JPS63297860A - Control method for lockup clutch - Google Patents

Abstract

PURPOSE:To reduce a lockup shock at the time of speed change and to improve accelerating performance by not completely releasing a lockup clutch at the time of speed change, and gradually increasing oil pressure from the state where oil pressure is kept at a designated low pressure. CONSTITUTION:At the time of changing speed, a controller 10 calculates internal pressure of a torque converter 25 from output of an engine speed sensor 21 and lowers lockup clutch oil pressure to a designated pressure through an oil pressure supply device to be held for a while. Secondly, when a point of time for starting build-up is taken as the time the interval time determined by a throttle opening S or the clutch relative rotational frequency of a transmission 30 obtained by signals of input and output shaft rotation sensor 22, 23 becomes near zero and the time torque converter E value = n2/n1 is more than a preset value, oil pressure is gradually increased at the optimum build-up rate calculated by a throttle opening S, a car weight I and a gear ratio of a shaft selector 80, and gradual increase is stopped just near the E-value. Thus, a lockup shock at the time of changing speed can be reduced to improve accelerating performance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a method of controlling a lock-up clutch in a construction machine or a traveling machine.

[Conventional Technique #X] Conventional lock-up clutches are configured to be hydraulically controlled by a mechanical modulation valve, so it is impossible to change the hydraulic pressure arbitrarily, and clutch engagement is always controlled using a uniform hydraulic pressure. will be carried out.

When the lock-up clutch is engaged, the transmission input shaft is directly connected to the engine output shaft, so engine torque fluctuations are transmitted to the transmission output shaft, but with conventional devices, relatively high pressure is applied to the lock-up clutch. Since this is supplied, engine torque fluctuations are directly transmitted to the transmission output shaft. Therefore, in the conventional device, lock-up driving is not performed not only in a low speed range where the engine speed is low, but also in a low speed range where the engine speed is relatively high, resulting in a problem of poor fuel efficiency.

In addition, when changing gears, the clutch pressure oil is drained to completely release the lock-up clutch during gear shifting.In addition, because the system adopts a method of supplying pressure oil again (during gear shifting, the torque converter is used to reduce the load on the gear shifting clutch). There are problems such as variations in the filling time of the lock-up clutch and the generation of a large shock when the lock-up clutch engages.

[Problems to be Solved by the Invention] This invention has been made in view of the above-mentioned circumstances, and provides a lock-up clutch control that improves fuel efficiency, reduces lock-up shock, and improves acceleration. It is intended to provide a method.

[Means and operations for solving the problem] Therefore, in the present invention, a pressure control valve operated by an electric command is provided for the lock-up clutch, and by controlling this pressure control valve, the following steps are performed during gear shifting. Execute.

- Lower the lock-up clutch oil pressure to a predetermined non-zero pressure as the gear shift begins, and maintain this predetermined pressure.

・Detects the end of gear shifting.

- After the above detection, the lock-up clutch oil pressure is gradually increased at a predetermined rate of increase.

-Calculate the E value of the torque converter, and end the oil pressure gradual increase when this E value reaches the set value.

Also, when starting, perform the following steps.

- When a start command is input, the lock-up clutch oil pressure is kept in a high pressure state for a predetermined period of time, then lowered to a predetermined non-zero pressure, and this predetermined pressure is maintained.

・Detect the end of filling.

- After the above detection, the lock-up clutch oil pressure is gradually increased at a predetermined rate of increase.

- Calculate the E value of the torque converter, and end the oil pressure 'Kf1111 when this Effl reaches the set value.

Furthermore, during normal driving, the engine output torque is calculated sequentially, and if the engine rotation speed is equal to or higher than the minimum lock-up rotation speed, the lock-up clutch oil pressure is set to the oil pressure corresponding to the calculated value of the engine output torque or a value slightly larger than the calculated value. Control the lock-up clutch oil pressure so that the value is reached.

[Embodiment] An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a schematic configuration of a transmission system to which the present invention is applied, in which the output of an engine 20 is applied to a gear-type transmission 30 via a torque converter (torque converter) 25. The output is transmitted to the drive wheels 41 via the final reduction gear 40.

