accelerator pedal 36. As a result, the output of the engine 4 itself decreases, so that the driving force of the rear wheel RW, which is the driving wheel, also decreases, and the spin state is eliminated.

As apparent from the above description, the controller 26 is a common controller for the ABS and ASR systems. In addition, the controller 26 includes A
An ABS warning light 38 that lights up when the BS fails and an ASR information light 39 that lights up during ASR control are connected, and these warning light 38 and information light 39 are provided on the tractor side.

In the case of a semi-tractor, a trailer information controller 40 is mounted on the trailer. The information controller 40 is connected to an ABS information light 41 and a connector 42. . Further, a warning light 38 for ABS is connected to the trailer. Note that FIG.
Reference numeral 43 denotes a relay valve, reference numeral 44 denotes a quick release valve, reference numeral 45 denotes an emergency line, and reference numeral 46 denotes a service line. That is, in the case of this embodiment, the area surrounded by the dashed line in FIG. 2 is on the trailer side connected to the tractor.

The controller 26 operates as described above for A
In addition to performing the BS control and the ASR control, the control of the drive wheel switching is also controlled. The drive wheel switching control is performed in accordance with the F / D clutch switching control routine shown in FIG. The engine output control routine shown in FIG. These control routines are executed in parallel, and during the execution of these control routines, the above-described differential lock of the inter differential 10 may be in either the ON state or the OFF state.

First, in step S1, it is determined whether or not the F / D clutch of the transfer 8 has been switched on. In step S2, it is determined whether or not the brake switch has been turned on, that is, the brake pedal has been turned on. It is determined whether or not is depressed. Further, in step S3, it is determined whether or not the above-described ABS control start condition is satisfied, that is, whether or not the ABS control has been started.

Here, specifically, the controller 26
It has a first electric circuit for judging whether the F / D clutch is switched on and a second electric circuit for judging whether the brake switch is turned on. These first and second electric circuits are provided. The electric circuit is electrically connected to the AND circuit. Further, the controller 26 also has a third electric circuit for determining whether or not the ABS control has been started, and the second and third electric circuits are also electrically connected to the AND circuit.

Accordingly, in a driving situation in which all of the front wheels and the rear wheels, that is, all the wheels are the driving wheels, and when the brake pedal is depressed, the result of determination in step S3 is positive, that is, when the ABS is in the control start state, In the next step S4, the F / D clutch is turned off. However, when the result of the determination is NO (NO), that is, when the ABS is in the inactive state, or when the result of the determination in step S2 is NO, that is, when one of the determinations in steps S2 and S3 is NO. If so, the operation of turning off the F / D clutch is not performed.

When the result of the determination in step S3 becomes positive and the process proceeds to step S4, in this step, the F / D clutch is switched from on to off. That is, even if the F / D clutch is in the ON switching position, the above-described ABS
As soon as the control is started, it is switched off. In the next step S5, it is determined whether or not the ABS control is being performed, and in the next step S6, it is determined whether or not the brake switch has been turned on, as in the case of step S2 described above. If the determination results in steps S5 and S6 are both maintained to be positive, step S4 is repeatedly performed, and the F / D clutch is maintained in the off state. In other words, with the brake pedal depressed,
While the ABS control is being performed, only the rear wheel RW of the tractor is a driving wheel, and the front wheel FW is maintained as a driven wheel.

However, when the depression of the brake pedal is released or when the ABS control ends, the result of the determination in step S5 or S6 is negative, and in this case, the process proceeds to step S7. In step S7, the F / D clutch is turned on again, the process returns to step S1, and the steps from this step onward are repeatedly performed.

In the above situation, if the accelerator pedal is suddenly depressed immediately after the F / D clutch is turned on, spin occurs on the rear wheel RW or the F / D clutch is smoothly turned on. However, in the present invention, the engine output control routine shown in FIG. 4 described below is executed in parallel with the above-described F / D clutch switching control routine. The ON operation of the F / D clutch can be smoothly performed.

First, in step S10, the wheel speeds VF, VR of the front and rear wheels FW, RW are read based on the sensor signals from the wheel speed sensors 25, respectively. In the next step S11, the wheel speeds of the rear wheels RW are read. VR and the wheel speed VF of the front wheel FW are compared to determine whether or not the speed deviation between these wheel speeds is within a predetermined value. That is, in this step, the following expression is evaluated.

VR-VF≤VK Here, VK is set according to the allowable maximum speed difference between the front wheel FW side and the rear wheel RW side in order to smoothly connect the above-mentioned F / D clutch. I have. If the result of the determination in step S11 is negative, the next step S12 is performed, in which the output of the engine 4 is reduced by a certain ratio. Specifically, a drive signal is output from the controller 26 to the servo motor 33, whereby the servo motor 33 operates the fuel injection pump 3 via the metering lever 32.
The amount of fuel supplied from 1 to the engine 4 is reduced, and as a result, the output of the engine 4 is reduced. That is, step S12 is executed using the above-described ASR system.

From step S12, returning to step S10, the steps subsequent to this step are repeated. Therefore, as long as the determination result of step S11 is maintained as negative, step S12 is repeatedly performed.
The output of the engine 4 will be reduced. on the other hand,
As the output of the engine 4 is reduced in this way, the wheel speed VR of the rear wheel RW is reduced, and step S11 is performed.
If the determination result of step S11 is positive or the determination result of step S11 is positive from the beginning without performing step S12, the process proceeds to step S13 instead of step S12. , The engine output is gradually returned in the increasing direction. That is, in such a situation, the ASR system does not operate, and the output of the engine 4 is gradually increased as the accelerator pedal 36 is depressed. However, if the wheel speed of the rear wheel exceeds the allowable value by performing step S13, the engine output is reduced by performing step S12. Therefore, since the above-described engine output control routine is constantly executed, the speed deviation between the front wheel FW and the rear wheel RW is within the allowable maximum speed difference VK.

Therefore, in the method of the present invention, even if the F / D clutch is immediately switched from off to on at the end of the ABS control or the end of the depression of the brake pedal, the controller 26 executes the engine output control routine described above. , The speed deviation of the front and rear wheels is constantly monitored, and the output control of the engine 4
It is contained within the maximum allowable speed difference VK. As a result, even if the F / D clutch is switched from off to on, only a relative speed difference within an allowable limit occurs before and after the F / D clutch at the time of this switching, and the wheel speed of the rear wheel RW is also increased. By gradually increasing VR, the meshing engagement of the F / D clutch, that is, the meshing of the dog gear of the F / D clutch is smoothly and reliably performed.

As described above, the front wheel FW and the rear wheel RW
Needless to say, since only a speed deviation within the allowable limit is generated between the two, the spin of the rear wheel RW is also effectively prevented. The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in one embodiment, the present invention is applied to a semi-trailer tractor having two rear shafts, but the present invention is also applicable to a tractor having one rear shaft as shown in FIG.

[0031]

As described above, according to the drive wheel switching control method of the present invention, the output control of the engine is always performed so that the speed deviation between the front wheels and the rear wheels falls within a range smaller than a predetermined value. However, by performing the precursor clutch switching control in parallel with the engine output control, even if the precursor clutch is immediately switched from off to on when the anti-skid brake control ends, the front and rear wheel speeds at the time of this switching can be changed. Is smaller than the predetermined value,
There are excellent effects such as the ON operation of the precursor clutch, that is, the smooth engagement and engagement of the precursor clutch.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a driving force transmission system of a tractor.

FIG. 2 is a schematic configuration diagram showing an anti-skid brake system and an anti-spin regulator system of a tractor.

FIG. 3 is a flowchart showing an F / D clutch switching control routine.

FIG. 4 is a flowchart showing an engine output control routine.

FIG. 5 is a schematic view showing another type of tractor.

[Explanation of symbols]

 4 Engine 8 Transfer 23 Control Valve 24 Brake Chamber 25 Wheel Speed Sensor 26 Controller 31 Fuel Injection Pump 33 Servo Motor FW Front Wheel RW Rear Wheel

Claims (1)

(57) [Claims] An anti-skid brake system is provided while a transfer clutch for transmitting drive power from an engine to a front wheel and a rear wheel via a transfer and enabling the transmission of drive power to a front wheel to be intermittently provided to the transfer. Speed deviation between the rear wheel speed and the front wheel speed,
If the speed deviation is greater than a predetermined value, the velocity deviation is performed the engine output control for reducing the output of the engine to be smaller than the predetermined value, through working under the engine output control, anti-skid when the brake control is started and the front wheels and the driven wheels by switching off the precursor clutch, thereafter, when the anti-skid brake control is terminated and wherein the switching control of the precursor clutch switching on the precursor actual clutch Hodokosuru Drive wheel switching control method for a vehicle.