JP4047474B2 - Drive down shift control device for automatic transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of a drive-down shift control device for an automatic transmission that controls to release the release-side engagement element pressure in an inertia phase start region during accelerator depression downshift.
[0002]
[Prior art]
Drive downshifts often begin when you are running and run out of power and depress the accelerator pedal, and are sometimes referred to as torque demand shifts, or shifts that require more torque. In this downshift, the fastened elements are released, the engine rotation starts to rise, and the downshift is completed when the released elements are fastened as the engine speed reaches the gear level after the gear shift. Become. Although this seems to be simple, it is difficult to match the fastening timing, and it is a one-way clutch that automatically performs this, but if the one-way clutch is incorporated into the transmission mechanism, space and weight And disadvantageous in terms of cost.
[0003]
Therefore, as a drive down shift control device for a conventional automatic transmission that can control the release side and engagement side hydraulic pressures well at the time of drive downshift by accumulator back pressure control, and can eliminate the one-way clutch, Japanese Patent Laid-Open No. 9-152026 An apparatus described in the Japanese Patent Publication is known.
[0004]
In this conventional publication, the release side hydraulic pressure is increased in the latter half of the shift, the change in the turbine speed is maintained at approximately zero near the post-shift gear ratio (the progress of the downshift is delayed), and a margin that allows some deviation. A gear shifting technique based on anti-blur control that attempts to perform a rotation-synchronized gear shift that suppresses the occurrence of a pull-in shock or a push-up shock by raising the engagement-side hydraulic pressure at the timing of providing the above is described.
[0005]
[Problems to be solved by the invention]
However, in the drive down shift control device of the conventional automatic transmission described above, the release side hydraulic pressure at the initial stage of the inertia phase after the start of slipping of the fastening element indicates whether the shift progress is fast or slow. Regardless of this, since control is performed so that a constant pressure is uniquely obtained, when the gear shift ratio at the initial stage of the inertia phase is compared with the gear ratio, the turbine rotation difference before and after the gear shift becomes slow at high speeds, and the turbine rotation before and after the gear shift If the shift time is greatly different (FIG. 10) such that the difference becomes faster at low speeds (FIG. 10), appropriate shift control according to the driving situation is not achieved.
[0006]
That is, at the time of drive down shift, it is preferable that the shift time is short in order to meet the driver's acceleration request. Therefore, if the release-side hydraulic pressure is excessively released at a high speed when the turbine rotation difference before and after the shift is large (low pressure holding), the shift is completed in a very short time compared to the high speed when the turbine rotation difference before and after the shift is small. Therefore, preparation for operation on the engagement side or preparation for release-side hydraulic pressure startup by the idling prevention control is not in time, and engine idling occurs as shown in the low-speed turbine rotation characteristics in FIG.
[0007]
On the other hand, if the release-side hydraulic pressure is kept from being released when the turbine rotation difference before and after the shift is small (maintaining high pressure), the shift progress speed at the initial phase of the inertia phase is slowed at high speeds, and the shift time becomes longer, resulting in a feeling of extended shifting. Will not respond to the driver's acceleration request.
[0008]
The problem to be solved by the present invention is an automatic shift that stably optimizes the shift speed in the initial inertia phase according to the magnitude of the turbine rotation difference before and after the shift without using feedback control in the drive down shift. It is an object of the present invention to provide a drive down shift control device for a machine.
[0009]
[Means for Solving the Problems]
(Solution 1) As shown in the claim correspondence diagram of FIG. 1, when the downshift command is output by the accelerator depressing operation, the solving means 1 (Claim 1) of the above problem is the gear stage before the downshift. In a drive-down shift control device for an automatic transmission that achieves a gear position after downshifting by releasing the first fastening element a that has been fastened and fastening the second fastening element b that has been released. Inertia phase start detector c for detecting the phase start, shift progress speed estimator d for estimating the shift progress speed, and turbine rotation increase speed at which the pressure value decreases as the shift progress speed estimated value indicates a slower progress. Control pressure Based on the starting pressure of the inertia phase When the turbine rotation increase speed control pressure setting unit e to be set and the start of the inertia phase are detected, a control command for decreasing and maintaining the hydraulic pressure from the inertia phase start pressure to the set turbine rotation increase speed control pressure is the first hydraulic pressure. A release-side hydraulic pressure control unit h including a turbine rotation increase control unit g that outputs to the control actuator f is provided.
