JPH0526983B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a shift control device that controls the shift position of an automatic transmission for a vehicle, and more particularly to a shift control device that performs shift control that can prevent rotational slip of drive wheels. (Prior Art) If slips occur between the wheels and the road surface while the vehicle is running, steering control becomes extremely difficult and dangerous, so various measures to prevent slips have been devised. For example, an anti-skid brake that weakens the braking force if the wheels slip when the brake is applied is one example.
As disclosed in No. 102773, a proposal has also been made to shift the gear position of the automatic transmission to a position where engine braking is less likely to be applied during anti-skid operation, thereby preventing slippage caused by engine braking and increasing the effectiveness of the anti-skid device. ing. Slip becomes a problem not only when the brakes are applied as described above, but also when the accelerator is depressed on wet or icy roads, or when shifting gears. wet road surface,
When the stiffness coefficient between the tires and the road surface decreases due to freezing, etc., and the grip force of the tires decreases, the driving force that the tires can transmit to the road surface decreases by the amount that the grip force decreases. Hereinafter, such a road surface will be referred to as a low μ road. Therefore, in such a state, slips are likely to occur due to changes in the torque transmitted to the tires when the accelerator is depressed or when changing gears. The driver can adjust the accelerator depression according to his will, but in the case of so-called automatic cars equipped with an automatic transmission, the gear shift is determined at the time of manufacture, and the driver is free to adjust the gear shift even if the road is slippery. It's not something that can be adjusted. For this purpose, it would be better to use an automatic transmission with fewer gear shifting shocks from the time of manufacture.
In this case, there is a strong possibility that the durability of the frictional engagement member may be reduced due to an increase in heat generation in the frictional engagement member that changes gears. (Object of the Invention) The present invention has been made in view of the above circumstances, and provides a vehicle for use in which the engagement speed of a frictional engagement member is reduced only during gear shifting when slippage of the drive wheels is detected, thereby softening the gear shifting shock. An object of the present invention is to provide a shift control device for an automatic transmission. (Structure of the Invention) The shift control device of the present invention determines the occurrence of slip in the driving wheels by the slip determination means, and when the slip occurrence is detected, outputs a slip detection signal to the shift buffer means, and the shift buffer means detects the slip. The present invention is characterized in that the engagement speed of the friction member is reduced during a gear shift performed while receiving a detection signal. (Effects of the Invention) According to the present invention, when the slip determination means detects the slip of the driving wheels from the rotation difference between the front and rear wheels and it is determined that the vehicle is traveling on a low μ road, the shift buffer means is activated when the gear is changed. It operates to reduce the engagement speed of the friction member, which suppresses the rate of change in torque transmitted to the tires that occurs during gear shifting, allowing for gentle and less shock shifting, which prevents tire slippage and improves vehicle stability. spin etc. can be effectively prevented. Further, the transmission control device of the present invention requires only a partial improvement of a conventional automatic transmission, and can be easily used in conventional automatic vehicles. (Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 schematically shows the operating system of the speed change control device of the present invention. In this example, the output of the engine 3 is changed speed by the automatic transmission 4, transmitted to the differential gear 6 via the propeller shaft 5, and By rear wheel 2
L and 2R are driven. Front wheel rotation speed detection means 11L, 11R for detecting rotation of front wheels 1L, 1R
Then, the slip determining means 13 receives the signals from the rear wheel rotational speed detecting means 12L, 12R for detecting the rotation of the rear wheels 2L, 2R, and determines whether or not there is a slip based on the difference in the rotational speed of the front and rear wheels. In other words, when there is no slip, the rotational speed of both wheels is the same as long as the outer diameters of the front and rear wheels are the same, but if the rear wheel, which is the driving wheel, slips, the rotational speed of the rear wheel becomes greater, so slipping occurs. can be detected. When the occurrence of a slip is detected, a slip detection signal is output from the slip determination means 13 to the shift buffer means 14, and the shift buffer means 14 receives the slip detection signal.
is the automatic transmission 4 when changing gears in the automatic transmission 4.
It operates to reduce the engagement speed of the friction member that changes gears. A preferred embodiment of the speed change buffering means 14 includes one in which engagement of the friction member is performed by hydraulic pressure, and a line pressure adjustment device for reducing the hydraulic pressure is used as the buffering means. FIG. 2 shows an automatic transmission 4 according to an embodiment of the present invention.
FIG. 2 is a diagram showing a cross section of the hydraulic pressure control circuit which is an adjustment device. The automatic transmission 4 includes a torque converter 41 on an engine output shaft 40 that converts and outputs the output of the engine 3 according to the load and speed ratio, and an overdrive planet arranged in series that changes the output of the torque converter 41. It consists of a gear transmission mechanism 42 and a multi-stage gear transmission mechanism 43, and hydraulic pressure is selectively supplied to the hydraulic clutches and brakes in both mechanisms 42, 43 by a hydraulic control circuit to effect gear changes. The hydraulic control circuit includes a town pressure valve 21 and a select valve 2.
2, 1-2 shift valve 23, 2-3 shift valve 24,
3-4 shift valve 25, first to fourth solenoid valves
SL1 to SL4, a second lock valve 26, a cutback valve 27, a vacuum throttle valve 28, a throttle back-up valve 29, etc. are arranged as shown in the figure. The select valve 22 and the first to fourth solenoid valves SL1 to SL4 are operated in conjunction with the driver's shift lever operation.
Depending on the ON/OFF state, these valves selectively supply hydraulic pressure to the clutches and brakes of the transmission mechanisms 42, 43, thereby changing speeds in a well-known manner. The actuators 44 and 45 are used to operate the brakes within the transmission mechanisms 42 and 43. Also,
The fourth solenoid valve SL4 is the torque converter 4
The first to third solenoids SL1, SL2, SL3 are used to operate the first lock-up mechanism 41a.
is used for shifting. The relationship between the ON/OFF combinations of the first to third solenoids SL1, SL2, and SL3 and the shift position is set as shown in Table 1, for example.

[Table] Furthermore, this hydraulic control circuit includes a clutch that acts on the lower end of the pressure regulating valve 21 in the figure to change gears, and a line pressure in hydraulic pressure supply lines 31a and 31b that determines the magnitude of the hydraulic pressure supplied to the brake. Adjustment valve 31
is provided. This line pressure regulating valve 31 is
It is activated by the signal from the 2AND circuit 35, and when the signal from the 2nd AND circuit 35 is OFF, the normal line pressure determined only by the pressure regulating valve 21 is generated, and when the above signal is ON, the pressure regulating valve It operates so that the line pressure of 21 is lower than normal oil pressure. To explain the generation circuit of this signal,
The shift controller 32 outputs an ON signal when shifting, and the front wheel and rear wheel rotational speed detection means 1
The slip determining means which receives the signals from the terminals 1 and 12 outputs an ON signal when a slip is detected. The first AND circuit 33 that receives both of these signals outputs an ON signal when both of these signals are ON, that is, when a gear shift is being performed and a slip is detected. The output of the first AND circuit 33 is 2 on the way
One is input directly and the other is input to the second AND circuit 35 via the timer 34. Therefore, when the ON signal is output from the first AND circuit,
The second AND circuit 3 is activated for a certain period of time determined by the timer 34.
5 outputs an ON signal to the line pressure regulating valve 31. With the above configuration, when changing gears when a slip is detected, the line pressure is reduced for a certain period of time from the start of the gear change. As a result, it is possible to reduce the engagement speed of the friction member during gear shifting and achieve smooth gear shifting.
Furthermore, after a certain period of time has elapsed from the start of the shift and the engagement of the friction member is completed, the line pressure is returned to its original state to prevent abnormal slippage of the friction member and to prevent a decrease in durability. FIG. 3 shows an overall flowchart of the shift control, and as can be seen from this figure, the shift control is first performed from initialization settings. In this initialization setting, first initialize the ports of each control valve that switches the hydraulic control circuit of the automatic transmission and the necessary counters, and then
is set to first gear, and the lock-up clutch 41a is set to released. After this, various working areas of the electronic control circuit are initialized to complete the initialization settings. Next, 1 is subtracted from the value of timer T, which is used to set the speed at which this flowchart is executed, and that value is replaced by T. For example, if T = 20, this means that the timer will be reset by executing the flow 20 times, and if the timer is reset every second, the main program will be reset 20 times per second. is carried out. After this, a step is performed to read the position of the select valve 22, that is, the shift range. Next, it is determined whether the read shift range is the 1st range. When this determination is NO, it is determined whether the shift range is the 2nd range.
When this determination is YES, that is, when the shift range is the 2nd range, a signal is generated to control the shift valve so as to release the lockup and shift the gear transmission mechanism 43 to the second speed, and then the process proceeds to step S1. On the other hand, when the above-mentioned determination of 2 ranges is NO, the shift range is the D range, so a shift and lockup map including a shift change control line and a lockup control line corresponding to the gear position in the D range is set. Next, shift-up speed change control including a shift-up determination is performed. This shift-up speed change control is
The shift-up speed change control subroutine shown in FIG. 5 is executed, and then the shift-down speed change control according to the shift-down speed change control subroutine shown in FIG. 7, and the lock-up control according to the lock-up control subroutine shown in FIG. 9 are executed in this order. is carried out, and the process proceeds to step S1. Further, when it is determined that the shift range is in the 1st range, the lockup is first released, and then it is calculated whether or not the engine will overrun when downshifting to the 1st speed. After this, based on this calculation, it is determined whether or not there will be an overrun.
When the determination is NO, the gear is shifted to the first gear, and when this determination is YES, the gear is shifted to the second gear. After this, step
Proceed to S1. In step S1, a certain time delay is created in order to determine the speed at which this flowchart is executed; for example, after creating a time delay of 50 milliseconds, the flowchart is re-executed. This time delay in step S1 is related to timer T. For example, if the initial value of timer T is T = 20, a time delay of 50 msec is repeated 20 times, resulting in a time delay of 1 second, so timer T will be reset every second. Thereafter, it is determined whether or not the vehicle is traveling on a low μ road, and the process returns to step S2, where this flow is repeated. The determination of whether or not the vehicle is traveling on a low μ road is made based on the subroutine shown in Fig. 4. After reading the driving wheel rotation (N _D ) and the driven wheel rotation (N _C ) using the rotation speed detection means, both The absolute position of the difference |N _D −N _C | is compared with the slip judgment reference value N _L , and |N _D −N _C |
>N _L , set the low μ flag to 1, |N _D −N _C |
When ≦N _L , the low μ flag is set to 0. Shift-up speed change control This shift-up speed change control, as shown in FIG.
The process starts by determining whether or not the vehicle is currently in fourth gear. When this judgment is YES, it is not possible to shift up any further, so
Terminates shift-up speed change control. On the other hand, if the above judgment as to whether or not it is in 4th gear is NO,
The throttle opening is read by the throttle opening sensor, and the turbine speed: TSP (MAP) corresponding to the read throttle opening is read from the shift up map shown in FIG. 6, for example. That is, in FIG. 6, the turbine rotational speed corresponding to the throttle opening is read on the shift-up speed change line Mfu (solid line). Next, the actual turbine rotation speed is determined by the turbine rotation speed sensor:
Detect TSP and turbine rotation speed on map:
Compare with TSP (MAP). When TSP≦TSP(MAP), that is, when the actual turbine speed is on the lower side (left side) than the shift-up speed line Mfu (solid line) in Fig. 6,
2nd shift up line equal to TSP (MAP) x 0.8
Set Mfu′ (dashed line), TSP(MAP)×0.8 and TSP
Compare with. When TSP>TSP(MAP)×0.8, that is, when TSP is located on the higher rotation side than the second shift-up transmission line Mfu' (broken line), the shift-up transmission control is terminated. When TSP≦TSP(MAP)×0.8, that is, when TSP is located on the lower rotation side than the second shift up shift line Mfu' (broken line), the flag 1 is set to 0 and the shift map shift control is ended. This flag 1 is set when a shift-up is executed, and is used to store the shift-up state. When TSP > TSP (MAP), that is, in Fig. 6, the shift-up speed is higher than the speed line Mfu.
When there is TSP, determine whether flag 1 = 1 or not,
When flag 1=1, it indicates that upshifting has already been performed, and the upshifting speed change control is ended as it is. When flag 1 = 0, after setting flag 1 = 1, it is determined whether the low μ flag = 1. If the low μ flag = 1, the line pressure regulating valve is turned on to lower the line pressure and the line pressure is Set the decline flag to 1. When the low flag=0, the line pressure drop flag is kept at 0, and the line pressure is also kept as is. In either case (both when the low μ flag = 1 and when the low μ flag = 0), a one-stage shift-up is performed and a lockup release timer is set. Thereafter, it is determined whether the line pressure drop flag is 1 or not, and if it is 1, the line pressure drop flag is set to 0 after a certain period of time has elapsed and this flow is ended, and if it is 0, this flow is ended as is. When the shift-up speed change control is completed as described above, the shift-down speed change control shown in FIG. 7 is executed next. Downshift Control This downshift control first reads the gear position, that is, the position of the gear transmission mechanism 43, and based on this read gear position,
The process starts by determining whether or not the vehicle is currently in first gear. When this judgment is YES, no further downshifts can be performed, so
Terminate downshift control. On the other hand, if the above determination of whether or not it is in 1st gear is NO,
The throttle opening is read by a throttle opening sensor, and for example, in the downshift map shown in FIG. 8, the turbine speed: TSP (MAP) corresponding to the throttle opening is read. That is, in FIG. 8, the downshift line Mfd
Read the turbine rotation speed corresponding to the above throttle opening on the (solid line). Next, the actual turbine rotation speed: TSP is detected by the turbine rotation speed sensor, and the turbine rotation speed: TSP is displayed on the map.
