JPS6243324A - Brake controller for four-wheel drive car - Google Patents

Abstract

PURPOSE:To reduce the influence to the traveling performance by installing a means for detecting the chassis deceleration speed and the wheel revolution deceleration speed in brake application and releasing the front/rear-ward direct- connection state when the difference between the both output signals exceeds a prescribed value and operating an antiskid brake system (ABS). CONSTITUTION:A clutch 45 for 2-4 wheel switching is operated by a modulator 13, and a controller 14 controls the slip rate of a wheel on the basis of the signal of a speed sensor 56a, etc. When the difference between the wheel revolution deceleration speed and the chassis deceleration speed becomes larger than a prescribed value, an ABS operates after switching to 2-wheel drive is performed by the modulator 13. Since the releasing switching of the front/rear- wheel direct-connection state is carried out only when the wheel deceleration speed in brake application is larger than the chassis deceleration speed, the influence to the traveling performance due to the releasing switching can be reduced.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is a four-wheel drive vehicle that can drive both front and rear wheels, and an anti-skid brake system (
The present invention relates to an automobile having ABS (hereinafter also referred to as ABS).

(Prior art) When a brake is operated while a car is running, the maximum braking force occurs when the wheel slip rate is around 20%. Anti-skid braking systems, which prevent wheels from locking by preventing the slip rate from becoming too large and maintain braking force close to maximum, have been known and put to practical use in two-wheel drive vehicles. For example, as disclosed in Japanese Unexamined Patent Publication No. 57-7747, in a two-wheel drive vehicle, the brake hydraulic pressure is controlled according to the deceleration of the wheel speed to prevent the wheels from locking during braking. There is something I did. However, a four-wheel drive vehicle using ABS has not yet been realized.

This is because ABS operates by detecting the slip rate of the wheels, so when measuring the speed of the slipping wheel and the actual vehicle speed, currently the rotation of each of the four wheels is detected, and the rotation of each of the four wheels is detected. This is because the slip rate is calculated using the actual vehicle speed calculated from the speed of the wheels that are not slipping, and the ABS of this method is 4.
This is because when incorporated into a wheel drive vehicle, all four wheels are mechanically connected, so all four wheels slip at the same time, making it difficult to calculate the actual vehicle speed. Although it is technically possible to detect the actual vehicle speed using a sensor such as a sonic detector, there are problems with practical implementation at this stage due to cost and other reasons.

For this reason, 4-wheel drive vehicles are equipped with ABS, which is conventionally used in 2-wheel drive vehicles.
It is conceivable to switch from four-wheel drive to two-wheel drive in a situation where S Ill ¥jul is performed, that is, when the brakes are applied. In this case, there are many ways to detect brake operation, such as detecting whether the brake pedal switch or brake fluid pressure switch is ON or OFF. If the brake pedal were to be switched from 1 to 2 wheel drive, the switch from 2 to 4 wheel drive would occur frequently when the brake pedal was depressed lightly or repeatedly. Unfavorable from a performance standpoint.

(Object of the Invention) In view of the above-mentioned circumstances, the present invention provides a brake control device for a four-wheel drive vehicle, which allows a four-wheel drive vehicle to be equipped with the ABS conventionally used in two-wheel drive vehicles. This objective is achieved by switching from 4-wheel drive to 2-wheel drive when the brakes are applied, but by having the A B S fttlJ control perform this switching only when necessary. It is an object of the present invention to provide a brake control device that can reduce the influence on driving performance caused by.

(Structure of the Invention) The brake control device of the present invention includes a four-wheel drive device that drives both the front and rear wheels, and an anti-skid brake system, and detects the deceleration of the vehicle body and the rotational deceleration of the wheels when the brakes are applied. When it is detected that the difference between the speeds of the two wheels is greater than or equal to a preset value, the release means releases the direct connection between the front and rear drive systems, and the AB
This feature is characterized in that S is activated.

(Embodiments) Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing the drive system and AB8 control system of a four-wheel drive vehicle equipped with the brake control device of the present invention.

The driving force of the engine 9 is shifted in a transmission 10 and then transmitted to a transfer 20. The transfer 20 is provided with a 2-4 wheel switching clutch 45, and when 2-wheel drive is selected by the 2-4 wheel switching clutch 45, the transmission 10
The driving force of the engine 9 transmitted to the transfer 20 is output to the rear propeller shaft 8, the rear wheel differential 5, and the left and right rear axle shafts 6a.

