JP2936117B2 - Hydraulic control device for automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a hydraulic pressure control device for an automatic transmission that includes a solenoid valve that changes a hydraulic pressure according to a current or voltage command value, and that causes an overshoot when outputting the command value.

[Prior art]

A gear shift mechanism and a plurality of friction engagement devices are provided, and the engagement of the friction engagement devices is selectively switched by operating a hydraulic control device, so that any one of a plurality of shift speeds is achieved. A shift control device for an automatic transmission for a vehicle configured as described above is conventionally widely known. In such an automatic transmission, there has been proposed a hydraulic control device having a solenoid that is driven by an electric command in a hydraulic control device and adopting a configuration in which the hydraulic pressure is controlled by the solenoid. As a solenoid driven by the electric command, a solenoid that generates a hydraulic pressure corresponding to this position by positioning the spool at a position corresponding to a command value (voltage, current, or duty ratio), or Value (duty ratio)
There is known a type that repeatedly turns on and off at a high speed corresponding to the above, and as a result, generates a hydraulic pressure according to a duty ratio. When the hydraulic pressure is controlled by the duty ratio control, a predetermined value (not a command value) is overexcited as shown in FIG. 11 to improve the responsiveness and downsize the solenoid. Such a technique is also known (Mitsubishi Heavy Industries Technical Report Vol.19 No.2 (1982-3)). Further, although not publicly known, in order to speed up the response of the solenoid, a technique has been proposed by the present applicant to overshoot according to the oil temperature when changing the command value (Japanese Patent Application No. 63-296865).

[Problems to be solved by the invention]

However, in general, the solenoid valve that changes the oil pressure by an electric command in this manner is provided after a command from the computer (after a change in the command value).
There is a dead time and a delay time before the clutch engagement pressure actually changes. Therefore, when this kind of solenoid valve is used for feedback control of a clutch of an automatic transmission, for example, how to deal with dead time becomes a problem. That is, feedback control adds operation, and corrects the amount of operation by looking at the result.
Because the control amount is close to the target, if there is a dead time in the solenoid valve, no response will be made even if the operation amount is changed, so that the stability of the feedback control will be greatly affected, especially. . As a specific method for coping with the dead time, there is a method of reducing the gain of the feedback control to make the system insensitive to the dead time, thereby stabilizing the system. However, in this method, the ability to follow the target is also reduced. As another method, there is a method of configuring a feedback control system in consideration of the dead time. This method can complicate the control device. However, when the dead time varies under various driving conditions, the logic becomes too complicated, and it cannot be dealt with by an ordinary in-vehicle computer. The present invention has been made in view of such a problem, and when controlling a hydraulic pressure using a solenoid valve that changes the hydraulic pressure by an electric command value, the present invention reduces the amount of variation in dead time, and By improving the follow-up to the target value by shortening the dead time and the delay time and improving the feedback control, the durability of the friction engagement device in the automatic transmission is improved and the shift shock is reduced. An object of the present invention is to provide a hydraulic control device for an automatic transmission as described above.

[Means for achieving the object]

As shown in FIG. 1, the present invention provides an automatic transmission having a solenoid valve for changing a hydraulic pressure according to a current or voltage command value, and configured to overshoot when the command value is output. A hydraulic control device for the machine, comprising: means for detecting a variation width of the command value; and means for setting the amount of overshoot to be larger as the variation width is smaller, depending on the variation width. As a result, the above object has been achieved. In this specification, the “change width of the command value” includes the concept of “change rate of the command value”.

[Action]