A lock-up clutch 50 is interposed between the input and output shafts of the torque converter 25 to directly connect these shafts.

The engine 20 has an engine rotation sensor 21 that outputs a number of signals corresponding to the rotation speed n1, and the transmission 30 has the rotation speed n of its input shaft 2 and output shaft 3.
2. Rotation sensor 22 that outputs a number of signals corresponding to n3
and 23 are provided, respectively, and the outputs of these sensors are applied to the controller 10.

The throttle sensor 70 detects the amount of depression of the throttle pedal and inputs a signal S indicating this amount of depression to the controller 10. The vehicle weight sensor 75 detects fiffiI (vehicle weight + loaded object weight) and inputs this detected value to the controller 10. The shift selector 80 selects a shift position (R, N, D, 1...) selected by the shift lever 81.
A signal indicating 〉 is input to the controller 1-〇-controller 10.

The transmission 30 has four shift clutches 31, 32, 33, and 34, as shown in FIG. clutches are selectively engaged.

As shown in FIG. 9152, this clutch oil pressure supply device 60 includes separate electronically controlled pressure control valves 61, 62, 6 for applying oil pressure to the four shift clutches 31 to 34.
3.64, a pump 65, a relief valve 66, etc.

Further, a lock-up clutch hydraulic pressure supply device 51 that applies hydraulic pressure to the lock-up clutch 50 is provided with an electronically controlled pressure side u (I valve 55) similar to that described above, as shown in FIG.

FIG. 3 shows an example of the configuration of the pressure limiting valves 61 to 64 and 55. This pressure control valve is connected to the first piston portion 9
01. Second piston part 902 and third piston part 90
3, the spool 904 has a
The left end is the plunger 906 of the proportional solenoid 905,
Further, the right ends of the spools are respectively abutted against retainers 908 that are urged leftward by springs 907.

The first piston part 901 and the second piston part 902 define an oil chamber 909, and the second piston part 902 and the third piston part 903 define an oil chamber 910. and oil chamber 9
09 and the oil chamber 910, an input boat 911 and a tank boat 912 are opened, respectively.

Oil chamber 91 in which spring 907 and retainer 908 are arranged
3 is connected to an output boat 915 via a passage 914.

The proportional solenoid 905 is provided as an actuator for moving the spool 904, and its plunge v906 is in contact with the left end surface of the spool 904. As is well known, this proportional solenoid has a characteristic in which the thrust force F of the plunger 906 is proportional to the input current i.

Now, the proportional solenoid 905 is actuated and the subroutine 90
4 moves to the right, the oil being supplied to the input boat 911 flows into the output boat 915;
A part of the oil passing through the oil chamber 9 passes through the passage 914.
13.

Here, P
d, a force A-Pd acts in the direction of moving the spool 904 to the left.

Thus, the spool 904 operates so that the thrust force F of the plunger and the above-mentioned force A-Pd are balanced, that is, so that the balanced relationship shown in the following formula is satisfied.

F=A-Pd...(1) Furthermore,
The spring 907 acts to bias the spool 904 to the left, but since a spring with a small spring constant is used as the spring 907, the effect of this spring is ignored in the above description.

As mentioned above, there is a relationship between the thrust force F of the plunger 906 and the drive current i of the solenoid: F = -i... (2) However, K: proportionality constant, so (1), (2 ) from the formula 1
=A-Pd (3) is established, and from this, the hydraulic pressure PdG of the output boat 915 is expressed as Pd=K<i/A> (4). As is clear from this equation (4), the oil pressure Pd of the output boat is proportional to the solinoid drive 111J current i.

Therefore, the command signal i output from the controller 1o
By appropriately varying the speed change clutches 31 to 3
4 and the lock-up clutch 50 can be applied with any clutch pressure.

In this configuration, the controller 1o performs the lockup control as described below. This will be explained with reference to the flowchart in FIG. 4 and the like.

This control consists of three processes.

(I) Lock-up engagement control other than when shifting gears.