6b to the rear wheels 4a, 4b.
Drive b. At this time, no power is transmitted to the front propeller shaft 7, and the front wheels 1a and 1b are in a state where they can freely rotate.

On the other hand, when four-wheel drive is selected by the 2-4 wheel switching clutch 45, the 2-4 wheel switching clutch 45 operates to directly connect the front propeller shaft 7 to the input shaft of the transfer 20. Thereby, the driving force of the engine 9 transmitted to the transfer 20 is transmitted to the front and rear propeller shafts 7.
The transmission is divided into 8 parts, and the front wheel and rear wheel differential 2
, 5 and the front and rear axle shafts 3a, 3b.

5a, 5b to the front wheels 1a, 1b and the rear wheels 4a, 4b, respectively, and the front wheels 18.1b and the rear wheels 4a
, 4b are both driven.

As described above, the 2-wheel drive state or the 4-wheel drive state can be selected, and this 2-4 wheel switching clutch 4
5 is performed by a direct connection release modulator 13, and the operation control of this direct connection release modulator 13 is performed by a direct connection release controller 12.

This car also has ABS installed. This ABS has a speed sensor 56 that detects the rotational speed of each wheel.
AB based on signals from a, 56b, 57a, 57b
The S controller 14 calculates the slip rate of each wheel, outputs an activation signal to the ABS modulator 15, adjusts the brake pressure of each wheel, and controls the slip rate so that it does not exceed a predetermined value. However, when four-wheel drive is selected by the 2-4 wheel switching clutch 45, each wheel is in a directly coupled state, making calculation of the slip ratio inaccurate. Therefore, in this automobile, a brake operation switch is provided, and when the brake is operated, an operation signal 17 is input to the direct connection release controller 12 via a line 17a, and the ABS controller 14 controls the rotational speed of each wheel over time. The wheel rotation deceleration signal obtained by differentiation is also input to the direct connection release controller 12 via line 14a, and furthermore, the vehicle body deceleration signal 16 from the acceleration sensor is also input to line 1.
The signal is input to the direct connection release controller 12 via 6a. Then, when a brake operation is performed and the operation signal 17 is input to the direct connection release controller 12, the vehicle body deceleration signal and the wheel rotation deceleration signal are compared, and when this difference exceeds a predetermined value, In other words, when the rotational deceleration of the wheels is large compared to the deceleration of the vehicle body and the slip rate of the wheels tends to increase rapidly, AB S 61
Since it is necessary to perform J till, the direct connection release controller 12 first operates the direct connection release modulator 13 to switch to two-wheel drive, and then the ABS controller 14 and ABS modulator 15 operate the ABS.

As a result, even if the brake pedal is pressed, the system switches to two-wheel drive and performs ASS control only when the wheel rotational deceleration caused by this brake operation is greater than the deceleration of the vehicle body and ABS control is necessary. This prevents unnecessary switching between 2 and 4 wheels when the brake pedal is depressed or repeatedly depressed, and also reduces the impact on driving performance. .

In addition, detection of brake operation includes detection of brake pedal operation, detection of ON/OFF of a brake pedal switch,
This is done by detecting whether the brake fluid pressure switch is ON or OFF.

Next, the control contents of the direct connection release controller 12 and the ABS controller 14 will be explained with reference to the flowchart of FIG. 2.

This flow starting from step S1 determines whether or not the 2-4 wheel switching clutch 45 is operated in step S2, that is, this clutch 45 is operated and the front and rear propeller shafts 7
．． 8 is directly connected to detect whether or not the vehicle is in four-wheel drive mode. When the vehicle is not directly connected, that is, when the vehicle is in a two-wheel drive state, the process advances to step S3 and this flow ends. however,
If the brakes are activated at this time, the ABS is immediately activated.

When directly connected, that is, when in four-wheel drive mode, step S
4, it is detected whether the brake switch is ON or not based on the brake switch operation signal 17, and if it is OFF, the process advances to step S5 and the flow is ended as it is. When the brake switch is ON, the process proceeds to step S8, where the difference (Ba-Bb) between the wheel deceleration (8a) detected in step $6 and the vehicle body deceleration detected in step S7 is calculated.
) is compared with a predetermined value (Bn).