(Solution 2) The solution 2 (Claim 2) of the above-mentioned problem is the drive down shift control device for an automatic transmission according to Claim 1, as shown in the claim correspondence diagram of FIG. The portion d is used to estimate the turbine rotation difference before and after the drive down shift immediately after the start of the shift, and the estimated turbine rotation difference is large In some cases, the turbine rotation difference estimation unit is configured to set the shift progress speed estimated value to a value indicating slow progress.
(Solution 3) The solution 3 (Claim 3) of the above-mentioned problem is the drive down shift control device for an automatic transmission according to claim 1 or 2, as shown in the claim correspondence diagram of FIG. The turbine rotation increase control unit g is a control unit that lowers at a stretch to a control command for obtaining a turbine rotation increase speed control pressure when the start of the inertia phase is detected.
(Solving means 4) Solving means 4 (Claim 4) of the above-mentioned problem is the drive down shift control device for an automatic transmission according to Claim 1 or Claim 2, as shown in the claim correspondence diagram of FIG. The turbine rotation increase control unit g is a control unit that gradually decreases with a draft before the start of the inertia phase until a control command for obtaining a turbine rotation increase speed control pressure is detected when the start of the inertia phase is detected. .
(Solution 5) The solution 5 (Claim 5) of the above-described problem is the drive down shift control device for an automatic transmission according to any one of Claims 1 to 4, as shown in the claim correspondence diagram of FIG. The release side hydraulic control means h is provided with an air blow prevention control unit i that temporarily increases the release side hydraulic pressure at the end of the inertia phase of the drive-down shift to suppress the rising speed of the turbine rotation.
(Solving means 6) The solving means 6 (Claim 6) of the above-mentioned problem is the drive down shift control device for an automatic transmission according to any one of Claims 1 to 5, as shown in the claim correspondence diagram of FIG. Pressure control in which the hydraulic control actuators f and j of the first fastening element a and the second fastening element b are electronically controlled independently of each other by control commands from the release-side hydraulic control means h and the fastening-side hydraulic control means k at the time of shifting. It is a valve.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
The first embodiment is a drive-down shift control device for an automatic transmission corresponding to claims 1 to 6.
[0011]
First, an overall outline of an automatic transmission to which the drive down shift control device of the first embodiment is applied will be described.
[0012]
FIG. 2 is a skeleton diagram showing a power transmission mechanism of the automatic transmission.
[0013]
In FIG. 2, IN is an input shaft, OUT is an output shaft, FPG is a front planetary gear, RPG is a rear planetary gear, and the front planetary gear FPG includes a first sun gear S1, a first ring gear R1, a first pinion P1, and a first planetary gear. The rear planetary gear RPG has a first sun gear S2, a second ring gear R2, a second pinion P2, and a second pinion carrier C2.
[0014]
Reverse clutch REV / C (hereinafter referred to as R / C), high clutch HIGH / C (hereinafter referred to as H / C), 2-4 brake as engagement elements for obtaining the forward fourth speed and the reverse first speed using the gear train. 2-4 / B, low clutch LOW / C (hereinafter referred to as L / C), low & reverse brake L & R / B, and low one-way clutch LOW OWC are provided.
[0015]
The first sun gear S1 is connected to the input shaft IN via a first rotating member M1 and a reverse clutch R / C, and is connected to a case via a first rotating member M1 and a 2-4 brake 2-4 / B. Connected to K.
[0016]
The first carrier C1 is connected to the input shaft IN via the second rotating member M2 and the high clutch H / C, and is connected to the case K via the third rotating member M3 and the low & reverse brake L & R / B. It is connected. The first carrier C1 is connected to the second ring gear R2 via the third rotating member M3 and the low clutch L / C. A low one-way clutch LOW OWC is provided in parallel with the low & reverse brake L & R / B.
