JPS6313954A - Transmission control method - Google Patents

Abstract

PURPOSE:To reduce a speed-change-shock, by elevating the clutch pressure of a speed-change-clutch for the next stage when the transmission-input-shaft- revolving-speed becomes equal to the product of the output shaft revolving speed and the gear ratio in the next speed-stage. CONSTITUTION:When the clutch pressure (d) at the time of the 'power-on and shift-down' is gradually lowered, the transmitting torque is decreased, while the vehicle body acceleration (a) is gradually decreased as well. At the same time, the revolving speed (c) of the transmission input shaft starts rising. Next, the difference in the revolving speeds (or relative revolving speed) (b) between the clutch input shaft and the clutch output shaft, which occurs when the clutch for the next stage to which the speed is to be shifted down is connected, is calculated. This difference can be obtained as the difference between the actual input-shaft-revolving-speed and the value converted into an input-shaft-revolving- speed that can be obtained by multiplying the transmission-output-shaft- revolving-speed by the gear ratio in the next speed stage. When this difference becomes nearly zero, the pressure of the speed-change-clutch for the next speed stage is gradually elevated. Accordingly, the torque can be transmitted smoothly, thereby minimizing the speed-change-shock.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a control method for variable speed shift, and particularly to control during power-on downshifting in a transmission equipped with a plurality of clutches for selecting speed stages. Regarding the method.

[Conventional technology]

When using this type of conventional gear shifter to automatically downshift when the driving force from the engine is being transmitted to the driving system (power on), the vehicle body acceleration will be as shown in Figure 9 (a).
It fluctuates as shown in .

That is, during the time (filling time) from time t1 when the shift starts to time t2 when the clutch pressure (fXSQ diagram (C)) of the shift clutch at the next speed starts to rise, the clutch is off and the engine torque is reduced. Because the transmission is not transmitted, the vehicle body acceleration becomes negative, and when the clutch pressing force of the shift clutch at the next speed starts to increase, the acceleration becomes even more negative due to the mismatch in the rotation speed between the input and output shafts of the clutch. occurs.

When the relative rotational speed of the clutch becomes zero, the ninth
(See Figure (1))), engine torque is transmitted and the vehicle starts accelerating.

[Problem that the invention seeks to solve]

In conventional transmissions, as shown in Fig. 9(C), the clutch pressing force is gradually increased to prevent sudden changes in vehicle acceleration, but the range of this prevention is as shown in Fig. 9(a).
Only in the range A shown in , after Mrt in this range A, the vehicle body acceleration suddenly changes, and this acts as a shift shock.

Another method is to reduce the shift shock by revving the engine during the clutch-off period and turning on the gear shifting clutch for the next gear when the clutch relative rotational speed in the next gear becomes zero. However, even with this method, since the transmitted torque is zero during the clutch-off period, the vehicle body acceleration changes rapidly, especially at the moment when the clutch is turned off, and the shock during gear shifting cannot be completely resolved.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a transmission control method that can prevent shift shock during power-on downshifting.

[Means for solving problems]

According to the present invention, there is provided a transmission that automatically shifts up or down the speed gears one by one in relation to the driving state of the vehicle, and includes a plurality of gear shifting clutches that select each speed gear. In a transmission that changes gears by individually controlling the clutch pressure of each gear shifting clutch using an electric command,
A power-on state is detected, and when the current first speed gear is downshifted to the next second speed gear in the power-on state, the clutch pressure of the shift clutch in the first speed gear is gradually increased. At the same time, the transmission input shaft rotation speed and the transmission output shaft rotation speed are constantly detected, and the product of the transmission output shaft rotation speed multiplied by the gear ratio in the second speed stage and the transmission input shaft rotation speed are determined. When the two speeds almost match, the clutch pressure of the speed change clutch in the second speed stage is increased.

[Effect]

That is, by gradually reducing the clutch pressure of the shift clutch at the first speed stage, the torque transmitted to the traveling system is reduced. At this time, since torque is being transmitted to the driving system, the vehicle acceleration does not change drastically.

On the other hand, due to the decrease in the transmitted torque, the transmission input shaft rotational speed gradually increases due to the eaves load. Then, when the product of the transmission input shaft rotation speed, the transmission output shaft rotation speed, and the gear ratio at the second speed stage [approximately matches], the clutch pressure of the second shift clutch is increased. Power-on downshifting with small shift shock is achieved.