When (Ba-Bb)<3n, the process proceeds to step S7 and it is determined whether the brake switch is OFF.

If the brake switch is OFF, the process proceeds to step S10 and this flow ends, and if the brake switch is ON, the process returns to step S8. As a result, when the brake pedal is depressed, the wheel deceleration (Ba) is A88 compared to the vehicle body deceleration (8b).
Determine whether a patent featuring control is eligible. In step S8, if it is determined that (Ba-Bb)≧3n, the process advances to step 811 and the direct connection release controller 12
outputs a release signal to the direct connection release modulator 13, and
- Activate the four-wheel switching clutch 45 to switch to two-wheel drive. In step 813, the direct connection release is completed and 2
Once the switch to wheel drive is confirmed, step 8
Proceeding to steps 14 to 816, ABS operation is performed.

ABS is a speed sensor 56a, 56b for each wheel.

The wheel slip rate is calculated from the speed signals from 57a and 57b, and when this slip rate exceeds a predetermined value, an activation signal is issued.When the activation signal is turned ON in step 814, the process proceeds to step S15 and the ABS is activated. is activated, and the ABS modulator 15 lowers the brake fluid pressure acting on the wheels with a large slip ratio to maintain the slip ratio at an appropriate value so that the braking force is always maximized.

Then, the slip ratio decreases and the ABS operation signal turns OFF.
When it is detected that it has become (step 816), the process returns to step S14. In step 314, if the ABS operation signal is not ON, the process advances to step S17 to determine whether the brake switch is OFF, and if it is ON, the process returns to step 814 again to perform ABS operation.

When the brake switch is turned OFF, steps 818~
The process proceeds to step S819, where the direct connection signal is turned OFF, and the front and rear propeller shafts 7.8 are directly connected again by the 2-4 wheel switching clutch 45, returning to four-wheel drive, and then the process proceeds to step S20, where this flow ends.

Next, according to FIG. 3, 411i ff of the transfer 20
2-4 wheel drive switching will be explained.

The input shaft 21 and the output shaft 22 of this transfer 20 are arranged coaxially and separately, and the input shaft 21 is provided with a low speed clutch 23 and a high speed clutch 24, and the output shaft of the high speed clutch 24 is provided with a low speed clutch 23 and a high speed clutch 24. , is formed on the inner surface of an input gear 25 connected to the inner shaft end of the output shaft 22, and when this high-speed clutch 24 is turned on, the output of the input shaft 21 is directly transmitted to the output shaft 22. .

An output gear 26 is formed on the output side of the aforementioned low-speed clutch 23 and is supported on the input shaft 21 via a bearing, and this output gear 26 is connected to the input side 27 of the reduction gear 27.28.
The output side 28 thereof meshes with the input gear 25 described above, and the reduction gears 27 and 28 are rotatably supported by a support shaft 30 installed in the case 29 via bearings.

The above-mentioned output shaft 22 is equipped with a clutch 45 for switching between 2-4 wheel drive.
An output block 31 for front drive is formed on the output side of the clutch 45, and the output shaft 2
It is supported on the second shaft via a bearing. In the lower part of the case 29 mentioned above, there is an input block block 3 for front drive.
2 is pivotally supported via a bearing, and the above-mentioned output block block 3
A chain 33 is strung between 1 and 1. According to the drive system described above, when the low speed clutch 23 is turned on, the output shaft 22 is driven via the output gear 26, the reduction gear 27, 28, and the input gear 25, and when the high speed clutch 24 is turned on, the output shaft 22 is driven. , the output shaft 22 is directly driven. Also 2-4
When the wheel drive switching clutch 45 is turned ON, the driving force of the output shaft 22 is transmitted to the input hex brocket 32 via the output hex brocket 31 and the chain 33.

The flange 34 fixed to the outer end of the output shaft 22 is connected to the aforementioned rear propeller shaft 8, and the rear wheel 4a,
A flange 35 connected to the output side of the manwheel brocket 32 is connected to the front propeller shaft 7 and drives the front wheels 1a and 1b.

