JPH0534550B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a shift control method for an automatic transmission used in a vehicle such as an automobile, and more particularly to a shift control method using an electronic shift control device. [Prior art] A hydraulic joint such as a hydraulic torque converter,
As one of the shift control methods for an automatic transmission including a gear transmission equipped with a plurality of frictional engagement devices to obtain a plurality of gears, a target shift is determined in advance according to the vehicle speed, engine load, and shift range. The gears are determined and stored in the storage means, and the information is stored in the storage means according to the actual vehicle speed detected by the vehicle speed sensor, the actual engine load detected by the load sensor, and the actual gear shift range detected by the shift range sensor. It is known that an electronic shift control device is used to read out a target gear and control the operation of the frictional engagement device to achieve the target gear. [Problems to be Solved by the Invention] When a vehicle is running with a relatively small throttle opening, the electronic transmission control device changes to the target gear due to sudden deceleration caused by changing the gear range or by sudden braking. If a downshift to a gear position accompanied by engine braking occurs suddenly by lowering the engine speed, the sudden engine braking will act, causing a large gear shift shock and deteriorating ride comfort. An object of the present invention is to provide a shift control method for an automatic transmission that is improved to avoid shift shock caused by sudden downshifting to a gear position where engine braking is applied. This is an issue. [Means for Solving the Problems] According to the present invention, the above-mentioned problems are solved by providing a plurality of frictional engagement devices, and changing the engagement of the frictional engagement devices to change at least three gear stages. A gear position control method for controlling the gear position of an automatic transmission equipped with a gear transmission to achieve the following: downshifting from a certain first gear position to a certain second gear position where engine braking can be applied. At this time, the gear is shifted once to a certain third gear in which the engine brake does not act, and then the gear is shifted to the second gear after a time set by a different timer depending on whether the throttle opening is above or below a predetermined value. This is achieved by a gear position control method characterized by the following. [Operations and Effects of the Invention] As described above, according to the present invention, when downshifting is to a gear where engine braking can be applied, the gear is first shifted to another gear where engine braking cannot be applied. death,
By shifting to the originally scheduled gear after a time set by a different timer depending on whether the throttle opening is above or below a predetermined value, it is possible to prevent sudden downshifts when driving the vehicle, regardless of the throttle opening. As a result, shift control of the automatic transmission can be achieved while avoiding the occurrence of shift shock. [Example] The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a schematic diagram illustrating an example of an automatic transmission and a speed change control device thereof that implements a speed change control method according to the present invention. The automatic transmission includes a hydraulic torque converter 1 and a gear transmission 2 with three forward speeds and one reverse speed.
Contains. The hydraulic torque converter 1 is of a known type and includes a pump 3, a turbine 4 and a stator 5, the pump 3 being connected to an engine crankshaft 6 and the turbine 4 being connected to a turbine shaft 7. The turbine shaft 7 forms the output shaft of the hydraulic torque converter 1, and also serves as the input shaft of the gear transmission 2. The gear transmission 2 has an intermediate shaft 8, a sun gear shaft 9, and an output shaft 10. A clutch 11 is provided between the input shaft 7 and the intermediate shaft 8, and a clutch 12 is provided between the input shaft 7 and the sun gear shaft 9. A brake 14 is provided between the sun gear shaft 9 and the transmission housing 13 for selectively fixing the sun gear shaft 9 to the transmission housing 13. Further, one clutch element of a one-way clutch 15 is connected to the sun gear shaft 9, and this one-way clutch 15 is selectively fixed to the transmission housing 13 by a brake 16 at the other clutch element. ing. Sun gear 1 is on sun gear shaft 9.
7 is attached, and this sun gear 17 meshes with a planetary pinion 19 carried by a carrier 18. A brake 20 and a one-way clutch 21 are provided between the carrier 18 and the transmission housing 13. The planetary pinion 19 meshes with a ring gear 22, and the ring gear 22 is connected to the output shaft 10.
