JPH01193441A - Speed change control device for automatic transmission - Google Patents

Abstract

PURPOSE:To avoid the danger due to slip, when slip is detected by both the acceleration calculated from the front and rear wheels of a vehicle and the vehicle body acceleration and if it is judged that a road surface is to be a low mu load surface, by shifting up the gear to a higher speed change stage than the ordinary speed change stage. CONSTITUTION:The acceleration Gv of wheels is calculated from the respective average wheel velocities of a vehicle having been input into a speed change stage control part 26a, and then the difference G between this Gv and the vehicle body acceleration G detected by an acceleration sensor 22 is obtained. By comparing this G with a predetermined threshold valve G, if G> Gs, it is judged that there is slip, and further the vehicle body acceleration G is made to be the maximum frictional coefficient mumax of a road, which is compared with the criterion value mus for a low mu road surface, and if mumax<mus, it is judged that the road surface is to be a low mu road surface. On the other hand, the speed change stage signal P comforming to the present operating condition is corrected by the correcting signals or the like from a low mu road surface judging means 35, and a speed change stage control signal 29 is output.

Description

[Detailed description of the invention] [Industrial application field]

The present invention is based on a speed change control device G (system) for an automatic transmission, in particular, it shifts gears according to fluctuations in the maximum coefficient of friction between the wheels in motion and the road surface, thereby reducing the risk of slipping during driving. The present invention relates to a device that controls the vehicle to avoid the problem.

[Prior Art] If slip occurs between the wheels and the road surface while the vehicle is running, it may become difficult to control the cow, resulting in a dangerous situation. In other words, on wet or frozen roads (low μ road surfaces), the maximum coefficient of friction with the tire surface becomes smaller.
The tire's grip on the road decreases, so if you press the accelerator in this condition, the tire will slip. Therefore, various control devices have been considered to prevent the above-mentioned slip. For example, the device described in Japanese Patent Application Laid-Open No. 60-176828 detects this slip based on the difference in rotational speed between the front wheels and the rear wheels, shifts the gear to the high speed side based on this detected value, and By reducing the transmitted driving force, the dangers caused by slipping are avoided. [Problems to be Solved by the Invention] However, in the conventional transmission control device as described above, slip is detected based on the rotation difference between the front and rear wheels, and the automatic transmission is operated based on the detected slip amount to change the gear position. Since the shift is performed, slipping is not avoided, and depending on the degree of slippage before the shift operation, the vehicle may reach a dangerous state. The present invention has been made to solve these problems, and is based on the driving environment such as the wheel speed and acceleration of the vehicle in motion. If so, it is predicted that the vehicle will be traveling on a low-μ road for a predetermined period of time, and the vehicle will accelerate. The object of the present invention is to provide a shift control device for an automatic transmission that can avoid danger caused by slips and drive safely by correcting the gear position so as to prevent slips when restarting. .

[Means to solve the problem]

In order to achieve the above object, a shift control device for an automatic transmission according to the present invention has a gear position determining means for determining a gear position according to the operating state, and a signal from the gear position determining means is transmitted to a hydraulic control unit. In a shift control device for an automatic transmission that switches gears based on a given amount of time, a slip determination means determines the slip state of the vehicle, and the output of the slip determination means and the acceleration of the vehicle body detected by an acceleration sensor are used to detect danger on the road surface. A low-μ road surface determination means for determining a friction coefficient, and a low-μ
a gear position correcting means for correcting the gear position determined by the gear position determining means when it is determined that the vehicle is on a road surface, and a gear position control signal outputted to the hydraulic control unit in response to an output of the gear position correcting means. The gear shift control means is also provided with a gear position control means. (Function 1 Based on the above configuration, when a slip is detected from the acceleration obtained by differentiating the average wheel speed of the front and rear wheels of the vehicle and the vehicle body acceleration detected by the acceleration sensor, the low μ road surface determination means determines that the road surface is low μ. Then, the gear position correction means shifts up the gear position, and then predicts that the vehicle will be traveling on a low μ road surface for a predetermined period of time, and shifts up from the normal gear position before the vehicle starts slipping when accelerating or restarting. This avoids slips and ensures driving safety.

