JPH02229954A - Automatic speed change gear control device - Google Patents

Abstract

PURPOSE:To perform proper shift down by a method wherein when shift down operation is detected, from the coefficient of a change in a car speed, a car speed change amount in a given shift time during descending or in a given shift time during ascending is computed, and according to the computing coefficient of a change in a car speed, an overrun decision car speed during shift down operation set at each step is regulated. CONSTITUTION:A control device 9 determines the coefficient of a change in a car speed from a car speed output from a car speed sensor 8 when shift down is detected from an output from a select lever position sensor 7a. From the determined coefficient A of a change in a car speed and a predetermined time B required for shift down, a car speed change amount v=AXB during shift down is computed. Overrun decision car speeds 1-4 during shift down set at each step is regulated by the car speed change amount v, and shift down to a lowermost step at which no overrun occurs is effected. Namely, no overrun occurs by reducing an overrun decision car speed to a low value during descending, and an engine output is prevented from lowering because of the overrun decision car speed being increased to a high value during ascending.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic transmission control device, and particularly to a control device for an electronically controlled automatic transmission having a fixed gear range. [Prior Art] In the conventional automatic transmission control device for large vehicles, etc., which has a fixed gear range as shown in Fig. 4 (D5 is a variable gear position with a maximum of 5 gears), when the select lever is pressed while driving, ,
When a fixed gear range is selected, the transmission or engine may overrun due to a downshift to a lower fixed gear range due to a human error in selecting the fixed gear range. To prevent this, conventionally, a permissible high vehicle speed for downshift judgment is set for each fixed gear range.
If a fixed low gear range is selected, compare the actual vehicle speed at that time with the maximum allowable vehicle speed, and if the actual vehicle speed is greater than the maximum allowable vehicle speed, downshifting is prohibited or a low gear that does not overrun is selected. It was supposed to downshift to the next gear. [Problem to be Solved by the Invention] However, since only one value for the above-mentioned allowable high vehicle speed in the fixed gear range was set for each fixed gear range, the following occurs when downshifting due to range change. There was a problem. (1) When going downhill, the vehicle speed may increase by 2' during the gear shift, and in this case, the engine will overrun when the gear shift is actually completed.

(2) When climbing a hill, the vehicle speed decreases during the gear shift, so the engine speed drops by the time the gear shift is actually completed. If the setting is near the number, the engine output cannot be fully utilized.

Here, when descending (+) above, it can be prevented by setting the allowable maximum vehicle speed lower than the actual overrun, but if you do that, it will be necessary to set it higher when climbing a slope (2). Therefore, it is not possible to satisfy both (1) and (2) above with one maximum allowable vehicle speed as in the past.Therefore, the present invention provides a system that allows the speed to be adjusted even when the fixed gear range is incorrectly selected. It is an object of the present invention to provide an automatic transmission control device that can perform downshifting at appropriate timing.

(Means for Solving the Problems) In order to achieve the above object, an automatic transmission control device according to the present invention includes a gear position sensor, a select lever position sensor, a vehicle speed sensor, and a select lever position sensor. When a downshift operation is detected from the output, the amount of change in vehicle speed during a predetermined downshift time when descending or climbing a slope is calculated based on the vehicle speed increase rate determined from the output of the vehicle speed sensor, and the amount of change in vehicle speed is determined for each gear based on the amount of change in vehicle speed. The present invention is equipped with control means for first shifting down the transmission to the lowest gear that does not cause an overrun by increasing or decreasing the set vehicle speed for determining overrun during downshift operation. This will be explained with reference to Fig. 3.The downshift map of a vehicle equipped with an automatic transmission is roughly set in advance based on the vehicle speed and the amount of depression of the accelerator pedal, as shown by the solid line in Fig. 3. This is well known from Japanese Patent Laid-Open Publication No. 11769/1983 by the present applicant. In such a downshift map, 1 to ■ indicate gears, and each gear has a maximum permissible value that does not cause the engine to overrun. There are vehicle speeds, each indicated by a dashed-dotted line■〜■
It is indicated by , and there is a high possibility that the engine will overrun if the maximum allowable vehicle speed for each gear exceeds ■~■. However, with only these maximum allowable vehicle speeds ■ to ■, problems occur when descending and climbing hills as described above. Therefore, it can be seen that in order to achieve both when going downhill and when going uphill, it is necessary to adjust the maximum allowable vehicle speed according to each case. In other words, in order to prevent an overrun from occurring when the shift is completed even if the vehicle speed increases while shifting when going downhill, the maximum allowable vehicle speed for overrun determination should be set to a low value, and when shifting when going uphill. In order to prevent the engine speed from dropping when the shift is completed due to a drop in vehicle speed during the shift, it would be helpful to set the maximum allowable vehicle speed for overrun judgment to a high value. The present invention attempts to set the maximum allowable vehicle speed variation amount ΔV according to the vehicle speed, and when the control means detects a downshift operation from the output of the select lever position sensor, the control means determines the amount of variation ΔV from the vehicle speed output of the vehicle speed sensor. Find the rate of change in vehicle speed. Then, the vehicle speed change position Δv-AXB during downshifting is calculated from this heavy speed change rate A and the predetermined time B required for downshifting, and the downshifting is performed by this vehicle speed change amount ΔV set for each gear. Increase or decrease the overrun judgment vehicle speed during operation to shift down to the lowest gear that will not cause an overrun. In this case, it is not necessary to specifically determine when the vehicle is going downhill and when it is going uphill because the polarity of the vehicle speed change rate is positive and negative, respectively. In this way, in the present invention, the overrun judgment vehicle speed is lowered when exiting the vehicle, so there is no overrun, and when climbing a slope, the overrun judgment vehicle speed is increased, thereby preventing a decrease in engine output. It is possible to operate at a good engine speed even when climbing hills.

