JPS61109963A - Creep prevention device for automatic transmission - Google Patents

Abstract

PURPOSE:To avoid a reduction of creep prevention effect by maintaining the friction elements under a coupled condition which is nearly the same as that which was existing at the time of ending the creep prevention. CONSTITUTION:During the initial set time period in which a creep prevention device 3 starts the creep prevention by limiting the coupling of the friction elements 2, an initial power output retaining means 5 assumes as its initial output a value close to the final output of the creep prevention device 3 at the time of ending the creep prevention which has been memorized by a means 4, and such a command is given to the creep prevention device 3. In this manner, the friction elements are maintained under a coupled condition which is nearly the same as that which was existing at the time of ending the creep prevention during starting from the creep prevention through the set time period to achieve a complete creep prevention.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a creep prevention device for an automatic transmission.

(Prior art) Since an automatic transmission is equipped with a torque converter in the power transmission thread, it is possible to change the driving range, that is, forward automatic transmission driving (DJ range) or reverse driving (R1 range and the corresponding 9 friction elements (D range) , in the R range, the front clutch) σ) Even if the vehicle becomes capable of transmitting power by operating it, the vehicle can be stopped as long as the engine is kept idling.However, the torque converter cannot reduce the transmission torque to zero. If the brake is left inactive, a so-called creep phenomenon will occur in which the vehicle is driven at a slow speed in the above or R range (state in which power transmission is possible).

In order to eliminate this creep phenomenon, the applicant of the present application has previously proposed a creep prevention device as disclosed in Japanese Patent Application No. 74590/1983. This creep prevention device eliminates the creep phenomenon by keeping the friction elements in a limited engagement state while the vehicle is stopped in the driving range, and then reducing the creep torque to a value necessary for creep prevention.

For this purpose, the above-mentioned creep prevention device sets the torque converter human output rotational difference (slip blue) ΔN from the instant t-worker to the target slip amount ΔN8 required for creep prevention, as shown by the dotted line in Fig. 8. Difference between the two ΔN−ΔN8
Based on <PI (feedback) control, the friction element is changed from a fully engaged state to a limitedly engaged state.

(Unfortunate problem that the invention is trying to solve) However, in such a creep prevention device, the slip amount ΔN during the time T2 immediately after the stop instant t1 is the target slip amount Δ
Since it has a large error with respect to NS, the degree of engagement of the friction element is greatly hunting as shown by point mA, and the friction element is almost temporarily released at instant t2 during time T.

By the way, the hunting mentioned above depends on the torque converter output rotation speed and j! ! The output torque of Kaoru Kaori is also hunted as shown by the dotted line B113, and each time these peak, a creep phenomenon occurs intermittently, making it impossible to completely prevent leap. Also, when starting at instant t2 immediately after stopping, the friction element is fully engaged from a state close to release at instant t2 to enable the start; It is necessary to take time for the friction elements to break down, and a considerable time delay is inevitable.During this time, the engine may start revving, which increases the noise, and also causes a delay in starting, which cannot be ignored and has a negative effect on starting performance. I confirmed that.

(Means for Solving the Problems) The present invention does not obtain the engagement limit of the friction element by feedback control at the beginning of the creep prevention control, but by keeping the engagement limit close to the end of the previous creep prevention. This is an attempt to solve the above problem, and the first
As shown in the figure, a creep prevention device 8 includes a friction element 2 that continues to operate in the driving range and transmits the output rotation of the torque converter 1, and prevents creep by setting the frictional element in the fastening restriction state while stopped in the driving range. In an automatic transmission equipped with the above, the final output memorization means 4 stores the final output of the creep prevention bag @8 at the end of the creep prevention, and the output of the creep prevention bag @S is stored in the final output for a set time from the start of the creep prevention. An initial output holding means 5 is provided to hold the output at a value substantially corresponding to the output.

(Function) During the current FJJ setting time when the creep prevention device 8 starts creep prevention by restricting the engagement of the friction element 2, the initial output holding means 5 maintains the final output of the creep prevention device 3 at the end of the previous creep prevention stored in the means command. A value near the output is set as an initial output and a command is given to the creep prevention device 3.