At the top of the case 29, there are a pressure regulator valve 36, a manual valve 37. shift valve 38
is provided.

The pressure regulator valve 36 described above is connected to the input shaft 2
The pump discharge pressure of the hydraulic pump 39 provided on the input side of the pump 1 is controlled to a constant pressure.

Further, the manual valve 37 is switched between two-wheel drive and four-wheel drive by operating the operating lever 40 by the driver, and in conjunction with this, the 2-4 wheel switching clutch 45 is operated.

In addition, the shift valve 38 is operated by the direct connection release modulator 13 by the direct connection release controller 12.
The 2-4 wheel switching clutch 45 is operated to switch between 2 wheel drive and 4 wheel drive.

Note that the oil passage 42 from the shift valve 38 is connected to the back side of the piston 43 of the 2-4 wheel switching clutch 45,
By supplying pressure oil thereto, the piston 43 moves and the clutch is turned on. Note that the low-speed and high-speed clutches 23 and 24 are similarly configured.

FIG. 4 shows the operating position of the operating lever 40, and A is the auto position, in which 2-4 wheel drive switching is controlled by a separately provided controller and automatically performed according to driving conditions. In this case, the high-speed clutch 24 is turned on, and the four-wheel drive is set only to high-speed drive.

B, C, and D are positions for manual operation by the driver, and position B is an operation position for two-wheel drive, and the 2-4 wheel drive switching clutch 45 is operated to be OFF. The C position is the high-speed four-wheel drive position, and the high-speed clutch 24.2-4
The wheel drive switching clutch 45 is turned on. The D position is the low-speed four-wheel drive position, and the low-speed clutch 23.2-
The four-wheel drive switching clutch 45 is turned on.

In the above, we have explained the case of a so-called part-time type 4-wheel drive vehicle, but the case of a full-time type 4-wheel drive vehicle has been explained.
The same applies to wheel drive vehicles, and a transformer 7760 for a full-time type is shown in FIG. 5, and its structure and operation will be explained below.

In this transfer 60, a transmission output shaft 61 having a drive gear 61a at one end extends in the vehicle width direction. And this drive gear 6
1a meshes with a large-diameter input gear 71a integrally formed on the outer periphery of a ring gear 71 in the inter-axle differential device 70.

This inter-axle differential device 70 includes the ring gear 71, a sun gear 72 arranged correspondingly thereto, and the ring gear 71.
and a plurality of onions 73 meshing with the sun gear 72...
・73 and these binions 73...73 to bin 74
... 74, and a pinion carrier 75 supported via a planetary gear mechanism. here,
As shown in FIG. 6, a plurality of pinions 7 between a ring gear 71 and a sun gear 72 in the inter-axle differential 70
3...73 are a binion 73a that meshes with the ring gear 71, and the binion 73a and the sun gear 72.
It is a double binion consisting of a binion 73b that meshes with the pinion 73b.

Further, on one side (right side in the figure) of the axle mounting gear @70, a pair of differential case 76 and a pair of radial bins 77 supported at both ends by the case 76 are rotatably fitted. A front wheel differential 80 is arranged, which is comprised of a pinion 78, 78 and a pair of left and right bevel gears 79, 79 that mesh with both the pinions 78, 78. A left front wheel drive shaft 81 and a right front wheel drive shaft 82 extending in the left-right direction are coupled to the bevel gears 79 and 79 of the front wheel differential device 80, respectively. It passes through the center and reaches the left front wheel, and the right front wheel drive shaft 82 reaches the right front wheel.

Binion carrier 75 in the inter-axle differential device 70
and the differential case 76 of the front wheel differential device 180 located on the side thereof are integrated as the same part. Further, the ring gear 7 in the inter-axle differential device 1ff70
1 and the binion carrier 75 (differential case 76) are extended to the right in the figure beyond the front wheel differential device 80, and the same-shaped splines 85 and 86 are formed adjacent to the outer periphery of the extended portion.
and a slider 87 that can slide from a state fitted to one of them to a state fitted across both, thereby coupling the ring gear 71 and the binion carrier 75 in the inter-axle differential device 70. A separate differential lock mechanism 88 is configured.