The sun gear 17 also meshes with a planetary pinion 24 carried by another carrier 23. The carrier 23 is connected to the output shaft 10. The planetary pinion 24 meshes with another ring gear 25, which is connected to the intermediate shaft 8. The clutches 11, 12 and the brakes 14, 16, 20 are each driven by hydraulic pressure, and are engaged or released in the combinations shown in Table 1 by the speed change control device, which will be explained in detail below, to provide three forward and three reverse speeds. It is designed to achieve each gear stage of one gear.

[Table] In Table 1, the ○ mark indicates engagement of the clutch or brake, the Δ mark indicates engagement when the vehicle is being driven from the engine side (released during engine braking), and the X mark indicates open state. ing. The transmission control device has a hydraulic control device 30 that selectively supplies hydraulic pressure to the clutch or brake, and this hydraulic control device includes a hydraulic pump, a pressure regulator valve, a 1-2 shift valve, and a 2- 3 shift valve,
The 1-2 shift valve is operated by the 1-2 shift solenoid 31, and the 2-3 shift valve is operated by the 2-shift solenoid 31.
-3 shift solenoid 32 switches and drives the shift solenoid 32. The hydraulic control device 30 operates a manual valve operated by a manual shift (range) lever and operates the clutch or brake according to the switching position and the operation of the 1-2 shift solenoid 31 and the 2-3 shift solenoid 32 as shown in Table 1. Hydraulic pressure is supplied in such combinations to achieve a predetermined gear position. The operation of the 1-2 shift solenoid 31 and the 2-3 shift solenoid 32 is controlled by a shift control computer 33. Shift control computer 33 is better shown in FIG. The computer 33 includes a vehicle speed sensor 34, a throttle opening sensor 40, and a shift range sensor 43.
Each of the solenoids 31 and 32 is given a generated signal, and the energization of the solenoids 31 and 32 is controlled based on the signals. The vehicle speed sensor 34 generates a pulse signal with a frequency proportional to the vehicle speed, and this pulse signal is input to the gate counter circuit 35 as a gate signal. The gate counter circuit 35 receives a clock signal from the clock generation circuit 36, counts clock pulses during one cycle of the gate signal,
The count result is output from the input port 37 to a central processing unit (hereinafter referred to as CPU) 39 via a common bus 38 at a predetermined time. The throttle opening sensor 40 is designed to generate an analog signal (voltage signal) corresponding to the opening of a throttle valve provided in an intake system of an engine (not shown). Throttle opening sensor 4
The analog signal in which 0 is generated is input to the A/D converter 41. The A/D converter 41 receives a clock signal from the clock generating circuit 36, and based on this, converts the analog signal into a digital signal. A digital signal generated by the A/D converter 41 is input to the CPU 39 from the input port 42 via the common bus 38 at a predetermined time. The shift range sensor 43 detects the shift range determined by the driver's intention using the manual shift lever, and generates a signal corresponding to the shift range. This signal is input from the input port 44 to the CPU 39 via the COMOS bus 38 at a predetermined time. The CPU 39 is a well-known device including a general register, an arithmetic circuit, a program counter, etc., and controls a memory control unit (MCU) 46 that controls a memory device 45 and input ports 37, 42, and 44. A control command signal is output to each device control unit (DCU) 47 via a control bus 48. Memory device 45 is bidirectional common bus 38
It is connected to the CPU 39 by a ROM and includes read-only memory (ROM) and random access memory (RAM). Read-only memory is
It stores programming that determines computer routines, target gears based on vehicle speed and engine load for each shift range, and various coefficients for calculations. The target gears stored in the read-only memory are determined so that the gears are set in the patterns shown in FIGS. 3 to 5. Furthermore, Fig. 3 shows the shift pattern in the D range, Fig. 4 shows the shift pattern in the 2 range, and Fig. 5 shows the shift pattern in the L range. The solid lines indicate shift-up lines, and the broken lines indicate shift-down lines. Dunram access memory includes vehicle speed sensor 34, throttle opening sensor 40, and shift range sensor 43.
