JP2572575Y2 - Control device for automatic transmission for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] <Industrial Application Field> The present invention relates to a control device for an automatic transmission for a vehicle for performing a shift control of a transmission suitable for use in an automobile, for example.

2. Description of the Related Art Conventionally, in an automatic transmission that automatically performs a shifting operation of a transmission used in an automobile or the like in accordance with a vehicle speed and an engine load such as a throttle opening and a negative pressure in an intake pipe, the vehicle speed is reduced. The speed is automatically changed according to a shift line for upshift and downshift set in advance according to the engine load.

In general, the shift characteristics are set in advance in accordance with running under certain conditions, and it is difficult to adapt to all running conditions. In particular, in mountainous areas, the vehicle often travels on uphill roads, downhill roads, and high altitudes where the atmospheric pressure is low.On an uphill road, the engine output is substantially reduced due to the uphill resistance, and the engine output is actually reduced at high altitudes. I do. Therefore, in order to obtain the same feeling of acceleration as when traveling on a flat road or lowland, the driver must depress the accelerator pedal greatly,
The shift operation is performed by switching the shift lever to select a low gear, or by selectively operating one of the shift characteristics set in advance according to a plurality of running patterns by operating a switch. There was a hassle of doing it inside. Also, when traveling on a downhill, the driver returns the accelerator pedal, but at this time, there is a case where the automatic transmission causes a shift-up operation by upshifting and the engine brake may be lowered, in which case, The operation is cumbersome, such as depressing a brake pedal or switching a shift lever to select a low gear and apply an engine brake.

For example, as disclosed in JP-B-51-27054 and JP-B-58-27420, it is conceivable to automatically switch the shift characteristics using a gradient sensor and a plurality of other sensors. The use of such a sensor complicates the apparatus. Particularly, in the case of a gradient sensor which is not affected by acceleration in the front-rear direction, there is a problem that the system becomes complicated and the cost of parts increases.

<Problems to be solved by the present invention> In view of the problems of the related art, a main object of the present invention is to automatically select a suitable shift automatically according to a traveling state at that time without using many sensors. This is achieved by providing a control device for a vehicle automatic transmission that is improved to change characteristics.

[Constitution of the Invention] <Means for Solving the Problems> According to the present invention, an object of the present invention is to provide an automatic shift control that automatically performs a shift operation according to a shift characteristic preset according to a vehicle speed and an engine load. Automatic transmission with a fluid type torque converter comprising: means for predicting engine torque according to an engine load and an engine speed under specific driving conditions; An actual engine torque calculating means for calculating an engine torque given from a speed change rate, and the predicted engine torque value when a predetermined time elapses after a shift command is issued until the torque converter enters a coupling state. Means for changing the shift characteristic in accordance with a result of comparison with an engine torque value. It is achieved by providing a device.

<Operation> In this way, when a predetermined time from when the gearshift command is issued to when the torque converter enters the coupling state has elapsed, the torque converter is in the coupling state. Since the engine output torque is output to the transmission as it is, a suitable automatic shift control can be performed by comparing the predicted engine torque value with the actual engine torque value. For example, when traveling on an uphill road, the actual engine torque value during actual traveling becomes smaller than the previously stored predicted engine torque value based on the traveling conditions at that time. By changing the upshift operation so that it occurs on the higher vehicle speed side than usual, it is possible to travel at a lower gear position on an uphill road until a relatively high vehicle speed is reached.

<Embodiment> Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing an outline of an automatic transmission of an automobile to which the present invention is applied. In FIG. 1, engine 1
The automatic transmission 2 includes a torque converter 3 with a lock-up clutch 3a and, for example, a forward 4-speed reverse 1-speed gear transmission 4 with a hold clutch. The final drive gear 4a of the gear transmission 4 is meshed with a ring gear of a differential device 6 connected to the drive wheels 5, and the output torque of the engine 1 is transmitted to the drive wheels via the torque converter 3 and the gear transmission 4. It is conveyed to 5.