In this way, during the set time from the start of creep prevention, the friction element is maintained in almost the same fastening restriction state as it was at the end of the previous creep prevention, and even when normal creep prevention control is subsequently started, no large hunting occurs in the control and creep is maintained. This can be completely prevented, and even if the vehicle is started during the set time, engine revving and delay in starting will not occur.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

Figure 2 is a system diagram showing one embodiment of the present invention.
0 is a torque converter, 11 is a clutch as a friction element that continues to be hydraulically operated in the driving range of the automatic transmission, 12
indicates the engine, torque converter 1o is the crankshaft of engine 12) 12 pump impeller c driven by a is input hair? 1floa, turbine runner (outgoing element) 10b, and stator (reaction force f!91
10C, the turbine runner 1ob is drivingly connected to the torque converter output shaft (input shaft of the clutch 11) 13, and when the clutch 11 is hydraulically operated, the shaft 13 is connected to the clutch output shaft 4 to drive the automatic transmission. It shall be in a state where it can be transmitted.

Working oil pressure P of the clutch 11. The operating hydraulic pressure P is generated in the circuit 16 using the line pressure P supplied to the circuit 15 only in the driving range of the automatic transmission as the source pressure. A pressure regulating valve 17 is provided between circuits 15 and 16 to control the pressure. Pressure regulating valve 17
is equipped with a spool 17a, and its both end faces are connected to chambers 17b, 17.
Let's face G.

Chamber 17b is connected to circuit 15 via circuit 18, and
When the orifice 19 is inserted into the chamber 17 and the paddle is enlarged, the hydraulic pressure is drained from the drain orifice 20.
The line pressure PL should not be reduced even if the inside of b is brought to a no-pressure state.

The chamber 170 is connected to the circuit 16 via the circuit 21, so that the operating oil pressure P is supplied to the chamber 170. An orifice 22 for preventing pulsation is inserted into the circuit 21.

A strain/id 23 is connected to the drain orifice 20, and when this solenoid 23 is in the retracted position shown in the figure, in which the plunger 2aa opens the drain orifice 20 in a normal state, the plunger 28a advances to close the drain orifice 20 when energized. shall be taken as a thing. Since the solenoid 23 is duty-controlled as described later, when it is left energized with a duty of 100%, a control pressure P that is the same as the line pressure PL is created in the chamber 17b.
8, the control pressure Ps is lowered as the duty ratio decreases, and the control pressure Ps can be brought to the lowest value at a duty of 0%, and the change characteristics of the control pressure P8 with respect to the duty are as shown in FIG.

The control pressure P8 is the working oil pressure P in the chamber 17C. Therefore, as the control pressure Ps increases, the spool 17a is moved leftward from the upper half position in the figure to the lower half position in the figure. The spool 17a is in the upper half position, and the circuit 16 is connected only to the drain boat 17d, so that the operating pressure P
. is set to 0, and the circuit 16 is connected only to the circuit 15 at the lower half position to maintain the working oil pressure P. The circuit 16 is connected to both the circuit 15 and the drain boat 17d between the two positions, but the degree of communication of the circuit 16 to the (b) path 15 decreases as the spool ll& moves to the left. As the spool 17a moves to the left, the working oil pressure P decreases as the spool 17a moves to the left. can be gradually increased. And the working oil pressure P
. is regulated to the same value as the control pressure P8, and since the control pressure Ps changes as described above, this working oil pressure P. changes as shown in Fig. 4 according to the driving duty of the solenoid 23,
It can be controlled by this driving duty.

