JPH0531027B2 - - 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, automatic transmissions are capable of automatically changing gears according to a preset shift pattern, and maintain good shifting characteristics by changing engine torque during gear shifting. Regarding a control device.

[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 in such a manner that the engine torque of the automatic transmission is expected to be reduced by a predetermined amount.

[Purpose of the invention]

The present invention has been made in view of such conventional problems. For example, when the engine torque that should normally be changed is not changed for some reason, and this causes an abnormality in gear shifting. To provide a shift control device for an automatic transmission, which can promptly detect such a situation, ensure the durability of a friction engagement device of the automatic transmission, and ensure good shift characteristics. The purpose is to

[Means to solve the problem]

As the gist of the present invention is shown in FIG. In a shift control device for an automatic transmission that maintains good characteristics, means for detecting shift abnormalities including shift abnormalities that occur when at least the engine torque cannot be changed as planned;
The above object is achieved by comprising means for detecting engine load, and means for changing the shift point to a lower position only when the engine load is equal to or higher than a predetermined value when an abnormality in shift is detected. has been achieved.

[Effect]

In the present invention, due to some reason such as a failure of the sensor system or a request from the engine side, for example, even though the engine torque change control is supposed to be performed, the engine torque change control is actually executed as planned. Abnormalities in gear shifting that occur when the gear is not adjusted are detected promptly, and the gear shifting point is changed to a lower position. 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 combined equipment can be improved, and
Since the shift time can also be kept within the buffer area of the accumulator, deterioration of the shift characteristics can be prevented. Furthermore, in the present invention, the shift point is changed only when the engine load is equal to or higher than a predetermined value. The advantages of doing so are as follows. That is, when the engine load is small, the durability of the frictional engagement device is generally not a problem, and the gear shift is completed relatively quickly. Therefore, changing the shift pattern at the time of failure becomes truly effective when the engine load is high to a certain extent. Therefore, there is no problem if the forced change of the gear shift pattern is performed only when the engine load is above a predetermined value.In fact, when the engine load is below a predetermined value, it is normal to ensure power performance within that range. This makes it possible to drive with the same speed change pattern, which makes it better. Preferably, the low gear shift point is
The shift point is determined in advance so that the amount of energy absorbed by the frictional engagement device is equal to or less than the allowable value even if the engine torque reduction control that should be performed at the time of shifting is not performed. As a result, even if engine torque change control is not performed during gear shifting,
As a result, even if an abnormal speed change occurs, the durability of the frictional engagement device is not impaired, and a small speed change is possible with the speed change shock. 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. Preferably, in the fail shift pattern consisting of the low gear shift points, the shift point for downshift is set lower than the shift point for upshift compared to the normal balance. It is. As a result, the shifting frequency,
In particular, the frequency of upshifts can be reduced, and the load on the frictional engagement device can be reduced accordingly. It should be noted that "shifting at a shift point" naturally includes a technique for substantially "changing a shift point" by correcting, for example, the value of 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 information such as 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, and the throttle opening degree (representative of the engine load) detected by the throttle sensor 12. ), vehicle speed from the vehicle speed sensor 13, engine water temperature from the engine water temperature sensor 14, and brake ON signals from the brake switch 15 are input. 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, an abnormality in gear shifting is detected by monitoring the engine rotation speed Ne and detecting the time during which the engine rotation 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 an abnormal shift has occurred, and when F ₂ = 1, that is, when an abnormal shift has occurred, the throttle opening θ (engine load) is set to a predetermined value. The fail shift pattern is set only when θ1 or _more . The reason why the fail shift pattern is thus set is limited to when the throttle opening θ is equal to or greater than the predetermined value θ ₁ is as follows. That is, when the throttle opening degree θ is smaller than the predetermined value θ ₁ , the durability of the frictional engagement device is generally not a problem, and the gear shift ends relatively quickly. Therefore, changing the shift pattern at the time of failure becomes truly effective when the throttle opening (engine load) is high to a certain extent.
Therefore, there is no problem in forcing the shift pattern to be changed only when the throttle opening θ is greater than or equal to the predetermined value θ _1.In fact, when the throttle opening θ is less than the predetermined value θ ₁ , the throttle opening θ is within that range. This makes it possible to drive with the normal shift pattern that ensures power performance, which makes it better. To realize this control, for example, as shown in the route of the imaginary line in Fig. 1, a step is provided to determine the throttle opening θ when F ₂ =1 is determined in step 99, and the throttle opening is The process may proceed to step 103 (adopting a fail change pattern) only when θ is greater than or equal to a predetermined value, and proceed to step 100 (normal flow) when the throttle opening degree θ is less than a predetermined value. However, in this embodiment, the same effect can be obtained by making use of the fact that the shift pattern itself is composed of the throttle opening θ and the vehicle speed V, and by devising the shift pattern itself, the same effect can be obtained. (described later). Step 100: When F ₂ =0 (normal), check whether the pattern select switch 17 operated by the driver selects a low speed shift pattern (see Fig. 4A) in which the engine 1 shifts in a low rotation range. judge. Step 101: When step 100 is YES, a low speed shift pattern is set as selected by pattern select switch 17. Step 102: If F ₂ =0 (normal) and a low speed shift pattern is not selected, a high speed shift pattern (see FIG. 4B) is set. Step 103: When it is determined in step 99 that flag F ₂ =1, a fail shift pattern (see FIG. 4C) is set. In this fail shift pattern, the shift point is set lower than the low speed shift pattern so that there is no problem with the frictional engagement device even if engine torque change control during gear shifting is not executed. More specifically, in this fail shift pattern, the throttle opening θ is greater than or equal to a predetermined value θ ₁ , considering that the durability of the frictional engagement device becomes a problem when the throttle opening is high to a certain extent. Normally, when the vehicle speed increases, the upshift is first performed, but the upshift is started when the vehicle speed is low. Step 104: A shift decision is made according to the shift pattern set in steps 101, 102, and 103. 