In this way, the inter-axle differential device 70 and the front wheel differential device W
80 and a differential lock mechanism 88 of the inter-axle differential 70 are arranged coaxially with the front wheel differential 80 in the center.

On the other hand, an intermediate shaft 89 is arranged parallel to the axle center of the inter-axle differential device 70 and the front wheel differential device 80 at a constant distance. A gear 90 integrally formed with the intermediate shaft 89 is meshed with a gear 91 integrally formed with the sun gear 72 of the inter-axle differential device 70.
A second intermediate shaft 92 is disposed on the extension of the rain intermediate shaft 89.
A slider 95 is fitted into a spline 93.94 formed at an adjacent end of the shaft 92, and the rain intermediate shaft 89.92 is connected or separated by the sliding of the slider 95. Further, the second intermediate shaft 92 has an output gear 96.
A bevel gear 98 integral with a propulsion shaft 97 extending in the longitudinal direction of the vehicle body is meshed with the gear 96. This propulsion shaft 97 leads to a rear wheel differential device, and drives the left and right rear wheels via left and right rear wheel drive shafts extending left and right from the device.

According to the above configuration, the rotation of the crankshaft in the engine is input to the transmission, and after a reduction ratio is selected in the transmission, the rotation is transmitted from the drive gear 61a on the output shaft 61 to the input gear 71a to the axle. The signal is input to the ring gear 71 in the differential gear 70 . The power input to the ring gear 71 is divided by the inter-axle differential 6o and outputted from the binion carrier 75 and the sun gear 72, respectively.
The output from the binion carrier 75 drives the left and right front wheel drive shafts 81 and 82 or the left and right front wheels via the front wheel differential device 80. Further, the output from the sun gear 72 is transmitted to the gear 91.
．． 90, a propulsion shaft 97 is driven through an intermediate shaft 89.92 and an output gear 96, and the left and right rear drive shafts or rear wheels are further driven through a rear wheel differential. In this case, the splines 93°94 of the intermediate shaft 89 and the second circular shaft 92
If the slider 95 fitted across the front wheel is slid as shown by y in FIG. 5 to separate the rain intermediate shaft 89°92, the output of the engine will be transmitted only to the front wheels. That is, by operating the slider 95, it is possible to switch between two-wheel drive and four-wheel drive, thereby enabling two-wheel drive and ABS operation as needed.

In addition, the state in which the rain intermediate shafts 89 and 92 are combined, that is, 4
In the wheel drive state, slide the slider 87 in the differential lock mechanism 88 of the inter-axle differential 70 as shown by the chain line
If you fit across splines 85 and 86 in
By coupling the ring gear 71 and the binion carrier 75, the differential function of the axle mounting gear WI70 is eliminated, and a differential lock can be performed.

