JPH0531028B2 - - Google Patents

Description

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

The present invention relates to a speed change control device for an automatic transmission,
In particular, it is possible to automatically change gears according to a preset shift pattern depending on the position of the pattern select switch, and to maintain good shift characteristics by changing engine torque during gear shifting. The present invention relates to a shift control device for an automatic transmission.

[Conventional technology]

Equipped with a gear transmission mechanism and multiple frictional engagement devices,
The configuration is configured such that engagement of the frictional engagement device is selectively switched by operating a hydraulic control device, and one of a plurality of gears is achieved according to a preset shift pattern. Automatic transmissions for vehicles are already widely known. Furthermore, in such an automatic transmission for a vehicle, an automatic transmission and an engine that change engine torque during gear shifting to obtain good shifting characteristics and ensure and improve the durability of the frictional engagement device are provided. Various integrated control devices have also been proposed (for example, in
55−69738).

[Problems to be solved by the invention]

However, in the case of a gear shift that should normally be controlled to change the engine torque, if the engine torque change control cannot be executed due to a sensor system problem or a request from the engine, friction engagement on the automatic transmission side may occur. As the amount of energy absorbed by the device increases, not only does the durability of the frictional engagement device deteriorate, but also the shift time becomes longer and the shift does not end in the buffer area of the accumulator, causing the problem that the shift shock becomes larger. do. this is,
This is because, on the automatic transmission side, shift tuning specifications such as oil pressure are set with the expectation that the engine torque will be reduced by a predetermined amount during the shift.

[Purpose of the invention]

The present invention has been made in view of such conventional problems. For example, when a change in engine torque that should normally be made is not made for some reason, an abnormality in gear shifting occurs. To provide a speed change control device for an automatic transmission capable of quickly detecting such a situation, ensuring durability of a friction engagement device of the automatic transmission, and ensuring good speed change characteristics. With the goal.

[Means to solve the problem]

As summarized in FIG. 1, the present invention makes it possible to automatically change gears according to a gear shift pattern set in advance according to the position of a pattern select switch, and to reduce engine torque during gear shifting. In a shift control device for an automatic transmission that maintains good shift characteristics by changing the engine torque, the shift control device includes at least a shift abnormality that occurs when the engine torque is not changed as planned. means for detecting a shift abnormality; and when the shift abnormality is detected, the shift pattern is changed to:
The above object is achieved by including means for changing to a fail shift pattern in which the shift point is set to a low level for abnormal situations in accordance with the position of the pattern select switch.

[Effect]

