JPH07100418B2 - Clutch engagement control method - Google Patents

Description

The present invention relates to a clutch engagement control method for reducing shift shock.

[Conventional technology]

A shift shock occurs because the vehicle body acceleration changes suddenly in a short time due to the torque mismatch between the drive side and the load side during a gear shift, and is generally evaluated by the time change rate (jerk value) of the vehicle body acceleration. To be done.

In conventional transmissions, a mechanical modulation valve is used to gradually increase the clutch pressure and gradually increase the transmission torque of the clutch to reduce the shock. When the up ratio) is made uniform, it may not be possible to cope with changes in speed stage, load weight, etc., and excessive shift shock may occur.

Therefore, the clutch pressure is controlled by an electric command, and a build-up rate for obtaining a desired jerk value is stored according to the speed stage, the loaded weight, etc.
A method has been proposed in which an optimum buildup rate is selected based on the speed at which gear shifting is to be performed and the currently loaded weight, and the clutch pressure is controlled so as to attain the selected buildup rate (Japanese Patent Application No. 60-31097). ).

[Problems to be solved by the invention]

However, even if the clutch pressure is controlled to the optimum build-up rate selected as described above, if the friction coefficient of the clutch fluctuates from the value measured in advance, the clutch transmission torque changes and the desired jerk occurs. There is a problem that the value cannot be obtained.

By the way, the friction coefficient of the clutch changes due to various factors such as material variation, aging, oil temperature, oil quality, etc.
There is variation of 10% or more.

The present invention has been made in view of the above circumstances, and provides a clutch engagement control method capable of controlling the clutch pressure so that a desired jerk value can be obtained even when the friction coefficient of the clutch changes. To aim.

[Means for solving problems]

According to the present invention, in a transmission having a friction clutch, the clutch pressure of the friction clutch is controlled by an electric command so as to achieve a build-up rate stored in advance for each speed stage, thereby performing a shift. At the same time, the clutch pressure of the friction clutch of the speed stage corresponding to the shift is controlled so as to be the build-up rate stored according to the speed stage, and the jerk value during the clutch engagement transition period is obtained, Based on the ratio or difference between the calculated jerk value and the target jerk value, of the build-up rates stored for each speed stage, the build-up rate used at the time of shifting or each stored for each speed stage I am trying to correct the build-up rate.

[Action]

That is, since the build-up rate of the clutch pressure stored for each speed stage is corrected so that the measured jerk value matches the target jerk value, the fluctuation of the clutch friction coefficient and other jerk values are determined. Even if various parameters for the change, the clutch engagement control can be appropriately performed.

〔Example〕

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

First, the principle of the present invention will be described.

The jerk value, which is the evaluation value of the shift shock, is the time change rate of the vehicle body acceleration, so if the power line system is assumed to be rigid, And the above equation is It is represented by. In equations (1) and (2), J: jerk value α: acceleration T: clutch transmission torque K: conversion coefficient G: speed stage coefficient I: total inertia mass μ: clutch friction coefficient P: clutch pressure Is. The speed stage coefficient G does not change during shifting, but the value varies depending on each speed stage (reduction ratio, number of clutches, etc.), and the total inertial mass is the weight of the vehicle (including the loaded weight) and the inertia of each part converted to output shaft inertia. Is.

Here, as shown in the graph of FIG. 8, the clutch friction coefficient μ is substantially constant when the clutch relative rotation speed is above a certain value, so if the jerk value at this time is adopted, (Dμ / dt) in the equation (2) can be zero, and therefore the equation (2) is Can be rewritten as

That is, the jerk value J is proportional to the product of the clutch pressure buildup rate (dp / dt) and the dynamic friction coefficient μ. On the contrary, if the jerk value at that time is measured accurately by controlling the build-up rate, the dynamic friction coefficient μ can be calculated from the rate of change of this jerk value.
You can know the rate of change.

Now, in the case where the dynamic friction coefficient is μo and the target jerk value Jo is obtained at the predetermined buildup rate, (However, A = KG / I) When the dynamic friction coefficient μo changes and the rate of change becomes μc,
The measured jerk value Jc is Becomes From the above equations (4) and (5), the change rate μc is It is represented by.

Therefore, in order to obtain the target jerk value regardless of the change of the dynamic friction coefficient, as shown in the following equation, The buildup rate may be multiplied by the reciprocal of the change rate (1 / μc), that is, (Jo / Jc), and the clutch pressure may be controlled according to the buildup rate.

Next, specific examples of the present invention will be described.

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

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

The throttle amount detector 24 detects the depression amount of the throttle pedal 22, outputs a throttle signal indicating this depression amount to the controller 30, and the payload meter 25 detects the loaded weight, and the load signal indicating this loaded weight is controlled by the controller. 30
Output to. Furthermore, the shift selector 28 is a shift lever
Shift position selected by 26 (R, N, D, 2,1)
To the controller 30.

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

The controller 30 corrects the buildup rate of the clutch pressure during gear shifting so as to always obtain a desired jerk value, and performs clutch engagement control with less gear shift shock. Details will be described later.

Now, when the shift position D is selected by the shift lever 26, if automatic shifting is possible in the speed range from the first forward speed to the third forward speed, shift up or down of the speed range in this speed range is performed. Gear shifting is performed in the pattern shown in FIG. 2 according to the T / M input shaft speed and the throttle signal. That is, the throttle signal
In the case of S ₂ (see Fig. 3), when the T / M input shaft speed is r ₄ or more, the gear shifts up by one step, and conversely, when it is r ₂ or less, 1
Shift down.

The transmission 12 has, for example, four speed change clutches, and a hydraulic signal from the clutch hydraulic pressure supply device 32 selectively engages an appropriate clutch corresponding to the speed stage among these clutches. Shift to.

Here, details of the clutch hydraulic pressure supply device 32 will be described with reference to FIG.

This clutch hydraulic pressure supply device 32 includes different electronically controlled pressure control valves 33a, 33b, 33c, 33d and a pump 34 for applying hydraulic pressure to the clutch pressure generating portions 13a, 13b, 13c, 13d of the four shift clutches. Then, it is composed of means for supplying a predetermined pressure oil to each of the pressure control valves such as the relief valve 35.

FIG. 6 shows a structural example of the pressure control valves 33a to 33d. This pressure control valve includes a spool 304 having a first piston portion 301, a second piston portion 302 and a third piston portion 303.
The left end of the spool 304 is in contact with the plunger 306 of the proportional solenoid 305, and the right end of the spool is in contact with the retainer 308 biased to the left by the spring 307.

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

The oil chamber 313 in which the spring 307 and the retainer 308 are arranged is connected to the output port 315 via the passage 314. The second piston portion 302 is located at the opening end of the output port 315 on the spool 304 side, and the opening end is closed by the second piston portion 302 in the illustrated state.

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, the proportional solenoid has a characteristic that the thrust F of the plunger 306 is proportional to the input current i.

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 35
Is kept constant (for example, 35 kg / cm ² ) by the action of.

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 that time, part of the oil passing through the output port 315 passes through the passage 314. Flows into the oil chamber 313.

Therefore, assuming that the pressure receiving area of the third piston portion 303 is A and the hydraulic pressure at the output port 315, that is, the hydraulic pressure in the oil chamber 313 is P _a , the force A · P _a acts in the direction to move the spool 304 to the left. As a result, the spool 304 moves leftward as the hydraulic pressure in the oil chamber 313 rises. Then, when the spool 304 is moved to the left, the inflow of oil to the output port 315 is cut off, and
Oil is drained from the output port 315 side to the tank port 312 side.

Thus, the spool 304 operates so that the thrust force F of the plunger and the force A · P _a are balanced, that is, the balance relationship shown in the following formula is satisfied.

F = A · P _a (8) The spring 307 acts to urge the spool 304 to the left, but since a spring having a small spring constant is used as the spring 307, the spring 307 has been described above. Ignoring the action of the spring.

As described above, the thrust F of the plunger 306 and the driving current i of the solenoid are: F = K · i (9) However, there is a relationship of K; proportional constant, so the equations (8) and (9) are used. From this, the relationship K · i = A · P _a (10) is obtained, and from this, the hydraulic pressure P _{a of the} output port 315 is obtained.
Is expressed as P _a = K · (i / A) (11). As is apparent from the equation (11), the oil pressure P _{a of the} output port is proportional to the drive current i of the solenoid, and this relationship is shown in FIG.

Therefore, the controller 30 can shift to a desired shift speed by outputting the drive current i to the pressure control valve of the shift clutch corresponding to the shift speed to control the clutch pressure.

Next, the operation of the controller 30 according to the present invention will be described.

A plurality of controllers 30 (in this case, 4
The storage unit stores the optimum build-up rate for shifting to that shift stage, and the controller 30 stores the build-up rate from the storage unit of the speed stage corresponding to the shift when shifting. Is output, and the drive current i is output to the pressure control valve of the shift clutch so that the clutch pressure of the shift clutch corresponding to the speed stage corresponds to the read build-up rate.

Now, in the storage unit corresponding to each speed stage, the conversion coefficient K, the speed stage coefficient G, and the total inertial mass I are obtained so that a preset jerk value J is obtained, as shown in the above-mentioned formula (3).
The buildup rate (dp / dt) is calculated based on the dynamic friction coefficient μ (design value) of the clutch, and the calculated buildup rate is stored in advance. It should be noted that the total inertial mass I, which is one of the factors necessary to obtain this buildup rate,
Varies depending on the loaded weight.
Calculated and corrected based on the load signal from 25. Also,
Since the dynamic friction coefficient μ of the clutch also changes due to secular change, oil temperature, etc., the build-up rate is corrected as shown below.

That is, the controller 30 controls the clutch pressure of the shift clutch at the buildup rate stored in the storage unit according to the speed stage, obtains the actual jerk value at this time, and sets the obtained jerk value in advance. Correct the build-up rate based on the ratio to the target jerk value.

Now, typical behaviors of the vehicle body speed V, the vehicle body acceleration α and the clutch pressure P when shifting up to a certain speed stage are shown in FIGS. 7 (a), 7 (b) and 7 (c).