[Example] Hereinafter, the present invention will be specifically described with reference to an example. FIG. 1 is a configuration diagram showing an example of a drive system of a four-wheel drive vehicle equipped with a center differential and capable of torque split control. Reference numeral 1 is an engine, which transmits power to a transmission 3 via a torque converter 2. It looks like this. The output shaft 4 of this transmission 3 is connected to a carrier 5a of a planetary gear type differential gear device 5, and is connected to a sun gear 5 via a planetary pinion 5b provided on this carrier 5a.
Output torque is distributed to C and ring gear 5d, respectively. This torque distribution is, for example, 40% to the sun gear 5C and 60% to the ring gear 5d. The sun gear 5C is connected to the rear drive shaft 6, and transmits torque to the rear axles 8R, 8L via the differential device 7. On the other hand, the ring gear 5d is integrated with the output shaft 4.
It is connected to a front drive shaft 11 via a gear 9 rotatably provided and a gear 10 that meshes with the gear 9, and from the front drive shaft 11 is connected to a front axle 13R713 [Hetorque] via a differential gear device 12. communicate. Further, a distribution shaft 15 for torque split control is connected to the rear end of the front drive shaft 11 via a wet multi-disc split clutch 14. axis 1
1 is transmitted to the rear drive shaft 6 via gears 16 and 17. The split clutch 14 is hydraulically controlled via a hydraulic control circuit 18 to enable torque transfer between the front drive shaft 11 and the rear drive shaft 6. The hydraulic control circuit 1
8 exhibits its #Ja function through the action of the solenoid valve 19. The above four-wheel drive vehicles are each car! ! Rotation speed sensor 21FR installed in 20FR, 20FL and 20RR, 20R+,
21FL, 21RR, 21RL, and an acceleration sensor 22. Gear position sensor 23. Throttle opening sensor 24. Accelerator operation amount sensor 25. Furthermore, it is equipped with various other sensors, and the output signals of these sensors are supplied to the electronic control unit 26. Then, the electronic control unit 26 calculates a clutch pressure control signal 27 for the solenoid valve 19 based on the given information according to a predetermined program. transmission 3
A gear position control signal 29 for shifting the gear position. The pond outputs an output signal for operation control. The transmission 3 has a hydraulic control unit 3a for automatic gear shifting operation, and actuators such as electromagnetic valves in the hydraulic control unit 3a are operated by a gear position control signal 29 from the electronic control unit 726. By doing this, the gear stage is changed. FIG. 2 shows the gear stage control section 26a in the electronic control unit 26 and each sensor 21FR input thereto. It is a plotter diagram showing the configuration of 21FL, 21RR, 21RL, 22, 23.24. Each wheel rotation speed sensor 21 input to the gear stage control section 26a
The detected values of FR, 21FL, 21RR, and 21RL are processed by calculating the average wheel speed V in the average wheel speed calculating means 30, and from this V, the differential value GV =
dV/dt is calculated, the difference ΔG between this Gv and the detected value G of the acceleration sensor 32 is determined by the difference signal detection means 32, and the slip determination means 34 compares the above ΔG with a preset threshold value ΔGs. , ΔG>ΔGs, it is determined to be a slip. Furthermore, at this time, the low μ road surface determining means 35 stores the detected value G of the acceleration sensor 22 in the memory as the maximum 1 friction coefficient μn1aX of the road surface, and combines this μInaX with the low μ road surface. It is compared with the determination value μS, and when μmax < μS, it is determined that the road surface has a low μ. The low-μ road surface determining means 35 determines that the low-μ road surface continues for a predetermined period of time after the previous slip detection on the low-μ road surface. On the other hand, the gear stage determining means 36 includes an average wheel speed calculating means 30. Gear position sensor 23. Signals from each of the throttle opening sensors 24 are input to determine a gear stage suitable for the current driving condition, and this determined 3M gear stage signal P is converted into a correction signal SR from the low-μ road surface determining means 35. The gear position correction means 37 corrects the change rate of the accelerator operation amount detected by the accelerator operation amount sensor 25, and the actuator such as a solenoid valve that constitutes the hydraulic control unit of the transmission 3 is corrected by the corrected gear position correction signal PR. The gear position control means 38 that drives the gear position control means 38 is activated, and the gear position control signal 29 is output. Next, the procedure for executing calculations in the electronic control unit 26 configured as described above will be specifically explained based on the flowchart shown in FIG. First, in step 5100, the slip flag S is cleared (
First, the difference ΔG between the differential value Gv = dv/dt of the average wheel speed ■ obtained by the differentiating means 31 in step 5101 and the detected value G from the acceleration sensor 22 is Compare 〇s to the threshold, ΔG〉ΔG
If S, it is determined that there is a slip and step 510
2, the maximum friction coefficient μnax of the road surface is detected based on the acceleration G of the vehicle (μ≠G), and the next step 510
Move to 3. Here, the maximum friction coefficient μlaX is compared with a predetermined value μS, and when μmax×μS, it is determined that the road surface has a low μ. If it is determined in step 5103 that the road surface is a low μ road surface, a low μ road surface flag F is set in step 5104, and then the process moves to step 5105, and it is determined that the acceleration or start time is determined based on the rate of change of the accelerator operation amount d'//dt. If dIp/dt≧β (β is a predetermined value) and it is time to accelerate or start, in step 5106, for example, the gear determined by the gear determining means 36 or 43M (forward 4
If the speed is 4, then step 5.
At step 107, it is determined whether the shift up flag S is set.
If not, issue a signal to shift the gear by one gear (step 5108), and step 5109, 5.
Steps 110 and 5111 are set, and the shift up flag S is set (S=1), and the gear stage is held in the 1 shift door knob state until a predetermined time period has elapsed (t1=Tt), and after the predetermined time period has elapsed, the step 5113. At step 3114, the shift up flag S is lowered (5=0) and the timer t1 is cleared (t1=O), and then normal shift control is resumed. In addition, if it is determined in step 5103 that the road surface is not low μ, and if it is determined in step 5104 that the road surface is not accelerating or starting, then step 31
If the gear position is 4th speed in step 06, the process moves to step 5112, and if the shift-up flag S is not set (S=0), no shift operation is performed, and if the shift-up flag S is set ( S=1), step 5113,5
After proceeding to step 114 and lowering the shift-up flag S and clearing the timer t1, normal shift control is resumed. Also, in step 5107 above, the shift up flag S
is set, steps 5108 and 5109 are skipped, the timer is counted in the same manner as above, and it is determined whether or not a predetermined time has elapsed. Furthermore, if it is determined in step 5101 that there is no slippage at ΔG, then step 811
In step 6, it is determined whether or not the shift-up flag S is set, and if the shift-up flag S is set and shift-up control is in progress when a slip is detected on a low μ road surface, the process moves to step 8106, and as described above. control,
If the shift up flag S is off, proceed to step 5.
At step 117, it is determined whether the low μ road surface flag F is set and the vehicle is running on a low μ road. If it is set, when it is determined at step 5118 that the vehicle is accelerating or starting, the process jumps to step 5106 to prevent a slip from occurring. To prevent this, the gears must be upshifted. On the other hand, unless you are accelerating or starting,
In steps 5119, 3120, and 5121, a predetermined time T2 after slipping is avoided while driving on a low μ road surface is measured, and it is predicted that the vehicle will be traveling on a low μ road surface within the predetermined time T2, and after the predetermined time T2 has elapsed, the low μ road surface Lower flag F (F=0
) It is predicted that the low μ road surface will be released (step 3123). Further, when it is determined in step 5119 that the vehicle is stopped based on the signal from the average wheel speed calculating means, the count of the timer t2 is also stopped. Through the execution procedure described above, a slip condition is detected based on wheel speed, acceleration, etc., and if it is determined that the vehicle is driving on a low μ road surface, the acceleration is suppressed by shifting up the gear and the dangerous situation due to slip is eliminated. In addition, even after avoiding a slip condition on a low-μ road surface, the system predicts that the low-μ road surface will be lifted within a predetermined time, and if acceleration or starting is performed within that time, the system will shift before the slip occurs. By moving up, you can avoid dangerous situations caused by slipping. In the above embodiment, the case of four forward speeds has been described, but the same effects as in the above embodiment can be obtained even if the present invention is applied to control of a plurality of other gears. Further, the determination of slip is not limited to the above-mentioned embodiment, and any other method may be used, such as, for example, in the case of a two-wheel drive vehicle, determination may be made based on the rotational speed difference between the driving wheels and the driven wheels. [Effects of the Invention] As explained above, the present invention determines a low μ road surface when a slip condition is detected based on the wheel speed of a running vehicle, the acceleration of the vehicle body, etc. In this case, the system predicts that the vehicle will continue to run on low-μ roads for a predetermined period of time, and shifts gears when accelerating or starting to prevent slips and slips, thereby avoiding the risk of slipping on low-μ roads. , can ensure driving safety.