This first control is hydraulic modulation control when the engine speed exceeds the minimum lock-up speed after the vehicle starts moving in response to a command from the shift lever 81. Fifth
The figure shows an example of the characteristics over time of lock-up hydraulic pressure commands, etc. under this control.

After starting, the controller 1o measures the engine speed n1 from the output of the engine speed sensor 21, and when this engine speed n1 exceeds the minimum rotation speed nr for lock-up (Fig. 5(b)), Step 100), by inputting a high-pressure trigger command to the solenoid of the pressure control valve 55 of the lock-up clutch 50 for a certain period of time, high-pressure oil is supplied to the lock-up clutch 50 and filling is accelerated (step 110). Thereafter, in order to completely complete the filling, the oil pressure command is lowered to a value corresponding to the oil pressure (Pt+β) that is higher than the torque converter internal pressure Pt, and this value is held for a certain period of time (steps 120 and 130). The reason why a hydraulic pressure higher than the torque converter internal pressure is applied is because in this case, the torque converter internal pressure acts on the piston back pressure part of the lock-up clutch 50, and if such a configuration is not used, such consideration is not necessary. . Since the internal pressure of the torque converter is approximately proportional to the engine speed, the engine speed sensor 2
nm based on the output of 1, etc. Note that if the change in engine rotation is small, a constant oil pressure (upper limit of variation) may be applied to the lock-up clutch. Furthermore, although in this case the filling is completed by time management, an appropriate filling detection sensor may be provided and the completion of the filling may be detected from the output of this sensor.

Next, when the controller 10 confirms the completion of filling, the controller 10 gradually increases the hydraulic pressure command applied to the pressure control valve 55 to engage the lock-up clutch 50, thereby gradually increasing the lock-up clutch hydraulic pressure. The slope (build-up rate) at this time is changed depending on the throttle opening and the vehicle weight position. Normally, lock-up engagement at the time of starting is performed at the lowest speed gear, but when performing lock-up engagement at other speed gears, the reduction ratio is added to the above parameters, and the lock-up engagement is performed at the lowest speed gear. The build-up rate is changed appropriately (step 140).

The gear shift shock of a gear type transmission is evaluated by the 91-unit value J, which is determined by the following formula. J: Jerk value α: Vehicle acceleration: Conversion coefficient G: Reduction ratio constant Weight) μ: Clutch disc I! Jiff coefficient P: Clutch oil pressure The reduction ratio constant G is determined from the speed stage, but also includes coefficients that indicate the number and area of clutch plates stacked at each speed stage. Therefore, the value of this constant G varies slightly depending on the speed stage.

Of course, if the number and area of stacked clutch plates for each speed stage are equal, G will be the same as the reduction ratio.

This term is relevant when the difference between friction and dynamic friction is large, and the effect appears when clutch engagement ends, but it can be ignored when there is no difference between the two.

The following explanation will be given while ignoring the second term.

Therefore, the jerk value of the above equation (5) is as follows.

becomes.

In the above equation (7), since K and μ are known, 1,
Just find J and G.

(2) can be determined from the output of the weight sensor 75, and G can be determined from the reduction ratio. J is the target shock, and is a value determined by the degree of load (a smaller one is better for a light load, and a larger one is better for a heavy load).

Here, although the load applied to the car body cannot be measured, since the load is proportional to the engine power, the above target jerk value J
can be determined by the throttle opening. That is, the jerk value J can be determined from the output of the throttle suspension sensor 70, and the jerk value is varied in proportion to the sensor output.

In this way, the controller 10 measures the throttle opening, vehicle weight, and gear ratio, calculates the optimal build-up rate dp/dt based on the measured values, and calculates the calculated +1+/dt.
Increase the oil pressure gradually. At this time, di)/dt with the throttle opening, weight, and gear ratio as variables is stored in advance in the memory of the controller 10 in a map format.
Do/dt corresponding to the detected values of the three variables may be read from the memory. As the above-mentioned stored data, the calculated value according to the above-mentioned formula (7) may be used, and furthermore, the data actually measured on the actual vehicle may be used.

After increasing the oil pressure, the controller 10 controls the engine rotation sensors 21 and 1 to the transmission input shaft rotation sensor 22.
Based on the output of the torque converter E value (-r+2/n1.rz
: torque converter input shaft rotation speed, n2 ; torque converter output shaft rotation speed) is measured (step 160), and when this E value reaches "1" or a predetermined value "EO" close to 1 (5th Figure (c)), stop the oil pressure gradual increase (step 19
0). In addition, during this gradual increase, if the E value is "1" or the set value E
The clutch pressure reaches the upper limit setting pressure Pa (5th
When the value exceeds the upper limit set pressure p, the controller 10 controls the clutch pressure to this upper limit setting pressure p until the E value reaches EO.
a (steps 170 and 180).

When determining the E value, the torque converter output shaft rotation speed may be determined using the output of the transmission output shaft rotation sensor 23 and the gear ratio.

(II) Lock-up clutch hydraulic control during normal driving.

This second control is performed during normal driving after a gear change or a start.

When the oil pressure gradual increase control described above is completed, the controller 10 lowers the lock-up clutch oil pressure to a value corresponding to the engine output torque or a value slightly larger than this value Pb (FIG. 5(a)).

Specifically, the controller 10 determines in step 200 whether or not the gear is being shifted, and if the gear is not being shifted, first the throttle amount sensor 70 and the engine rotation sensor 21 are Engine torque T is calculated from outputs S and rz (step 230).

As shown in FIG. 6, the torque T output from the engine is closely related to the engine speed and the throttle opening, and the torque value T corresponding to the six values of these parameters is stored in the memory in the controller 10. Remember each seed. Then, the engine torque T is determined by reading out the torque values corresponding to the detection outputs of the engine rotation sensor 21 and the throttle amount sensor 70 from this memory. In reality, values that completely match the pre-stored parameter values are not always input from each sensor, so interpolation techniques or the like are used to find intermediate appropriate values.

The controller 10 then controls the lock-up clutch 5.
Clutch oil pressure is controlled so that the transmission torque of 0 matches the engine output torque T determined from the engine speed and throttle opening, or so that the transmission torque of the lock-up clutch becomes a value slightly larger than the engine output torque T. do.

Here, the clutch transmission torque T' can be expressed by the following formula (8). Therefore, the engine output torque T can be converted into the clutch pressure P by determining the clutch pressure P at which T'=T holds based on the above equation (8).

That is, the controller 10 calculates the engine torque T from the outputs of the throttle amount sensor 70 and the engine rotation sensor 21, and converts the calculated torque value T or a slightly larger value into the clutch pressure P according to the above equation (8). 240), a hydraulic pressure command corresponding to the converted clutch pressure is applied to the pressure control valve 55 (step 250).

While the vehicle is running, the engine output torque T fluctuates as shown in FIG. 7(b). However, according to the above control, the lock-up clutch pressure is the oil pressure exchange value of the engine output torque (
Since the oil pressure is lowered to a level slightly higher than the sieve value (broken line in Figure 7(a)) or slightly higher than the displacement value (solid line in Figure 7(a)), fluctuations in the transmission output shaft due to fluctuations in engine output torque are avoided. As a result, even if a large fluctuation occurs in the engine speed as shown in Fig. 7 (fc), the fluctuation of the transmitter output shaft can be suppressed as shown in Fig. 7 (d). Can be done. Therefore, the minimum rotation plate nr for lock-up can be set to a lower speed than before, and fuel efficiency is also improved.

In this example, when the torque converter E value reaches the set value Eo, the clutch oil pressure is immediately lowered to the value Pb corresponding to the engine output torque, but after the oil pressure is gradually increased, the time is measured and a predetermined time has elapsed. The rear clutch oil pressure may be lowered to the value pb.

(I[) Lock-up engagement control during gear shifting This third control is performed during gear shifting.

In conventional gear shifting, in order to reduce the load on the gear shifting clutch, the lock-up clutch is engaged after being completely released, but in this proposal, the lock-up clutch is not completely released during gear shifting, and the internal pressure is higher than the internal pressure of the controller. After maintaining the oil pressure as low as possible, a gradual increase operation is performed. therefore,
There is no filling time required to fill the crudge pack in the water press μ.

FIG. 8 shows the temporal characteristics of the lock-up hydraulic pressure command during this shift.

When changing gears, the controller 1o calculates the torque converter internal pressure Pt based on the output of the engine rotation sensor 21 (FIG. 4(b) step 260), and adjusts the lock-up clutch oil pressure based on the calculated torque converter internal pressure as shown in FIG. value P
The pressure is lowered to t plus a predetermined pressure β (Pt+β), and this oil pressure value Pt+β is held for a while (step 270).

In this state, the controller 10 determines the build-up start time ts at which to start gradually increasing the oil pressure (step 280).
. There are the following three methods for determining the timing to start this build-up.

(a) Interval time setting The optimum interval time TI (see Fig. 8) is determined in advance using each gear and engine power (throttle opening) as parameters through simulations, actual vehicle tests, etc., and this is shown in Fig. 9. As shown, the data is stored in the memory in the controller 10 in a map format. Then, during gear shifting, the output of the throttle Φ sensor 70 and the interval time TI corresponding to the current gear stage are read out from this memory, and the oil pressure build-up is started when the interval time TI has elapsed.

(b) Crudge relative rotation speed sensitive type] - Calculate the cradle relative rotation speed (=n3G-n2.G: gear ratio) from each output n2 and n3 of the input shaft rotation sensor 22 and output shaft rotation sensor 23 of the transmission,
When this output value becomes zero or a value close to zero as shown in FIG. 10, it is defined as build-up 1 river 0 o'clock.

(c) From the output of the torque converter E value sensitive engine speed sensor 21 and the transmission input shaft sensor 22 (or output shaft 23), the torque converter E
The value (=n2/rN) is calculated, and when this E value exceeds a certain set value E1 as shown in FIG. 11, it is determined that the build-up is started.

Among the above three methods, (a) is the simplest and most practical. Although (b) and (c) require a rotation sensor, (b) is an advantageous method for improving acceleration performance, and (c) is an advantageous method for reducing shift shock.

When the controller 10 determines the build-up start time ts using one of the above methods (step 290>
, Similar to the control at the time of starting, the throttle opening degree S, vehicle weight, and gear ratio are measured, and the optimum build-up rate dp/dt is calculated using the measured values and the above equation (7) (step 300). The oil pressure is gradually increased by the meter value dp/dt (step 310).

This hydraulic pressure gradual increase operation is similar to the above-mentioned start-up, when the torque converter internal value is 1.
The E value is stopped when the clutch pressure reaches "1" or the set value [EO] close to 1, and the clutch pressure exceeds the upper limit set pressure pa before the E value reaches "1" or the set pressure value EO. The clutch pressure is maintained at this upper limit set value pa until it reaches the set value EO (steps 320 to 350). and,
During subsequent driving, the second control for controlling the lock-up oil pressure to a value corresponding to the engine output torque T is performed.