In the present invention, for some reason such as a failure of the sensor system or a request from the engine side, the engine torque change control is actually executed as planned, even though the engine torque change control is originally supposed to be performed during a gear shift. The abnormality in the shift that occurs when the shift occurs is quickly detected, and the change pattern is changed to a fail shift pattern in which the shift point is set to a low level, which is prepared for the abnormality. Therefore, the gear shift is performed earlier (while the vehicle speed is low, that is, while the inertia torque of the engine is small), and the energy applied to the frictional engagement device is reduced accordingly. The durability of the coupling device can be improved, and the shift time can be kept within the buffer area of the accumulator, so that deterioration of the shift characteristics can be prevented. Furthermore, in the present invention, two or more types of fail shift patterns are provided, and one of the two or more fail shift patterns is selected depending on the selection state of the pattern select switch. As a result, even when the engine torque is not changed as planned, the vehicle can still be driven while respecting the driver's intentions to some extent. Preferably, the fail shift pattern is configured with shift points determined in advance such that the amount of energy absorbed by the frictional engagement device becomes less than an allowable value when engine torque reduction control that should be performed at the time of shift is not performed. This is what is being done. As a result, even if engine torque change control during gear shifting is not performed for some reason, the durability of the friction engagement device will not be impaired, and small gear shifting of the gear shifting shock will be possible. Become. Note that the absorbed energy E of the frictional engagement device can be determined by the following equation. E=A・N ₀・t _S・T _T +B・N ₀ ² E: Energy absorbed by the frictional engagement device A: Constant determined depending on gear ratio N ₀ : Output shaft rotation speed of automatic transmission t _S : Shift time T _T : Turbine torque (≒ engine torque at high throttle) B: Constant determined depending on gear ratio and moment of inertia of each member As is clear from the above equation, absorption in the friction engagement device Energy has a low shift point (N ₀ is small)
And it becomes that much smaller. Also, preferably, in the fail shift pattern, the shift point for downshift is set lower than the shift point for upshift, compared to the normal balance. As a result, the frequency of gear changes, particularly the frequency of upshifts, can be reduced, and the load on the frictional engagement device can be reduced accordingly. It should be noted that "changing the shift pattern" naturally includes techniques for substantially "changing the shift pattern" by, for example, correcting an input vehicle speed signal or the like.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 2 is an overall schematic diagram of a shift control device for an automatic transmission to which the present invention is adopted. The engine 1 and automatic transmission 2 are well known. In the engine 1, the engine control computer 7 controls the fuel injection amount at the injection valve 19 and the ignition timing at the distributor 20, so that an engine output corresponding to the accelerator opening degree and the engine rotation speed is obtained. It's becoming like that. Also, automatic transmission 2
The solenoid valves _S1 to _S3 of the hydraulic control device 3 are controlled by the automatic transmission control computer 8,
As a result of changing the oil passage in the hydraulic control device 3, the engagement state of each frictional engagement device is selectively changed, so that a gear stage corresponding to the vehicle speed and the accelerator opening degree can be obtained. That is, the engine control computer 7 has the engine rotation speed detected by the engine rotation sensor 9, the intake air amount detected by the intake amount sensor 10, the intake air temperature detected by the intake air temperature sensor 11, the throttle opening degree detected by the throttle sensor 12, and the vehicle speed sensor 1.
3, engine water temperature from the engine water temperature sensor 14, and brake ON signals from the brake switch 15 are input. The engine control computer 7 determines the fuel injection amount and ignition timing based on these signals. In addition, each solenoid signal of the solenoid valves _S1 to _S3 , which are ON-OFF controlled by the automatic transmission control computer 8, is also input to the engine control rule computer 7 in parallel. Determines when to shift gears. On the other hand, automatic transmission control computer 8
includes the throttle sensor 12 and the vehicle speed sensor 1.
3. In addition to signals from the engine coolant temperature sensor 14, brake switch 15, etc., the shift lever position is determined by the shift position sensor 16, driving selection patterns such as fuel economy-oriented driving or power performance-oriented driving, and overdrive are determined by the pattern select switch 17. A signal such as permission to shift to overdrive from the switch 18 is input, and the solenoid valves S ₁ to _{S 3} are controlled ON-OFF so that a gear position corresponding to the vehicle speed and accelerator opening is obtained. There is. FIG. 3 is a flowchart of integrated control of the engine and automatic transmission. In this embodiment, the engine rotational speed Ne is monitored and a change abnormality is determined by detecting the time during which the engine rotational speed Ne is decreasing. Each step will be explained below. Step 99: Determine whether flag _F2 is 1 or not. This flag F ₂ becomes 1 when it is determined in step 120 that the shift is abnormal, and when F ₂ =1, the process proceeds to step 99A to set a fail shift pattern in accordance with the position of the pattern select switch 17. If flag _F2 is not 1, proceed to step 100. The case where the flag _F2 is not 1 will be explained. Step 100: It is determined whether the pattern select switch 17 has selected a low speed shift pattern (see FIG. 4A) in which the engine 1 shifts in a low rotation range. Step 101: When step 100 is YES, a low speed shift pattern is set as selected by pattern select switch 17. Step 102: If the low speed shift pattern is not selected and the flag _F2 is not 1, the high speed shift pattern (see FIG. 4B) is set. Step 99A: When YES is determined in step 99 (when flag F ₂ =1), it is determined whether the pattern select switch 17 is set to the low speed shift pattern. Step 103A; Pattern select switch 17
is a low speed shift pattern, the fourth
Select a fail low speed shift pattern as shown in Figure D. In this fail low speed shift pattern, the shift point is set to be low so that even if the engine torque change control during the shift is not executed as planned, the durability of the friction engagement device will not be affected. In particular, when the engine load (throttle opening) increases beyond a certain level, the durability of the frictional engagement device begins to suffer, so when the engine load exceeds a predetermined value, the gear shift is executed before the vehicle speed increases. ing. Step 103B: When the pattern select switch is set to the high speed shift pattern, the pattern shown in FIG.
A fail high speed shift pattern as shown in is selected. This fail high-speed shift pattern has a slightly higher shift point than the previous fail low-speed shift pattern, and is used when the driver desires high power performance (when the pattern select switch is set to the high-speed shift pattern). The system is designed to allow for driving that takes full advantage of its power performance, taking into account the durability of the frictional engagement device. Even in this case, if the throttle opening exceeds a predetermined value, there is a risk that the durability of the friction engagement device will be compromised, so the gear shift is executed before the vehicle speed becomes too high. . Step 104; Step 101, 102, 103A, 103B
Shift determination is made according to the shift pattern set in . Step 105: Determine whether flag _F1 is zero or not, and if it is set to zero, proceed to step 106. Step 106: Determine whether or not there is an upshift. Step 107: A command is given to the solenoid valves S ₁ to _{S 3} to supply hydraulic pressure to the relevant frictional engagement device (speed change command). Step 108: Determine whether power is ON (engine output is positive). Step 109: The engine rotation speed Ne is monitored in order to detect the time to start shifting by upshifting. Step 110: It is determined whether the detected engine rotational speed Nei is smaller than the previous detected value Ne _i-1 .