The signals generated by each of the above, other output signals, signals used for saving registers, etc. are temporarily stored. The CPU 39 reads the current target gear from the memory device 45 in accordance with the vehicle speed detected by the vehicle speed sensor 34 and the throttle opening detected by the throttle opening sensor 40, and outputs the signal to the output port 49. There is. The signal given to the output port 49 passes through amplifiers 50 and 51 to the 1-2 shift solenoid 31 and the 2-3 shift solenoid 3.
2, and these energization controls are performed. Further, as described above, the CPU 39 determines whether or not the step difference between the target gear position read from the memory device 45 and the current actual gear position is 2 or more, and if the step difference is not 2 or more, the gear position is changed immediately. A control signal is output to the output port 49 so that the gear changes to the target gear, or if the gear difference is two or more, the actual gear changes one step at a time to the target gear after a predetermined time. There is. Next, a method for controlling a shift in an automatic transmission according to the present invention will be explained with reference to the flowchart shown in FIG. First, the CPU 39 inputs vehicle speed, throttle opening, and shift range data from the vehicle speed sensor 34, throttle opening sensor 40, and shift range sensor 43, respectively. Based on this data, the CPU 39 reads the gear St from the memory device 45 and sets the target gear. Next, the CPU 39 determines what range the gear shift range is at this time. As long as this shift range is the N (neutral) range, R (reverse) range, or P (parking) range, there is no need to set the shift stage, so the control process according to this flowchart returns to data input. When the shift range is D range, 2 range, or L range, the CPU 39 determines whether or not the shift is up. When the gear position does not change, the control process advances to NO in this step, and then it is determined whether it is a downshift, but at this time, the control process advances to NO in this step as well, and the CPU continues to The same gear position setting control signal is output. Therefore, sometimes the gear position is not changed. In the step of determining whether the shift is up or not, if it is determined that the shift is up.
The CPU 39 then determines whether the throttle opening degree T is smaller than a predetermined value _A1 . When the throttle opening degree T is not smaller than the predetermined value _A1 , St is immediately set as the target gear for gear shift control, and even if the difference between the actual gear Sr and the target gear at that time is two or more, the gear is changed. A gear position setting control signal is outputted so as to immediately change to the target gear position. As a result, the gear transmission 2 is shifted up by one or two steps. When shifting up under a condition where the throttle opening degree T is not smaller than the predetermined value _A1 , that is, during power-on shift-up, even if the shift-up is performed in two gears at once, a very large shift shock will not occur. Sometimes, it is allowed to shift up two gears at once in order to achieve a more responsive gear shift. In the throttle opening degree comparison step, if the throttle opening degree T is smaller than the predetermined value _A1 , the CPU
Step 39 determines whether the first timer is on. At this time, since the first timer is not on at first, the CPU 39 next determines whether the difference between the target gear St and the current actual gear Sr is two or more. If this step difference is not 2 or more, the first timer is turned on, and if the step difference between the target gear St and the actual gear Sr is 2 or more, St = Sr.
After performing the operation of +1, the first timer is turned on. Next, a gear position setting control signal is outputted so that St is set as the target gear position for gear position control and is shifted up by one gear from the previous gear position. As a result, the gear transmission 2 has a final target gear St at this time.
For example, even if the vehicle is in third gear, it is first set to second gear. The first timer maintains an on state for a predetermined period of time, and turns off after a predetermined period of time. Since the computer 33 repeats the control process as described above, in the step of determining whether or not the timer is on in the next control process, the control process advances toward YES for the above-mentioned predetermined time, and the first The target gear St calculated by the CPU is reversely adjusted to the actual gear Sr and that gear is maintained until the time set by the timer elapses. In the first control process after the time set by the first timer has elapsed, when it comes to the step of determining whether or not the first timer is on, the first timer is not on at this time and is in the off state. Since it has returned, the routine advances to NO and again determines whether the difference between the target gear St and the actual gear Sr is two or more. Even if the calculated target gear St at this time is still the third gear, the actual gear Sr of the gear transmission 2 is already the second gear at this time, so the step difference is 1. Therefore, after turning on the first timer, the CPU 39 outputs a gear setting control signal so that the gear becomes the calculated final target gear St, that is, the third gear.