[0017]
The first ring gear R1 is directly connected to the second carrier C2 via the fourth rotating member M4, and the output shaft OUT is directly connected to the second carrier C2.
[0018]
The second sun gear S2 is directly connected to the input shaft IN.
[0019]
The power transmission mechanism is characterized by a one-way clutch that was used to obtain a change-over timing without shifting shocks during downshifts such as 4-3 and 4-2, and an engine brake that was used with this one-way clutch. It is in the point which achieved size reduction and weight reduction by abolishing the clutch by the hydraulic fastening required for ensuring, and reducing the number of fastening elements.
[0020]
FIG. 3 is a diagram showing an engagement logic for obtaining the fourth forward speed and the first reverse speed by the power transmission mechanism.
[0021]
The first speed (1st) is obtained by engaging the low clutch L / C hydraulically and the low & reverse brake L & R / B hydraulically engaged (when the engine brake range is selected) or the low one-way clutch LOW OWC mechanically engaged (when accelerating). It is done. That is, the second sun gear input, the second ring gear fixed, and the second carrier output.
[0022]
The second speed (2nd) is obtained by engaging the low clutch L / C and the 2-4 brake 2-4 / B. That is, the second sun gear input, the first sun gear fixed, and the second carrier output.
[0023]
The third speed (3rd) is obtained by hydraulic engagement of the high clutch H / C and the low clutch L / C. That is, the second ring gear and the second sun gear are simultaneously input and the second carrier output (speed ratio = 1).
[0024]
The fourth speed (4th) is obtained by engaging the high clutch H / C and the 2-4 brake 2-4 / B. That is, it becomes an overdrive shift stage by the first carrier and the second sun gear input, the first sun gear fixed, and the second carrier output.
[0025]
The reverse speed (Rev) is obtained by hydraulic engagement of the reverse clutch REV / C and the low & reverse brake L & R / B. That is, the first and second sun gear inputs, the first carrier fixed, and the second carrier output.
[0026]
FIG. 4 shows a DESC system (direct electronic shift control system) with a fastening element, a control valve unit, and an electronic control unit for achieving automatic transmission of the D range 1st to 4th speed and the reverse speed of the R range. FIG.
[0027]
In FIG. 4, 1 is a line pressure oil passage, 2 is a manual valve, 3 is a D range pressure oil passage, 4 is an R range pressure oil passage, 5 is a pilot valve, 6 is a pilot pressure oil passage, and 7 is a first pressure control. 8 is a second pressure control valve, 9 is a third pressure control valve, 10 is a fourth pressure control valve, 12 is a low clutch pressure oil passage, 13 is a high clutch pressure oil passage, and 14 is 2-4 brake pressure oil. Road, 15 is a low & reverse brake pressure oil path, 16 is a reverse clutch pressure oil path, 17 is an A / T control unit, 18 is a vehicle speed sensor, 19 is a throttle sensor, 20 is an engine rotation sensor, 21 is a turbine rotation sensor, 22 is an inhibitor switch, and 23 is an oil temperature sensor.
[0028]
Each of the pressure control valves 7, 8, 9, 10 is a solenoid valve that generates a solenoid pressure (a base pressure based on a pilot pressure Pp by a constant pressure) in response to a duty command from the A / T control unit 17, and signals the solenoid pressure. It is a valve by an amplifier valve that regulates the D range pressure as the pressure. Each of the pressure control valves 7, 8, 9, 10 may be a linear solenoid valve and an amplifier valve that regulates the D range pressure using the solenoid pressure as a signal pressure, or directly adjusts the D range pressure. A solenoid valve that regulates the pressure may be used.
[0029]
Here, the shift control for automatically shifting the first to fourth gears in the D range is detected based on, for example, a shift point characteristic model diagram as shown in FIG. 5 and the detected throttle opening and vehicle speed. A shift command is issued when the operating point crosses the upshift shift line (solid line) or the downshift shift line (dotted line), and the gear stage to be transferred next is determined by this shift command, so that the determined gear stage is obtained. The A / T control unit 17 outputs a duty command for hydraulic control that releases the fastening element that is fastened before the shift and fastens the fastening element that is released before the shift.