[Effects of the Invention] As explained above, according to the present invention, during gear shifting, the oil pressure is gradually increased from a state where the lock-up clutch oil pressure is maintained at a predetermined low pressure without completely releasing the lock-up clutch. This makes it possible to reduce lock-up shock during gear shifting. Further, at this time, the timing of starting the gradual increase in oil pressure is detected, and the gradual increase in oil pressure is started in accordance with this detection, so that acceleration performance can be improved. Furthermore, during driving, the lock-up clutch oil pressure is lowered to a value equivalent to the engine output torque, which suppresses the transmission of engine torque fluctuations to the transmission output shaft, making it possible to implement lock-up driving from a lower rotation range. , fuel efficiency improves.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of the configuration of a transmission system to which the present invention is applied, FIG. 2 is a hydraulic circuit diagram showing an example of the internal configuration of a clutch hydraulic pressure supply device, and FIG. 3 is a detailed configuration of the pressure control i0 valve. 4 is a flowchart showing an example of the operation of an embodiment of the present invention, FIG. 5 is a time chart for explaining the behavior of each part at the time of starting, and FIG. 6 is a diagram showing engine speed, throttle contention, and engine speed. A graph showing the relationship with output torque, Figure 7 is a time chart to explain the behavior of each part during driving, Figure 8 is a time chart of lock-up hydraulic pressure command during gear shifting, and Figure 9 determines the lock-up start timing. FIGS. 10 and 11 are time charts for explaining other methods for determining the build-up start timing, respectively. 10... Controller, 20... Engine, 21.
... Engine rotation sensor, 22 ... Transmission input shaft sensor, 23 ... Transmission output shaft sensor, 25 ... Torque converter, 30 ... Transmission, 40 ... End area M fold, 41 ... Drive wheel, 50...Lockup clutch, 55.61~6
4... Pressure control valve, 51.60... Clutch hydraulic pressure supply device, 70... Throttle Q sensor, 75... Vehicle weight sensor, 80... Shift selector, 905... Solenoid. Fig. 5 Time Fig. 6 Fig. 7 Zhen Kai Ling Fig. 8 Fig. 9 Fig. 10 Fig. 1I

Claims (7)

[Claims] (1) A lock-up clutch control method in which a pressure control valve operated by an electric command is provided for the lock-up clutch, and the pressure control valve is controlled as follows. (a) When the shift starts, the lock-up clutch oil pressure is lowered to a predetermined non-zero pressure, and this predetermined pressure is maintained. (b) Detecting the end of gear shifting. (c) After the above detection, the lock-up clutch oil pressure is gradually increased at a predetermined rate of increase. (d) Calculate the E value of the torque converter, and end the oil pressure gradual increase when the E value reaches the set value. (e) After sequentially calculating the engine output torque and completing the oil pressure gradual increase, if the engine rotation speed is equal to or higher than the predetermined lockup minimum rotation speed, the lockup clutch oil pressure is the calculated value of the engine output torque or the calculated value. The hydraulic pressure is controlled to correspond to a slightly larger value. (2) A lock-up clutch control method in which a pressure control valve operated by an electric command is provided for the lock-up clutch, and the pressure control valve is controlled as follows. (a) When a start command is input, the lock-up clutch oil pressure is kept in a high pressure state for a predetermined period of time, then lowered to a predetermined non-zero pressure, and this predetermined pressure is maintained. (b) Detecting the end of filling. (c) After the above detection, the lock-up clutch oil pressure is gradually increased at a predetermined rate of increase. (d) Calculate the E value of the torque converter, and end the oil pressure gradual increase when the E value reaches the set value. (e) After sequentially calculating the engine output torque and completing the oil pressure gradual increase, if the engine rotation speed is equal to or higher than the predetermined lockup minimum rotation speed, the lockup clutch oil pressure is the calculated value of the engine output torque or the calculated value. The hydraulic pressure is controlled to correspond to a slightly larger value. (3) The lock-up clutch control method according to claim (1) or (2), wherein the predetermined non-zero pressure is a value slightly larger than the internal pressure of the torque converter. (4) A patent that presets the time from the start of shifting to the end of shifting according to the gear position and throttle amount, and detects the time when the set time corresponding to the detected throttle amount and gear position has elapsed as the end of shifting. A lock-up clutch control method according to claim (1). (5) The clutch relative rotation speed is detected based on the input shaft rotation speed and the output shaft rotation speed of the transmission, and the point in time when the detected value reaches zero or a value near zero is detected as the end of shifting. The lock-up clutch control method described in (1). (6) A lock-up clutch control method according to claim (1), wherein the E value of the torque converter is calculated, and the time when the calculated E value becomes equal to or greater than a set value is detected as the end of the shift. (7) When the oil pressure is gradually increased, if the lock-up clutch oil pressure reaches the predetermined upper limit setting pressure before the E value reaches the set value, the oil pressure is not gradually increased until the E value reaches the set value. A lock-up clutch control method according to claim 1 or 2, wherein the lock-up clutch is stopped and the lock-up clutch oil pressure is maintained at this upper limit setting pressure.