〔Example〕

FIG. 1 shows an embodiment of an automatic transmission control system according to the present invention, in which 1 is an engine, and 2 is a clutch body, which is composed of a well-known friction clutch. 3 is a clutch actuator that controls the engagement amount of the clutch body 2; 3a;
4 is a clutch position sensor, 4 is an automatic transmission, 5 is a transmission actuator that changes the gear position of R4, and 5a
is the gear position sensor, and 6 is the output shaft (drive shaft). In addition, 7 is the gear selection range of shift l14 (see Figure 4)
7a is a select lever position sensor that outputs a signal indicating the position of the selected select lever 7; 8 is a select lever position sensor that outputs a vehicle stray signal detected from the rotation speed of the drive shaft 6; This is a vehicle speed sensor that Furthermore, 9 is a control for performing a downshift operation at an appropriate timing by controlling the clutch actuator 3 and the transmission actuator 5 based on signals from the clutch position l sensor 3a, gear position sensor 5a, and select lever position sensor 7a. Control unit as a means (CP
U) and is composed of a microcomputer. Next, the operation of the embodiment shown in FIG. 1 will be explained based on the flowchart shown in FIG. 2 and the shift map shown in FIG. 3. The program shown in the flowchart of FIG. 2 is executed at a set time period (for example, several tens of milliseconds! IJI), and when this program is started, the control device 9
are a clutch position sensor 3a, a gear position sensor 5a,
The current gear position, clutch position, select lever position, and vehicle speed are read from the select lever position sensor 7a and the vehicle speed sensor 8 (step S1 in FIG. 2). Next, the vehicle speed change rate A is determined from the vehicle speed read in step Sl.
(κg+/h/ssec) (step S2
), in this case, the vehicle speed change rate A is set so that the value becomes positive during acceleration (downhill). Next, the current select lever position read in step S1 is checked (same step 33), and if the select lever position is neutral (hereinafter simply abbreviated as N), the current gear position is checked (same step S4
). If the current gear position is N in step S4, it is determined that the shift operation has been completed (for example, when starting the engine, etc.), and the processes of steps S5 and S6 described later are performed, but the current gear position is N.
If not, a shift operation is required, and the process proceeds to step S9, which will be described later, to execute this operation. If the select lever position is other than N in step S3, change the current gear position (step S3).
7). There are three cases in which the check in step S7 is determined as follows. (i) When the current gear position = select lever position, that is, when the current gear position is the current position of the select lever 7: In this case, there is no need to perform a gear shift operation, so first Clear the memory K, which will be described later, in which the target gear stage value is stored (
Same step S5). After this, the routine automatic clutch control is performed according to the vehicle condition, and the process ends (
Same step S6). (ii) When the current gear position and the select lever position or the current gear position = N, that is, when an upshift operation is selected or when N is in the middle of a gear change: In this case, first, the target gear value of the gear change operation The memory K in which is stored is checked (step S8), and K≠
If it is 0, it is N in the middle of a shift, so the process goes to step SIO. However, if it is K-0, the target gear value for the gear shift operation has not been set, so the current select lever position is stored in memory K (see Figure 4). ) (step S9). Next, a gear shift operation is performed to the set target gear K (step SIO), and the process ends. The gear shifting operation in this case is as described in Japanese Patent Application Laid-Open No. 1983-1981 by the applicant mentioned above. It is well known as described in Japanese Patent No.-11769. (ii) Current gear position> Select lever position, that is, when downshifting is selected: In this case, the maximum allowable vehicle speed (-
This is the value (■~■) set as the value when there is no change in vehicle speed during gear shifting. Using the i change rate A and the shift time B during a normal shift, correction is made so that the vehicle speed reaches the maximum allowable speed at the end of the shift shift. Incidentally, the shift time B is, for example, when the select lever position is changed from the D5 range to the 4th gear in the selector gear shown in FIG.
This is the fixed time required when downshifting from gear to third gear, etc., and is determined through experiments and set in advance in the control device 9. For this reason, first, the current select lever position is temporarily stored in the memory K that stores the target gear position value for the shift operation (step Sll). Next, from the vehicle speed change rate A obtained in step S2 and the shift time B set in the control device 9, the vehicle speed change falsehood Δ■ during shifting is calculated from the following calculation formula (1) (step S12). Δv=AXB (Km/h) ...0) Here, A