For example, in the case of a 3-2 drive downshift performed when the driving point shifts from the point A to the point B in FIG. The high clutch H / C (corresponding to the first engagement element a) engaged at the speed is released by a duty command to the second pressure control valve 8 (corresponding to the hydraulic control actuator f), and is released at the third speed. 2-4 brake 2-4 / B (corresponding to the second engagement element b) is engaged by a duty command to the third pressure control valve 9 (corresponding to the hydraulic control actuator j).
[0030]
Next, the operation will be described.
[Drive down shift control]
Drive down shift control with accelerator operation among the various shift modes is executed according to the flowchart shown in FIG. Hereinafter, each step will be described with reference to the time chart shown in FIG.
* Release side control (equivalent to release side hydraulic control means h)
In step 30, release-side element removal control for shifting to the inertia phase by reducing the hydraulic pressure of the release-side element is performed in the region from the output time of the downshift command to the start of the inertia phase.
[0031]
In step 31, it is determined whether or not the inertia phase starts depending on whether or not the turbine rotation speed Nt has reached the shift start determination rotation speed NTSTART (or the actual gear ratio is the shift start determination gear ratio).
[0032]
In step 32, in the region from the start of the inertia phase until the turbine speed Nt reaches the first set speed NT1, the hydraulic pressure of the disengagement side element is made lower than the inertia phase start pressure by the turbine rotation speed increase control pressure PR3. A command is output, and by maintaining this command as it is, turbine rotation increase control is performed to advance downshift using engine torque.
[0033]
In step 33, it is determined whether or not the turbine speed Nt has reached the first set speed NT1.
[0034]
In step 34, in the region from the first set speed NT1 to the second set speed NT2, the output of the duty element corresponding to the hydraulic pressure command rising at a predetermined gradient in the region from the first set speed NT1 to the second set speed NT2. Turbine rotational speed increase control is performed to suppress the increase in turbine rotational speed by increasing the hydraulic pressure. Subsequently, in the region from the second set rotational speed NT2 to the end of the inertia phase, the release side hydraulic pressure is increased. Disengagement side sharing control for outputting a duty command corresponding to the command oil pressure of the ascending gradient for obtaining the target value is performed (corresponding to the idling prevention control unit i).
[0035]
In step 35, it is determined whether or not the inertia phase is ended depending on whether or not the turbine rotation speed Nt has reached the shift end determination rotation speed NTEND (or the actual gear ratio is the shift end determination gear ratio).
[0036]
In step 36, after completion of the inertia phase, release completion control is performed to gradually decrease the release side hydraulic pressure so that the command hydraulic pressure becomes the minimum value at the set time TR2.
* Engagement side control (equivalent to engagement side hydraulic control means k)
In step 40, in the region from when the downshift command is output until the turbine speed Nt reaches the second set speed NT2, a duty command for obtaining the initial pressure PA1 is issued for the engagement side element hydraulic pressure for the set time TA1. After that, a duty command for maintaining the set hydraulic pressure PA2 is issued, and after the inertia phase starts, torque capacity is controlled by peak and hold control, which is a control for issuing a duty command corresponding to the hydraulic pressure of the input gradient RmpA3 to obtain an additional pressure with respect to the predetermined hydraulic pressure PA2. Control is performed to stroke the piston of the fastening side element to the position immediately before holding. Here, the added pressure refers to a hydraulic pressure that must be applied to the predetermined hydraulic pressure PA2 in order to reliably end the piston stroke in the peak and hold control (synonymous with precharge control).
[0037]
In step 41, it is determined whether or not the turbine speed Nt has reached the second set speed NT2.
[0038]
In step 42, in a region where the turbine rotational speed Nt is from the second set rotational speed NT2 to the end of the inertia phase, a duty command corresponding to the hydraulic pressure of the rising gradient at which the engagement side hydraulic target value is obtained when the inertia phase is predicted to be output is output. The engagement side sharing control is performed.