[Example of a real swallow]

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

FIG. 1 shows a case in which the control method for each gear shift according to the present invention is applied.
It is a schematic diagram of g position. In the figure, the output torque of the engine 10 is determined by the transmission 12, the final reduction 3ilI
i device and the differential device 14 to the tires 16 .

The rotation ranges 18 and 20 detect the rotational speed of the input shaft and output shaft of the transmission 12, respectively, and output a T/M input shaft rotational speed signal and a T/M output shaft rotational speed signal indicating these rotational speeds. controller 30
The output is as follows.

The throttle amount detector 24 detects the amount of depression of the throttle pedal 22 and outputs a throttle signal indicating this amount of depression to the controller 30, and the shift selector 28 detects the shift position (R, N) selected by the shift lever 26.
, D, 2.1) and sends the position signal to controller 3.
Output to 0.

The controller 30 determines the speed range to be automatically shifted based on the shift position signal input from the shift selector 28, and the above-mentioned speed range based on the T/M input shaft rotation speed signal and throttle signal input from the rotation sensor 18 and the throttle suspension detection 24. The transmission 12 is supplied to the transmission 12 via a clutch oil pressure supply device 32 that controls the clutch pressure of the shift clutch according to the speed range of the transmission controller 12 so that the optimum speed U is selected among the speed ranges in which automatic shifting is possible.
Shift up or down the speed gears one by one.

This controller 30 receives T input from the rotation sensors 18 and 20, especially when performing a power-on downshift.
Based on the /M input shaft rotational speed signal and the T/M output shaft rotational speed signal, downshift control with less shift shock according to the present invention is performed, details of which will be described later.

Now, when shift position D is selected by the shift lever 26, if automatic gear shifting is enabled in the speed range from 1st forward speed to 3rd forward speed, upshifting or downshifting of the speed stage in this speed range is possible. The pattern shown in FIG. 2 is used in accordance with the transmission, T/M input shaft rotation speed, and throttle signal. That is, when the throttle signal is 82 (see FIG. 3), when the T/M input shaft rotational speed exceeds r4, the gearshift is shifted up by one step, and conversely, when it becomes below r2, it is shifted down by one step. In addition, the power-on shift down that the present invention targets is a shift down when driving force is being transmitted to the driving system.
For example, when accelerating a vehicle, this is true when the throttle pedal 22 is depressed and the throttle signal becomes 83 while the vehicle is running at a T/M input shaft rotation speed of r3 or less.

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

Here, the details of the clutch hydraulic supply system @32 are explained in the fourth section.
This will be explained using figures.

This clutch hydraulic pressure supply device 32 includes clutch pressure generating sections 13a and 13b of four shift clutches.

13c, 13d, each electronically controlled pressure control valve 33a, 33b, 33c, 33d, pump 34, relief valve 35, and other means for supplying predetermined pressure oil to each of the pressure control valves 33a, 33b, 33c, 33d, etc. It is configured.

FIG. 6 shows an example of the configuration of the ten pressure ffjJ valves 33a to 33d. This pressure control valve is connected to the first piston portion 301. The spool 304 has a second piston part 302 and a third piston part 303.
The left pant of 04 is the plunge T306 of the proportional solenoid 305.
Furthermore, the right end of the spool is urged leftward by a spring 307 and is brought into contact with a tape 308.

The first piston part 301 and the second piston part 302 define an oil chamber 309, and the second piston part 302 and the third piston part 303 define an oil chamber 310. and oil chamber 3
09 and the oil chamber 310, an input capo-j-311 and a tank boat 312 are opened, respectively.

Spring 307 and oil chamber 3 in which Ridena 308 is installed
13 is in communication with an output port 315 via a passage 314. Further, the second piston portion 302 is located at the frontage end of the output port 315 on the spool 304 side, and in the illustrated state, the frontage end is located at the second piston portion 304 side.
It is blocked by 02.

The proportional solenoid 305 is provided as an actuator for moving the spool 304, and its plunger 306 is in contact with the left end surface of the spool 304. As is well known, this proportional solenoid has a characteristic in which the thrust of its plunge t306 is proportional to the input voltage t, +.

As shown in FIG. 4, oil discharged from the pump 34 is supplied to the input boat 311 of the hydraulic control valves 33a to 33d having such a structure.

Note that the oil pressure of this oil is kept constant (eg, 35 kg/i>) by the action of the relief valve 35.

Now, the proportional solenoid 305 is activated and the spool 30
4 overturns to the right, the oil being supplied to the input boat 311 flows into the output port 315;
A part of the oil passing through the oil chamber 3 flows through the passage 314.
13.

Therefore, P
Then, a force A-Pa acts in a direction to move the spool 304 to the left, and as a result, the spool 304 moves to the left as the oil pressure in the oil chamber 313 increases. When the spool 304 is moved to the left, the flow of oil into the output port 315 is cut off, and the oil is drained from the output boat 315 side to the tank boat 312 side.

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

F=A-P, (1) The spring 307 has the effect of biasing the spool 304 to the left, but since a spring with a small spring constant is used as the spring 307, the above The explanation ignores the action of this spring.

As mentioned above, between the force F of the plunger P306 and the driving current i of the solenoid, there is F=−i.
...(2) However, since there is a relationship where K: constant of proportionality, from equations (1) and (2), -1-A
-P, . . . (3) is obtained, and from this, the oil pressure Pa of the output port 315 is expressed as Pa-K.(i/A) . . . (/1). As is clear from this equation (4), the oil pressure Pa of the output port is proportional to the drive current i of the solenoid, and the fifth
The figure shows this relationship.

Therefore, the controller 30 can shift to a desired speed by controlling the clutch pressure by outputting the drive flJ+thunder flow i to the pressure control valve a of the speed change clutch corresponding to the speed.

Next, the operation of the controller 30 during power-on downshifting will be explained in detail with reference to flowcharts (not shown in FIG. 7).

First, when the controller 30 detects a state in which a downshift is to be performed as described above, it determines whether or not the power is currently in the power-on state. This determination is made, for example, when the throttle signal exceeds a certain reference value, it is determined as a power-on state. When a power-on downshift is detected, the process shown in FIG. 7 is started.

At the same time, the transmission torque of the current transmission clutch is used as a sieve (step 100). This transmission torque can be determined by 1) a method of calculating n from the torque converter characteristics and the shaft rotational speed, 2) a method of sieving out from the engine output characteristics and the shaft rotational speed, 2) a method of directly measuring with a torque meter, etc.

Next, the transmission torque of the current transmission clutch (before the transmission) is set to be equal to or less than the sifted torque (step 101). Here, the transmission torque T of the transmission clutch is expressed by the following formula, T=K・μ(V)・P...(5)
It can be expressed as Therefore, the clutch pressure that satisfies the equation (5) is determined, and the clutch pressure is made equal to or lower than this clutch pressure. Note that the clutch is engaged at a higher clutch pressure than the clutch pressure when the transmission torque is generated so that the clutch does not easily disengage due to load fluctuations or the like.

Subsequently, as shown by the dashed line in FIG. 8(d), the current oil pressure of the gear shifting clutch is gradually lowered from the clutch pressure (step 102).

As a result, the clutch transmission torque gradually decreases and the vehicle acceleration also gradually decreases (Fig. 8(a)), while the engine speed, that is, the T/M input shaft speed begins to increase (Fig. 8(a)).
Figure (C)).

The T/M input shaft rotation speed and T/M output shaft rotation speed at this time are measured, and the next gear that is about to shift down (after shifting)
Calculate the rotation difference (relative rotation speed) between the clutch output shafts that occurs when the transmission clutch is connected (Step 1)
03). This relative rotation speed is calculated by multiplying the T'/M output shaft rotation speed by the gear ratio of the next gear and converting it into the T/M input shaft rotation speed, and the actual T/M input shaft rotation speed. Find it by taking the difference. This relative rotational speed gradually approaches zero as the T/M input shaft rotational speed increases (see FIG. 8(b)).

When it is confirmed that the relative rotation speed has become zero in step 104, the transmission torque of the current transmission clutch, which has been gradually decreasing the clutch pressure, is announced, and this transmission torque and the gear ratio of the current speed are determined. Transmission output torque is calculated from the product of (step 105). Note that the above transmission torque is

It can be determined using the above-mentioned equation (5) or the like.

Next, the clutch pressure of the shift clutch in the next speed stage is set to a value that generates the same transmission output torque as the above-mentioned transmission output torque (Step 1
06), and the clutch pressure of the current shift clutch is made zero (step 107). Note that the clutch pressure in step 106 is determined by first determining the transmission torque of the transmission clutch by dividing the transmission output torque by the gear ratio of the next gear, and then substituting this transmission torque into equation (5). It can be found by

Subsequently, as shown in FIG. 8(d), the clutch pressure of the next gear shifting clutch is gradually increased from the above clutch pressure (step 108).

Note that the clutch pressure cannot be controlled within the time from when hydraulic oil is supplied to the clutch pack until it is filled (filling time), so the shift clutch for the next gear is controlled by the downshift control described above. Supply of hydraulic oil is started at the time of start, and the clutch back is filled with hydraulic oil by the time point 1 when the shift clutch is controlled.

Furthermore, in this embodiment, the clutch pressure of the transmission clutch in the current gear is immediately lowered to the value at which the transmission torque is generated, and then gradually lowered. It's okay. In this case, there is a drawback that the start point of the actual downshift sub-portion is delayed.

Furthermore, in this embodiment, the clutch pressure of the shift clutch in the next gear is immediately increased to a value that generates the same transmission output torque as the current transmission output torque, but the clutch pressure is gradually increased from O. You may also do so.

(Effect of Light) As explained above, according to the present invention, it is possible to reduce fluctuations in vehicle acceleration by gradually reducing the transmitted torque during power-on downshifting and transmitting torque even during the gear shifting period. In addition, by gradually increasing the clutch pressure of the shift clutch at the next speed stage from the time when the relative rotational speed of the clutch reaches almost zero, torque can be transmitted smoothly and shift shocks can be minimized. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus to which the method of the present invention is applied, FIGS. 2 and 3 are diagrams used to explain automatic shift timing determination, and FIG. Fig. 5 is a hydraulic circuit diagram showing details of the clutch hydraulic supply system shown in Fig. 4, and Fig. 6 is a graph showing the relationship between the control current and output pressure of the pressure control valve shown in Fig. 4. 7 is a sectional view (not showing details) of the pressure control valve shown in FIG. 7, a flow chart used to explain the control operation of the controller shown in FIG. 1 according to the present invention, and FIGS. 9 is a timing chart showing an example of the behavior of each part during a power-on downshift according to the present invention, and FIGS. 9(a) to (C) are timing charts showing an example of the behavior of each part during a conventional power-on downshift. 10...engine, 12...transmission,
18.20... Rotation sensor, 22... Throttle pedal, 26... Shift lever 130... Controller, 32... Clutch hydraulic pressure supply device, 33a to 33d
...Pressure control valve. Figure 3

Claims (4)

[Claims] (1) A transmission that automatically shifts speeds up or down one speed step at a time in relation to the driving condition of the vehicle, and includes a plurality of speed change clutches that select each speed step;
In a transmission that changes gears by individually controlling the clutch pressure of each gear shifting clutch using an electric command, a power-on state is detected, and when the power is on, the current first speed gear is changed to the next gear's second speed. When downshifting to a gear, the clutch pressure of the shift clutch in the first gear is gradually lowered, and the transmission input shaft rotation speed and the transmission output shaft rotation speed are constantly detected, and the detected transmission input shaft rotation speed is When the rotational speed and the product of the transmission output shaft rotational speed multiplied by the gear ratio in the second speed stage are approximately equal to each other, the clutch pressure of the shift clutch in the second speed stage is increased. A method of controlling a transmission. (2) Detect the transmission torque of the transmission clutch in the first speed stage, and when downshifting, increase the clutch pressure of the transmission clutch to a clutch pressure that transmits a torque close to the detected transmission torque. Immediately lowering the clutch pressure, and then gradually lowering the clutch pressure.
1) The transmission control method described in item 1). (3) If the detected transmission input shaft rotational speed and the product of the transmission output shaft rotational speed multiplied by the gear ratio in the second speed gear approximately match, the clutch of the transmission clutch in the first speed gear A method for controlling a transmission according to claim (1), wherein the pressure is immediately brought to zero. (4) When the detected transmission input shaft rotational speed and the value obtained by multiplying the transmission output shaft rotational speed by the gear ratio in the second speed gear almost match, the transmission clutch in the first speed gear is activated. Immediately increase the clutch pressure of the shift clutch in the second gear to a value where the transmission output torque and the transmission output torque by the gear change clutch in the second gear are matched, and then gradually increase the clutch pressure. A method for controlling a transmission according to claim (1).