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 or not the power is ON (engine output is positive: the engine brake has not been applied and power is being transmitted from the engine to the wheels). This is to limit changes in engine torque during gear shifting to only when power is on. The reason for doing this is that when the power is off, the shift shock is not much of a problem, so the degree of demand for changing the engine torque is small.On the other hand, changing the engine torque is likely to cause problems such as an increase in exhaust temperature. be. 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 the number n of successive occurrences of Nei<Ne _i-1 is greater than or equal to a predetermined value n (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 gear shifting is in progress (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: It is determined that an abnormal gear shift has been performed, and the flag _F2 is set to 1. As mentioned above, when F ₂ = 1, the shift point is set low in order to reduce the amount of energy absorbed by the frictional engagement device, especially in the region where the throttle opening θ is greater than the predetermined value θ ₁ . It is designed to be able to switch to a fail shift pattern. Step 121: A warning light is displayed to inform the driver that an abnormal gear shift has been detected. 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 is set such that it is not reset unless the cause is resolved, for example, when the battery terminal is turned off (released). 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 start points from t ₁ to _{t 3} are all engine output down commands c', so the time lag that occurs first is irrelevant. The above-mentioned t ₃ 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 Fig. 6, when the engine torque change control is performed normally (solid line), the working oil pressure of the friction engagement device is set lower in advance than when the engine torque change control is not performed (double-dashed line). It is set. Therefore, fluctuations in the output shaft torque T of the automatic transmission are becoming smaller. When engine torque change control is not performed for some reason (dashed line)
Since the working oil pressure of the frictional engagement device is low relative to the load torque of the frictional engagement device, the gearshift progress rate (rate of change in engine rotational speed Ne) becomes small, and the shift time t becomes longer. ₄ , and an extremely large shock will occur after the stroke end of the accumulator piston. According to the embodiment described above, this state is detected based on the length of the shift time t, and when it is determined that an abnormal shift has occurred in a state where the engine torque change is not executed as planned, for example, the shift pattern is changed. In particular, in the region where the throttle opening θ is greater than or equal to the predetermined value θ ₁ , the shift pattern is changed to a fail shift pattern in which the shift point is set to a low value. As a result, the heat load on the frictional engagement device during gear shifting is reduced, and the durability of the frictional engagement device can be improved, and the gearshift time t is also shortened to prevent large gearshift shocks from occurring. You will be able to do it. Furthermore, when the engine load is less than the predetermined value θ ₁ , the shift shock is small to begin with and the durability of the friction engagement device is not much of a problem, so there is no need to further lower the shift point. It is possible to prevent the power performance from deteriorating further. Note that when an abnormal gear shift is detected, the driver can be informed of this by the warning device, so that he or she can promptly take measures such as checking the cause of the malfunction. 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. If a problem that is likely to increase occurs, the shift point will be set lower only when the engine load is high, reducing the thermal load on the friction engagement device and reducing the speed of the shift. An excellent effect is obtained in that the time can be kept within the buffer area of the accumulator, and the speed change shock can be made smaller.
In addition, when the engine load is low, problems with the durability of the frictional engagement device and problems with the gear shift shock do not occur in the first place, so gear shifts are performed according to the normal gear shift pattern, so power performance is not lowered more than necessary. You can also get the effect that you can get away with it.

[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 4C 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)

[Claims] 1. To enable automatic gear shifting according to a preset gear shifting pattern, and to maintain good gear shifting characteristics by changing engine torque during gear shifting. A shift control device for an automatic transmission comprising: means for detecting a shift abnormality, including a shift abnormality that occurs when the engine torque cannot be changed as planned; means for detecting engine load; and a shift control device for an automatic transmission. A shift control device for an automatic transmission, comprising: means for changing a shift point to a lower level only when the engine load is equal to or higher than a predetermined value when an abnormality is detected. 2. The gear shift point set at the lower level is a gear shift determined in advance so that the amount of energy absorbed by the frictional engagement device is below the allowable value even if the engine torque reduction control that should be performed at the time of gear shifting is not performed. A speed change control device for an automatic transmission according to claim 1, which is defined as a point. 3. The fail shift pattern consisting of the shift points set to a lower value has the shift point for downshift set lower than the shift point for upshift compared to the normal balance. A speed change control device for an automatic transmission according to item 1 or 2.