[Brief explanation of the drawing]

Fig. 1 is a schematic plan view of a four-wheel drive vehicle showing an embodiment of the present invention, Fig. 2 is a block diagram showing the configuration of an electronic control unit according to the invention, and Fig. 3 is the electronic control unit of Fig. 2. 2 is a flowchart for explaining the execution procedure. 22... Acceleration sensor, 29... Gear position control signal,
30... Average wheel speed calculating means, 31... Differentiating means, 32... Difference signal detecting means, 33... Comparing means, 3
4...Slip determination means, 35...Low μ road surface determination means, 37... Gear stage correction means, 38... Gear stage control means, ΔG... Threshold value. Patent applicant: Fuji Heavy Industries Co., Ltd. Agent: Patent attorney: Makoto Kobashi Ukiyo Patent attorney: Susumu Murai

Claims (1)

[Claims] In a shift control device for an automatic transmission, which has a gear position determining means that determines the gear position according to the driving state, and which switches the gear position by giving a signal from the gear position determining means to a hydraulic control unit, the vehicle slip a slip determining means for determining the state; a low μ road surface determining means for determining the maximum friction coefficient of the road surface based on the output of the slip determining means and the acceleration of the vehicle body detected by the acceleration sensor; Then, a gear position correcting means for correcting the gear position determined by the gear position determining means, and a gear position control means for receiving the output of the gear position correcting means and outputting a gear position control signal to the hydraulic control unit. A speed change control device for an automatic transmission, comprising: