JPH0289860A - Hydraulic control device for automatic transmission - Google Patents

Abstract

PURPOSE:To prevent shock due to gear shifting from being increased by lowering transitional hydraulic pressure at the time when the next gear shifting command is directed before gear shifting control for one gear shifting has not been brought to an end yet. CONSTITUTION:When the first gear shifting command is directed, electronic control on the first gear shifting for transitional hydraulic pressure in accordance with usual logic, for example, electronic control corresponding to throttle opening is executed. But when the second gear shifting command is directed before the transitional hydraulic control has not been brought to an end yet, gear shifting is performed at lower pressure set exclusively for continuous gear shifting at the time. As a result, gear shifting can be performed at low hydraulic pressure which meets actual loading torque, shock due to gear shifting can thereby be reduced.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an improvement in a hydraulic control device for an automatic transmission that electronically controls the transient hydraulic pressure when an a! friction engagement device is engaged during gear shifting.

[Prior art 1] An automatic vehicle equipped with a gear transmission mechanism and configured to selectively change the engagement state of a frictional engagement device by operating a hydraulic control device to achieve one of a plurality of gears. The speed change is already widely known. In such an automatic transmission, in order to reduce the shock during gear shifting as much as possible, the transient hydraulic pressure when the frictional engagement device is engaged must be accurately controlled. A technique is known in which the transient hydraulic pressure during engagement of the coupling device is precisely controlled by electronic control means. Generally, when controlling transient hydraulic pressure electronically, a method is to connect an accumulator with a cylinder-piston structure in the middle of the oil path that supplies and discharges hydraulic pressure to the frictional engagement device, and to electronically control the back pressure of this accumulator. It will be done. This is because by changing the back pressure of the accumulator, it is possible to control the oil pressure supplied to the frictional engagement device. The transmission torque capacity of the frictional engagement device is
Since it depends on the supplied hydraulic pressure at this time, the transmission torque capacity of the friction engagement device can be controlled by changing the back pressure of the accumulator, and as a result, it is possible to perform a shift with a small shift shock. It becomes like this. Conventionally, when electronically controlling the back pressure of this accumulator, it was basically controlled so that the oil pressure corresponded to the throttle opening.
l-149657). Problem to be Solved by the Invention 1 However, when two or more gear shifts are executed at the same time, for example, when consecutive gear shifts from second gear to third gear to fourth gear are executed, As is clear from the above, the clutch C2 and the third
Brake B2 for upshifting from gear to 4th gear
In this case, the capacity of each accumulator is different, and if a shift occurs with the same throttle opening, the brake Bo will be engaged first. By engaging this brake Bo, the load torque of the clutch C2 decreases by the amount that the gear ratio becomes smaller, and as a result, the hydraulic pressure set to the actual load torque of the clutch C2 becomes excessive, and the shift shock increases. There was a problem. In other words, even if the throttle opening is the same, there are times when the gear is only shifted from the second gear to the third gear, and cases where the gear is shifted from the second gear to the third gear and then directly to the fourth gear. So,
Although the actual load torque to clutch C2 that is engaged to form the third gear is different, conventionally the accumulator back pressure determined by the throttle opening (this accumulator back pressure is naturally applied to the second gear) Clutch C2 was engaged (tuned when only shifting from gear to third gear is being performed), so in the case of continuous gear shifting, the oil pressure becomes too high as a result, worsening the shift shock. It is something that Further, when the gear is directly shifted from the first gear to the second gear and then to the third gear, the brake B2 and the brake B2, which achieve the second gear by stopping the reverse rotation of the sun gear 61 (FIG. 2), By changing the sun gear 61 from a stopped state to a forward rotating state that corresponds to the rotation of the output shaft, the clutch C2 that achieves the third gear is simultaneously engaged. Therefore,
The torque shared by clutch C2 from the time when sun gear 61 rotates from reverse to stop is different from the torque shared during forward rotation. OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art. To provide a hydraulic control device for an automatic transmission that can satisfactorily execute transient hydraulic control and prevent a situation where a shift shock increases even when a second shift command is issued during an automatic transmission. The purpose is to

[Means to solve the problem]

As summarized in FIG. 1, the present invention is a hydraulic control device for an automatic transmission vehicle that electronically controls the transient hydraulic pressure when a frictional engagement device is engaged during a transmission. means for detecting whether or not the shift control has been completed; and means for reducing the transient oil pressure at that point when a next shift command is issued before the shift control for one shift has been completed. , the above objective has been achieved.