[0039]
In step 43, it is determined whether or not the inertia phase has ended based on whether or not the turbine speed Nt has reached the gear shift end speed NTEND (or the actual gear ratio is the gear shift end determination gear ratio).
[0040]
In step 44, after completion of the inertia phase, engagement completion control is performed to gradually increase the engagement side oil pressure so that the command oil pressure becomes the maximum value at the set time TA2.
[0041]
Here, in step 34 and step 42, in the drive-down shift, the gear ratio (turbine speed) after the shift is maintained by the sum of torques transmitted between the disengagement side engagement element and the engagement side engagement element, and smooth rotation synchronization is achieved. Cooperative fastening control is performed to achieve shifting. In this cooperative fastening control, each of the fastening elements generates a hydraulic pressure that generates a fastening element torque that is just balanced against the torque output by the engine at a gear stage in which each fastening element is independent, without increasing or decreasing the turbine rotation. Each of the release side hydraulic pressure and the engagement side hydraulic pressure is lower than the shared pressure in the gear stage after the downshift, and the release side fastening element and the fastening side fastening element can be transmitted. The sum of the values converted to turbine torque is the hydraulic pressure that satisfies the condition that the torque is slightly higher than the turbine torque at the gear stage after the downshift. The hydraulic pressure PR5 that transmits the input torque corresponding to the turbine torque x 0.8, and the hydraulic pressure PA3 that transmits the input torque corresponding to the turbine torque x 0.4 as the fastening side hydraulic pressure ). This means, for example, hydraulic control that obtains the characteristics shown in FIG.
[Turbine rotation increase control operation]
FIG. 8A is a flowchart showing the specific operation of the turbine rotation increase control in step 32, and each step will be described below.
[0042]
The pre-inertia phase release side control step of step 301 corresponds to the release side element removal control step of step 30 of FIG. .
[0043]
The step of determining whether or not the inertia phase has started in step 302 corresponds to the inertia phase start determining step of step 31 in FIG. 6 (corresponding to the inertia phase start detection unit c).
[0044]
Steps 303 to 305 correspond to the turbine rotation increase control step of step 32 of FIG.
[0045]
In step 303, the turbine rotation difference NTDIF before and after the shift of the drive down shift is calculated (corresponding to the shift progress speed estimation unit d). The turbine rotation difference NTDIF before and after the shift is obtained by the following equation if the change in the output shaft rotation speed in the inertia phase is ignored.
[0046]
NTDIF = {( 1-ga / gb) } Nt or (gb-ga) No
ga: gear ratio before shifting gb: gear ratio after shifting
No: Output shaft speed at the start of inertia phase (= vehicle speed)
Nt: Turbine speed at the start of inertia phase
In step 304, the turbine rotation increase speed control required differential pressure PR3 is calculated such that the larger the turbine rotation difference NTDIF before and after the shift for estimating the shift progress speed is a value indicating the slower progress, the larger the pressure value. This turbine rotation increase speed control required differential pressure PR3 is obtained by the following equation.
[0047]
PR3 = A · NTDIF-B A and B are constants
FIG. 8 (b) shows this expression on a map.
[0048]
In step 305, when the start of the inertia phase is detected, the release side oil pressure is obtained by subtracting the turbine rotation increase speed control necessary differential pressure PR3 set from the release side oil pressure at the start of the inertia phase (turbine rotation increase speed control pressure setting unit). e), and a duty command for maintaining the hydraulic pressure until the turbine rotational speed Nt reaches the set rotational speed NT1 is output (corresponding to the turbine rotational increase controller g).
Here, when the start of the inertia phase is detected, the release side hydraulic pressure may be lowered at a stretch to the duty command that provides the turbine rotation increase speed control pressure (= the release side hydraulic pressure is the release side hydraulic pressure at the start of the inertia phase−PR3). Further, when the start of the inertia phase is detected, it corresponds to gradually releasing the hydraulic pressure at the draft RmpR1 before the start of the inertia phase until the turbine rotational speed increasing control pressure is obtained from the release side hydraulic pressure at the start of the inertia phase. The duty command may be lowered (FIG. 9).
[Turbine rotation increase control]
When the drive-down gear shift command is issued and the release side hydraulic pressure is released, the input torque becomes larger than the torque converted from the transfer torque of the release side element to the input torque, the release side element slips, and the inertia phase in which the shift proceeds Begins.
[0049]
In other words, the release side hydraulic pressure at the start of the inertia phase should become the shared pressure on the release side with respect to the input torque if the response delay of the hydraulic pressure is eliminated (because the release side is kept engaged and starts to blow idle) . Accordingly, the turbine rotational speed increase required pressure difference PR3 subtracted therefrom is proportional to the subsequent rotational speed of the turbine rotation. This is because only the torque corresponding to the hydraulic pressure of the turbine rotation increase speed control necessary differential pressure PR3 among the turbine torque can be used for increasing the turbine rotation. By giving this control necessary differential pressure PR3 as a variable value by a predetermined element, the shift speed can be freely determined.
[0050]
In the present invention, the above-mentioned predetermined factor is the turbine rotation difference NTDIF before and after the shift that is optimal for estimating the shift progress speed regardless of the speed, the speed, or the type of the shift pattern.
[0051]
In this case, at low vehicle speeds where the turbine rotation difference NTDIF before and after the shift is small, the change in the turbine rotation required for the shift is small, and if left unattended, the shift will be completed in a short time. Want to raise slowly). On the other hand, when the turbine rotation difference NTDIF before and after the shift is small, the turbine rotation increase speed control required differential pressure PR3 is set to a small value, so that the hydraulic pressure torque of the small control required differential pressure PR3 is used for the turbine rotation increase. The speed change can proceed slowly (solid line characteristic in FIG. 9).
[0052]
On the other hand, at high vehicle speeds where the turbine rotation difference NTDIF before and after the shift is large, it is desired to make the turbine rotation start up as quickly as possible in a form close to neutral and end the shift quickly. On the other hand, when the turbine rotation difference NTDIF before and after the shift is large, the turbine rotation increase speed control required differential pressure PR3 is set to a large value, so that the hydraulic component torque of the large control required differential pressure PR3 can be used for the turbine rotation increase. As a result, the shift can be quickly advanced (dotted line characteristic in FIG. 9).
[0053]
As a result, in the release side hydraulic control of the drive-down shift, by maintaining the hydraulic pressure obtained by subtracting the required control differential pressure PR3 from the inertia phase start hydraulic pressure, and performing the shift in the initial inertia phase, a high detection accuracy requirement can be obtained. Stable optimization of the speed change speed in the initial inertia phase according to the turbine rotation difference NTDIF before and after the shift without using feedback control that causes problems such as instability due to response delay Can do. In other words, at low vehicle speeds where the turbine rotation difference NTDIF before and after the shift is small, the engine preparation on the engagement side or the engine blow-off prevention control can prevent the engine blow-off due to the failure to prepare for the release-side hydraulic startup. When NTDIF is large and the vehicle speed is high, it is possible to prevent the feeling of extension of the shift by quickly raising the turbine rotation.
(Other embodiments)
The drive-down shift control device of the present application is not limited to the automatic transmission shown in the first embodiment, and can be applied as a drive-down control device for various electronic control type automatic transmissions.
[0054]
In the first embodiment, an example in which the turbine rotation increase speed control necessary differential pressure PR3 is determined by the turbine rotation difference NTDIF before and after the shift is shown. However, if the shift progress speed can be estimated, other elements can be used to estimate the difference in turbine rotation increase speed control. The pressure PR3 may be determined. For example, it can be determined by the vehicle speed and the shift pattern (adjacent gear shift or jump shift).
[0055]
【The invention's effect】
In the first aspect of the invention, in the drive downshift control device of the automatic transmission that achieves the gear position after the downshift by changing the fastening element, the inertia phase start detection unit that detects the start of the inertia phase; A shift progress speed estimation unit that estimates a shift progress speed, a turbine rotation increase speed control pressure setting unit that sets a turbine rotation increase speed control pressure that has a smaller pressure value as the shift progress speed estimated value indicates a slower progress, and When the inertia phase start is detected, a turbine rotation increase control unit that outputs a control command to the first hydraulic control actuator to reduce and maintain the hydraulic pressure from the inertia phase start pressure to the set turbine rotation increase speed control pressure; In the drive-down shift, feedback control is provided. There is an effect that it is possible to provide a drive-down shift control device for an automatic transmission that stably optimizes the shift progress speed in the initial inertia phase according to the magnitude of the turbine rotation difference before and after the shift without using it. .
[0056]
According to a second aspect of the present invention, in the drive down shift control device for the automatic transmission according to the first aspect, the shift progress speed estimation unit estimates the turbine rotation difference before and after the drive down shift immediately after the start of the shift. When the estimated turbine rotation difference is small, the shift progress speed estimate is a value indicating slow progress. In addition to the above-described effects, in addition to the above-described effects, not only the shift speed is estimated based on the vehicle speed, but also, for example, a step-shift such as a 4 → 2 shift where the shift speed is increased even if the vehicle speed is low. Even at this time, the shift progress speed can be accurately estimated.
[0057]
According to a third aspect of the present invention, in the drive-down shift control device for an automatic transmission according to the first or second aspect, the turbine rotation increase control unit causes the turbine rotation increase speed to be detected when the start of the inertia phase is detected. Since the control unit reduces the control pressure to obtain the control pressure at once, in addition to the effect of the first or second aspect of the invention, it is possible to control the shift speed at the initial stage of the inertia phase with good response.
[0058]
According to a fourth aspect of the present invention, in the drive-down shift control device for an automatic transmission according to the first or second aspect, the turbine rotation increase control unit causes the turbine rotation increase speed to be detected when the start of the inertia phase is detected. In addition to the effect of the invention according to claim 1 or 2, in addition to the effect of the invention of claim 1 or 2, the output shaft torque fluctuation due to a sudden change in hydraulic pressure is achieved because the control unit gradually reduces the draft before the start of the inertia phase until the control command for obtaining the control pressure. Can be prevented.
[0059]
According to the fifth aspect of the present invention, in the drive-down shift control device for an automatic transmission according to any one of the first to fourth aspects, the release-side hydraulic control means is provided with a release-side hydraulic pressure at the end of the inertia phase of the drive-down shift. In addition to the effects of the inventions according to claims 1 to 4, since there is little oil pressure loss, a shift at a low speed or the like is provided. When the traveling speed is slow, it reacts quickly to the control to raise the release side hydraulic pressure, and it becomes easier to suppress low-speed spacetime blow.
[0060]
According to a sixth aspect of the present invention, in the drive-down shift control device for an automatic transmission according to the first to fifth aspects, the hydraulic control actuators of the first fastening element and the second fastening element are disengaged at the time of shifting. Since the pressure control valve that electronically controls the hydraulic pressure independently by the control commands from the hydraulic pressure control means and the fastening side hydraulic pressure control means, in addition to the effects of the inventions of claims 1 to 5, the shelf pressure and timing are controlled. Compared to a conventional centralized control system equipped with a control valve unit and a shift valve in the control valve unit, the degree of freedom of control is high, and the control valve unit can be simplified and reduced in weight.
[Brief description of the drawings]
FIG. 1 is a claim correspondence diagram showing a drive-down shift control device for an automatic transmission according to the present invention.
FIG. 2 is a skeleton diagram showing a power transmission mechanism of an automatic transmission to which the drive-down shift control device of the first embodiment is applied.
FIG. 3 is a diagram showing an engagement logic table of an automatic transmission to which the drive down shift control device of the first embodiment is applied.
FIG. 4 is a DESC system diagram of an automatic transmission to which the drive down shift control device of the first embodiment is applied.