By the way, the turbine rotation speed of the torque converter IO (torque converter output rotation speed) NT at a stop in the driving range where creep is to be prevented (when the engine speed is 120 rpm, that is, the torque converter input rotation speed NE is 650 rpm). and slip amount ΔN (ΔN ””
NE-NTl changes with respect to duty as shown in FIG. Low working oil pressure P with duty less than 20%. If the clutch 11 is released, the slip Δ
N is the minimum, and the turbine speed NT is the engine speed NK
The value is kept lower by the amount of slip. Operating oil pressure P due to increase in duty. As the torque increases and the engagement of the clutch 11 progresses, the turbine rotational speed NT gradually decreases and the slip amount ΔN increases ~ [because it is controlled by the output shaft 14 via this clutch. When the duty is 70% or more, the turbine rotation kNT becomes O due to the complete engagement of the clutch 11, and the slip amount ΔN is maintained at the same maximum value as the engine rotation speed NFJ (stall state with maximum creep torque).

Duty control of the solenoid 23 is performed by a controller 24, which is connected to a throttle opening sensor 25 that detects the throttle opening 11TH of the engine 12.
A signal from the idle switch 26 which closes when the accelerator pedal is released, a signal from the engine rotation sensor 27 that detects the rotation speed of the crankshaft 12a (torque converter input rotation speed rNE), a signal from the turbine runner 1
0b rotational speed (a signal from the turbine rotation sensor 28 that detects the torque converter output rotational speed I NT, a signal from the clutch output rotation sensor 29 that detects the rotational speed N of the shaft 14, and a selected range of the automatic transmission gear). A signal L1 from a range switch 30, which is closed when the clutch 11 is in the running range, and a signal from a clutch output torque sensor 31, which detects the torque T of the shaft 14, are input, respectively.

The controller z4 is constituted by an ordinary microcomputer, and executes the control program shown in FIG. 3 based on the above-mentioned various input information. This control program is started at step 40 when the engine 12 is started;
1, various input information and output duty initialization (initial value setting) is performed. In the next step 42, the throttle opening TH and the idle signal 1 are read, and in the next step 48, the time T during which the counter should perform regular processing is determined.
Determine whether □ is indicated. While the counter is < T, the loop is repeated in which the counter is incremented (step a) in step 44 and the control is returned to step 42, and each time the counter is ≧T, the following control is executed.

First, in step 45, the above-mentioned counter is cleared, and in step 46, the engine rotation speed fiNE and the turbine rotation speed N are cleared.
T and clutch output rotation speed N. Sensor 2 corresponding to each
It is calculated based on the signals from 7 to 29. Next step 4
At step 7, it is determined whether the vehicle is at a stop based on whether the clutch output (b) rotation number No. is 0 or not.
In other words, it is determined whether or not the accelerator pedal is released without a desire to start. No in step 47. '@, 0 while driving or idle switch OFF in step 48
When starting, the duty D is set to α% in step 49.
The duty increases step by step, and it is determined in step 50 whether or not this duty has reached 100 curses.

If D>1.00%, set D to 100% in step 51, then set the timer to the set time T, (see Fig. 8) in step 52, while keeping D (if 100%, σ), and then control. Return to step 42. Thus, the output duty D during running or starting is gradually increased to 100%, and then kept at 100%, so that the working oil pressure P.

As is clear from FIG. 4, the pressure is set to a value equivalent to the line pressure PL, and the clutch 11 is fully engaged, making it possible to start and drive.

If it is determined in steps 47 and 48 that the vehicle is stationary with no intention of starting, in step 53 the clutch 11
It is determined whether or not this is the range in which the vehicle should be operated, that is, whether or not it is the range in which creep should be prevented in this example. If not, in step 54, the timer is set to 2 for the set time, as in step 52, and then in step 55, the counter 2 is cleared. During this time, the duty is not updated, but in the range where step 58 selects step 54, there is no line pressure PL toward the clutch 11.
Regardless of the driving duty of the solenoid 23, the clutch 11 is kept in a released state.

If it is determined in step 58 that the driving range is one in which creep should be prevented, step 56 is selected. In step 56, it is determined whether or not the timer is 0, that is, whether or not a set time T2 has elapsed since the start of creep prevention. When setting II
If it is less than J1T2, the timer has been decremented in step 57, and the counter ■
is 0 or not, that is, the previous step 58 was the step 54,
55t - Determine whether the range is suitable for selection.