(Effects of the Invention) As described above, according to the present invention, when the brake is operated, the wheel deceleration (Ba) and the vehicle body deceleration <Bb) are detected, and the difference between these decelerations ( Ba-8b)
is above a predetermined value (8n), the direct connection between the front and rear drive systems is released, the system becomes two-wheel drive, and the anti-skid braking system (ABS) is activated. , ABS conventionally used in two-wheel drive vehicles can be used as is in four-wheel drive vehicles.
Not only is it possible to perform good brake control even in 4-wheel drive I, but it is also possible to switch to 2-wheel drive with A.
B S 11m is applied only when the brake pedal is required, that is, when the wheel deceleration during brake activation is larger than the vehicle body deceleration, thereby preventing the so-called "single depression" or repeated depression of the brake pedal. Therefore, it is possible to prevent unnecessary 2-4 wheel drive switching from being performed, and the influence of 2-4 wheel drive switching on the driving performance of the vehicle can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the drive system and ABS control system of a 4-wheel drive vehicle equipped with the brake control m+ device of the present invention, Fig. 2 is a flowchart showing the details of ABS control, and Fig. 3 is a part-time 4-wheel drive vehicle. Fig. 4 is a front view showing the 2-4 wheel switching operation lever; Fig. 5 is a sectional view showing the transfer of a full-time four-wheel drive vehicle; Fig. 6 is the same as Fig. 5. It is a sectional view taken along arrow T. 7.8... Propeller shaft 10... Transmission 20... Transfer 23... Low speed clutch 24... High speed clutch 31... Sprocket 3
3...Chain 40...Operation lever 45.
...2-4 wheel drive switching clutch 70...Axle suspension gear fit 71...Ring gear 72...Sun gear 73...Binion 75...Binion carrier 80...Front wheel differential gear Figure 1 (Voluntary) Procedure Neho, Commissioner of the Patent Office, September 1986
9th 2, Name of the invention: Brake control device for four-wheel drive vehicles 3, Relationship to the case of the person making the amendment Patent applicant address: 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Name: Mazda Motor Corporation 4, Agent: 106 5-2-18 Roppongi, Minato-ku, Tokyo, Contents of amendment 1) Page 3, line 10 of the specification, after ``in case,'' ``For example, when the four wheels are part-time, in a driving state, or in a full-time differential lock state, etc. ” is inserted. 2) Line 11 of the same page, “Correct the connection j to ``direct connection.'' 3) Line 20 of the same page to line 1 of page 4, “Four-wheel drive...possible.” was changed to “Cancelling the four-wheel direct connection state, such as releasing the differential lock, or switching the four-wheel drive to two wheels.” ``One possibility is to switch to wheel drive.'' he corrected. 4) On page 4, lines 5 and 6, "4-wheel drive...drive" is corrected to "disengaged state from front and rear wheels directly connected state." 5) Line 8 of the same page [2-4 wheel drive J is corrected as "from the front and rear wheels directly connected state to the released state". 6) In line 16 of the same page, ``4-wheel drive is replaced by 2-wheel drive'' is corrected to ``the state in which the front wheels are directly connected is released.'' 7) Delete "2-4 wheel drive... will be implemented" in lines 13 to 15 of page 15. 8) After "operated" on page 16, line 5 of the same book, [when the brakes are applied, the front and rear wheels can be switched from the directly connected state to the released state, regardless of the lever position, at any position A, C, or D. Switching between direct connection and release is controlled by a separately provided controller and is automatically performed according to driving conditions. ” is inserted. 9) After "Drive" on page 20, line 11, [in the state where the intermediate shafts 89 and 92 are connected, that is, in the four-wheel drive state, the slider 87 in the differential lock mechanism 88 of the inter-axle differential device 70 is indicated by a chain line. If the ring gear 11 and the binion carrier 75 are slid together as shown by x and fitted across the spline f35.86 of the ring gear 11 and the binion carrier 75, the inter-axle differential device 70
This eliminates the differential capability of the engine, allowing differential lock to be performed. By operating the slider 87, the front and rear wheels can be directly connected and disconnected, thereby allowing the direct connection to be canceled and the ABS to be activated as needed. ” is inserted. 10) On the same page, ``In this case,'' was changed to ``Also, as shown in Figure 5,
” he corrected. 11) In the 14th line of the same page, "as indicated by the demotion y" is corrected to "the position of the chain line y". 12) In line 19 of the same page, ``koto'' is corrected to ``kotomo.'' 13) Same page, line 20 to page 21, line 9 “In addition,...
...It's happening. ” to be deleted. 14) On page 21, line 15 of the same page, correct J to [cancel or cancel]. 15) "Two-wheel drive" in the first line of page 22 is corrected to "a state in which the front and rear wheels are directly coupled to a released state." 16) On the same page, cylinder 611, "2-4 wheel drive" is corrected to "from a directly connected state of the front and rear wheels to a released state." 17) Tubes 7 to 8 on the same page (1 "2-4 wheels" to "from a directly connected state of the front and rear wheels to a released state")
I am corrected. 18) On the 9th line of the same page, correct "I can do it." to "I can do it."

Claims (1)

[Scope of Claims] A brake control device for a four-wheel drive vehicle, comprising a four-wheel drive device that drives front and rear wheels, and an anti-skid brake system that controls braking force during braking and prevents the wheels from locking up. A vehicle deceleration detection means for detecting the deceleration of the vehicle body when the brakes are applied, a wheel deceleration detection means for detecting the rotational deceleration of the wheels when the brakes are applied, and output signals from both detection means are compared. and a release means for releasing the direct connection between the front and rear drive systems of the four-wheel drive device and activating the anti-skid brake system when the difference between the output signals exceeds a preset value. A brake control device for a four-wheel drive vehicle characterized by the following features: