CA1332574C - Method for controlling a change-over between two and four-wheel drive modes for a vehicle - Google Patents
Method for controlling a change-over between two and four-wheel drive modes for a vehicleInfo
- Publication number
- CA1332574C CA1332574C CA 602151 CA602151A CA1332574C CA 1332574 C CA1332574 C CA 1332574C CA 602151 CA602151 CA 602151 CA 602151 A CA602151 A CA 602151A CA 1332574 C CA1332574 C CA 1332574C
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- CA
- Canada
- Prior art keywords
- wheel drive
- drive mode
- wheel
- over
- detected
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- B60K23/00—Arrangement or mounting of control devices for vehicle transmissions, or parts thereof, not otherwise provided for
- B60K23/08—Arrangement or mounting of control devices for vehicle transmissions, or parts thereof, not otherwise provided for for changing number of driven wheels, for switching from driving one axle to driving two or more axles
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Arrangement And Mounting Of Devices That Control Transmission Of Motive Force (AREA)
- Arrangement And Driving Of Transmission Devices (AREA)
- Regulating Braking Force (AREA)
Abstract
ABSTRACT
It is an object of the present invention to provide a method for controlling the change-over between two and four-wheel drive modes of a vehicle wherein the two-wheel drive mode is smoothly changed to the four-wheel drive mode during acceleration in the two-wheel drive mode.
It is an object of the present invention to provide a method for controlling the change-over between two and four-wheel drive modes of a vehicle wherein the two-wheel drive mode is smoothly changed to the four-wheel drive mode during acceleration in the two-wheel drive mode.
Description
The present invention relates to a method for controlling the change-over between two and four-wheel drive modes of a vehicle. The four-wheel drive mode is changed to the two-wheel drive mode when at least one wheel produces a locking tendency during braking.
In a control of change-over from a two to a four-wheel drive mode, conventional practice is to restore the drive mode from the two-wheel drive mode to the four-wheel drive mode when there is no tendency for all the wheels to be locked, after the drive mode has been changed from the four-wheel drive mode to the two-wheel drive mode.
Some of the operators or drivers may be accelerating while braking in vehicles equipped with an automatic transmission. In such a case, in spite of a desire to restore the drive mode from the two-wheel drive mode to the four-wheel drive mode, the restoration cannot be achieved when there is a locking tendency produced in the wheels which are driven wheels in the two-wheel drive mode.
The present invention provides a method for controlling the change-over between two-wheel and four-wheel drive modes of a vehicle comprising the steps of: changing a four-wheel drive mode to a two-wheel drive mode when at least one wheel produces a locking tendency during braking; and changing the two-wheel drive mode to the four-wheel drive mode when the driving wheels in the two-wheel drive mode have no locking tendency.
A first feature of the present invention is in that the two-wheel drive mode is changed to the four-wheel drive mode when the driving wheels in the two-wheel drive mode have no locking tendency. With this first feature, it is possible .. ,~ ' ~r A
to smoothly change over the drive mode to the four-wheel drive mode, when a driver is accelerating while braking in the two-wheel drive mode, by changing over to the four-wheel drive mode, even if the driven wheels in the two-wheel drive mode are in a locking tendency.
A second feature of the present invention is that when a driven wheel tends to be locked, the two-wheel drive mode is maintained until a predetermined time has elapsed after changing over from the four-wheel drive mode to the two-wheel drive mode. With the second feature, two-wheel drive mode is not changed back to the four-wheel drive mode during an initial stage of changing over from the four-wheel drive mode to the two-wheel drive mode, when the driven wheels are in a locking tendency and the driving wheels are not in a locking tendency.
A third feature of the present invention is that even if a locking tendency is prod~ced in a driven wheel in the two-wheel drive mode, the four-wheel drive mode is maintained until a predetermined time has elapsed after changing over from the two-wheel drive mode to the four-wheel drive mode. With the third feature, the four-wheel drive mode is not changed back to the two-wheel drive mode during an initial stage of changing over from the two-wheel drive mode to the four-wheel drive mode, when the driven wheels are in a locking tendency and the driving wheels are not in a locking tendency.
B
In a control of change-over from a two to a four-wheel drive mode, conventional practice is to restore the drive mode from the two-wheel drive mode to the four-wheel drive mode when there is no tendency for all the wheels to be locked, after the drive mode has been changed from the four-wheel drive mode to the two-wheel drive mode.
Some of the operators or drivers may be accelerating while braking in vehicles equipped with an automatic transmission. In such a case, in spite of a desire to restore the drive mode from the two-wheel drive mode to the four-wheel drive mode, the restoration cannot be achieved when there is a locking tendency produced in the wheels which are driven wheels in the two-wheel drive mode.