As shown in the figure, the buildup rate (dp
/ dt) is controlled to be constant, the vehicle body acceleration α also increases at a constant magnitude for a certain period (a period in which the friction coefficient μ of the clutch does not change).

Therefore, the vehicle body speed V is set to the vehicle body speed V in the initial period and the latter period of the clutch engagement (it is necessary to prevent μ from approaching static friction or the clutch ending the engagement in the latter period). To measure. Since both of these measurements are for obtaining the vehicle body acceleration α, a plurality of points are measured at a certain sampling interval. If the vehicle body speed signal contains noise or the like, the acceleration is measured at several points and averaged at both times. Since it is possible to roughly predict the behavior of the clutch engagement in the determination of the early and late stages of the clutch engagement, it is sufficient to manage the time (t ₁ , t ₂ ) after the gear shift command is issued. Also, if the load fluctuation is large and you are concerned about the time alone, you can detect it more accurately by incorporating the relative rotation speed of the clutch (calculated from the T / M input shaft / output rotation speed and the gear ratio) into the criteria. Late engagement timing etc.).

In this embodiment, the vehicle speed V is input from the rotation sensor 20.
Calculated from the signal that indicates the T / M output shaft speed.

In this way, the acceleration a ₁ (= ₁ ) obtained by time-differentiating the vehicle body speeds V ₁ and V ₂ in the early and late stages of clutch engagement, respectively.
And acceleration a ₂ (= ₂ ) are obtained, and the jerk value during shifting is calculated by dividing the difference between the accelerations at these two points by the sampling time.

The calculated jerk value is Jc, and the target jerk value is
Assuming Jo, the ratio of these values (Jo / Jc) is multiplied by the build-up rate adopted during the shift to obtain the build-up rate for obtaining the target jerk value.

Then, the build-up rate adopted during the shift is corrected to the obtained build-up rate (the contents of the storage unit corresponding to the speed stage are rewritten to the obtained build-up rate),
At the next shift to the same speed, the clutch pressure is controlled so that the corrected buildup rate is obtained.

In this embodiment, the buildup rate is corrected based on the ratio between the target jerk value and the measured jerk value, but it is also possible to correct the buildup rate based on the deviation between both jerk values. Is.

In addition, the change in the clutch friction coefficient, which is the main cause of the change between the target jerk value and the measured jerk value, changes almost uniformly regardless of the speed stage, so the target jerk value and the measured jerk value are Based on the above, each build-up rate stored for each speed stage may be corrected at the same time. Further, it is possible to diagnose the degree of clutch wear and the failure of the clutch by monitoring that the clutch friction coefficient is decreased or abnormally increased.

〔The invention's effect〕

As described above, according to the present invention, the jerk value is actually measured, and the buildup rate of the clutch pressure is corrected so that the jerk value matches the target jerk value. The clutch engagement control can be properly performed.

[Brief description of drawings]

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 for explaining timing determination for automatic gear shifting, and FIG. 4 is the clutch shown in FIG. FIG. 5 is a hydraulic circuit diagram showing details of the hydraulic pressure supply device, FIG. 5 is a graph showing a relationship between control current and output pressure of the pressure control valve shown in FIG.
FIG. 6 is a sectional view showing details of the pressure control valve shown in FIG. 4, and FIGS. 7 (a), (b), and (c) explain the operation of the controller shown in FIG. 1 according to the present invention. FIG. 8 is a timing chart used for this purpose, and FIG. 8 is a graph showing the relationship between the clutch relative rotation speed and the friction coefficient. 10 ... Engine, 12 ... Transmission, 18, 20 ... Rotation sensor, 22 ... Throttle pedal, 25 ... Payload meter, 26 ... Shift lever, 30 ... Controller, 32 ... Clutch hydraulic pressure supply device, 33a-33d ... Pressure control valve.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-59-106751 (JP, A) JP-A-61-108017 (JP, A) JP-A-62-278347 (JP, A) Japanese Patent Publication 6- 70471 (JP, B2)

Claims (2)

[Claims] 1. A transmission having a friction clutch, wherein the clutch pressure of the friction clutch is controlled by an electric command so as to achieve a build-up rate stored in advance for each speed stage, thereby performing a shift operation. , The clutch pressure of the friction clutch of the speed stage corresponding to the speed change is controlled so as to be the build-up rate stored according to the speed stage, and the jerk value during the clutch engagement transition period is obtained. The clutch engagement is characterized in that the build-up rate used during the shifting is corrected among the build-up rates stored for each of the speed stages based on the ratio or difference between the calculated jerk value and the target jerk value. Control method. 2. A transmission having a friction clutch, wherein the clutch pressure of the friction clutch is controlled by an electric command so as to achieve a build-up rate stored in advance for each speed stage, thereby performing a shift operation. , The clutch pressure of the friction clutch of the speed stage corresponding to the speed change is controlled so as to be the build-up rate stored according to the speed stage, and the jerk value during the clutch engagement transition period is obtained. A method for controlling clutch engagement, wherein each build-up rate stored for each speed stage is simultaneously corrected based on a ratio or a difference between the calculated jerk value and a target jerk value.