In the present invention, when the command value (excitation current value, etc.) to the solenoid is changed, the hydraulic pressure rises or falls promptly so that the target hydraulic pressure can be quickly reached. Means for overshooting the target command value and thereafter returning to the target command value is adopted. Especially, in this overshoot, paying attention to the difference in the dead time due to the difference in the change width of the electrical command value, the overshoot amount depends on the change width of the command value, and when the change width is small, As a result, the variation in the dead time is reduced. Among solenoid valves that change the oil pressure by an electric command value, in particular, in a solenoid valve that changes the oil pressure by increasing or decreasing a current value as a command value,
FIG. 9 shows the relationship between the change width of the command value and the dead time. In the figure, a solid line with a cross indicates a characteristic when no overshoot is applied. It can be seen that the dead time Tβ significantly changes according to the change width of the exciting current, that is, the ratio (%) of the change width of the command value. In this ninth view of a solenoid valve, the dead time Tβmi when a large dead time Tibetamax ₁ when the change width of the command value is smaller
4 times or more compared to n. The reason why the dead time varies depending on the change width of the command value will be described with reference to FIG. FIG. 7 shows a transient characteristic of the hydraulic pressure after the command value is stepped up when no overshoot is performed in the solenoid valve that changes the hydraulic pressure by the excitation current. In this figure, Fvalve is the sliding resistance of the actuator of the solenoid valve. That is, if the hydraulic pressure change width due to the step-up of the exciting current is smaller than the sliding resistance Fvalve of the actuator of the solenoid valve, the actuator does not move, and thus the hydraulic pressure does not change before the command value changes. As shown in FIG. 7, when the change width of the command value is large, it takes only Ta time for the hydraulic pressure to become larger than the sliding resistance Fvalve. This is the dead time when the command value change width of the solenoid valve is large. However, when the command value change width is small, the Tb time (longer than Ta) is required for the hydraulic pressure to become larger than the sliding resistance Fvalve. Therefore, this is a dead time when the command value change width of the solenoid valve is small. The difference between the dead times Ta and Tb is the variation in the dead time due to the difference in the electrical command value change width. The present invention pays attention to such a point, and when there is a change in the command value, first obtains a change width of the command value, and increases the overshoot amount α according to the change width as the change width is smaller. It is set to be. As a result, as will be described later, for example, as indicated by a solid line with a circle in FIG.
Even if the range of change of the command value is different, it is possible to prevent the waste time from varying so much. Incidentally, the overshoot of the command value to the solenoid valve may be a one-stage overshoot as shown in FIGS. 6A and 6B or a two-stage overshoot. Alternatively, any other overshoot method may be used as long as the effect of the overshoot can be changed according to the difference in the command value change width. In FIG. 6 (A) and FIG. 6 (B), the overshoot amount (I ₂ −I ₁ or I ₂ / I ₁ , (I ₂ −I ₁ ) / I _1, etc.) according to the change width of the command value (I ₂ −I ₁ ). α, α ₁ , α ₂ ) and overshoot time (T ₁ , T ₂ , T ₃ ) are determined. As a result, variations in dead time due to differences in the command value change width are reduced. In the case of a solenoid of a type that controls oil pressure by changing the duty ratio as a command value, the amount of overshoot is determined with respect to the change width of the original command duty ratio, and this overshoot amount is added. The command duty ratio (including-) may be given only when the command duty ratio changes.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this embodiment, in order to electronically control the transient hydraulic pressure at the time of engagement of the friction engagement device, the back pressure of the accumulator is feedback-controlled. In this feedback control, the hydraulic pressure is controlled by the exciting current so that the actual clutch C ₀ rotation speed (torque converter / turbine rotation speed) N _CO changes along the locus of the clutch C ₀ target rotation speed N _CO ^*. This is performed by electronically controlling a linear solenoid (SN) that can be operated by a command from a computer. The clutch C ₀ target rotation speed N _CO ^* is obtained from the relationship between the actual clutch C ₀ rotation speed N _CO and the clutch synchronization speed (vehicle speed × gear ratio after shifting) at the end of shifting. FIG. 2 shows an overall outline of an automatic transmission for a vehicle to which this embodiment is applied. This automatic transmission includes a torque converter section 20 as a transmission section thereof and an overdrive mechanism section 40.
And an underdrive mechanism 60 having three forward stages and one reverse stage. The torque converter section 20 includes a pump 21 and a turbine 2
2, a well-known one provided with a stator 23 and a lock-up clutch 24. The overdrive mechanism 40 includes a set of planetary gear units including a sun gear 43, a ring gear 44, a planetary pinion 42, and a carrier 41. The rotation state of the planetary gear unit is determined by a clutch C ₀ , a brake B ₀ , and a one-way. Clutch F
Controlled by ₀ . The underdrive mechanism 60 includes a common sun gear 6
