JP2779801B2 - Restoring device for coasting control of automatic transmission for vehicles - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reset device for coast control of an automatic transmission for a vehicle. 2. Description of the Related Art A gear shift mechanism and a plurality of friction engagement devices are provided, and a hydraulic control device is actuated to selectively switch engagement of the friction engagement devices, and a predetermined shift map is provided. Automatic transmissions for vehicles configured to achieve any one of a plurality of shift speeds according to the shift point are already widely known. One of the most fundamental matters in designing an automatic transmission is how to reduce the gear shift shock during gear shifting or the rattling noise generated in the power transmission system. Conventionally, various developments have been made. Problems to be Solved by the Invention However, it has been a fact that almost no effective countermeasures have been taken so far with respect to a shift shock or a rattling sound generated at the time of a downshift in a cost state of a vehicle. For example, Japanese Patent Application Laid-Open No. Sho 56-46150 discloses a technique for detecting a coast state of a vehicle and forcibly performing a downshift, but this technique can automatically secure an engine brake during a coast. This is not intended to reduce the shifting shock that occurs at the time of downshifting in the coast state, and the configuration is naturally different.) In view of such a point, the applicant has disclosed in Japanese Patent Application No. 62-7556 (unknown), in order to prevent a shift shock occurring at the time of a downshift in the coast state, detects the coast state and executes a dedicated control during the coast. The technology to do it was proposed. This technology is based on the finding of the following facts. That is, a start point and an end point of a shift period (a period from a moment when the friction engagement device starts engagement (or disengagement) to execute the shift to a completely engaged (or disengaged) state). At this point in time, when the driving state of the previous gear is changed to the driving state of the subsequent gear, sudden shocks of the one-way clutch generate strong shift shock and rattling noise. On the other hand, when the driving state of the previous gear stage changes to the coast state of the following gear stage, and when the coast state of the previous gear stage changes to the coast state of the following gear stage, the gear shift shock and rattling noise are generated. Almost no occurrence. Therefore, the invention of Japanese Patent Application No. 62-7556 focused on this fact, and in order to shift the downshift in the coast state from the drive state to the coast state or from the coast state to the coast state at the start and end of the shift period, the coast shift is performed. The shift point is changed together with the detection of the state, and a shift command is issued before the engine output becomes a state in which the vehicle is driven, so that the shift shock and rattling noise are eliminated. However, when performing such a coasting-only control, it is necessary to return from the coasting-dedicated control when certain conditions are satisfied, but in this case, if this return is not performed properly. Sometimes, a large traveling shock may occur. SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and when returning from a special control for reducing a shift shock during a downshift in a coasting state, the present invention is applied to this return. It is an object of the present invention to provide a reset device for coasting control of an automatic transmission for a vehicle, which can prevent a new large shift shock from occurring and obtain good running characteristics as a whole. SUMMARY OF THE INVENTION As shown in FIG. 1, the present invention is directed to a vehicle for automatic shifting of a shift speed in accordance with a predetermined shift point of a shift map. Means for detecting whether or not the vehicle is in a coasting state, a control device for the automatic transmission during coasting, and at least a downshift among shift points of the shift map when the vehicle is detected to be in a coasting state. Means for changing the point to such an extent that a shift command is issued before the engine output drives the vehicle; means for detecting whether a specific return condition is satisfied; Means for setting a return delay time for delaying the return, and setting the return delay time shorter when the shift speed is higher than when the shift speed is lower. The purpose has been achieved. In this specification, the "coast state"
In the "state where the vehicle is not driven by the engine output", specifically, "the state where the turbine speed of the automatic transmission is higher than the engine speed" and "the state where the engine speed and the turbine speed are approximately equal" The output shaft torque of the torque converter indicates a state where the torque is negative, zero, or close to zero. First, the basic operation of the present invention will be described with reference to FIGS. 8 (A) and 8 (B). FIG. 8A shows a conventional shift characteristic. The 2 → 1 downshift point (downshift point from the second gear to the first gear) is determined by the vehicle Nw (specifically, detected by the output shaft rotation speed N ₀ of the automatic transmission).
Set when Nw1 is reached. This value Nw1 is set to a considerably low value mainly due to the demand for fuel economy performance. When the vehicle speed is this value Nw1, the vehicle is in the driving state even when the throttle is fully closed. In FIG. 8 (A), at time a, the engine speed Ne and the turbine speed Nt of the automatic transmission are substantially equal, that is, a coast state. However, since the 2 → 1 downshift point is set to the vehicle speed Nw1, the 2 → 1 shift command is issued only at the time point b. A friction engagement device (in the embodiment described below, a brake
Hydraulic pressure of B ₂₎ is drained, the engagement of the frictional engagement device is released. However, at this point, the engine speed
Ne is maintained at almost idle speed,
The turbine rotation speed Nt is reduced to about half.
