JPS5943667B2 - Control method for automatic transmission for vehicles - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method of controlling an automatic transmission for a vehicle.

Automatic transmissions for vehicles have been proposed in various configurations, including a torque converter, a gear transmission mechanism that switches between a plurality of gear speeds, and a direct coupling clutch that directly couples the torque converter.

In such automatic transmissions, the direct coupling clutch is provided with the intention of improving the fuel efficiency of the vehicle, and it is preferable that its operating range be as wide as possible. In the operating range of 20-30% or more, the direct coupling clutch is engaged along the shift line when the gear transmission mechanism is switched to the highest speed gear.

However, if we look at the relationship between the vehicle speed and the torque applied to the vehicle's drive shaft under a certain throttle opening, at each gear stage, when the vehicle is in a high vehicle speed range that exceeds a certain value of the vehicle speed, , a larger output shaft torque can be obtained when the direct-coupled clutch is engaged in the direct-coupled drive state than when the direct-coupled clutch is disengaged and the torque converter is in the drive state.
When the vehicle speed is in a low vehicle speed region below the wave value, a larger output shaft torque is obtained when the direct coupling clutch is disengaged and the torque converter 1 is driven than when the direct coupling clutch is engaged and the torque converter 1 is in the driving state, The drivability of the vehicle is improved.

This is especially important when high output shaft torque is required while the vehicle is running at low speeds, such as when the vehicle is climbing.

The present invention addresses the above-mentioned problems regarding switching control between engagement and release of a direct-coupled clutch in a conventional automatic transmission equipped with a direct-coupling clutch, and the present invention addresses the above-mentioned problems regarding switching control between engagement and disengagement of a direct-coupling clutch, and makes it possible to use a direct-coupling clutch to control a portion of a vehicle's driving range. An object of the present invention is to provide an improved control method for an automatic transmission for a vehicle, which controls the automatic transmission so that the drivability and power performance of the vehicle are not impaired.

According to the present invention, the present invention provides a method for controlling an automatic transmission for a vehicle, which includes a torque converter, a gear transmission mechanism that is switched between a plurality of gears, and a direct coupling clutch that directly couples the torque converter. The gear transmission mechanism is switched between the plurality of gears based on a plurality of input signals including a signal related to the throttle opening, and the direct coupling clutch is switched between engagement and disengagement, and at this time, the gear transmission mechanism is switched between engagement and disengagement. A shift line that defines a switching boundary between the plurality of gears based on a throttle opening value, and a direct clutch switching line that defines a switching boundary between engagement and disengagement of the direct coupling clutch based on vehicle speed and throttle opening values. When setting the vehicle speed and throttle opening using a diagram with two coordinate axes,
The direct-coupled clutch switching line is shifted so that the direct-coupled clutch is not engaged in a region where the transmitted torque when the direct-coupled clutch is disengaged is greater than the transmitted torque when the direct-coupled clutch is engaged. This is achieved by a control method characterized by positioning the vehicle in a region on the high vehicle speed side of the line.

The invention will now be described in detail by way of example embodiments with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing the configuration of an apparatus for carrying out the method of controlling an automatic transmission for a vehicle according to the present invention.

FIG. 1 schematically shows the configuration of an automatic transmission controlled by the control method of the present invention.

Such an automatic transmission is known per se, and includes an input shaft 1 connected to the output shaft of an engine (not shown), a hydraulic torque converter 2, and an input shaft that bypasses the torque converter 2. 1 is directly connected to the output shaft 4 of the torque converter, a direct coupling clutch 3, a shaft 5 connected to the output shaft 4 of the torque converter is connected to the input shaft, and several speed change characteristics are given to this, and the output shaft 7 is used to drive the vehicle. It includes a gear transmission mechanism 8 that outputs driving force for driving the wheels.

The gear transmission mechanism 8 includes a sun gear 9°10 and a ring gear 11.
12 and planetary pinions 13 and 14, clutches 15 and 16 selectively connecting the ring gear 11 and sun gears 9 and 10 to the input shaft 5, respectively, and a one-way clutch 17 connecting the sun gears 9 and 10. a brake 18 selectively secured to the housing via the
, a brake 19 that selectively fixes the sun gears 9 and 10 directly to the housing, a one-way clutch 20 that fixes the carrier carrying the planetary pinion 14 to the housing against rotation in one direction, and a one-way clutch 20 that selectively fixes the carrier to the housing. It includes a brake 21 to

These clutches and brakes are configured to selectively receive hydraulic pressure from the automatic transmission hydraulic control device 22, or to selectively discharge the supplied hydraulic pressure.

FIG. 2 is a list showing the engagement or release of each clutch and brake for the gear transmission mechanism 8, and the relationship between the gears achieved thereby.

In this list, an ○ mark indicates that the relevant clutch or brake is engaged, an X mark indicates that the relevant clutch or brake is released, and a △ mark indicates that the vehicle is driven from the engine side. It is engaged when the engine is driving,
Indicates that it is released during engine braking when the engine is driven from the vehicle side.

By switching the clutch or brake between engagement and release in the manner described above, the gear transmission mechanism shifts to the first speed,
When set to 2nd or 3rd gear, when the direct coupling clutch is not engaged and torque is being transmitted by the torque converter, the throttle opening is set to one value. The relationship between the vehicle speed and the output shaft torque at this time is as shown by the solid line in FIG.

On the other hand, when the direct coupling clutch is engaged and direct coupling operation is performed, the vehicle speed decreases below the values corresponding to points a, b, and c, and the torque converter transitions from the coupling region to the torque conversion region. Even if the vehicle attempts to do so, it is blocked by the direct coupling clutch, so as the vehicle speed decreases, the output shaft torque follows the course shown by the broken line in the diagram.
This results in a lack of output shaft torque.

Therefore, in order to avoid such a problem, the direct coupling clutch is released when the vehicle speed is below the value corresponding to point a, b, or C for any throttle opening at each gear stage. is preferable.

FIG. 4 is a diagram obtained by plotting the vehicle speeds corresponding to the above points a, b, and c against each throttle opening value.

In this diagram, region A is a region where, when the gear transmission mechanism is switched to the first speed, it is preferable to release the direct coupling clutch and perform operation using the torque converter.

In region B, when the gear transmission mechanism is switched to the first speed, it is preferable to engage the direct coupling clutch and perform direct coupling drive, and in this region B, when the gear transmission mechanism is switched to the first speed, it is preferable to engage the direct coupling clutch and perform direct coupling drive.
In this range, it is preferable to release the direct coupling clutch and operate the torque converter when the engine is switched to high speed.

Region C is a region in which it is preferable to engage the direct coupling clutch and perform direct coupling drive when the gear transmission mechanism is switched to second speed, and region C is a region where it is preferable to engage the direct coupling clutch and perform direct coupling drive when the gear transmission mechanism is switched to third speed. When the transmission is switched, it is preferable that the direct coupling clutch be released and the torque converter be used for operation.

This region is a region in which it is preferable to engage the direct coupling clutch and perform direct coupling drive when the gear transmission mechanism is switched to the third speed.

Returning now to FIG. 1, the automatic transmission hydraulic control system 22 is of the type controlled by a solenoid 23. As shown in FIG.

A hydraulic control device configured to be controlled by a solenoid in this manner has been proposed, for example, in Japanese Patent Application No. 1983-69110 filed by the same applicant as the present applicant.

The hydraulic control device controlled by the solenoid as described above can be controlled by an electronic arithmetic unit, that is, a so-called computer, and the method for controlling an automatic transmission for a vehicle according to the present invention can also be carried out by computer control. is convenient.

Block 24 in FIG. 1 schematically represents a computer for such purposes.

By adopting computer control for controlling vehicle automatic transmissions, we can collect information on air pressure, which changes depending on the vehicle's driving altitude, oil temperature, which represents engine temperature, vehicle speed, throttle opening, manual range, gears, etc. Time
Based on this information, calculation processing is performed in a cycle time of about a few seconds, and the gear transmission mechanism can be set to any gear position to achieve the optimum driving condition at each moment during vehicle operation. A command signal indicating whether the direct coupling clutch should be engaged or released is sent to the
It is possible to send a message to 3.

To this end, in the illustrated embodiment, computer 24
a circuit 25 that determines operating characteristics of the engine, torque converter, and gear transmission mechanism based on input information supplied thereto; a circuit 26 that calculates power performance and determines the operating range of the direct coupling clutch; It includes a control circuit 27 for the clutch.

FIG. 5 shows that by approximating the operating characteristics of the direct coupling clutch for each gear stage of the gear transmission mechanism shown in FIG. 4 as a digital relationship between vehicle speed and throttle opening,
FIG. 3 is a diagram in which direct-coupled clutch switching lines for engaging and disengaging the direct-coupled clutch for each gear stage are set with appropriate hysteresis therebetween.

FIG. 6 is a diagram showing a shift line for switching the gear transmission mechanism, and in this case too, the shift line is set as a digital relationship between vehicle speed and throttle opening.

In the figure, the solid lines 1→2 and 2→3 are the upshift lines from 1st to 2nd gear and from 2nd to 3rd gear, respectively, and the broken lines 1←2 and 2←“3 are the upshift lines from 1st to 2nd gear and from 2nd to 3rd gear, respectively. These are downshift lines from 2nd speed to 1st speed and from 3rd speed to 2nd speed.

In FIG. 6, the direct coupling clutch switching lines for 3rd gear direct coupling ON and 3rd gear direct coupling OFF in FIG. 5 are shown superimposed on the shift line.

As is clear from this superimposed diagram, there is a dotted line in the diagram (indicated by hatching) between the shift line 2 → 3 and the 3rd gear direct connection ON switching line, that is, the area where the gear transmission mechanism switches to 3rd gear. There is also a region in which the direct coupling clutch remains in a disengaged state and operation is performed by the torque converter until the vehicle speed increases by a considerable amount even after the vehicle speed has been increased.

Also, regarding the relationship between the shift line 2←3 and the 3rd gear direct coupling off switching line, when the gear transmission mechanism is switched from 3rd gear to 2nd gear due to a drop in heavy speed, the direct coupling clutch is switched off prior to that. A releasing action is performed, and third speed operation is performed in which the direct coupling clutch is released in the area indicated by the dotted line hatching in the figure.

By providing such a torque converter operating range, the drivability of the vehicle in this operating range, particularly its output characteristics, is greatly improved.

FIG. 7 shows an example of a flowchart when the automatic transmission as described above is controlled by a control device using a computer.

When the control operation begins at the start of the figure, each circuit within the computer 24 is first reset to its initial state.

Next, values such as air pressure and oil temperature are read, and the characteristics of the engine, torque converter, and direct clutch are determined.

Next, power performance is calculated, hysteresis is determined, and the operating range of the direct coupling clutch is determined.

Here, further inputs include vehicle speed (■), throttle opening (θ), manual/L/L/N), 3, L, P, N) gear positions (1st, 2nd, 3rd), etc. The value is read.

Next, the process moves to the next step, where it is determined whether the vehicle speed V is less than or equal to the critical vehicle speed Vdw for downshifting determined by various conditions at that moment, and if the determination result is YES. A downshift is performed.

If the result of this determination is no, a determination is made as to whether the vehicle speed V is greater than or equal to the critical vehicle speed Vup' for upshifting determined by various requirements at that moment; If so, an upshift is performed.

When both of the above two determination results are negative, neither downshift nor upshift is performed.

Next, it is determined whether the direct coupling clutch is on, that is, in an engaged state.

When the direct coupling clutch is engaged, it is determined whether the vehicle speed at that moment is equal to or less than the critical vehicle speed V d e for disengaging the direct coupling clutch determined under various conditions at that moment.

If the determination is yes, the direct coupling clutch is released and the scanning process is returned before the engine, torque converter, and direct coupling clutch characterization step.

V≦Vde? is NO (in this case, the scanning circuit is returned as is without changing the engagement state of the direct coupling clutch).

Direct connection on? If the determination result is NO, it is determined whether the vehicle speed V at that moment is higher than the critical vehicle speed Ven for direct coupling clutch engagement determined under various requirements at that moment, If the determination result is YES, the direct coupling clutch is engaged and the scanning process is returned.

If the determination result of V≧Ve11';' is NO, the scanning process is returned as is without changing the state in which the direct coupling clutch is released.

This scanning process is repeated continuously with an extremely short cycle time of about 5m5ec, and as a result, the automatic transmission is set at each moment in a setting that best suits the driving conditions of the vehicle at that time. The switching of the gear transmission mechanism and the engagement or release of the direct coupling clutch are controlled.

Although the present invention has been described in detail with respect to one embodiment above, the present invention is not limited to this embodiment, and various modifications can be made to this embodiment within the scope of the present invention. This will be clear to those skilled in the art.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a vehicle automatic transmission and a control device therefor to which the control method according to the present invention is applied;
The figures are a list showing the gears in the gear transmission mechanism shown in Figure 1 and the engagement states of the clutches or brakes that achieve them, and Figure 3 is an automatic transmission having a torque converter, a direct clutch, and a gear transmission mechanism. A constant throttle consisting of [
Below is a diagram showing the state in which vehicle speed and output shaft torque change relative to each other, and Figure 4 is a diagram showing the range of the preferred relative relationship between vehicle speed and throttle opening for each gear of the gear transmission mechanism. Figure 5 is a diagram showing the state in which the switching line of the direct clutch to implement the relationship shown in Figure 4 is set as a digital relationship between vehicle speed and throttle opening, and Figure 6 is a diagram showing the state in which the switching line of the direct coupling clutch is set as a digital relationship between vehicle speed and throttle opening. FIG. 7 is a flowchart showing a mode of control performed by the control device shown in FIG. 1. 1...Input shaft, 2...Fluid torque converter, 3...Direct clutch, 4...
・Torque converter output shaft, 5... Gear transmission mechanism input shaft, 7... Gear transmission mechanism output shaft, 8...
... Gear transmission mechanism, 9.10 ... Sun gear, 11.12 ... Ring gear, 13°14 ...
...Planetary pinion, 15.16...Clutch, 17...One-way clutch, 18゜19...Brake, 20...One-way clutch, 21. ...Brake, 22...
・Hydraulic control device, 23... Solenoid, 24.
...computer, 25...engine,
Torque converter, gear transmission mechanism characteristic determination circuit, 26.
...Power performance calculation and direct coupling clutch operating range determination circuit, 2γ... Gear transmission mechanism and direct coupling clutch control circuit.

Claims (1)

[Claims] 1. A method for controlling an automatic transmission for a vehicle, including a torque converter, a gear transmission mechanism that switches between a plurality of gears, and a direct coupling clutch that directly couples the torque converter,
switching the gear transmission mechanism between the plurality of gears based on a plurality of input signals including signals related to vehicle speed and throttle opening, and switching the direct coupling clutch between engagement and disengagement; A shift line that defines switching boundaries between the plurality of gears based on vehicle speed and throttle opening values, and a direct coupling clutch that defines switching boundaries between engagement and disengagement of the direct coupling clutch based on vehicle speed and throttle opening values. When setting the switching line using a diagram with vehicle speed and throttle opening as two coordinate axes, the transmission torque when the direct coupling clutch is disengaged is greater than the transmission torque when the direct coupling clutch is engaged. A control method characterized in that the direct-coupling clutch switching line is located in a region on the higher vehicle speed side of the shift line so that the direct-coupling clutch is not engaged in a region in which the direct-coupling clutch is larger.