In other words, by upshifting, the engine rotational speed Ne
Determine whether or not the value has started to decrease. In this case, even if hydraulic pressure is supplied to the upshift frictional engagement device in step 107, the shift will not normally start immediately, so step 110 will initially be NO and the step will continue.
Proceed to 111. Step 111; After the hydraulic pressure supply command for upshifting is issued, set the flag F1, which indicates that monitoring of the engine rotation speed Ne has started, to ₁ , and set Nei to 1.
Set the number of times n of <Ne i _-1 to zero to zero. Step 113: If Nei<Ne _i-1 is established in step 110, 1 is added to the number of times n is established. Step 114: It is determined whether or not the number of times n in which Nei<Ne _i-1 is continuously established is equal to or greater than a predetermined value n ₀ (for example, n ₀ =3).
If YES, that is, it is determined that the engine rotation speed drop is not a temporary rotation fluctuation but a rotation drop (change) due to an upshift, and the process recognizes that the shift has started and proceeds to step 115. Step 115: At the same time as outputting the engine output down command, a timer is started to measure the shift time t. Step 116: In order to detect when the shift ends, the Ne after the shift is calculated in advance.
I am monitoring with Neo which is set slightly higher.
Ne is compared, and if Ne<Neo, it is assumed that the gear is still changing (engine output is down) and step 117 is performed.
If Ne<Neo holds true, it is determined that the shift is about to end, and the process proceeds to step 118. Step 117; Set flag _F1 to 2. Step 112: Since it was determined in step 105 that F ₁ is not 0, in this step it is determined whether F ₁ is 1 or not. When F ₁ = 1, a step is executed to determine whether or not gear shifting has started.
The process proceeds to step 110, and when F ₁ =1, that is, when F ₁ =2, the process proceeds to step 116 to determine whether or not the shift is completed. Step 118: Since the shift is about to end, a command to restore the engine output is output, and the timer t for measuring the shift time is stopped. Step 119: The shift time t is compared with an abnormal shift determination time _t0 , which is set in advance according to the type of shift, throttle opening, and shift point, and when t≧ _t0 , the process proceeds to step 120. Step 120: Determine abnormal gear shift and set flag _F2 to 1
Make it. When F ₂ =1, as described above, the fail shift pattern is set in which the shift point is forcibly set to a low value in order to reduce the amount of energy absorbed by the frictional engagement device according to the state of the pattern select switch 17. Switch. Step 121: Display a warning light to inform the driver that the shift pattern is fixed to a fail shift pattern for the purpose of protecting the frictional engagement device because the engine torque is not being changed as planned. . Step 122: Set the flag F ₁ , the number n of times Nei<Ne _i-1 is satisfied, and the measured shift time t to zero. Step 123: Determine whether or not to downshift. If yes, proceed to step 124. Step 124: Issue a command to release the hydraulic pressure of the relevant clutch. Although the reset of the flag _F2 is not shown in the flowchart, it should be done when the battery terminal is turned OFF (released) if it goes to zero so that it will not be reset unless the cause of the abnormal gear shift is resolved. FIG. 6 shows the speed change transient characteristics when the above control flow is executed. The shift command b is executed a predetermined time after the shift determination a, as in the conventional case. This is to deal with so-called multiple speed changes. The engine output down command is the engine rotation speed
Since the time point c' is determined by monitoring Ne and Nei<Ne _i-1 is repeated n times in a row, the timing is slightly delayed from the actual shift start time. The shift end time when engine output control is normal is t ₂ , but the measured value in the above flow is t ₁ ,
Therefore, the shift time t is measured to be smaller by _t2 - _t1 . _t3 in the figure is the stroke end time (end time of the buffer region) of the accumulator piston to the frictional engagement device. The actual shift time must be before this stroke end time, so if measuring the shift time is used as a means of determining abnormal shift, at least the abnormal shift determination time
t ₀ must be less than t ₃ . Furthermore, as mentioned above, in the case of the method of determining the time before the end of the shift based on Ne ₀ , t ₂ − _{t 1} is measured smaller than the actual value, so in the end, t ₀ < t ₃ − The abnormal shift determination time t ₀ is set so that (t ₂ −t ₁ ). Note that the time lags that occur initially are irrelevant for the time start points from t ₁ to _{t 3} because they are all engine output down commands c'. The above-mentioned _t3 may be determined based on the design capacity of the accumulator, orifice system, line oil pressure, etc., or may be determined based on experimental data. Since the measured value t ₄ at the time of engine output control abnormality becomes larger than t ₃ −(t ₂ −t ₁ ), as a result, YES is determined in step 119. In the figure, when the engine torque change control is performed normally (solid line), the working oil pressure of the friction engagement device is set to a lower value in advance than when the engine torque change control is not performed as planned (double-dashed line). It is set to . Therefore, the output shaft torque T of the automatic transmission
fluctuations are becoming smaller. When engine torque change control is not performed for some reason (broken line), the working oil pressure of the friction engagement device is low relative to the load torque of the friction engagement device, so the gear change progress rate (engine rotation speed Ne Since the change rate (rate of change) becomes smaller, the shift time t becomes longer and takes up to _t4 , and an extremely large shock occurs after the stroke end of the accumulator piston. According to the above embodiment, this abnormality is detected based on the length of the shift time t, and the shift pattern is forcibly changed to a fail shift pattern in which the shift point is set to a low value. Since the gear shift is performed in a region where the shear torque is small, the heat load on the friction engagement device during gear shifting is reduced, making it possible to improve the durability of the friction engagement device and shortening the shift time t. , it becomes possible to prevent large shift shocks from occurring. Moreover, when changing to this fail shift pattern, the fail shift pattern adopted differs depending on the position of the pattern select switch 17, so the driver's intention can be respected to a certain extent while the driver can adjust the power performance. When desired, it becomes possible to execute a shift that ensures as much power performance as possible while taking into consideration the durability of the frictional engagement device. In addition, in this case, the driver can be informed of the abnormality by the warning system, so that he can avoid the discomfort caused by the low gear shift point and promptly check the cause of the problem. You will be able to do this. In addition, in the above embodiment, the shift time t is t ₀
It used to be that an abnormal shift was determined when t≧t 0 was established only once, but in order to prevent it from being easily determined as an abnormal shift within the range of variation, when t≧t ₀ was established a certain number of times. It may be determined that the shift is abnormal. In addition, in the above embodiment, in determining whether or not there is an abnormal gear shift, the engine rotation speed is monitored, and it is determined whether or not the time period during which the engine rotation speed has decreased is longer than a preset value. However, the present invention is not limited to this; for example, the output shaft torque T of an automatic transmission is monitored, and the output shaft torque T varies from the minimum value _T1 to the maximum value. Time to change to T ₂ (5th
The determination may be made based on whether t ₅ ) in the shift characteristic diagram shown in the figure is longer than a preset value. Furthermore, the output shaft torque T of the automatic transmission is monitored, and the determination is made based on whether the maximum value T ₂ of the output shaft torque (see also FIG. 5) is larger than a preset value T ₀ or not. You can do it like this.

【Effect of the invention】

As explained above, according to the present invention, for example, the engine torque is not changed as planned for some reason, and as a result, an abnormal gear shift occurs and the durability of the friction engagement device decreases, or the gear shift shock is stopped. When a failure occurs, the gear shift is performed according to a fail shift pattern in which the shift point is set lower depending on the position of the pattern select switch, reducing the thermal load on the friction engagement device. This has the advantage that the shift time can be kept within the buffer area of the accumulator, and the shift shock can be made smaller.
Also, since the fail shift pattern is selectively adopted depending on the position of the pattern select switch,
The driver's intention can be reflected to that extent.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the gist of the present invention, and FIG. 2 is an overall block diagram of a vehicle automatic transmission and engine showing the configuration of an embodiment of a shift control device for an automatic transmission according to the present invention. FIG. 3 is a flowchart showing the control routine adopted in the above embodiment device;
4A to 4D are graphs showing examples of shift patterns, and FIG. 5 is a shift transient characteristic diagram when the above control routine is executed. 1...Engine, 2...Automatic transmission, 7...Engine control computer, 8...Automatic transmission control computer, t...Shift time, T...Output shaft torque.

Claims (1)

[Scope of Claims] 1. A system for automatically changing gears according to a gear shift pattern set in advance according to the position of a pattern select switch, and also for changing gears by changing engine torque during gear shifting. In a shift control device for an automatic transmission that maintains good characteristics, there is provided a means for detecting a shift abnormality, including a shift abnormality that occurs when the engine torque is not changed as planned. , means for changing the shift pattern to a fail shift pattern in which a shift point is set at a low level for abnormalities in accordance with the position of the pattern select switch when a shift abnormality is detected; A speed change control device for an automatic transmission characterized by: 2. The fail shift pattern is composed of shift points determined in advance so that the amount of energy absorbed by the frictional engagement device is equal to or less than an allowable value even if the engine torque reduction control that should be performed at the time of shift is not performed. A speed change control device for an automatic transmission according to claim 1. 3. The automatic transmission according to claim 1 or 2, wherein the fail shift pattern has a downshift shift point set lower than a normal balance with respect to an upshift shift point. transmission control device.