Functions and Effects of the Invention In the present invention, when the first shift command is issued, the first shift is performed according to the normal logic of transient hydraulic pressure electronic ii'1I12! l.For example, electronic control is executed according to the throttle opening, but if a second shift command is issued before this transient oil pressure control is completed, at that point the low gear shift command set exclusively for continuous shifting is executed. Shifting is performed using hydraulic pressure. As a result, it becomes possible to shift gears with a low oil pressure commensurate with the actual load torque, and shift shocks can be reduced. Also, such continuous gear shifting occurs mostly when an upshift is performed, which occurs when the accelerator is released, and therefore, the engine speed is reduced at this time. in a state. Therefore, rather than suddenly engaging the frictional engagement device with high oil pressure and forcibly lowering the engine speed, it is better to use the natural reduction due to the engine's own friction torque to reduce the shift shock (and It is also possible to ensure the durability of the frictional engagement device.The present invention is well suited to such circumstances because, when continuous gear shifting is detected, the transient oil pressure is changed to a lower level at that point. In automatic transmissions, assuming continuous shift requests (shift decisions) that occur when the accelerator is suddenly released, when one shift decision occurs, the shift command is not issued for a predetermined period of time. It is configured to issue a command to directly shift to the gear position associated with the R model gear shift determination that occurred within the predetermined time.
For example, if a second shift decision is made from the second gear to the fourth gear within a predetermined time after a first shift decision is made from the second gear to the third gear, the second shift decision from the second gear to the third gear is made. In order to shift to the fourth gear at once, the first shift from the second gear to the third gear and the second shift from the third gear to the fourth gear are output simultaneously. According to the present invention, in such a case, the gear shift is performed from the beginning, that is, after the predetermined time has elapsed, using a low oil pressure dedicated to continuous gear shifting. Note that the present invention does not preclude feedback control of the transient oil pressure when electronically controlling the transient oil pressure. In this case, the feedback control is stopped when the second gear shift is output, and the oil pressure is changed to a lower oil pressure exclusively for continuous gear shifting. [Embodiments] Examples of the present invention will be described in detail below based on the drawings. In this embodiment, the back pressure of the accumulator is feedback-controlled in order to electronically control the transient oil pressure when the frictional engagement device is engaged. This feedback control is performed by electronically controlling the linear solenoid (So) so that the actual turbine rotation speed NT changes along the trajectory of the turbine target rotation speed NTo. The turbine target rotation speed NTo is the actual turbine rotation speed NT and the turbine synchronous rotation speed (
It is determined from the relationship between vehicle speed and gear ratio after shifting. FIG. 2 shows an overall outline of a vehicle automatic transmission to which this embodiment is applied. This automatic transmission includes a torque converter section 20 and an overdrive mechanism section 40 as its transmission sections.
and an underdrive mechanism section 60 with three forward stages and one reverse stage. The torque converter section 20 is of a well-known type and includes a pump 21, a turbine 22, a stator 23, and a lock-up clutch 24. The overdrive mechanism section 40 includes a set of planetary gears including a sun gear 43, a ring gear 44, a planetary pinion 42, and a carrier 41. It is controlled by Fo. The underdrive mechanism section 60 includes a common sun gear 6
1. Ring gear 62.63, planetary pinion 64.
65 and carriers 66 and 67, and the rotation state of the two sets of planetary gear devices and the connection state with the overdrive 1 structure are controlled by the clutch C1,
C2, brakes 81 to B3, and one-way clutch FT
, F2. Since this transmission part itself is well known,
Regarding the concrete connection state of each component, only a skeleton diagram is shown in FIG. 2, and detailed explanation will be omitted. This automatic transmission includes a transmission section as described above,
and a computer (ECU) 84. The computer 84 includes a throttle sensor 80 that detects the throttle opening θ to reflect the output (torque) of the engine 1.
．． A vehicle speed sensor (rotational speed sensor of the output shaft 70 of the automatic transmission) 82 that detects the vehicle speed no., and the turbine 22 of the automatic transmission as an information source for reflecting the speed change transient state.
Various signals are input from an NT sensor 99, etc., which detects the rotational speed NT of the turpentine shaft 22A. The computer 84 controls the solenoid valves SL and 82 (for shift valves) and Ill valve 5L (for O-drive up clutch) in the hydraulic control circuit 86 according to a preset throttle opening-vehicle speed shift map.