: Vehicle speed change rate (κ-/h/ssec) B: Change time (
(msec) The shift time B may be determined and set experimentally for each gear, or may be determined by learning without relying on experimental values. Next, the maximum allowable city speed V corrected according to the change in vehicle speed during gear shifting.
(step 313). This is the maximum allowable vehicle speed set when there is no change in vehicle speed during gear shifting.
It can be found by subtracting the vehicle speed change ΔV during gear shifting from ■. As mentioned above, vehicle speed change 4! Since A is set to be positive when accelerating and negative when decelerating, the vehicle speed change ΔV is also positive when accelerating and negative when decelerating.Since this is subtracted from the maximum allowable vehicle speed, the maximum allowable vehicle speed is When accelerating, the correction is made lower by ΔV, and when decelerating, the correction is made higher by ΔV. Of course, in that case, it goes without saying that the value of ΔV will vary depending on the rate of change in vehicle speed. Next, the control unit W9 compares the current vehicle speed read in step 31 with the corrected maximum allowable vehicle speed obtained in step SI3 (same step SI4), and if the current vehicle speed is lower than V, the engine is overloaded. Since no run occurs and it is possible to downshift to the gear K temporarily set in step Sll, the gear K is officially set as the target gear and the process proceeds to step 310 described above. However, if it is determined in the check at step 314 that the current vehicle speed exceeds ■, downshifting at this point will cause an overrun, so the control device 9 first uses a temporary gear to find the lowest gear that can be downshifted. Add 1 to the shift operation target gear stage value K (step 315)
．． This is done to find out whether there is a gear that can be downshifted at a higher speed than the gear selected by the select lever 7. Then, K-}1 is compared with the current gear read in step sl (step S16), and if K- is the current gear, there is no need to downshift, so the process advances to step S5 and the current gear is The gear is held and normal clutch control is executed (step S6). Conversely, if K is less than the current gear, step S1
By repeating steps 2 to 316, a gear position in which downshifting is possible is found. In addition, in the flowchart of Fig. 2, the case with automatic clutch was explained, but with AC
T(＾i 『Control Transmission』
), which is equipped with a clutch pedal and only gear shifting is performed automatically by air pressure according to the select lever position, the reading of "clutch position" in step 31 of the flowchart is changed to "clutch disengaged/engaged state J". The same effect can be obtained by changing the shift operation to reading and performing the gear shift operation in step 310 only when the clutch is disengaged. [Effects of the Invention] As described above, according to the present invention, the select lever position is adjusted to the shift down operation. When the vehicle speed change rate is determined from the current vehicle speed, the vehicle speed change mark during a predetermined shift down time when descending or climbing a slope is determined, and the shift down operation is performed by the vehicle speed change amount set for each gear. The overrun judgment vehicle speed is increased or decreased to shift down to the lowest gear that does not cause an overrun, so even if the select lever is moved by mistake, the engine will not overrun when driving on a hill, It is possible to downshift one gear at an appropriate timing without causing a decrease in engine output while driving, and it is possible to ensure both engine durability and performance.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of an automatic transmission control device according to the present invention, Fig. 2 is a flowchart of a control program executed by @control means of the present invention, and Fig. 3 is an automatic transmission control device according to the present invention. FIG. 4 is a shift map diagram for explaining the operation, and a diagram showing the position of the select lever.

Claims (1)

[Claims] A gear position sensor, a select lever position sensor,
When a downshift operation is detected from the output of the vehicle speed sensor and the select lever position sensor, the amount of change in vehicle speed during a predetermined downshift time when descending or climbing a slope is calculated based on the vehicle speed change rate obtained from the output of the vehicle speed sensor. The automatic transmission is characterized by comprising: control means that increases or decreases an overrun judgment vehicle speed during a downshift operation that is set for each gear according to the amount of change in vehicle speed, and first shifts down the transmission to the lowest gear that does not cause an overrun. Transmission control device.