If so, step 59 sets duty D to step 4.
After initializing the initial value D at 0 (INI), set the counter ■ to 1 at step 60 and step 58
selects step 61. In step 61, creep can be prevented by setting the duty D to a final value D (FI l) at the end of creep prevention, which will be described later.

When the timer, which is decremented in step 57 every time the above loop is repeated, becomes 0, that is, when the set time T2 has elapsed since the start of creep prevention, step 56 moves to step 6.
2 is now selected, and here the actual slip amount ΔN (ΔN=Ng-NT) of the torque converter is calculated, and in the next step 63, the target slip amount Δ necessary for creep prevention is calculated.
Necessary slip lid ΔN for N8 (7) After calculating the error "rr, step 64. In FI5, PI calculation of the update duty D (NEW) is performed based on the error Err. That is, in step 64, when the error Err is positive, , that is, ΔN
〉When Δ198, the previous duty D (OLDI.

From the verification constant Ki and error “rr, DIINEWI-Df
OLDl- is calculated in the duty decreasing direction by ``rr to find the integrally corrected duty D(INEWI. Conversely, when the error Err is negative, that is, when ΔN<ΔNS, D(engine NEWI-D(OL D ] + K4−
Calculations are performed in the direction of increasing the duty using Err to obtain the integrally corrected duty DIINEW. Furthermore, in step 65, when ΔN>ΔNS, D−D (
I NEW )-Kp-Krr (Kp is a proportionality constant)
Calculation in the duty decreasing direction is performed to obtain the update duty D, and conversely, when ΔN<ΔNS, D-D f I
NEW l+Kp-R: Calculate the duty reduction method using rr to obtain the updated duty D calculated by PI.

Thus, the actual slipping device ΔN with respect to the target slipping amount ΔN8
If the chamber is too large, the duty D will be reduced and the oil pressure P will decrease as is clear from FIG. (weakens the engagement force of the clutch 11), and as is clear from Fig. 5, the slip amount Δ
N can be decreased. Conversely, the target slip amount ΔN
If the required slip amount ΔN is too small with respect to s, the duty D is increased and the oil pressure P is increased. (strengthens the engagement force of the clutch 11), thereby increasing the slip liquid ΔN. Therefore, the torque converter slip amount ΔN can be maintained at the target slip amount ΔNS by 1, and creep can be prevented.

Note that the duty D updated as described above is re-stored in step 66 at the corresponding address in the memory as the final duty D (FI1), and this final duty D (FI1) is used when step 61 is executed.

The above operation is shown in a time chart as shown by the solid line in Fig. 8. From the instant t of stopping to the instant t8 during the set time T2, the duty D is F, and the final duty D at the end of the previous creep prevention is shown. held in (FI);
Thereafter, the duty D, like G, is subjected to PI calculation based on the error Err.

Therefore, the degree of engagement of the clutch 11 determined by the duty D does not greatly hunt, and the torque converter output rotational speed NT and clutch output torque do not greatly hunt as shown by H and J, respectively, so whenever these peak. It is possible to solve the problem that creep phenomenon occurs intermittently and it becomes impossible to achieve complete leap prevention. Also, when starting immediately during the set time T2 after stopping, the clutch 11 will be fully engaged from the engagement restriction state corresponding to duty D (FII), and this complete engagement will be completed promptly, so that the engine It is possible to perform a smooth start without causing racing or delay in starting.

In the above example, in step 61, the duty D during the set time T2 is set to the same value as the final duty D (FI) at the end of the previous creep prevention.
There is no need to be particular about this; for example, as shown by the dashed line in Figure 8, the final duty is
The value may be held at a value approximately equivalent to the final duty, such as by increasing the value by a larger value.

Furthermore, as is clear from Fig. 8, the time during which the duty should be maintained at the final duty is the period from the creep prevention start instant t□ until the clutch is engaged to a certain extent, that is, until the slip amount ΔN is greater than or equal to the set value ΔN. , or clutch output torque T. may be greater than or equal to the set value TE. FIG. 6 shows an example of a control program from the former perspective, and FIG. 7 shows an example of a control program that determines the time to be held between the duty Di and the final duty D (li'll) from the latter perspective.

In the example of FIG. 6, step 52°54.56 in FIG.
．． 57 is omitted and step 6 is inserted between step f+2.63.
Insert 7. In step 67, it is determined whether the slip amount ΔN is greater than or equal to the set value ΔN0, and the above amount control is advanced to step 58 to change the duty D to the final duty D (FI
Hold at l, and when ΔN becomes ΔN, step 68
is selected to shift to PI control.

In the example shown in Fig. 7 σ), step 52°54.5 in Fig. 8
fl and 57 are omitted, and step 68 is inserted between steps 53 and 62. In step 68, the Clara hand output torque T detected by the sensor 81 (see FIG. 2) is determined. is greater than or equal to the set value 78, and the above amount control is advanced to step 58 where the duty D is changed to the final duty D (FI
], and when it becomes TO (TE), select step 62 and shift to PI control.

In the two cases of stiffness, the same effect as in the above-mentioned example with respect to the 8th fire can be obtained, and the same effect can be achieved, but in addition, in these examples, the clutch 11 and its operating hydraulic system change over time and due to product variations. Regardless of the magnitude of the clutch 110 activation delay, the duty D is changed to the final duty D (FI l
You can always accurately manage the amount of time that should be maintained.

(Effects of the Invention) Thus, as described above, the creep prevention device of the present invention changes the output during the set time T2 from the start of creep prevention (driving duty D of the solenoid 23 in the illustrated example) to the final output at the end of the previous creep prevention (in the illustrated example). Final duty D
Since the configuration is such that the friction element (clutch 11 in the illustrated example) is held at a position approximately equivalent to I F I IE, the friction element (clutch 11 in the illustrated example) is subject to almost the same engagement limit a' as at the end of the previous creep prevention.
Even when the current state is maintained and the control is then shifted to normal creep prevention control, large hunting does not occur in the control, and creep prevention can be prevented from becoming intermittently incomplete. Even when starting, the friction element is completely engaged not from a state close to release but from a limited state of engagement, so that it is quickly completed, and engine racing and delay in start do not occur.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram of the creep prevention device of the present invention, Fig. 2 is a system diagram showing an embodiment of the inventive device, Fig. 3 is a flowchart of a control program executed by the controller of the same side device, and Fig. 4 is a A custom diagram of changes in control pressure and clutch operating oil pressure with respect to the output duty of the same controller. Figure 5 is a characteristic diagram of torque converter performance changes with respect to the same duty. Figures 6 and 7 show two other examples of the RA control program. Flowchart FIG. 8 is an operation time chart of the apparatus of the present invention. 1.10... Torque converter 2... Friction element 3... Creep prevention device building... Final output storage means 5... Initial output holding means 11... Clutch (friction element) 12...・Engine 15... Line pressure circuit 16... Clutch actuation hydraulic circuit 17... Pressure regulating valve 23... Solenoid 2
4...Controller 25...Throttle opening sensor 26...Idle switch 27...Engine rotation sensor 28...Target rotation sensor 29...Clutch output rotation sensor 30...Range switch 31...・Clutch output torque sensor diagram 1

Claims (1)

[Claims] 1. A creep prevention device that includes a friction element that continues to operate in the travel range and transmits the output rotation of the torque converter, and that prevents creep by placing the friction element in a fastening and restricted state while the vehicle is stopped in the travel range. In the provided automatic transmission, final output storage means stores the final output of the creep prevention device at the end of creep prevention, and the output of the creep prevention device is set to a value approximately equivalent to the final output during a set time from the start of the creep prevention. 1. A creep prevention device for an automatic transmission, comprising: initial output holding means for holding the initial output. 2. The initial output holding means, from the start of creep prevention,
2. The creep prevention device for an automatic transmission according to claim 1, wherein the set time is a period of time until the slip amount of the torque converter becomes equal to or less than a set value. 3. The initial output holding means, from the start of creep prevention,
2. The creep prevention device for an automatic transmission according to claim 1, wherein the set time is a period until the output torque of the friction element becomes equal to or less than a set value.