JP2593648B2 - Transmission control method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission control method, and more particularly to a power-on downshift control method for a transmission having a plurality of shift clutches for selecting a speed stage. About.

[Conventional technology]

Conventionally, when a downshift is automatically performed by a transmission of this type in a state where the driving force from the engine is transmitted to the traveling system (power-on), the vehicle acceleration is shown in FIG. 9 (a).
Fluctuates as shown in FIG.

That is, during the clutch pressure of the transmission clutch in the next speed stage from the shift start time t ₁ (FIG. 9 (c)) the time until the time point t ₂ to start rising (filling time) the clutch is turned off, When the engine torque is not transmitted, the vehicle body acceleration becomes negative, and when the clutch pressing force of the shift clutch at the next speed stage starts to increase,
Further negative acceleration occurs due to the inconvenience of the rotational speed between the input and output shafts of the clutch.

When the relative rotation speed of the clutch becomes zero (see FIG. 9B), the engine torque is transmitted, and the vehicle starts accelerating.

[Problems to be solved by the invention]

In a conventional transmission, a sudden change in vehicle body acceleration is prevented by gradually increasing the clutch pressing force as shown in FIG. 9 (c), but this prevention range is the range shown in FIG. 9 (a). With only A, the vehicle body acceleration suddenly changes around this range A, which acts as a discoloration shock.

In addition, there is a method in which the engine is idled during the clutch off period, and when the relative speed of the clutch at the next speed stage becomes zero, the shift clutch at the next speed stage is turned on to reduce the shift shock. However, even in this method, since the transmission torque becomes zero during the clutch off period, the vehicle body acceleration changes abruptly, especially at the moment when the clutch is turned off, and the shock during shifting cannot be completely solved.

The present invention has been made in view of the above circumstances, and has as its object to provide a transmission control method capable of preventing a shift shock at the time of power-on downshift.

[Means for solving the problem]

According to the present invention, there is provided a transmission which automatically shifts speed stages one by one in relation to a running state of a vehicle, comprising a plurality of shift clutches for selecting each shift stage, wherein each shift clutch is selected by an electric command. The clutch pressures are individually controlled to perform a shift, and when the current first speed stage is downshifted to the next second speed stage in the power-on state, the first and second speed stages are switched to the next speed stage. The corresponding shift clutch is controlled as follows.

(A) When the power-on shift-down condition is satisfied, supply of hydraulic pressure to the shift clutch at the second speed stage is started, and transmission torque of the speed clutch at the first speed stage is detected. The clutch pressure of the shift clutch is immediately reduced to a clutch pressure that is smaller than the detected transmission torque and transmits the torque, and the shift clutch pressure at the first speed stage is gradually decreased thereafter.

(B) detecting a difference between a transmission input shaft rotation speed and a value obtained by multiplying the transmission output shaft rotation speed by the gear ratio of the second speed stage, and, when the difference becomes zero, the first speed; Immediately reduce the clutch pressure of the speed change clutch in the first gear to zero.

(C) When the difference becomes zero, the transmission output torque by the transmission clutch at the first speed stage at this time is obtained, and the transmission output by the transmission clutch at the second speed stage is further added to this output torque. The clutch pressure of the shift clutch at the second speed stage where the torques match is determined, and the clutch pressure of the shift clutch at the second speed stage is immediately adjusted to the determined clutch pressure value when the difference becomes zero. The clutch pressure is increased, and then the clutch pressure is gradually increased.

[Action]

That is, when the power-on shift-down condition is satisfied, first, the supply of hydraulic pressure to the shift clutch in the second speed stage (next speed stage) is started, and the shift in the first speed stage (current speed stage) is started. The transmission torque of the transmission clutch is detected, the clutch pressure of the transmission clutch is immediately reduced to a clutch pressure that is smaller than the detected transmission torque and transmits the torque, and the transmission clutch pressure at the first speed stage is thereafter reduced. Gradually lower.

Next, a difference between a transmission input shaft rotation speed and a value obtained by multiplying the transmission output shaft rotation speed by the gear ratio of the second speed stage is detected, and when the difference becomes zero, the first speed is reduced. Immediately reduce the clutch pressure of the speed change clutch in the first gear to zero.

Further, when the difference becomes zero, the transmission output torque by the transmission clutch at the first speed stage at this time is obtained, and the transmission output torque by the transmission clutch at the second speed stage is further added to this output torque. The clutch pressure of the shift clutch at the second speed stage that matches is determined, and the clutch pressure of the shift clutch at the second speed stage is immediately adjusted to the determined clutch pressure value when the difference becomes zero. And then gradually increase the clutch pressure.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of an apparatus to which a transmission control method according to the present invention is applied. In the figure, an output torque of an engine 10 is transmitted to a tire 16 via a transmission 12, a final reduction gear, and a differential gear 14.

The rotation sensors 18 and 20 detect the rotation speeds of the input shaft and the output shaft of the transmission 12, respectively.
A T / M input shaft rotation speed signal and a T / M output shaft rotation speed signal indicating these rotation speeds are output to the controller 30.

The throttle amount detector 24 detects the amount of depression of the throttle pedal 22 and outputs a throttle signal indicating the amount of depression to the controller 30.
And outputs a position signal indicating the shift position (R, N, D, 2, 1) selected by the controller 30 to the controller 30.

The controller 30 determines a speed stage region in which automatic shifting is performed based on a shift position signal input from the shift selector 28, and based on the T / M input shaft rotation speed signal and the throttle signal input from the rotation sensor 18 and the throttle amount detection 24, The speed stages of the transmission 12 are shifted one by one through a clutch hydraulic pressure supply device 32 that controls the clutch pressure of the shift clutch according to the speed stage of the transmission 12 so as to be the optimum speed stage within the speed range in which automatic shifting is possible. Shift up or down.

The controller 30 reduces the shift shock according to the present invention based on the T / M input shaft rotation speed signal and the T / M output shaft rotation speed signal input from the rotation sensors 18 and 20, especially when downshifting the power. Shift down control is performed, and details thereof will be described later.

Now, when the shift position D is selected by the shift lever 26, if automatic gear shifting is possible in the speed range from the first forward speed to the third forward speed, the shift up or down of the speed range in this speed range is performed. The gear shifting is performed according to the T / M input shaft speed and the throttle signal.
This is performed according to the pattern shown in the figure. That is, the throttle signal is 1 stage shifted up when the T / M input shaft speed is r ₄ than in the case of S ₂ (see FIG. 3), at the r ₂ below opposite 1
Shift down by one step. The power-on downshift present invention is targeted, the shift-down at the time when driving force is transmitted to the traveling system, for example, when accelerating the vehicle, traveling at T / M input shaft speed is r ₃ or less during the depression of the throttle pedal 22, the throttle signal is established in such a case where the S _3.

The transmission 12 has, for example, four shift clutches, and an appropriate clutch corresponding to a speed stage among these clutches is selectively engaged by a hydraulic pressure signal from a clutch hydraulic pressure supply device 32, whereby a desired speed stage Shift to

Here, the details of the clutch hydraulic pressure supply device 32 will be described in the fourth.
This will be described with reference to the drawings.

The clutch hydraulic pressure supply device 32 includes separate electronically controlled pressure control valves 33a, 33b, 33c, 33d for applying hydraulic pressure to the clutch pressure generating units 13a, 13b, 13c, 13d of the four shift clutches, and a pump 34. And a means for supplying a predetermined pressure oil to each of the pressure control valves such as the relief valve 35.

FIG. 6 shows a configuration example of the pressure control valves 33a to 33d. The pressure control valve includes a spool 30 having a first piston portion 301, a second piston portion 302, and a third piston portion 303.
4 and the left end of this spool 304 is a proportional solenoid 305
, And the right end of the spool is in contact with a retainer 308 urged leftward by a spring 307.

The first piston part 301 and the second piston part 302 are
The second piston portion 302 and the third piston portion 303 define an oil chamber 310. And oil chamber 309 and oil chamber 310
, An input port 311 and a tank port 312 are respectively opened.

The oil chamber 313 in which the spring 307 and the retainer 308 are disposed,
It communicates with the output port 315 via the passage 314. The second end of the output port 315 on the spool 304 side is
The piston 302 is located, and the opening end is closed by the second piston 302 in the state shown in the figure.

The proportional solenoid 305 is provided as an actuator for moving the spool 304, and the plunger 306 is in contact with the left end surface of the spool 304. As is well known, this proportional solenoid has a characteristic that the thrust F of the plunger 306 is proportional to the input current i.

The oil discharged from the pump 34 is supplied to the input ports 311 of the hydraulic control valves 33a to 33d having such a structure as shown in FIG. The oil pressure of this oil is
It is kept constant (for example, 35 kg / cm ² ) by the action of 35.

Now, when the proportional solenoid 305 is operated and the spool 304 moves to the right, the oil supplied to the input port 311 flows into the output port 315, and at this time, a part of the oil passing through the output port 315 passes through the passage 314. And flows into the oil chamber 313.

Therefore, when the pressure receiving area of the third piston portion 303 A, the hydraulic pressure in the hydraulic clogging oil chamber 313 at the output port 315 and P _{a, A} · P _a becomes a force acts in a direction to left row spool 304, the As a result, the spool 304 moves to the left as the oil pressure in the oil chamber 313 increases. When the spool 304 moves to the left, the flow of oil into the output port 315 is cut off,
Oil is drained from the output port 315 side to the tank port 312 side.

Thus, the spool 304 operates so that the thrust F of the plunger and the above-mentioned force A · Pa are balanced, that is, the balancing relationship shown in the following expression is satisfied.

_{F = A · P a ... (} 1) Here, the spring 307 is an action which biases the spool 304 to the left, a small things or more since it is used to describe the spring constant as the spring 307 this Ignores the action of the spring.

As described above, between the thrust F of the plunger 306 and the drive current i of the solenoid, F = K · i (2) where K is a proportional constant, and therefore, equations (1) and (2) are used. is obtained relationship _{K · i = a · P a} ... (3) from, than this pressure P _a of the output port 315
Is expressed as P _a = K · (i / A) (4) The (4) As is apparent from the equation, the hydraulic pressure P _a of the output port is proportional to the drive current i of the solenoid, the FIG. 5 and this relationship is shown.

Accordingly, the controller 30 can output the drive current i to the pressure control valve of the shift clutch corresponding to the shift speed and control the clutch pressure to shift to a desired speed.

Next, the operation of the controller 30 at the time of power-on shift-down will be described in detail with reference to the flowchart shown in FIG.

First, when the controller 30 detects the state to be shifted down as described above, it determines whether or not it is currently in the power-on state. In this determination, for example, when the throttle signal is equal to or more than a certain reference value, it is determined that the power is on. When the power-on shift-down state is detected, the processing shown in FIG. 7 is started.

That is, the current transmission torque of the transmission clutch is calculated (step 100). This transmission torque can be obtained by a method of calculating from the torque converter characteristics and the shaft speed, a method of calculating from the engine output characteristics / shaft speed, a method of directly measuring with a torque meter, and the like.

Next, the current (pre-shift) transmission torque of the shift clutch is set to be equal to or less than the calculated torque (step 101). Here, the transmission torque T of the shifting clutch is given by the following equation: T = K · μ (V) · P (5) Can be represented by Therefore, the clutch pressure that satisfies the equation (5) is determined, and is set to be equal to or lower than the clutch pressure. Note that the clutch is engaged with a clutch pressure higher than the clutch pressure at the time of transmission torque generation so that the clutch is not easily disengaged due to load fluctuation or the like.

Subsequently, as shown by the one-dot chain line in FIG. 8 (d), the current hydraulic pressure of the speed change clutch is gradually reduced from the clutch pressure (step 102).

As a result, the clutch transmission torque gradually decreases, and the vehicle body acceleration also gradually decreases (FIG. 8 (a)), while the engine speed, that is, the T / M input shaft speed starts to increase (eighth of FIG. 8).
Figure (c).

Measure the T / M input shaft rotation speed and T / M output shaft rotation speed at this time, and rotate the clutch input / output shaft that occurs when the next-stage (after shift) shift clutch to be shifted down is connected. Calculate the difference (relative rotation speed) (Step 10
3). The relative rotation speed is the difference between the value obtained by multiplying the T / M output shaft rotation speed by the gear ratio at the next shift stage and converted into the T / M input shaft rotation speed, and the actual T / M input shaft rotation speed. Ask by taking. The relative rotation speed gradually approaches zero as the T / M input shaft rotation speed increases (see FIG. 8 (b)).

Then, when it is confirmed that the relative rotational speed has become zero in step 104, the transmission torque of the current shift clutch, which has gradually decreased the clutch pressure, is calculated, and this transmission torque and the gear of the current speed stage are calculated. The transmission output torque is determined from the product of the ratio and the ratio (step 105). Note that the transmission torque can be obtained by the aforementioned equation (5) or the like.

Next, the clutch pressure of the transmission clutch at the next speed stage is set to a value that generates the same transmission output torque as the transmission output torque (step
Along with 106), the current clutch pressure of the speed change clutch is set to zero (step 107). The clutch pressure in step 106 is obtained by first dividing the transmission torque of the transmission clutch by dividing the transmission output torque by the gear ratio of the next gear, and substituting this transmission torque into equation (5). You can ask.

Subsequently, as shown in FIG. 8 (d), the clutch pressure of the next-stage shift clutch is gradually increased from the clutch pressure (step 108).

Note that the clutch pressure is the time from when the hydraulic oil is supplied into the clutch pack to when it is filled (filling time).
Therefore, supply of hydraulic oil to the shift clutch at the next shift stage is started at the start of the downshift control, and the hydraulic oil is stored in the clutch pack by the time the shift clutch is controlled. Is filled.

Further, in the present embodiment, the clutch pressure of the shift clutch at the current shift speed is immediately reduced to a value at which the transmission torque is generated, and then gradually decreased. However, the clutch pressure is gradually decreased without decreasing to the above value. Is also good. In this case, there is a disadvantage that the starting point of the substantial downshift control is delayed.

Furthermore, in this embodiment, the clutch pressure of the transmission clutch at the next shift speed is immediately increased to a value at which the same transmission output torque as the current transmission output torque is generated. However, the clutch pressure is gradually increased from zero. You may do so.

〔The invention's effect〕

As described above, according to the present invention, at the time of controlling the power-on shift down performed on an uphill or the like, when the relative rotation speed becomes zero, the clutch pressure to be turned off becomes zero from a predetermined low pressure state. At the time when the relative rotational speed becomes zero, the transmission output torque at the current speed stage at this time is actually obtained, and the clutch pressure such that the transmission output torque at the next speed stage matches this output torque is obtained. The transmission output torque at the time of clutch switching is adjusted by applying the shift clutch of the next speed stage when the relative rotation speed becomes zero, so that the power-on shift executed on an uphill etc. In the event of a down, it is possible to eliminate the torque-off period and to significantly reduce the shift shock.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a device to which the method of the present invention is applied, FIGS. 2 and 3 are diagrams used to explain the timing of automatic shifting, and FIG. 4 is a clutch shown in FIG. FIG. 5 is a hydraulic circuit diagram showing details of a hydraulic supply device, FIG. 5 is a graph showing a relationship between a control current and an output pressure of the pressure control valve shown in FIG. 4,
FIG. 6 is a sectional view showing details of the output control valve shown in FIG. 4, FIG. 7 is a flowchart used to explain a control operation of the controller shown in FIG. 1 according to the present invention, FIG. (A) to (d) are timing charts showing an example of the behavior of each part at the time of power-on shift-down according to the present invention, and FIGS. 9 (a) to (c) show the behavior of each part at the time of conventional power-on shift-down. 6 is a timing chart showing one example. 10 …… Engine, 12 …… Transmission, 18,20…
... Rotation sensor, 22 ... Throttle pedal, 26 ... Shift lever, 30 ... Controller, 32 ... Clutch hydraulic supply device, 33a-33d ... Pressure control valve.

Claims (1)

(57) [Claims] 1. A transmission for automatically shifting gears one by one in relation to a running state of a vehicle, comprising: a plurality of shift clutches for selecting each speed gear; The shift is performed by individually controlling the clutch pressures of the clutches, and when the current first speed stage is shifted down to the next second speed stage in the power-on state, the first and second speed stages are shifted.
A method for controlling a transmission, wherein a transmission clutch corresponding to a first speed stage is controlled as follows. (A) When the power-on shift-down condition is satisfied, supply of hydraulic pressure to the shift clutch at the second speed stage is started, and transmission torque of the speed clutch at the first speed stage is detected. The clutch pressure of the transmission clutch is immediately reduced to a clutch pressure that is smaller than the detected transmission torque and transmits the torque, and the transmission clutch pressure at the first speed stage is gradually reduced thereafter. (B) detecting a difference between a transmission input shaft rotation speed and a value obtained by multiplying the transmission output shaft rotation speed by the gear ratio of the second speed stage, and when the difference becomes zero, the first speed is detected; Immediately reduce the clutch pressure of the speed change clutch in the first gear to zero. (C) When the difference becomes zero, the transmission output torque by the transmission clutch at the first speed stage at this time is obtained, and the transmission output by the transmission clutch at the second speed stage is further added to this output torque. The clutch pressure of the speed change clutch at the second speed stage where the torques match is determined, and the clutch pressure of the speed change clutch at the second speed stage is immediately adjusted to the determined clutch pressure value when the difference becomes zero. The clutch pressure is increased, and then the clutch pressure is gradually increased.