The present invention provides a method for controlling the change-over between two-wheel and four-wheel drive modes of a vehicle comprising the steps of: changing a four-wheel drive mode to a two-wheel drive mode when at least one wheel produces a locking tendency during braking; and changing the two-wheel drive mode to the four-wheel drive mode when the driving wheels in the two-wheel drive mode have no locking tendency.
A first feature of the present invention is in that the two-wheel drive mode is changed to the four-wheel drive mode when the driving wheels in the two-wheel drive mode have no locking tendency. With this first feature, it is possible .. ,~ ' ~r A
to smoothly change over the drive mode to the four-wheel drive mode, when a driver is accelerating while braking in the two-wheel drive mode, by changing over to the four-wheel drive mode, even if the driven wheels in the two-wheel drive mode are in a locking tendency.
A second feature of the present invention is that when a driven wheel tends to be locked, the two-wheel drive mode is maintained until a predetermined time has elapsed after changing over from the four-wheel drive mode to the two-wheel drive mode. With the second feature, two-wheel drive mode is not changed back to the four-wheel drive mode during an initial stage of changing over from the four-wheel drive mode to the two-wheel drive mode, when the driven wheels are in a locking tendency and the driving wheels are not in a locking tendency.
A third feature of the present invention is that even if a locking tendency is prod~ced in a driven wheel in the two-wheel drive mode, the four-wheel drive mode is maintained until a predetermined time has elapsed after changing over from the two-wheel drive mode to the four-wheel drive mode. With the third feature, the four-wheel drive mode is not changed back to the two-wheel drive mode during an initial stage of changing over from the two-wheel drive mode to the four-wheel drive mode, when the driven wheels are in a locking tendency and the driving wheels are not in a locking tendency.
B
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In one aspect, the invention provides a method for controlling the change-over between two-wheel and four-wheel drive modes of a vehicle comprising the steps of:
changing a four-wheel drive mode to a two-wheel drive mode when it is detected that at least one wheel produces a locking tendency during braking;
changing the two-wheel drive mode to the four-wheel drive mode when it is detected that the driving wheel~ in the two-wheel drive mode have no locking tendency;
and maintaining the two-wheel drive mode until a first predetermined time has elapsed after the change-over from ~he four-wheel drive mode to the two-wheel drive mode when it is detected that a driven wheel tends to be locked even if no locking tendency is detected in the driving wheels in the two-wheel drive mode.
In preferred embodiments of this aspect, the invention provides:
The above method, further comprising the step of maintaining the four-wheel drive mode until a second predetermined time has elapsed after change-over from the two-wheel drive mode to the four-wheel drive mode even if a locking tendency is detected in a driven wheel in the two-wheel drive mode.
The immediately above method, wherein the vehicle includes a power transmission system provided with clutch means for changing over between the two-wheel and four-wheel drive modes of the vehicle, the method further comprising starting counting of sa~d first predetermined time from an .. .
` B
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instant when a disengaged state of said clutch means is detected, and starting counting of said second predetermined time from an instant when a command is generated for engaging said clutch means.
In a further aspect, the invention provides a method for controlling the change-over between two-wheel and four-wheel : drive modes of a vehicle comprising the steps of:
changing a four-wheel drive mode to a two-wheel drive mode when it is detected that at least one wheel produces a locking tendency during braking;
changing the two-wheel drive mode to the four-wheel drive mode when it is detected that the driving wheels in the two-wheel drive mode have no locking tendency;
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and maintaining the four-wheel drive mode until a predetermined time has elapsed after change-over from the two-wheel drive mode to the four-wheel drive mode even if a . 20 locking tendency is detected in a driven wheel in the two-wheel drive mode.
,' .
' In a still further aspect, the invention provides a . method for controlling the change-over between two-wheel ~: 25 drive modes of a vehicle comprising the steps of:
`
changing a four-wheel drive mode to a two-wheel drive mode when it is detected that at least one wheel produces a locking tendency during braking;
:' .
:~ changing the two-wheel drive mode to the four-wheel ` drive mode when it is detected that the driving wheels in the two-wheel drive mode have no locking tendency;
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and wherein the vehicle has an engine mounted at a front portion thereof and said driving wheels in the two-wheel drive mode are front wheels, said front wheels being subjected to anti-lock control independently from each other and rear wheels of said vehicle being together subjected to anti-lock control in a collective fashion, the method further comprising using signals which are used to carry out the anti-lock control for changing over between the two-wheel drive mode and the four-wheel drive mode.
The drawings illustrate one embodiment of the present invention, wherein:
Fig. 1 is a schematic illustration of a driving system;
- 2c -Fig. 2 is a circuit diagram illustrating the arrangement of an essential portion of a control means; and Fig. 3 is a timing chart.
The present invention will now be described with reference to the accompanying drawings, by way of one embodiment applied in a vehicle in which the front wheels are driving wheels and the rear wheels are driven wheels in a two-wheel drive mode. Referring first to Fig. 1, a pair of front wheels WfR and Wfr and a pair of rear wheels wrQ and Wrr are suspended respectively on a front portion and a rear portion of a vehicle body (which is not shown). Brakes Bf~
and Bfr; Br~ and Brr are provided on the front and rear wheels Wf~ and Wfr; Wr~ and Wrr, respectively. A hydraulic pressure control circuit 1, to which an anti-lock control means 2 is added for controlling the brakes BfQ and Bfr on the front wheels Wf~ and Wfr and the brakes Br~ and Brr on the rear wheels Wr~ and Wrr with different operation modes forms a brake device together with brakes BfR, Brf, Br~ and Brr. The anti-lock control means 2 is, for example, to separately control the hydraulic braking pressures for the brake Bf~ on the left front wheels Wfl, the brake Bfr on the right front wheel Wfr and the brakes BrR and Brr on the rear wheels wrQ and Wrr. The hydraulic braking pressure is reduced during anti-lock control.
A
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The front and rear wheels Wfe, Wfr, Wre and Wrr are connected through a driving system A to a power unit P. The driving system A comprises a front differential Df connecting the front wheels Wfe and Wfr with the power unit P, a rear differential Dr connecting the rear wheels Wrt and Wrr, and a propeller shaft 3 connecting the power unit P with the rear differential Dr. At the middle o~ the propeller shaft, there is a dog clutch 4 which permits changing over between the connection and disconnection between-the front and rear wheels Wfe, Wfr and wre, Wrr. An actuator 5, such as a cylinder for driving the dog clutch 4, is controlled by a control means 6.
Flg. 2 illustrates the arrangement of an essential portion of the control means 6. A signal indicative of an anti-lock control state is input from the anti-lock control means 2 to input terminals 7, 8 and 9. Specifically, when the brake Bfe of the left front wheel Wfe is being anti-lock controlled, a higher level signal than normal is input to the input terminal 7, and when the brake Bfr of the right front wheel Wfr is being anti-lock controlled, a higher level signal is input to the input terminal 8rl 8. When the brakes ~ and Brr of both rear wheels Wre and Wrr are being anti-lock controlled, the higher level signal is input to the input terminal 9. The input terminals 7 and 8 are connected in - parallel to an OR circuit 10, and the input terminal 9 is connected to an AND circuit 11.
The OR circuit lO ie connected to an AND circuit 12 which ` i8, in turn, connected to an output terminal 13 to deliver a higher level signal when the dog clutch 4 is disengaged to change over the four-wheel drive mode into the two-wheel drive mode. The AND
circuit 12 is also connected to an invertor circuit 14 which is connected, in an inverted manner, to an input terminal of a timer :'; 13 ~
circuit 15. The timer circuit 15 produces a higher level signal sustained for a given time TA from the moment when the output from the invertor circuit 14 has been changed from a lower level into a higher level, i.e., when the output from the AND circuit 12 has been changed from a higher level into a lower level to change over the two-wheel drive mode into the four-wheel drive mode. The output from the timer circuit 15 is input, in an inverted manner, to the AND circuit 11.
A detector 16 (see Fig. 1) is added to the dog clutch 4 for detecting the operated state thereof and produces a higher level signal when the dog clutch 4 is in a disengaged state~ The detector 16 is connected to a delay circuit 17 which produces a signal rising with a delay of a given time TB after the rising of a signal produced from the detector 16. The delay circuit 17 is invertedly connected to the AND
circuit 11. Thus, output from the AND circuit 11 becomes a higher level, when the rear wheels ~r~ and Wrr are in a locking tendency, and within a period from a point when the given time TA has elapsed after changing over of the two-wheel drive mode into the four-wheel drive mode to a point when the given time TB has elapsed after the change-over into the two wheel drive mode has been achieved.
A brake switch 18 is also connected to the AND circuit 12 and produces a lower level signal when a braking operation has been provided. Therefore, in order that the output from the AND circuit 12 goes to the lower level, the braking operation is a necessary condition.
The operation of this embodiment will be described below with reference to Figs. 3(a~ to 3(c). Fig. 3(a) illustrates the output from the AND circuit 12. Fig. 3(b) illustrates the output from the timer circuit 15. Fig. 3(c) illustrates the output from the delay circuit 17. Until the given time !
, ~ ~
TA elap~es after changing over from the two-wheel drive mode into the four-wheel drive mode, the output from the AND
circuit 11 is at the low level. After the given time TB has elapsed after changing over from the four-wheel drive mode into the two-wheel drive mode, the output from the AND
circuit 11 becomes the low level. Therefore, the output from the AND circuit 11 becomes the hi~h level, only when the rear wheels WrQ and Wrr show a tendency to be locked, and between a point A, after a lapse of the given time TA from changing over from the two-wheel drive mode into the four-wheel drive mode, and a point s, after a lapse of the given time TB after changing over from the four-wheel drive mode into the two-wheel drive mode.
If the breaking occurs when the dog clutch 4 is in an engaged state to provide the four-wheel drive mode in which the front wheels Wf~ and Wfr are connected to the rear wheels Wr~ and Wrr, the output from the AND circuit 12 becomes the high level in response to the output from the OR circuit 10 becoming the high level, so that the dog clutch 4 is disengaged to permit changing over from the four-wheel drive mode into the two-wheel drive mode. In other words, the dog clutch 4 is disengaged to provide the two-wheel drive mode, either in a condition where either one of the front wheels Wf~
and Wfr tends to be locked and is anti-lock controlled, or in a condition where the rear wheels wrQ and Wrr are being anti-lock controlled.
In changing over into the two-wheel drive mode, the output from the AND circuit 11 remains at the higher level to maintain the two-wheel drive mode, until the given time Tg has elapsed from the point of change-over, when the rear wheels WrD and Wrr, which are now driven wheels, tend to be locked. Thus, the drive mode is not immediately returned to ~ the four-wheel drive mode when it has been changed over into ,' :
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1 332~74 the two-wheel drive mode in a condition where the rear wheels wrQ and Wrr are in a locking tendency and the front wheels WfQ
and Wfr are not in a locking tendency in the four-wheel drive mode.
When at least the front wheels Wf~ and Wfr, which are driving wheels, have no locking tendency produced in the two-wheel drive mode, the output from the AND circuit ll is at the low level after the given time TB has elapsed after changing over, so that the output from the OR circuit 10 goes to the low level. In response to this, the output from the AND circuit 12 goes to the low level, thereby permitting the dog clutch 4 to be engaged, resulting in the four-wheel drive mode. When the vehicle is accelerating while the operator of the vehicle is braking, the drive mode can be rapidly restored from the two-wheel drive mode to the four-wheel drive mode.
With this change-over from the two-wheel drive mode to the four-wheel drive mode, the output from the AND circuit 11 remains at the lower level until the given time TA has elapsed after the change-over. Accordingly, the drive mode is not immediately returned to the two-wheel drive mode when it has been changed over into the four-wheel dive mode in a ~ condition where the rear wheels WrQ and Wrr are in a locking `; tendency and the front wheels WfQ and Wfr are not in a locking tendency in the two-wheel drive mode.
As discussed above, according to the first feature of the present invention, the two-wheel drive mode is changed to the four-wheel drive mode when the driving wheels have no locking tendency produced in the two-wheel drive mode.
Therefore, it is possible to smoothly change over the drive mode to the four-wheel drive mode when the vehicle is accelerating while the operator of the vehicle is braking during the two-wheel drive mode.
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According to the second featùre of the present invention, when the driven wheels tend to be iocked, the two-wheel drive modé `
is maintained until a predetermined time has elapsed after changing over Prom the four-wheel drive mode to the two-wheel drive mode.
Therefore, the two-wheel drive mode is not changed back to the four-wheel drive mode during an initial stage of changing over from the four-wheel drive mode to the two-wheel drive mode, when the driven wheels are in a locking tendency and the driving wheels are not in a locking tendency.
According to the third feature of the present invention, even if a locking tendency is produced in the driven wheels in the two-wheel drive mode, the four-wheel drive mode is maintained until a predetermined time has elapsed after changing over from the two-wheel drive mode to the four-wheel drive mode. Therefore, the four-wheel drive mode is not changed back to two-wheel drive mode during an initial stage of changing over from the two-wheel drive mode to the four-wheel drive mode, when the driven wheels are in a locking tendency, the driving wheels are not in a locking tendency.
From the foregoing description of the preferred embodiment of the invention, it will be apparent that many ` modifications may be made therein. It should be understood that these embodiments are intended as one example of the invention ` only, and that the invention is not limited thereto. Therefore, i 25 it should be understood that the appended claims are intended to cover all modifications that fall within the true spirit and scope of the invention.
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In one aspect, the invention provides a method for controlling the change-over between two-wheel and four-wheel drive modes of a vehicle comprising the steps of:
changing a four-wheel drive mode to a two-wheel drive mode when it is detected that at least one wheel produces a locking tendency during braking;
changing the two-wheel drive mode to the four-wheel drive mode when it is detected that the driving wheel~ in the two-wheel drive mode have no locking tendency;
and maintaining the two-wheel drive mode until a first predetermined time has elapsed after the change-over from ~he four-wheel drive mode to the two-wheel drive mode when it is detected that a driven wheel tends to be locked even if no locking tendency is detected in the driving wheels in the two-wheel drive mode.