1, two sets of planetary gear units consisting of ring gears 62, 63, planetary pinions 64, 65 and carriers 66, 67, and a clutch for determining the rotational state of these two sets of planetary gear units and the connection state with the overdrive mechanism. C _1, C _2, is controlled by the brake B ₁ ~B _3, and the one-way clutch F _1, F _2. Since this transmission unit is well known per se, the specific connection state of each component is only shown in the skeleton in FIG. 2 and detailed description is omitted. This automatic transmission includes the transmission unit as described above and a computer (ECU) 84. The computer 84 includes a throttle sensor 80 for detecting a throttle opening θ for reflecting the output (torque) of the engine 1, a vehicle speed sensor (a rotational speed sensor for the output shaft 70 of the automatic transmission) 82 for detecting a vehicle speed n ₀ , speed sensor for detecting a rotational speed NC ₀ of the clutch C ₀ of the automatic transmission as an information source for reflecting an oil temperature sensor 83 for detecting the oil temperature Te, and the transmission transients
Each signal such as 99 is input. The computer 84 drives and controls the solenoid valves S ₁ and S ₂ (for the shift valve) and the solenoid valve SL (for the lock-up clutch) in the hydraulic control circuit 86 in accordance with a preset throttle opening-vehicle speed shift map. The shift is executed by performing a combination of engagement of each clutch, brake and the like as shown in FIG. FIG. 4 shows a main part of the hydraulic control circuit 86. In FIG. 4, reference numeral SN denotes a linear solenoid, 108 denotes an accumulator control valve, 110 denotes a modulator valve, 112 denotes an accumulator, and 114 denotes a shift valve. In the fourth view, as a friction engagement device, the brake B ₂ are representatively shown. As it is apparent from Figure 3, the brake B ₂ is a friction engagement device is engaged when achieving a 1 → 2 shift. The line pressure PL is generated by a known method using a hydraulic pressure generated by an oil pump (not shown) as a base pressure. This line pressure PL is applied to the port 110A of the modulator valve 110. The modulator valve 110 uses this line pressure PL
Receiving and generating the port 110B predetermined modulator pressure PL ₀ in a known manner. Linear solenoid SN generates a solenoid pressure PS ₁ in accordance with the difference between the clutch C ₀ rotational speed N _CO and the clutch C ₀ target rotational speed N _CO ^* Receiving the module regulator pressure PL _0. That is, the computer 84, the rotational speed NC ₀ of the clutch C ₀ is entered as described above. This clutch C
₀ rotational speed N _CO is compared to the clutch C ₀ target rotational speed N _CO ^*. For example, in the case of 1 → 2 shift, the clutch C ₀ rotational speed N _CO is reduced by execution of the 1 → 2 shift. If the clutch C ₀ rotational speed N _CO clutch C ₀ target rotational speed N
_When it falls earlier than _CO ^* (when NC ₀ -N _CO ^* <0)
Means that the shift progresses too fast. Therefore, in order to reduce the engagement transition oil pressure of the brake B _2, the NC ₀ -N
A command current corresponding to a duty ratio corresponding to _CO ^* is applied to the linear solenoid SN, and the linear solenoid SN generates a solenoid pressure PS proportional to the duty ratio by the command current.
₁ is generated in a known manner. In this case, if the command current is now changed from I ₁ to I ₂ , the command current to the solenoid is normally stepped from I ₁ to I ₂ as shown by the broken line in FIG. 6 (A). Changed (no overshoot). However, as in this embodiment shown in the solid line in Figure No. 6 (A), the commander current when changing from I ₁ to I _2, the command value change width ((I ₂ -
An overshoot amount α (FIG. 8) according to I ₁ ) / I ₁ ) is overshot to return to the original target command current I ₂ after a predetermined time T ₁ from the change of the command current. As a result, the rise of the hydraulic pressure is improved accordingly. or,
In this case, the overshoot amount α is further determined depending on the signal of the oil temperature sensor 83 when the oil temperature Te is normal temperature and when the oil temperature Te is extremely low, so as to further improve the accuracy. The overshoot control will be described later in detail with reference to the flowchart of FIG. Thus the solenoid pressure PS ₁ generated in the is input to the port 108A of the accumulator control valve 108. Accumulator control valve 108, a throttle pressure Pth reflect the engine torque and an input signal to the solenoid pressure PS ₁ from the linear solenoid SN, the line pressure PL ₂ accumulator back pressure Pac port 108B
Adjust the pressure. That is, the accumulator back pressure Pac, the line pressure PL ₂ the throttle pressure Pth, are those which by regulating the biasing force of the solenoid pressure PS ₁ and the spring 108C, thus arbitrarily pressure regulating by the changing the solenoid pressure PS ₁ It is. When the shift determined by the computer 84 is performed, the shift valve 114 via a solenoid valve S ₁ is switched in a known manner (shift command), the line pressure PL (P _B0) starts to be supplied towards the brake B _2. Upon receiving this supply, the piston 112A of the accumulator 112 starts to rise. This piston 1
While 12A is rising, the hydraulic pressure (P _B0 ) supplied to the brake B2 is maintained at a hydraulic pressure balanced with the downward biasing force of the spring 112B and the downward force acting on the piston 112A. The force for pushing the piston 112A downward is generated by the accumulator back pressure Pac applied to the back pressure chamber 112C of the accumulator 112. Therefore, as described above, the accumulator back pressure Pac is set to the modulator valve 110,
By controlling via the linear solenoid SN and the accumulator control valve 108, it is possible to arbitrarily control the transient hydraulic pressure P _B0 when the brake B ₂ is engaged. The linear solenoid SN is connected to the clutch C ₀ as described above.
To be controlled in dependence on the difference between the rotational speed N _CO and the clutch C ₀ target rotational speed N _CO ^*, after all, by such hydraulic system, the clutch C ₀ rotational speed N _CO clutch C ₀ target rotational speed N Feedback control can be made to vary along with _CO ^* . Next, overshoot control in the linear solenoid SN for shifting from the first speed to the second speed will be described in detail with reference to FIG. The flag F in steps 201a to 201d is a flag for storing the current state of the automatic transmission and controlling the flow based on this state. Initially, the flag F is reset to 0, so that the process proceeds to step 202. In step 202, it is determined whether or not an upshift from the first speed to the second speed has been determined.
If there is a shift determination upshift from the first speed stage to the second speed stage, the process proceeds to step 203, performs brake B ₂ apply command. If it is determined in step 202 that the shift is not a shift from the first gear to the second gear, step 21 is executed.
In step 1, another shift control is executed, and thereafter, the process proceeds to reset. After the brake B ₂ apply command at step 203, in step 204, it is an automatic transmission state during the inertia phase state (state where the rotation member of the automatic transmission has occurred a speed change for the speed change) The determination of whether or not it is made is made by a well-known method. The automatic transmission is not in the inertia phase,
That is, when it is determined that the state is before the start of the inertia phase, the flag F is set to 1 in step 206, and the process proceeds to reset. If it is determined that the automatic transmission is in the inertia phase, the process proceeds to step 205. In step 205, for feedback control of the rotational speed of the clutch C _0, compares the current rotational speed N _CO of the clutch C ₀ that is detected by the target rotation speed N _CO ^* and the speed sensor 99 of the clutch C _0, the correct An output current (determined current) for exciting the linear solenoid SN to be corrected to obtain the rotation speed is obtained. In step 207, step 2
In accordance with the change width of the determined current (the ratio of the determined current to the current determined current) and the oil temperature Te detected by the oil temperature sensor 83, according to the determined current obtained in 05, the map shown in FIG. The overshoot current amount α is obtained, and the determined current + α is output to the linear solenoid SN. _{By 1} hour T after performing the output of the defined current + alpha it is determined whether the elapsed at step 208, the linear solenoid SN
, The excitation current of the definite current + α is output during the time T ₁ . After T ₁ times the (overshoot time) Step 2
At 10, the determined current is output to the linear solenoid SN. After outputting the final current + α in step 211, T ₀
By performing the determination whether the elapsed time, the determined current is output T ₀ -T ₁ hour to the linear solenoid SN. Steps 205 and steps 207 to 212 are repeatedly executed until the end of the inertia phase is determined in step 213. That is, repeated that the comparison confirm the current target rotational speed and the present rotational speed is corrected every T ₀ hours, outputs T ₁ times overshoot current, outputs the T ₀ -T ₁ hour confirm current. In step 213, whether the inertia phase of the automatic transmission has ended is checked by a known method. If it is determined that the inertia phase has not ended, the flag F is set to 4 in step 214, and the process proceeds to reset. . This flag F is 4
In the case of performs clutch C ₀ rotational speed feedback control for each T ₀ hours as described above. If it is determined that the inertia phase ends in step 213, performs an increase command for the brake B ₂ hydraulic in step 215, the process proceeds to reset to 0 the flag F at step 216,
The control of the series of shifts from the first speed to the second speed is completed. FIG. 10 illustrates steps 204 through 205 as described above.
And shows the state of overshoot of the solenoid excitation current when having conducted the feedback control process of the rotational speed of the clutch C ₀ from step 207 at step 212. In Figure 10, ₄ from overshoot alpha ₁ alpha is corresponding to [Delta] I from variation [Delta] I _l of the solenoid excitation current ₄ (strictly in this example is "change rate" instead of "difference") doing. As is apparent from the figure, the overshoot amount is large when the change width of the exciting current is small, and the overshoot amount is small when the change width of the exciting current is large. or,
When the change is negative, it overshoots on the negative side. FIG. 9 is a diagram showing a characteristic of a dead time with respect to a current change width of the linear solenoid valve SN used in the device of the above embodiment. In FIG. 9, a solid line with a cross indicates a dead time characteristic when overshoot is not performed when the exciting current of the solenoid valve changes, and a solid line with a circle indicates overshoot in this embodiment. 3 shows a dead time characteristic in the control device of FIG. As is clear from the figure, when the influence of the sliding resistance of the actuator of the solenoid valve is relatively small, such as when the current change width is about 12% or more, the variation in the dead time due to the difference in the current change width. However, the smaller the current change width, the greater the variation in the dead time due to the difference in the current change width. In particular, when overshoot is not performed as in the present embodiment, the variation in the dead time is remarkable (×
Marked solid line). However, as shown in this FIG. 9, compared with the maximum dead time Tibetamax ₂ at the maximum dead time Tibetamax ₁ as the present embodiment the control device when not performed conventional overshoot, the maximum waste of this embodiment device It can be seen that the time is less than 1/2. As described above, in the present embodiment, the variation in the dead time due to the difference in the change width of the exciting current of the solenoid valve can be significantly improved. In the present embodiment, as shown in FIG. 8, the overshoot amount α is determined continuously by the excitation current change width. However, in the present invention, it is not always necessary to determine the overshoot amount α continuously. , And the excitation current change width is divided into two zones, and the overshoot amount α is large and small (α is 2
The present invention includes a case where the value corresponds to the presence or absence of the overshoot amount α (α is a constant value).

【The invention's effect】

As described above, according to the present invention, in a hydraulic control apparatus for an automatic transmission including a solenoid valve that changes a hydraulic pressure according to a current or voltage command value, a variation in dead time caused by a difference in a change width of the command. To reduce
As a result, the durability of the friction engagement device in the automatic transmission can be improved and the effect of reducing the shift shock can be sufficiently obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the gist of the present invention, FIG. 2 is a skeleton diagram of an entire automatic transmission to which an embodiment of the present invention is applied, and FIG. 3 is a friction engagement device in the automatic transmission. FIG. 4 is a hydraulic circuit diagram showing a main part in the hydraulic control device of the automatic transmission, FIG. 5 is a flowchart showing a control flow of the control device of the embodiment, FIG. 6 (A) and 6 (B) are diagrams showing the overshoot method of the above embodiment, and FIG. 7 shows the hydraulic transient characteristics of the linear solenoid valve used in the present embodiment after the step-up of the exciting current. FIG. 8 is a diagram showing the relationship between the command value change width and the amount of overshoot α in the linear solenoid valve used in the present embodiment. FIG. 9 is a diagram showing no overshoot control with this embodiment. Diagram showing characteristics of dead time with the case, FIG. FIG. 11 is a diagram illustrating an example of a relationship between a command value and an overshoot amount according to the present embodiment. FIG. 11 is a diagram illustrating a relationship between a duty ratio (command value) and a hydraulic pressure when hydraulic pressure is controlled by duty ratio control; It is a diagram showing an example of an output waveform at that time. SN: Linear solenoid, 83: Oil temperature sensor, 108: Accumulator control valve, 110: Modulator valve, 112: Accumulator, PL: Line pressure, PL _0: Modulator pressure, PS _1: Solenoid pressure , Pac ...... accumulator back pressure, Te ...... oil temperature, α ...... overshoot value, T ₁ ...... overshoot to that time, the sliding resistance of the actuator of Fvalve ...... linear solenoid.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-121358 (JP, A) JP-A-62-141460 (JP, A) JP-A-1-279160 (JP, A) JP-A-63-1988 61653 (JP, A) JP-A-1-93663 (JP, A) JP-A-63-6281 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16H 59/00-61 / 12 F16H 61/16-61/24 F16H 63/40-63/48 G05B 11/36 501 F16K 31/06

Claims (1)

(57) [Claims] 1. A hydraulic control apparatus for an automatic transmission, comprising: a solenoid valve for changing a hydraulic pressure according to a current or voltage command value, and configured to overshoot when outputting the command value. And a means for setting the amount of the overshoot to be larger as the change width is smaller, depending on the change width. Hydraulic control device.