As a result, the gear position of the gear transmission 2 is shifted up to the third speed, and the shift up operation at this time is completed. That is, when shifting up under a condition where the throttle opening degree T is less than the predetermined value _A1 , for example, when power-off shift-up is performed, the gear position is prevented from changing two gears at once, and at this time, the gear position is first shifted to the next higher gear. A shift-up is performed, and the gear position, for example, second gear, is maintained until a predetermined time period determined by the first timer started along with this has elapsed, and after that, the gear is shifted to third gear, which is the final control target gear. It will be done. In this way, by maintaining the intermediate gear for a predetermined period of time and then shifting to the final control target gear, it is possible to avoid a large change in the gear ratio all at once, which would cause the engine speed to drop suddenly. This prevents the occurrence of a large shift shock. During downshifting, the CPU 39 determines whether the throttle opening degree T is larger than a predetermined opening degree _A2 . When the throttle opening degree T is not larger than the predetermined opening degree _A2 , it is determined whether this downshift is due to a change in the shift range, that is, a change in the manual shift range such as from the D range to the L range. conduct. If the manual shift range is not changed, the gear will be changed immediately.
A gear setting control signal is output so that Sr changes to the target gear St calculated by the CPU 39. Therefore, at this time, the gear transmission 2 is downshifted by one or two gears. This means that even if the predetermined value A ₂ is a relatively small value and the throttle opening T is fully closed or almost closed, even when downshifting is performed in two stages at once in the so-called power-off downshifting, D In cases where a large shift shock will not occur due to the slipping action of the one-way clutch 21, such as downshifting in the range, it is preferable to downshift two gears at once in order to reduce the number of gearshifts and speed up gearshifting. It is based on the judgment of If the throttle opening degree T is smaller than the predetermined opening degree _A2 and the downshift is due to a change in the shift range, the CPU 39 next determines whether or not the third timer is on. At this time, the third timer is not turned on at first, so the CPU selects the target gear St.
It is determined whether the step difference between the current actual gear Sr and the actual gear Sr is two or more. When this level difference is 1, the third timer is turned on and the target gear calculated by the CPU 39 is immediately set as the target gear St.
A gear setting control signal is output so that Sr becomes the target gear St. In contrast, the target gear St and the current actual gear
When the difference in level from Sr is 2 or more, the third timer is turned on after performing the calculation St=Sr-1, and then the gear stage is shifted down by one stage with this St as the target gear stage. That is, for example, when the shift range is changed from D range to L range and a downshift is to be made from third gear to first gear in L range, the gear is shifted so that third gear is first downshifted to second gear. A gear setting control signal is output, and the gear transmission 2 is set to the second gear even if the final target gear St at this time is the first gear. This state continues while the third timer is on. In other words, the next time it is determined whether the third timer is on, it will be determined as YES for the time being.
At this time, the target gear position calculated by the CPU 39 is reversely adjusted to the actual gear position Sr. When the third timer turns off, the CPU 39 outputs a gear position setting control signal so that the actual gear position becomes the calculated St, that is, the first speed. With this shift control, even when the shift range is changed from the D range to the L range, the one-way clutch 21 is prevented from slipping and the engine brake is activated, resulting in a sudden downshift from the third gear to the first gear in the L range. This is avoided, and after the D range second speed or the second range second speed in which the engine brake does not act is established, the shift is switched to the L range first speed. This suppresses the occurrence of a sudden engine braking effect and avoids the occurrence of a large shift shock. Throttle opening T is the specified opening during downshift.
When it is larger than A ₂ , the CPU 39 next determines whether or not the second timer is on. At this time, the second timer is not on at first, so
The CPU determines whether the step difference between the target gear St and the current actual gear Sr is two or more. When this step difference is 1, the second timer is turned on and a gear position setting post-control signal is outputted so that the gear position Sr immediately becomes the calculated target gear position St. On the other hand, when the difference in gears is 2 or more,
St = Sr - 1 is calculated, and after turning on the second timer, the gear stage is downshifted by one step based on St calculated here. For example, when in third gear, it is first shifted down to second gear. Outputs a gear setting control signal to As a result, the gear transmission 2 is set to the second speed even if the final target speed St at this time is the first speed. This state continues while the second timer is on, and when the second timer turns off, the CPU 39 outputs a gear setting control signal so that the actual gear becomes the final target gear, that is, first gear. do. As a result, the gear transmission 2 is downshifted to the first speed. In this case as well, the determination as to whether the second timer is on remains YES for a while after the second timer is turned on, and during that time the target gear St computed by the CPU is, conversely, the actual gear Sr.
After being replaced with , a gear change setting control signal is output. That is, during a power-on shift down, that is, a kick down, when the throttle opening degree T is equal to or greater than the predetermined value _A2 , the two gears are shifted at once, regardless of whether the shift is due to a change in the gear range or not. At this time, a downshift is first performed to the next lower gear, and the shift to the lower gear, for example, the second The speed is maintained, and then the shift to the first speed, which is the final control target speed, is performed. As a result, after the intermediate gear is maintained for a predetermined period of time, the gear is shifted to the final control target gear.
A large change in the gear ratio is avoided all at once, and a sudden increase in engine speed is avoided, and as a result, a large frictional force is instantaneously applied to the friction element of the frictional engagement device for gearshift control. This will ensure its durability and avoid engine overrun. In order to prevent the gears from changing two gears at once, the time period during which the intermediate gear is maintained may be different between when the gear is upshifted and when the gear is shifted down. Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited to the above-mentioned embodiments, and various other embodiments are possible within the scope of the present invention. This will be obvious to those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an example of an automatic transmission and a speed change control device implementing the speed change control method according to the present invention, FIG. 2 is a block diagram showing an example of a speed change control computer, and FIGS. 3 to 5 6 is a diagram showing a shift pattern in each shift range, and FIG. 6 is a flowchart illustrating one embodiment of the shift control method according to the present invention. 1...Hydraulic torque converter, 2...Gear transmission, 3...Pump, 4...Turbine, 5...
Stator, 6...Engine crankshaft (input shaft),
7... Turbine shaft (input shaft), 8... Intermediate shaft, 9
... Sun gear shaft, 10 ... Output shaft, 11, 12 ...
...Clutch, 13...Transmission housing, 14...Brake, 15...One-way clutch, 16...Brake, 17...Sun gear, 18
...Carrier, 19...Planetary pinion, 2
0...Brake, 21...One-way clutch, 22
...Ring gear, 23...Carrier, 24...Planetary pinion, 25...Ring gear, 30...
...Hydraulic control device, 31...1-2 shift solenoid, 32...2-3 shift solenoid, 33...
Shift control computer, 34...Vehicle speed sensor, 3
5... Gate counter circuit, 36... Clock generation circuit, 37... Input port, 38... Common bus, 39... Central processing unit (CPU), 40...
...Throttle opening sensor, 41...A/D converter, 42...Input port, 43...Shift range sensor, 44...Input port, 45...Memory device, 46...Memory control unit, 47... Device control unit, 48...control bus,
49...Output port, 50, 51...Amplifier.

Claims (1)

[Claims] 1. A gear shift for controlling the gears of an automatic transmission equipped with a gear transmission that has a plurality of frictional engagement devices and achieves at least three gears by switching the engagement of the frictional engagement devices. In the control method, when downshifting from a first gear to a second gear where engine braking can be applied, after once shifting to a third gear where engine braking is not applied, A gear position control method characterized in that the gear position is shifted to the second gear position after a time set by a different timer depending on whether the throttle opening degree is above or below a predetermined value.