The clutches, brakes, etc. are engaged in combinations as shown in FIG. 3 to execute gear changes. FIG. 4 shows the main parts of the hydraulic control circuit 86. In FIG. 4, the symbol SO is a linear solenoid, 108
is an accumulator control valve, 11o is a modulator valve, 112 is an accumulator, and 114 is a shift valve. In FIG. 4, a brake B2 is representatively shown as the AI friction engagement device. Third
As is clear from the figure, the brake B2 is a friction engagement device that is engaged when achieving a 1->2 shift. The line pressure PL is created by a well-known method using hydraulic pressure generated by an oil pump (not shown) as a violent pressure. This line pressure PL is the boat 11 of the modulator valve 110.
Applied to 0A. Modulator valve 110 receives this line pressure PL and generates a predetermined modulator pressure PLo in boat 110B using a well-known method. The linear solenoid So receives this modulator pressure PLo and sets the turbine rotation speed NT and the turbine target rotation speed NTo.
A solenoid pressure PS1 corresponding to the difference between the two is generated by a well-known method. That is, the rotation speed NT of the turbine 22 is input to the computer 84 as described above. This turbine rotation speed NT is compared with a turbine target rotation speed NTo. For example, in the case of a 1→2 shift, the turbine rotational speed NT decreases by executing the 1→2 shift. If the turbine rotation speed NT falls earlier than the target rotation speed NTo (N
If T NTo<O), the shift progresses too quickly. Therefore, in order to reduce the engagement transient oil pressure of the brake B2, a current equivalent to the duty ratio corresponding to this NT-NTo is applied to the linear solenoid So, and the linear solenoid So uses this current to generate a solenoid pressure PS+ proportional to the duty ratio. occurs in a well-known manner. This solenoid pressure PS+ is input to boat 108A of accumulator control valve 10B. The accumulator control valve 108 uses the throttle pressure pth reflecting the engine torque and the solenoid pressure PS+ from the linear solenoid So as input signals, and converts the line pressure PL2 of the boat 108B into the accumulator back pressure pa.
Adjust the pressure to c. That is, the accumulator back pressure pac is the line pressure PL2, the throttle pressure Pth, the solenoid pressure PS
+ and the biasing force of the spring 108C, and therefore, the pressure can be adjusted arbitrarily by changing the solenoid pressure PS. When a shift decision is made by the computer 84, the shift valve 114 is switched in a well-known manner via the electromagnetic valve S1 (shift command), and line pressure PL (1 day 0) begins to be supplied to the brake 82. In response to this supply, the piston 112A of the 7th cumulator 112 starts to rise. While this piston 112A is rising, the hydraulic pressure (0 for 1 day) supplied to the brake B2 is
The hydraulic pressure is maintained in balance with the downward urging force of B and the downward force acting on the piston 112A. The force pushing the piston 112A downward is the accumulator back pressure P applied to the back pressure of the accumulator 112 to 112c.
Generated by ac. Therefore, by controlling the accumulator back pressure pac through the modulator valve 110, the linear solenoid S port, and the accumulator control valve 108 as described above, the transient hydraulic pressure Pea when engaging the brake B2 is controlled.
can be controlled arbitrarily. As described above, the linear solenoid So is controlled depending on the difference between the turbine rotation speed NT and the turbine target rotation speed NTo. Feedback control can be performed to vary along NTo. Feedback control of the engagement transient oil pressure is performed in accordance with a normal feedback control procedure for the first shift. However, if the second shift command is issued before this first shift feedback control (transient oil pressure electronic control) is completed, the first shift feedback control will be canceled at that point. Further, feedback control is not executed for the second shift either. In other words, both gear shifts are controlled with a low oil pressure dedicated to continuous gear shifting. FIG. 5 shows a control flow regarding execution of this continuous speed change control. In step 101, it is determined whether a continuous shift has occurred. This determination is made by determining whether a command for the next shift has been issued before the feedback control for a particular shift has been completed. If there is no determination of continuous gear shifting in step 101, the process proceeds to step 103, where gear shifting is executed based on the continuous duty control (feedback control) as described above. On the other hand, if it is determined in step 101 that a continuous shift has occurred, the process proceeds to step 105, where it is determined whether or not the continuous shift was a 1→2→3 continuous shift. If it is a continuous shift of 1 → 2 → 3, step 1
Proceeding to step 07, the duty ratio D = Ds + corresponding to the basic hydraulic pressure exclusively for the continuous shifting of 1 → 2 → 3 is set, and from then on, control is performed with this exclusive basic hydraulic pressure until the continuous shifting of 1 → 2 → 3 is completed. is executed. That is, feedback control is not executed. On the other hand, if it is determined that the continuous shifting is not 1→2→3, the process proceeds to step 109, where it is determined whether the continuous shifting determined in step 101 is the continuous shifting 2→3→4. If it is determined that it is a continuous shift of 2→3→4, a duty ratio Ds2 corresponding to the basic oil pressure exclusively for the continuous shift of 2→3→4 is set, and thereafter this 2→3→4 shift is determined.
The continuous shift from 3 to 4 is performed by the hydraulic pressure corresponding to the duty ratio DS2. Therefore, feedback control is not executed in this case as well. On the other hand, if it is determined in step 109 that it is not a continuous shift of 2 → 3 → 4, the process proceeds to step 113 and 1
A duty ratio DS3 corresponding to the basic hydraulic pressure exclusively for continuous shifting of →2 →3 →4 is set. This is because normally a continuous shift is performed when an upshift is performed when the accelerator is released, and this type of upshift is a continuous shift of 1 → 2 → 3, 2 → 3 →4 continuous shifting,
This is because it is considered to be either a continuous shift of 1 → 2 → 3 → 4. Note that feedback control is not executed in this case j1 either. FIG. 6 shows an example of the basic setting duty ratio. As can be seen from this example, when continuous shifting is determined, the oil pressure is controlled to a constant low level depending on the type of continuous shifting, regardless of the throttle opening etc. at that time. . Note that the duty ratio is Ds
Ds 2 <Ds 3. The larger the duty ratio is, the lower the supplied hydraulic pressure is regulated. According to this embodiment, even when such a continuous shift is performed, the speed feedback control is stopped and the dedicated low oil pressure is switched to, so the shift is performed slowly and the engine This makes it possible to perform smooth gear shifts using friction. That is, this type of shift does not require very quick shift, and moreover, the engine speed tends to naturally decrease when the accelerator is released. Therefore, by lowering the oil pressure, the rise of the oil pressure is delayed,
By performing the gear shift slowly, it is possible to utilize the lower rotational speed of the engine itself, and the gear shift can be completed with almost no shift shock occurring. FIG. 7 shows that after the first shift from the second gear to the third gear is determined, the second shift from the third gear to the fourth gear is determined within a predetermined time T1, and the result is , shows a shift transient characteristic diagram when a continuous shift from 2 to 3 to 4 is commanded after a predetermined time T+ from the decision to shift from the second gear to the third gear. Due to the gear ratio, etc., the shift is completed faster with the brake Bo than with the clutch Co. However, conventionally, this brake S. The actual load torque of the clutch C2 decreases at the stage when the clutch C2 completes its engagement, and as a result, the hydraulic pressure of the clutch C2 becomes too high, so that the engagement of the clutch C2 is completed at the time T2, and the engagement of the clutch C2 is completed at time T2. A sudden change in the output shaft torque occurs due to the sudden change in the output shaft torque. On the other hand,
According to the invention, as a result of the reduced oil pressure, clutch C2
The torque load has been reduced, the end of gear shifting has been extended to T3, and fluctuations in the output shaft torque have been suppressed accordingly (see broken line).
In addition, in the above-mentioned embodiment, an example was shown in which the transient oil pressure at the time of gear shifting is feedback-controlled, but the present invention makes it essential to feedback-control this in controlling the gear shifting related to the first gear shifting. It's not something that exists. If the first shift is electronically controlled (oven) according to the throttle opening, for example, when the second shift command is issued, the electronic control according to the throttle opening is stopped, and the A low oil pressure setting exclusively for continuous shifting will be used. Furthermore, the present invention is not limited to how to determine whether or not the transient oil pressure control related to the first shift has been completed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the gist of the present invention, and FIG. 2 is a block diagram showing the gist of the present invention.
A schematic block diagram of an automatic transmission line for a vehicle to which an embodiment of the present invention is applied; FIG. 3 is a diagram showing the operating state of the friction engagement device in the automatic transmission; FIG. 4 is a diagram showing the operating state of the frictional engagement device in the automatic transmission. FIG. 5 is a flowchart showing the control procedure used in the above embodiment; FIG. 6 is a diagram showing an example of setting the duty ratio; FIG. The figure is a shift characteristic diagram. So... Linear solenoid, 108... Accumulator control valve, 11
0...Modulator valve, 112...Accumulator, PL...Line pressure, PLo modulator pressure, PS+...Solenoid pressure, pac...Accumulator back pressure, NT...Turbine rotation speed, NTo...・Turbine target rotation speed. Figure 1

Claims (1)

[Claims] (1) In a hydraulic control device for an automatic transmission that electronically controls transient hydraulic pressure when a frictional engagement device is engaged during a gear shift, there is provided a means for detecting whether or not gear shift control for one gear shift has been completed. , means for reducing the transient oil pressure at that point when a command for the next shift is issued before the shift control for one shift is completed. Hydraulic control device.