FIG. 5 is a diagram illustrating an example of a shift point characteristic model of the drive-down shift control device according to the first embodiment.
FIG. 6 is a flowchart showing a flow of drive down shift control operation of the first embodiment.
7 shows transitions of the output side torque, the turbine speed, the gear ratio, the release side hydraulic pressure corresponding to the release side duty command, and the engagement side hydraulic pressure equivalent to the engagement side duty command during the drive down shift control according to the first embodiment. It is a time chart which shows a characteristic.
FIG. 8 is a flowchart showing a turbine rotation increase control operation according to the first embodiment and a turbine rotation increase speed control pressure characteristic diagram with respect to a turbine rotation difference before and after the shift.
FIG. 9 is a time chart showing a release side hydraulic pressure command characteristic, a high-speed turbine rotation characteristic, and a low-speed turbine rotation characteristic in the drive-down shift control according to the first embodiment.
FIG. 10 is a time chart showing a release-side command pressure characteristic, a high-speed turbine rotation characteristic, and a low-speed turbine rotation characteristic in conventional drive-down shift control.
[Explanation of symbols]
a First fastening element
b Second fastening element
c Inertia phase start detector
d Shifting speed estimation unit
e Turbine rotation rising speed control pressure setting part
f Hydraulic control actuator (pressure control valve)
g Turbine rotation rise control unit
h Release side hydraulic control means
i Air blow prevention control unit
j Hydraulic control actuator (pressure control valve)
k Fastening side hydraulic control means

Claims (6)

When a downshift command is output by the accelerator depressing operation, the first shifting element that has been fastened at the gear stage before the downshifting is released, and the second fastening element that has been released is fastened. In a drive down shift control device for an automatic transmission that achieves the subsequent gear stage,
An inertia phase start detector for detecting the start of the inertia phase;
A shift progress speed estimating unit for estimating a shift progress speed;
A turbine rotation increase speed control pressure setting unit that sets a turbine rotation increase speed control pressure, which is a smaller pressure value as the shift progress speed estimated value is a value indicating slower progress, with reference to the inertia phase start pressure ;
When the inertia phase start is detected, and the turbine rotation increase control unit for outputting a control command to keep lowering the oil pressure from the start of the inertia phase pressure to the set turbine rotation increase speed control pressure to the first hydraulic pressure control actuator,
A drive-down shift control device for an automatic transmission, characterized in that a release-side hydraulic control means including The drive-down shift control device for an automatic transmission according to claim 1,
The speed change progress speed estimation unit estimates a turbine rotation difference before and after the drive down speed change immediately after the start of the speed change, and when the estimated turbine speed difference is large, the speed change speed estimation value is a value indicating a slow progress. A drive-down shift control device for an automatic transmission, characterized in that a rotation difference estimation unit is provided. In the drive down shift control device for an automatic transmission according to claim 1 or 2,
A drive-down shift control device for an automatic transmission, wherein the turbine rotation increase control unit is a control unit that reduces the turbine rotation increase speed control pressure to a control command that obtains a turbine rotation increase speed control pressure when an inertia phase start is detected. In the drive down shift control device for an automatic transmission according to claim 1 or 2,
The turbine rotation increase control unit is a control unit that gradually decreases with a draft before starting the inertia phase until a control command for obtaining a turbine rotation increase speed control pressure is detected when the inertia phase start is detected. Drive down shift control device for automatic transmission. The drive-down shift control device for an automatic transmission according to any one of claims 1 to 4,
An automatic transmission characterized in that the release-side hydraulic control means is provided with an anti-blowing prevention control unit that temporarily increases the release-side hydraulic pressure at the end of the inertia phase of the drive-down shift to suppress the rising speed of the turbine rotation. Drive down shift control device. The drive-down shift control device for an automatic transmission according to any one of claims 1 to 5,
The hydraulic control actuators of the first fastening element and the second fastening element are pressure control valves that electronically control the hydraulic pressure independently by control commands from the release side hydraulic control means and the fastening side hydraulic control means at the time of shifting. A drive down shift control device for an automatic transmission.

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