That is, the turbine rotation speed Nt is considerably lower than the engine rotation speed Ne at time b, and the vehicle is completely driven. Therefore 2 → 1 for the execution of downshift Atatsute turbine rotational speed Nt (accompanied connexion to the release of the sun gear 61 due to the release of the brake B ₂ in the embodiment described later) yo connexion temporarily higher engine rotational speed Ne The phenomenon of being pulled up occurs. However the time when the driving state of the first speed at the time of c is started (when the clutch F ₂ in one direction is engaged in the Examples below) to the turbine rotational speed Nt
Is reduced again, the rate of change of the turbine rotational speed Nt changes from the minus direction to the plus direction, and further changes from the plus direction to the minus direction. This is nothing but the fact that the power transmission direction is repeatedly reversed in the automatic transmission, and the rotational change of each rotating member is also abrupt. As a result, a large shift shock and rattling noise particularly occur at the time point c. On the other hand, in the present invention, as shown in FIG. 8 (B), when the establishment of the condition of the coast state of the vehicle is detected at time d, the vehicle speed map is changed from FIG.
It is changed as shown in FIG. 10 so that the 2 → 1 downshift point can be raised from Nw1 to Nw3. As a result, at time d when the condition is satisfied, a downshift command of 2 → 1 is issued at the same time. According to this command, the hydraulic pressure of the friction engagement device is drained, and the automatic transmission is shifted from the second speed to the first speed. The engine speed Ne and the engine speed Ne at the start and end of this shift period are changed. There is almost no difference in the turbine rotation speed Nt, and therefore, the vehicle is kept in the coast state at both time points. as a result,
Even if the driving state of the first speed stage is started at time e after a while, the turbine rotation speed Nt only needs to be reduced as it is, and the turbine reversely reverses from the minus direction to the plus direction and back again to the minus direction. There is no. Therefore, the power transmission direction does not reverse in the automatic transmission, and the rotation change of each rotating member is small, so that the shift shock and rattling noise do not occur strongly. The coast state may be detected, for example, by detecting whether the throttle opening is fully closed, the idle switch is ON, and the brake signal is ON. The definition of the “coast state” is as described above, and the present invention does not limit how to detect the “coast state”. This makes it possible to detect the coast state without error. In detecting the "coast state", it is also possible to take into account factors such as the type of gear (or vehicle speed). Incidentally, the return from the dedicated control during the coast is performed when the vehicle satisfies a specific condition. This particular condition does not necessarily have to match the condition for entering the dedicated control at the time of coasting, but the return will be performed when it is qualitatively determined that the vehicle has exited the "coast state". . In this case, as shown in FIG. 11, for example, the throttle shifts from the OFF state (coast state) to the throttle ON state (the state where the accelerator is depressed = non-coast state). Since the shift pattern is restored from the special shift pattern to the normal shift pattern, the upshift that occurs simultaneously with the return causes an acceleration shock and a drop in the torque of this upshift occurs successively. The problem of extremely large size occurs (solid line in FIG. 11). In the present invention, the return delay time T is provided in accordance with the type of the return condition or the traveling state of the vehicle at the time of the return, and the upshift by the acceleration shock and the return is performed.
The torque drop 'is temporally separated from the torque drop', so that a rapid change in torque does not occur and good running characteristics can be obtained (broken line in Fig. 11). By providing the return delay time, it is possible to improve running feeling due to the tip-in of the idle signal and the throttle opening signal. In addition, the running feeling can be improved even for multiple shifts when the throttle is depressed. The return delay time T is qualitatively set to be longer as the speed at the time of return is lower. This is because the lower the speed, the greater the drop in torque for acceleration shock and speed change. Conversely, if the gear is a high gear, the return delay time T may be short (for example, may be zero). Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, FIG. 2 shows an overall outline of an automatic transmission for a vehicle to which this embodiment is applied. This automatic transmission has a transmission section, a torque converter 20, an overdrive mechanism 40,
And a two-stage reverse drive mechanism 60. The torque converter 20 includes a pump 21, a turbine 22,
It is a well-known type including a stator 23 and a lock-up clutch 24. The pump 21 is connected to the crankshaft 10 of the engine 1.
The turbine 22 is connected to a carrier 41 of a planetary gear unit in the overdrive mechanism 40 via an output shaft 22A of the torque converter. In the overdrive mechanism 40, a planetary pinion rotatably supported by the carrier 41.