Compare with (MAP). When TSP≧TSP(MAP), that is, when the actual turbine speed is on the higher side (right side) than the downshift shift line Mfd (solid line) in Fig. 8, the second Set the downshift shift line Mfd′ (dashed line), TSP (MAP) x
Compare 1.25 and TSP. TSP＜TSP(MAP)×
At 1.25, that is, the second downshift line
When TSP is located on the lower rotation side than Mfd' (broken line), downshift control is ended. TSP≧TSP
When (MAP)×1.25, that is, when the TSP is located on the higher rotation side than the second downshift shift line Mfd' (broken line), the flag 2 is set to 0 and the downshift shift control is ended. This flag 2 is set when a downshift is executed, and is used to store the downshift state. When TSP<TSP(MAP), that is, in Fig. 8, the speed is lower than the downshift line Mfd.
When there is TSP, determine whether flag 2 = 1 or not,
When flag 2=1, it indicates that a downshift has already been performed, and the downshift speed change control is ended as it is. When flag 2 = 0, after setting flag 2 = 1, it is determined whether the low μ flag = 1. If the low μ flag = 1, the line pressure regulating valve is turned on to lower the line pressure and the line pressure is Set the decline flag to 1. When the low μ flag=0, the line pressure drop flag is kept at 0, and the line pressure is also kept as is. In either case (both when the low μ flag = 1 and when the low μ flag = 0), a one-stage downshift is performed and a lockup release timer is set. Thereafter, it is determined whether the line pressure drop flag is 1 or not, and if it is 1, the line pressure drop flag is set to 0 after a certain period of time has elapsed and this flow is ended, and if it is 0, this flow is ended as is. When the downshift control is completed as described above, the lockup control shown in FIG. 9 is executed next. Lock-up control This lock-up control first reads the lock-up release timer, and when the lock-up release timer is operating, that is, when the determination of whether the timer is 0 or not is NO, performs the lock-up release.
Finish this flow. Conversely, if the determination as to whether the timer=0 is YES, the preset lockup OFF map _MOFF is selected. This lockup OFF map _MOFF is shown by a broken line in FIG. 10, and is determined by the turbine rotational speed of the torque converter and the throttle opening of the engine. Then, the engine throttle opening is read and the lockup corresponding to this throttle opening is set.
OFF MAP M Turbine speed TSP (MAP) _on OFF
Read. Then the actual turbine speed
Read TSP and compare with TSP (MAP) above.
When TSP≧TSP(MAP), lockup is released and this flow ends. On the other hand, TSP＜TSP
(MAP), select lock-up ON map M _ON , which is set to higher rotation than OFF map M _OFF ,
Read the turbine rotation speed TSP′ (MAP) for the above throttle opening on this ON map M _ON ,
Compare this with the actual turbine rotation speed TSP.
When TSP≦TSP′(MAP), the lockup is activated to end this flow, and TSP＞
When TSP′ (MAP), the flow ends as is. As explained above, the present invention requires only adding a line pressure adjustment device to a conventional automatic transmission and partially changing the control system, thereby suppressing changes in the driving force during gear shifting of the transmission with a simple structure. This makes it possible to suppress slips.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the operating system of the control device of the present invention, Fig. 2 is a sectional view and hydraulic control circuit diagram of an automatic transmission according to an embodiment of the present invention, and Fig. 3 is the overall flow of shift control. Figure 4 is a flowchart for determining low μ road driving, Figure 5 is a flowchart for shift-up speed change control, Figure 6 is a graph showing a shift-up speed change map, and Figure 7 is a flowchart for shift-down speed change control. , FIG. 8 is a graph showing a shift-down speed change map, FIG. 9 is a flowchart of lock-up control, and FIG. 10 is a graph showing a lock-up map. 3...Engine, 4...Automatic transmission, 6...Differential, 13...Slip determination means, 21...Pressure regulating valve, 22...Select valve, 30...Hydraulic pump,
31...Line pressure adjustment valve.

Claims (1)

[Scope of Claims] 1. Slip determination means that detects the occurrence of slip in a driving wheel and outputs a slip detection signal; an automatic transmission in which a power transmission path is switched to multiple stages by a friction member; and a device that receives the slip detection signal. A speed change control device for an automatic transmission for a vehicle, comprising: a speed change buffer means for reducing the engagement speed of the friction member during speed change. 2. The automatic transmission for a vehicle according to claim 1, wherein the engagement of the friction member is performed by hydraulic pressure, and the shift buffer means is a line pressure adjustment device that reduces the hydraulic pressure. transmission control device.