In preferred embodiments of this aspect, the invention provides:
The above method, further comprising the step of maintaining the four-wheel drive mode until a second predetermined time has elapsed after change-over from the two-wheel drive mode to the four-wheel drive mode even if a locking tendency is detected in a driven wheel in the two-wheel drive mode.
The immediately above method, wherein the vehicle includes a power transmission system provided with clutch means for changing over between the two-wheel and four-wheel drive modes of the vehicle, the method further comprising starting counting of sa~d first predetermined time from an .. .
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- 2a -~`
instant when a disengaged state of said clutch means is detected, and starting counting of said second predetermined time from an instant when a command is generated for engaging said clutch means.
In a further aspect, the invention provides a method for controlling the change-over between two-wheel and four-wheel : drive modes of a vehicle comprising the steps of:
changing a four-wheel drive mode to a two-wheel drive mode when it is detected that at least one wheel produces a locking tendency during braking;
changing the two-wheel drive mode to the four-wheel drive mode when it is detected that the driving wheels in the two-wheel drive mode have no locking tendency;
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and maintaining the four-wheel drive mode until a predetermined time has elapsed after change-over from the two-wheel drive mode to the four-wheel drive mode even if a . 20 locking tendency is detected in a driven wheel in the two-wheel drive mode.
,' .
' In a still further aspect, the invention provides a . method for controlling the change-over between two-wheel ~: 25 drive modes of a vehicle comprising the steps of:
`
changing a four-wheel drive mode to a two-wheel drive mode when it is detected that at least one wheel produces a locking tendency during braking;
:' .
:~ changing the two-wheel drive mode to the four-wheel ` drive mode when it is detected that the driving wheels in the two-wheel drive mode have no locking tendency;
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: . . , ~, . ., :~: . ; . - . . .
and wherein the vehicle has an engine mounted at a front portion thereof and said driving wheels in the two-wheel drive mode are front wheels, said front wheels being subjected to anti-lock control independently from each other and rear wheels of said vehicle being together subjected to anti-lock control in a collective fashion, the method further comprising using signals which are used to carry out the anti-lock control for changing over between the two-wheel drive mode and the four-wheel drive mode.
The drawings illustrate one embodiment of the present invention, wherein:
Fig. 1 is a schematic illustration of a driving system;
- 2c -Fig. 2 is a circuit diagram illustrating the arrangement of an essential portion of a control means; and Fig. 3 is a timing chart.
The present invention will now be described with reference to the accompanying drawings, by way of one embodiment applied in a vehicle in which the front wheels are driving wheels and the rear wheels are driven wheels in a two-wheel drive mode. Referring first to Fig. 1, a pair of front wheels WfR and Wfr and a pair of rear wheels wrQ and Wrr are suspended respectively on a front portion and a rear portion of a vehicle body (which is not shown). Brakes Bf~
and Bfr; Br~ and Brr are provided on the front and rear wheels Wf~ and Wfr; Wr~ and Wrr, respectively. A hydraulic pressure control circuit 1, to which an anti-lock control means 2 is added for controlling the brakes BfQ and Bfr on the front wheels Wf~ and Wfr and the brakes Br~ and Brr on the rear wheels Wr~ and Wrr with different operation modes forms a brake device together with brakes BfR, Brf, Br~ and Brr. The anti-lock control means 2 is, for example, to separately control the hydraulic braking pressures for the brake Bf~ on the left front wheels Wfl, the brake Bfr on the right front wheel Wfr and the brakes BrR and Brr on the rear wheels wrQ and Wrr. The hydraulic braking pressure is reduced during anti-lock control.
A
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The front and rear wheels Wfe, Wfr, Wre and Wrr are connected through a driving system A to a power unit P. The driving system A comprises a front differential Df connecting the front wheels Wfe and Wfr with the power unit P, a rear differential Dr connecting the rear wheels Wrt and Wrr, and a propeller shaft 3 connecting the power unit P with the rear differential Dr. At the middle o~ the propeller shaft, there is a dog clutch 4 which permits changing over between the connection and disconnection between-the front and rear wheels Wfe, Wfr and wre, Wrr. An actuator 5, such as a cylinder for driving the dog clutch 4, is controlled by a control means 6.
Flg. 2 illustrates the arrangement of an essential portion of the control means 6. A signal indicative of an anti-lock control state is input from the anti-lock control means 2 to input terminals 7, 8 and 9. Specifically, when the brake Bfe of the left front wheel Wfe is being anti-lock controlled, a higher level signal than normal is input to the input terminal 7, and when the brake Bfr of the right front wheel Wfr is being anti-lock controlled, a higher level signal is input to the input terminal 8rl 8. When the brakes ~ and Brr of both rear wheels Wre and Wrr are being anti-lock controlled, the higher level signal is input to the input terminal 9. The input terminals 7 and 8 are connected in - parallel to an OR circuit 10, and the input terminal 9 is connected to an AND circuit 11.
The OR circuit lO ie connected to an AND circuit 12 which ` i8, in turn, connected to an output terminal 13 to deliver a higher level signal when the dog clutch 4 is disengaged to change over the four-wheel drive mode into the two-wheel drive mode. The AND
circuit 12 is also connected to an invertor circuit 14 which is connected, in an inverted manner, to an input terminal of a timer :'; 13 ~
circuit 15. The timer circuit 15 produces a higher level signal sustained for a given time TA from the moment when the output from the invertor circuit 14 has been changed from a lower level into a higher level, i.e., when the output from the AND circuit 12 has been changed from a higher level into a lower level to change over the two-wheel drive mode into the four-wheel drive mode. The output from the timer circuit 15 is input, in an inverted manner, to the AND circuit 11.
A detector 16 (see Fig. 1) is added to the dog clutch 4 for detecting the operated state thereof and produces a higher level signal when the dog clutch 4 is in a disengaged state~ The detector 16 is connected to a delay circuit 17 which produces a signal rising with a delay of a given time TB after the rising of a signal produced from the detector 16. The delay circuit 17 is invertedly connected to the AND
circuit 11. Thus, output from the AND circuit 11 becomes a higher level, when the rear wheels ~r~ and Wrr are in a locking tendency, and within a period from a point when the given time TA has elapsed after changing over of the two-wheel drive mode into the four-wheel drive mode to a point when the given time TB has elapsed after the change-over into the two wheel drive mode has been achieved.
A brake switch 18 is also connected to the AND circuit 12 and produces a lower level signal when a braking operation has been provided. Therefore, in order that the output from the AND circuit 12 goes to the lower level, the braking operation is a necessary condition.
The operation of this embodiment will be described below with reference to Figs. 3(a~ to 3(c). Fig. 3(a) illustrates the output from the AND circuit 12. Fig. 3(b) illustrates the output from the timer circuit 15. Fig. 3(c) illustrates the output from the delay circuit 17. Until the given time !
, ~ ~
TA elap~es after changing over from the two-wheel drive mode into the four-wheel drive mode, the output from the AND
circuit 11 is at the low level. After the given time TB has elapsed after changing over from the four-wheel drive mode into the two-wheel drive mode, the output from the AND
circuit 11 becomes the low level. Therefore, the output from the AND circuit 11 becomes the hi~h level, only when the rear wheels WrQ and Wrr show a tendency to be locked, and between a point A, after a lapse of the given time TA from changing over from the two-wheel drive mode into the four-wheel drive mode, and a point s, after a lapse of the given time TB after changing over from the four-wheel drive mode into the two-wheel drive mode.
If the breaking occurs when the dog clutch 4 is in an engaged state to provide the four-wheel drive mode in which the front wheels Wf~ and Wfr are connected to the rear wheels Wr~ and Wrr, the output from the AND circuit 12 becomes the high level in response to the output from the OR circuit 10 becoming the high level, so that the dog clutch 4 is disengaged to permit changing over from the four-wheel drive mode into the two-wheel drive mode. In other words, the dog clutch 4 is disengaged to provide the two-wheel drive mode, either in a condition where either one of the front wheels Wf~
and Wfr tends to be locked and is anti-lock controlled, or in a condition where the rear wheels wrQ and Wrr are being anti-lock controlled.
In changing over into the two-wheel drive mode, the output from the AND circuit 11 remains at the higher level to maintain the two-wheel drive mode, until the given time Tg has elapsed from the point of change-over, when the rear wheels WrD and Wrr, which are now driven wheels, tend to be locked. Thus, the drive mode is not immediately returned to ~ the four-wheel drive mode when it has been changed over into ,' :
~, 1~. s~. ~
1 332~74 the two-wheel drive mode in a condition where the rear wheels wrQ and Wrr are in a locking tendency and the front wheels WfQ
and Wfr are not in a locking tendency in the four-wheel drive mode.
When at least the front wheels Wf~ and Wfr, which are driving wheels, have no locking tendency produced in the two-wheel drive mode, the output from the AND circuit ll is at the low level after the given time TB has elapsed after changing over, so that the output from the OR circuit 10 goes to the low level. In response to this, the output from the AND circuit 12 goes to the low level, thereby permitting the dog clutch 4 to be engaged, resulting in the four-wheel drive mode. When the vehicle is accelerating while the operator of the vehicle is braking, the drive mode can be rapidly restored from the two-wheel drive mode to the four-wheel drive mode.
With this change-over from the two-wheel drive mode to the four-wheel drive mode, the output from the AND circuit 11 remains at the lower level until the given time TA has elapsed after the change-over. Accordingly, the drive mode is not immediately returned to the two-wheel drive mode when it has been changed over into the four-wheel dive mode in a ~ condition where the rear wheels WrQ and Wrr are in a locking `; tendency and the front wheels WfQ and Wfr are not in a locking tendency in the two-wheel drive mode.
As discussed above, according to the first feature of the present invention, the two-wheel drive mode is changed to the four-wheel drive mode when the driving wheels have no locking tendency produced in the two-wheel drive mode.
Therefore, it is possible to smoothly change over the drive mode to the four-wheel drive mode when the vehicle is accelerating while the operator of the vehicle is braking during the two-wheel drive mode.
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'~d` ' ' ' ' ' . ` . ' ~ .. ~ ; ' ' ' ' . . .' . ` `
According to the second featùre of the present invention, when the driven wheels tend to be iocked, the two-wheel drive modé `
is maintained until a predetermined time has elapsed after changing over Prom the four-wheel drive mode to the two-wheel drive mode.
Therefore, the two-wheel drive mode is not changed back to the four-wheel drive mode during an initial stage of changing over from the four-wheel drive mode to the two-wheel drive mode, when the driven wheels are in a locking tendency and the driving wheels are not in a locking tendency.
According to the third feature of the present invention, even if a locking tendency is produced in the driven wheels in the two-wheel drive mode, the four-wheel drive mode is maintained until a predetermined time has elapsed after changing over from the two-wheel drive mode to the four-wheel drive mode. Therefore, the four-wheel drive mode is not changed back to two-wheel drive mode during an initial stage of changing over from the two-wheel drive mode to the four-wheel drive mode, when the driven wheels are in a locking tendency, the driving wheels are not in a locking tendency.
From the foregoing description of the preferred embodiment of the invention, it will be apparent that many ` modifications may be made therein. It should be understood that these embodiments are intended as one example of the invention ` only, and that the invention is not limited thereto. Therefore, i 25 it should be understood that the appended claims are intended to cover all modifications that fall within the true spirit and scope of the invention.
. . ~
.~ ..
,
Claims (5)
1. A method for controlling the change-over between two-wheel and four-wheel drive modes of a vehicle comprising the steps of:
changing a four-wheel drive mode to a two-wheel drive mode when it is detected that at least one wheel produces a locking tendency during braking;
changing the two-wheel drive mode to the four-wheel drive mode when it is detected that the driving wheels in the two-wheel drive mode have no locking tendency;
and maintaining the two-wheel drive mode until a first predetermined time has elapsed after the change-over from the four-wheel drive mode to the two-wheel drive mode when it is detected that a driven wheel tends to be locked even if no locking tendency is detected in the driving wheels in the two-wheel drive mode.
changing a four-wheel drive mode to a two-wheel drive mode when it is detected that at least one wheel produces a locking tendency during braking;
changing the two-wheel drive mode to the four-wheel drive mode when it is detected that the driving wheels in the two-wheel drive mode have no locking tendency;
and maintaining the two-wheel drive mode until a first predetermined time has elapsed after the change-over from the four-wheel drive mode to the two-wheel drive mode when it is detected that a driven wheel tends to be locked even if no locking tendency is detected in the driving wheels in the two-wheel drive mode.
2. A method for controlling the change-over between two-wheel and four-wheel drive modes of a vehicle according to claim 1, further comprising the step of maintaining the four-wheel drive mode until a second predetermined time as elapsed after change-over from the two-wheel drive mode to the four-wheel drive mode even if a locking tendency is detected in a driven wheel in the two-wheel drive mode.
3. A method for controlling the change-over between two-wheel and four-wheel drive modes of a vehicle according to claim 2, wherein the vehicle includes a power transmission system provided with clutch means for changing over between the two-wheel and four-wheel drive modes of the vehicle, the method further comprising starting counting of said first predetermined time from an instant when a disengaged state of said clutch means is detected, and starting counting of said second predetermined time from an instant when a command is generated for engaging said clutch means.
4. A method for controlling the change-over between two-wheel and four-wheel drive modes of a vehicle comprising the steps of:
changing a four-wheel drive mode to a two-wheel drive mode when it is detected that at least one wheel produces a locking tendency during braking;
changing the two-wheel drive mode to the four-wheel drive mode when it is detected that the driving wheels in the two-wheel drive mode have no locking tendency;
and maintaining the four-wheel drive mode until a predetermined time has elapsed after change-over from the two-wheel drive mode to the four-wheel drive mode even if a locking tendency is detected in a driven wheel in the two-wheel drive mode.
changing a four-wheel drive mode to a two-wheel drive mode when it is detected that at least one wheel produces a locking tendency during braking;
changing the two-wheel drive mode to the four-wheel drive mode when it is detected that the driving wheels in the two-wheel drive mode have no locking tendency;
and maintaining the four-wheel drive mode until a predetermined time has elapsed after change-over from the two-wheel drive mode to the four-wheel drive mode even if a locking tendency is detected in a driven wheel in the two-wheel drive mode.
5. A method for controlling the change-over between two-wheel and four-wheel drive modes of a vehicle comprising the steps of:
changing a four-wheel drive mode to a two-wheel drive mode when it is detected that at least one wheel produces a locking tendency during braking;
changing the two-wheel drive mode to the four-wheel drive mode when it is detected that the driving wheels in the two-wheel drive mode have no locking tendency;
and wherein the vehicle has an engine mounted at a front portion thereof and said driving wheels in the two-wheel drive mode are front wheels, said front wheels being subjected to anti-lock control independently from each other and rear wheels of said vehicle being together subjected to anti-lock control in a collective fashion, the method further comprising using signals which are used to carry out the anti-lock control for changing over between the two-wheel drive mode and the four-wheel drive mode.
changing a four-wheel drive mode to a two-wheel drive mode when it is detected that at least one wheel produces a locking tendency during braking;
changing the two-wheel drive mode to the four-wheel drive mode when it is detected that the driving wheels in the two-wheel drive mode have no locking tendency;
and wherein the vehicle has an engine mounted at a front portion thereof and said driving wheels in the two-wheel drive mode are front wheels, said front wheels being subjected to anti-lock control independently from each other and rear wheels of said vehicle being together subjected to anti-lock control in a collective fashion, the method further comprising using signals which are used to carry out the anti-lock control for changing over between the two-wheel drive mode and the four-wheel drive mode.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP143867/88 | 1988-06-10 | ||
| JP63143867A JP2719926B2 (en) | 1988-06-10 | 1988-06-10 | Two- and four-wheel drive state switching control method for vehicle |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1332574C true CA1332574C (en) | 1994-10-18 |
Family
ID=15348839
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 602151 Expired - Fee Related CA1332574C (en) | 1988-06-10 | 1989-06-08 | Method for controlling a change-over between two and four-wheel drive modes for a vehicle |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JP2719926B2 (en) |
| CA (1) | CA1332574C (en) |
| DE (1) | DE3918612C2 (en) |
| GB (1) | GB2221739B (en) |
| SE (1) | SE466342B (en) |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60143170A (en) * | 1983-12-29 | 1985-07-29 | Nippon Air Brake Co Ltd | Anti-skid mechanism for four wheel drive car |
| DE3418520A1 (en) * | 1984-05-18 | 1985-11-21 | Teves Gmbh Alfred | SLIP-CONTROLLED BRAKE SYSTEM FOR ROAD VEHICLES WITH ALL-WHEEL DRIVE |
| US4991679A (en) * | 1985-06-21 | 1991-02-12 | Honda Giken Kogyo Kabushiki Kaisha | Four wheel-drive anti-locking braking |
| JPS61295132A (en) * | 1985-06-21 | 1986-12-25 | Honda Motor Co Ltd | Four-wheel drive car with antilock braking device |
| IT1185864B (en) * | 1985-08-06 | 1987-11-18 | Alfa Romeo Auto Spa | CONTROL EQUIPMENT FOR AN INTEGRAL DETACHABLE VEHICLE |
| US4770266A (en) * | 1985-08-13 | 1988-09-13 | Mazda Motor Corporation | Brake control system for four-wheel drive vehicle |
| DE3533745A1 (en) * | 1985-09-21 | 1987-04-02 | Opel Adam Ag | TRANSMISSION ARRANGEMENT |
| JPS632623U (en) * | 1986-06-25 | 1988-01-09 | ||
| JPS6483418A (en) * | 1987-09-22 | 1989-03-29 | Honda Motor Co Ltd | Power change-over device for four-wheel drive car |
-
1988
- 1988-06-10 JP JP63143867A patent/JP2719926B2/en not_active Expired - Fee Related
-
1989
- 1989-06-06 SE SE8902056A patent/SE466342B/en not_active IP Right Cessation
- 1989-06-07 DE DE19893918612 patent/DE3918612C2/en not_active Expired - Fee Related
- 1989-06-08 CA CA 602151 patent/CA1332574C/en not_active Expired - Fee Related
- 1989-06-09 GB GB8913330A patent/GB2221739B/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| SE466342B (en) | 1992-02-03 |
| JPH01311923A (en) | 1989-12-15 |
| GB8913330D0 (en) | 1989-07-26 |
| DE3918612C2 (en) | 1996-04-25 |
| GB2221739A (en) | 1990-02-14 |
| SE8902056D0 (en) | 1989-06-06 |
| SE8902056L (en) | 1989-12-11 |
| JP2719926B2 (en) | 1998-02-25 |
| DE3918612A1 (en) | 1989-12-14 |
| GB2221739B (en) | 1992-07-22 |
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