42 meshes with the sun gear 43 and the ring gear 44. or,
Between the sun gear 43 and the Kiyariya 41, clutches C ₀ and has a one-way clutch F ₀ is provided between the sun gear 43 and the transformer honey Chillon case Hu, brake B ₀ is provided. The underdrive mechanism 60 includes two rows of planetary gear units, a front side and a gear side. This planetary gear device has a common sun gear 61, ring gears 62 and 63, planetary pinions 64 and 65 and a carrier 66,
Consists of 67. The ring gear 44 of the overdrive mechanism 40 is
It is connected to the ring gear 62 via the C _1. Also, the clutch C ₂ is provided between the ring gear 44 and sun gear 61. Further, the carrier 66 is connected to the ring gear 63, and the carrier 66 and the ring gear 63 are connected to the output shaft 70. Meanwhile, the carrier 67 and the transmission case Hu
Between the, it is provided with a brake B ₃ and the one-way clutch F _2, further between the sun gear 61 and the transformer honey Chillon case Hu, the brake B ₂ via a one-way clutch F ₁
It is provided, also, between the sun gear 61 and the transformer honey Chillon case Hu, brake B ₁ is being provided. The automatic transmission includes the above-described transmission unit, and includes a throttle sensor 80 that detects a throttle opening degree reflecting a load state of the engine 1 and a vehicle speed sensor (specifically, an output signal) that detects a vehicle speed. The electromagnetic solenoid valves S _{1 to} S ₂ (shift valves) in the hydraulic control circuit 86 are controlled by a computer (ECU) 84 to which a signal such as a rotational speed sensor 82 of the shaft 70 is input in accordance with a preset shift map. ) And SL (for lock-up clutch) are driven and controlled, and a combination of engagement of each clutch, brake and the like as shown in FIG. In FIG. 3, the mark ○ indicates the engaged state, and the mark ◎ indicates that the engaged state is achieved only during driving. As shown in FIG. 4, the electromagnetic solenoid valve
S ₁ controls the 2-3 shift valve, the solenoid valve S ₂ controls the 1-2 shift valve and 3-4 shift valve. The shift control of the underdrive mechanism 60 from the first speed to the third speed is performed by the shift valves 1-2 and 2-3, and the shift of the overdrive mechanism 40 is controlled by the shift valve 3-4. (3rd speed and 4th speed), and the electromagnetic solenoid valve SL
Torque converter 20 via lock-up relay valve
The inside of the lock-up clutch 24 is controlled. In FIG. 2, reference numeral 90 denotes a shift position sensor, which is operated by the driver (N (neutral)).
The one that detects the position of the shift range such as D (drive) and R (reverse), 92 is a pattern select switch,
This figure shows the detection of the position of E (economic running), P (power running) and the like. Reference numeral 94 denotes a water temperature sensor for detecting a cooling water temperature of the engine, reference numerals 96 and 98 denote brake switches for detecting the operation of a foot brake and a side brake, and reference numeral 99 denotes an idle contact switch. FIG. 5 shows a control procedure in the apparatus of the above embodiment. In this control procedure, the "coast state" is performed by detecting whether or not the throttle opening is fully closed, the idle switch is ON, and the brake signal is ON. Further, the coast control is executed only when all of the conditions of the "coast state" are satisfied and the shift range of the automatic transmission is the drive range. On the other hand, the return of the coast control is performed under the conditions shown in FIG. Upon this return, a return delay time T as shown in FIG. 7 is set. Hereinafter, the control procedure of FIG. 5 will be specifically described. When the program is started by a predetermined initialization, first, at step 111, it is determined whether or not the shift range of the automatic transmission is within the drive range. Next, in step 112, it is determined whether or not the throttle opening θ is zero, that is, whether or not the throttle is fully closed. Further, at step 113, the idle contact O
N-OFF is determined. In steps 114 and 115, ON / OFF of the brake signal is determined. According to each state determined under the above conditions,
At steps 116 to 120, a flag A, a flag B, and a flag C are set, respectively. In this case, the flag A indicates the establishment of a change condition for setting the shift map M _A (see FIG. 10) dedicated to coasting by this control, and the flags B and C indicate the shift map for a normal drive range as a shift map. Variable speed mapp M
_This shows that the return condition for setting _B (see FIG. 9) is satisfied. However, the flag B indicates that the return condition has been satisfied by operating the shift range to a range other than the drive range, and the flange C indicates that the return condition has been satisfied by the throttle operation or the brake operation. I have. The reason why the flag B and the flag C are divided in this way is to change the return delay time depending on the type of the return condition. At step 116, the flag A becomes 1, indicating that the coasting control condition has been satisfied. Step 117, 1
At 18, the flags A, B, and C are all zero, indicating that neither the coast control condition nor the return condition is satisfied. At step 119, the flag C becomes 1, indicating that the return condition by the throttle operation or the brake operation is satisfied. Step 120 indicates that the return condition is satisfied by an operation outside the drive range. In step 121, it is determined whether or not the flag A is 1. If that has reached through the step 116 it is determined where the flag A = 1 and, the routine proceeds to step 122, shifting Matsupu M _A dedicated during coasting is excisional. At step 123, it is determined whether or not the flag B is 1. If that has reached through the step 120 is determined here by the flag B = 1 and, in step 124 the shifting M _B for ordinary drive range is excisional. That is, when the shift range is due connexion recovery conditions that have been operated to the range other than the drive range is established, and is returned to the transmission Matsupu M _B of the normal (return Deirei time zero) immediately this step 124. If it has passed through steps 117 and 118, the flag A =
0 and the flag B = 0, steps 122 and 124
In the shift point is not newly changed or excisional, so that the previous shift Matsupu M _A or M _B are used as continuous manner. In step 125, it is determined whether or not the flag C is 1. If the vehicle has passed through step 119, it is determined that the flag C = 1, and the return delay time is set in step 126 and subsequent steps according to the vehicle running state. At step 126, it is determined whether or not the shift speed is the first speed. In step 127, it is determined whether the vehicle speed Nw is less than 20 km / h. Based on these determination results, the return delay time of 1 second or 0.2 second is set in steps 128 and 129, respectively. As a result, the return delay time is set to zero when the shift speed is equal to or higher than the second speed, and a long return delay time is set when the shift speed is the first speed and the vehicle speed is lower than 20 km / h. A delay time (1 second) and a short return delay time (0.2 seconds) are set when the shift speed is the first speed and the vehicle speed is higher than 20 km / h. Step 1
In 30 shift Matsupu M _B for the normal drive range after the lapse of this return Deirei time excisional, that is, restored. Thus, according to this embodiment, the return delay time T
Is set to be shorter (zero in this example) when the shift speed at the time of return is a high shift speed (in this example, second speed or higher) than in a low shift speed (in this example, first speed). Is done. This is because, as described above, in the case of the high gear stage, the shock due to the torque reverse rotation is small, and no major problem occurs. If a major problem occurs, the more those who hasten the return becomes even less likely to occur new problems caused by the shift Matsupu M _A dedicated during the minute Coast to return sooner to the original shift control have been long excisional. This control procedure is repeated during traveling. In this embodiment, the optimal return delay time (including zero) is set in accordance with the type of the return condition and the vehicle running state (including the type of gear position) at the time of the return. In the present invention, the specific method of classification is not limited to this example. For example, the timing at the time of returning from the coast control is changed according to more types of classification to obtain better shift characteristics. It does not prevent application.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the gist of the present invention, and FIG.
FIG. 3 is a block diagram showing an overall outline of an automatic transmission for a vehicle to which an embodiment of the present invention is applied. FIG. 3 is a diagram showing an engagement state of each friction engagement device used in the embodiment device. 4th
FIG. 5 is a block diagram showing the relationship between the control systems, FIG. 5 is a flowchart showing the control procedure, FIG. 6 is a diagram showing conditions for returning from the coasting control, and FIG.
8 (A) and 8 (B) are diagrams showing shift transient characteristics of 2 → 1 downshift according to the prior art and the present invention, respectively, and FIG. 9 is a diagram showing drive conditions. Usually diagram showing a shift Matsupu M _B of the hob, FIG. 10, a line diagram showing a speed change Matsupu M _a dedicated during coasting, malfunction when FIG. 11 is a return from the coast time control has failed appropriate FIG. 7 is a rear axle torque diagram for explaining the following. 80: Slot sensor, 82: Vehicle speed sensor (rotating vehicle speed sensor for output shaft), 98: Foot brake switch, 99: Idle contact switch, M _A: Shift map dedicated to coast state, M _B: Normal shifting map.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-184261 (JP, A) JP-A-60-211155 (JP, A) Full-fledged 1988-18659 (JP, U) (58) Field (Int.Cl. ⁶ , DB name) F16H 61/10 F16H 61/18

Claims (1)

(57) [Claims] A coasting time control device for an automatic transmission for a vehicle configured to automatically switch gears according to a predetermined shift point of a shift map, wherein a means for detecting whether or not the vehicle is in a coasting state. When it is detected that the vehicle is in the coast state, at least a downshift point among the shift points of the shift map is
Means for changing the engine output to a high level so as to issue a gearshift command before the vehicle is driven to drive the vehicle; means for detecting whether or not a specific return condition is satisfied; and Means for setting a return delay time for delaying the return, and wherein the return delay time is set to be shorter when the shift stage is a high speed stage than when the shift stage is a low speed stage. Return device for coasting control of automatic transmission.