Each shift speed of the automatic transmission 2 is controlled by a control unit 7 as automatic shift control means to automatically shift according to a vehicle speed signal and a throttle opening signal as an engine load. Control unit 7
Consists of a combination of general circuits, CPU, ROM, RA
M and input / output circuits 7a and 7b. In the input circuit 7a,
For example, a pulse signal is input as a vehicle speed signal from a vehicle speed sensor 8 provided in the vicinity of the final drive gear 4a, and a voltage signal is also output from a throttle opening sensor 9 attached to a throttle body (not shown) of the engine 1 for example. It is input as a degree signal.
It should be noted that a signal of the engine speed from the engine speed sensor 10 is input to the input circuit 7a for use as a condition for the shift control.

In the control unit 7, a shift map control according to each signal input to the input circuit 7a is performed using a CPU, a ROM, and a RAM. A shift control signal and a lockup control signal are output from an output circuit 7b of the control unit 7 to each solenoid valve such as a shift control and a lockup control of the hydraulic control circuit 11. The gears of each shift speed of the automatic transmission 2 are automatically switched by the hydraulic control circuit 11.

FIG. 2 is a diagram showing a flow of control based on the present invention, and an operation procedure of a shift will be described below with reference to FIG. 3 showing an example of a shift characteristic.

As shown in FIG. 2, in step ST1, each detected value of the throttle opening TH from the throttle opening sensor 9, the engine speed Ne from the engine speed sensor 10, and the vehicle speed V from the vehicle speed sensor 8. Read. Next step ST
In step 2, the coupling state of the torque converter 3 is determined. To determine the coupling state, when the input / output rotational speed ratio of the torque converter reaches a coupling point of about 0.8, the torque ratio of the torque converter becomes 1 and the torque amplifying action is lost, so that the output torque of the engine is reduced. Is transmitted to the transmission as it is, and a comparison between a predicted engine torque value and an actual engine torque value, which will be described later, can be easily performed under this coupling state. Further, as a method for determining the coupling state, since a coupling state is almost established at a point in time when a certain time (predetermined time) has elapsed after the gear shift, the coupling state is determined in advance according to the shift map. It is preferable to set an area for determining whether or not the determination is made.

In step ST2, the presence or absence of the coupling state is determined by using any of the above-described methods. If the coupling state is established, the process proceeds to step ST3. Step S
At T3, based on a predicted engine torque value map which is stored in the ROM in the control unit 7 and which is obtained in advance under specific driving conditions such as running on a flat road and the like, in accordance with the throttle opening and the engine speed. Then, a search for a predicted engine torque value Ty at the time of coupling is performed. It should be noted that the specific running conditions preferably take into account conditions such as inclination, air pressure, load capacity, and auxiliary equipment. In the next step ST4, the actual engine torque value Tj is determined by the following equation by multiplying the acceleration obtained by differentiating the vehicle speed V, which is the rate of change of the vehicle speed, with time by a coefficient K that takes into account the vehicle weight and the gear ratio.

Tj ← K × dV / dt In the next step ST5, the predicted engine torque value Ty
And the actual engine torque value Tj obtained by the above equation. That is, for example, in the case of an uphill road, the reverse torque due to the inclination acts, so that the actual engine torque value Tj is smaller than the predicted engine torque value Ty corresponding to the throttle opening and the engine speed at that time. In step ST5, when the actual engine torque value Tj is equal to or larger than the predicted engine torque value Ty, that is, when the vehicle is not running on an uphill road or the like, the process proceeds to step ST6. In step ST6, the control of the shift operation based on the normal shift map having the shift characteristics indicated by the shift line shown by the solid line in FIG. 3 is performed, and in the next step ST7, the flag F is set to 0, and the step ST1 is executed. Return to

If the coupling state is not established in step ST2, the process proceeds to step ST8, where it is determined whether the flag F is 1 or not. If the flag F is not 1, the process proceeds to step ST6, and the same control as described above is performed thereafter. If the flag F is 1 in step ST8, or if the actual engine torque value Tj is smaller than the predicted engine torque value Ty in step ST5, the process proceeds to step ST9. In step ST5, not only the simple comparison but also the procedure may proceed to step ST9 when the actual engine torque value Tj is smaller than the predicted engine torque value Ty by a predetermined amount. In step ST9,
The shift operation is controlled by switching to a high vehicle speed shift map having shift characteristics according to a shift line indicated by an imaginary line in FIG. 3 in which an upshift is performed on a higher vehicle speed side with respect to a normal shift line. . In this case, the flag F is set to 1 in the next step ST10, and the process returns to step ST1.

By the way, in the case where the normal shift map is used, for example, when the vehicle speed decreases during traveling on an uphill road and a downshift shift operation is performed, it is attempted to return to the original vehicle speed or further increase the vehicle speed. Even if the driver depresses the accelerator pedal when trying to travel with great acceleration at a low gear, the driver immediately crosses the shift line and the upshift shift operation is performed. May not be able to obtain the acceleration desired by others. However, according to the present invention, as described above, the uphill traveling state and the like are determined, and in that case, the shift is performed after the coupling state as described above so that the upshift is performed at a higher vehicle speed side. Since the characteristics are changed, it is possible to drive with a large acceleration while maintaining the low shift speed until a relatively high vehicle speed is reached, and with a feeling of acceleration without discomfort due to the coupling state.

In the present embodiment, the normal shift map and the high vehicle speed shift map are switched. However, a correction coefficient calculated according to the comparison result in step ST5 and calculated from the difference is multiplied by the shift characteristic of the normal shift map. Thus, the shift line in the normal shift map may be changed. Also,
Although the present embodiment has shown the ascending road, even when traveling in a place where the atmospheric pressure is low, such as high altitude, the actual engine torque is reduced at the same throttle opening for lowland traveling,
Although the acceleration desired by the driver may not be obtained, the acceleration according to the present invention can be improved. By the way, it is good to obtain a large engine brake at a relatively low vehicle speed at a relatively high vehicle speed by using a high vehicle speed shift map even on a downhill road, but in this case, the actual engine torque value Tj is larger. Can be controlled by determining

[Effects of the Invention] As described above, according to the present invention, the torque converter is in the coupling state when a predetermined time from when the shift command is issued to when the torque converter enters the coupling state has elapsed. Therefore, at that time, the engine output torque is output to the transmission as it is, so that the predicted engine torque value and the actual engine torque value can be compared after the coupling state, and suitable automatic transmission control can be performed. Can be. When the actual engine torque value during actual traveling is smaller than the previously stored predicted engine torque value, for example, when traveling on an uphill road, the shift operation of the upshift on the high vehicle speed side with respect to the normal shift characteristics. By changing the shift characteristics so that the vehicle speed can be relatively high, the vehicle can run at a lower speed than usual until a relatively high vehicle speed is reached, so that the acceleration performance on an uphill road or the like can be improved and the coupling state can be improved. Since the shift characteristic is changed according to the result of calculating the predicted engine torque value and comparing with the actual engine torque value, the shift control is performed without using a gradient sensor or a complicated system. Can be
The effect is extremely large, for example, the control device can be simplified and inexpensive.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an outline of an automatic transmission of an automobile to which the present invention is applied. FIG. 2 is a flowchart of control based on the present invention. FIG. 3 is a diagram showing one example of shift characteristics of the automatic transmission. DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Automatic transmission, 3 ... Torque converter, 3a ... Lock-up clutch, 4 ... Gear transmission, 4a
... Final drive gear, 5 ... Drive wheels, 6 ... Differential device, 7 ... Control unit, 7a ... Input circuit, 7b ... Output circuit, 8 ... Vehicle speed sensor, 9 ... Throttle opening degree sensor,
10… Engine speed sensor, 11… Hydraulic control circuit

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI F16H 63:12

Claims (1)

(57) [Scope of request for utility model registration] An automatic transmission with a fluid torque converter having an automatic shift control means for automatically performing a shift operation according to a shift characteristic preset according to a vehicle speed and an engine load, and under a specific running condition. Predicted engine torque storage means for storing in advance engine torque predicted according to the engine load and the engine speed; actual engine torque calculation means for calculating engine torque given from the rate of change of the actual vehicle speed; Means for changing the shift characteristic in accordance with the result of comparing the predicted engine torque value and the actual engine torque value when a predetermined time elapses from when the torque converter is brought into the coupling state. A control device for an automatic transmission for a vehicle, comprising: