JP2005163838A - Method for controlling automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide shock-less shifting by eliminating hydraulic follow-up delay in engagement elements in a case of a power-on upshift is instructed after power-off downshift instruction by a manual change-over means. <P>SOLUTION: In a case where power-on upshift from step N-1 to step N is instructed during shifting from step N to step N-1 by a manual change-over means, determination of synchronism is conducted when turbine speed at instruction of power-on upfhift is close to input speed at step N. When hydraulic pressure of the engagement element B1 on the engagement side as synchronism is determined is lower than initial pressure in normal engagement, prescribed initial engagement pressure is forcedly supplied to the engagement element B1. Hydraulic pressure of the engagement element B1 is then gradually increased from the initial engagement pressure. Hydraulic pressure of the engagement element B1 can thus be quickly increased, and engine blow-up is restricted. Generation of shock due to delayed engagement of the engagement element B1 can thus be restricted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a shift control method for an automatic transmission, and more particularly to a shift control method when a power-off downshift is commanded by manual switching means and a power-on upshift is commanded during the shift period.

In general, an automatic transmission performs a shift by automatically determining a gear position from a shift map and engaging or releasing an engagement element in accordance with driving conditions such as a vehicle speed and a throttle opening. In the case of such an automatic transmission, in addition to the shift map, a map for determining the power-on region and the power-off region based on the throttle opening (accelerator opening) and the engine speed is also set. Or the power-off region, the method of transient control of the engagement element is changed.
6A is a map showing each region of power-on / power-off at the time of upshifting, and FIG. 6B is a map showing each region of power-on / power-off at the time of downshifting. These maps are individually set, and the boundary line at the time of upshift is set to the lower throttle side than the boundary line at the time of downshift.
When both maps are combined, as shown in FIG. 6C, the power-on up region and the power-off down region partially overlap. Therefore, in the state of point A, both a power-on upshift and a poweroff downshift can be established.

Incidentally, some automatic transmissions include manual switching means called OD (overdrive) switches. In such an automatic transmission, if the OD switch is turned OFF while traveling at OD (for example, 4th speed), it is forcibly downshifted to 3rd speed regardless of the vehicle speed and the throttle opening. In addition to the OD switch, there is an automatic transmission that selects an arbitrary gear position by manually operating an up switch and a down switch in the D range state.
In an automatic transmission that can manually switch between downshifts and upshifts by such manual switching means, the vehicle travels in a region where both the power-on upshift and the poweroff-downshift as described above can be established. When a power-off downshift is commanded by the manual switching means and a power-on upshift is commanded during the shift period, multiple shift shocks due to hydraulic response delay may occur.

FIG. 7 shows the engagement element B1 when a power-on upshift from the 3rd speed to the 4th speed is instructed immediately after the power-off downshift from the 4th speed to the 3rd speed is instructed by ON / OFF switching of the OD switch. The change over time of the hydraulic pressure and the command current of the B1 control electromagnetic valve, the hydraulic pressure of the engagement element C2, the command current of the C2 control electromagnetic valve, and the turbine speed is shown. The engagement element B1 is engaged at the fourth speed and released at the third speed, and the engagement element C2 is released at the fourth speed and engaged at the third speed.
In the case of a power-off downshift, rattling of the engagement element C2 is performed from the time when the shift command is issued at time t1 until time t2, the initial pressure is output to the engagement element C2 at time t2, and the hydraulic pressure is started from time t3. Increase gradually. On the other hand, the engagement element B1 is almost fully released when a shift command is issued at time t1. In this way, the hydraulic pressure of the disengagement-side engagement element B1 is fully released during the power-off downshift because the turbine rotation speed must be controlled by the engagement-side engagement element C2 to prevent dragging by the double clutch. It is.
When a power-on upshift is commanded at time t4, the hydraulic pressure of the engagement element C2 is substantially drained, and the hydraulic pressure of the engagement element B1 is increased again. However, since the hydraulic pressure of the engagement element B1 is almost fully released, the rise of the hydraulic pressure is delayed even if an engagement command is issued next, and the increase in the turbine speed is delayed. The controller of the automatic transmission constantly monitors the turbine rotation speed, and determines that the turbine rotation speed is synchronized when the turbine rotation speed approaches the rotation speed of the target high speed stage (fourth speed here). Therefore, if the turbine rotational speed is low at the time of the upshift command, it is apparently determined that the rotational speed is synchronized with the rotational speed of the high speed stage (fourth speed).
In the power-on upshift, the command current of the engagement element B1 on the engagement side is swept (gradually increased) at the time of synchronization determination. However, since the hydraulic pressure of the engagement element B1 is almost completely released as described above, It takes time to increase the hydraulic pressure. As a result, the engine blows up, and the engagement element B1 engages with a delay, causing a shock.
Note that time t5 is the start of drawing-in of the turbine speed due to the engagement of the engagement element B1, and time t6 is the engagement completion command.

Patent Document 1 proposes a shift control device for an automatic transmission that prevents a shift shock caused by multiple shifts in which another shift determination is performed in the middle of a shift that releases an engagement element.
For example, when a multiple shift is performed in which a shift from the first speed to the second speed is executed during the shift period from the second speed to the first speed, which is executed by releasing the engagement element, the control pressure of the engagement element is set. By maintaining the set pressure value, a change in the amount of oil when the engagement element is re-engaged during execution of the multiple shift is reduced, and the response delay is shortened.
However, in the multiple shift from the power-off downshift to the power-on upshift, it is necessary to fully release the engagement element B1 on the disengagement side during the power-off downshift to prevent dragging. It is not possible to use a control method that maintains the oil pressure of the element at a predetermined pressure.
JP-A-9-42434

Accordingly, an object of the present invention is to provide an automatic shift that can eliminate a delay in following the hydraulic pressure of an engagement element and realize a shock-free shift when a power-on upshift command is issued after a power-off downshift command by a manual switching means. Another object is to provide a speed change control method for a machine.

In order to achieve the above object, the invention according to claim 1 is set so that the power-on upshift region and the power-off downshift region partially overlap each other, and the manual switching means changes the speed from N speed to N−1. It is possible to manually switch between a downshift to the first gear and an upshift from the (N-1) th gear to the (N-1) th gear, and when the first shift element is shifted down from the Nth gear to the N-1th gear Automatic shift that releases and engages the second engagement element, engages the first engagement element and releases the second engagement element during upshift from N-1 speed to N speed In the machine, the manual switching means detects that a power-on upshift from N-1 speed to N speed is instructed during the shift-off period of power-off downshift from N speed to N-1 speed. And the power on When the input rotation speed at the time of the upshift command is in the vicinity of the input rotation speed at the Nth gear, the step of performing the synchronization determination and the hydraulic pressure of the first engagement element at the time of the synchronization determination is lower than the normal initial engagement pressure And forcibly supplying a predetermined initial engagement pressure to the first engagement element, and gradually increasing the hydraulic pressure of the first engagement element from the initial engagement pressure. A control method is provided.

When the power-off downshift is started, the first engagement element is fully released and the engagement of the second engagement element is started. However, if a power-on upshift is commanded while the engagement of the second engagement element hardly starts, the rise of the hydraulic pressure of the first engagement element is delayed, causing engine blow-up and delay. Thus, the first engagement element is engaged and a shock is generated.
Therefore, in the present invention, when a power-on upshift is commanded and synchronization determination is performed, the hydraulic pressure of the first engagement element at the time of synchronization determination is compared with the normal initial engagement pressure, and the first engagement is determined. When the hydraulic pressure of the combined element is lower than the normal initial engagement pressure, a predetermined initial engagement pressure is forcibly supplied to the first engagement element. Thereby, the hydraulic pressure of the first engagement element rises quickly, the engine blow-up is suppressed, and the occurrence of shock due to the first engagement element engaging later can be suppressed.

In the present invention, the initial engagement pressure is a hydraulic pressure for the engagement element to start engagement, and is a minimum hydraulic pressure at which the piston of the engagement element pushes the clutch plate.
The initial engagement pressure that is forcibly supplied to the first engagement element when the hydraulic pressure of the first engagement element is lower than the normal initial engagement pressure may be the same as the normal initial engagement pressure. Alternatively, a slightly higher hydraulic pressure may be used.
In the above description, the predetermined initial engagement pressure is forcibly supplied to the first engagement element when the hydraulic pressure of the first engagement element at the time of synchronization determination is lower than the normal initial engagement pressure. It is difficult to measure the oil pressure of the combined element one by one with a sensor or the like and use this oil pressure as a control factor. Therefore, actually, when the command current (or command duty ratio) to the hydraulic control solenoid valve of the first engagement element at the time of synchronization determination is lower than the command current corresponding to the normal engagement initial pressure, It is preferable to forcibly output an instruction current corresponding to a predetermined initial engagement pressure. This is because the command current to the solenoid valve substantially corresponds to the hydraulic pressure of the engagement element.

As described above, according to the present invention, when the power-off downshift is commanded by the manual switching means and the power-on upshift is commanded during the shift period, the first engagement element at the time of synchronization determination is When the hydraulic pressure is compared with the normal initial engagement pressure and the hydraulic pressure of the first engagement element is lower than the normal initial engagement pressure, the predetermined initial engagement pressure is forcibly set to the first engagement element. Therefore, the hydraulic pressure of the first engagement element rises quickly, the engine blow-up is suppressed, and the occurrence of shock due to the first engagement element engaging later can be suppressed.

Embodiments of the present invention will be described below with reference to examples.

FIG. 1 shows a vehicle system equipped with an automatic transmission according to the present invention.
The output of the engine 1 is transmitted to the transmission mechanism 4 via the torque converter 3 of the automatic transmission 2, and the transmission mechanism 4 is connected to wheels (not shown) via the output shaft 5. The automatic transmission 2 includes an oil pump 6 that is driven by the engine 1 via the torque converter 3, and the discharge pressure of the oil pump 6 is sent to the hydraulic control device 7. The hydraulic control device 7 includes first to third electromagnetic valves 21 to 23 for speed change control. By controlling these electromagnetic valves 21 to 23 with the AT controller 20, various mechanisms incorporated in the speed change mechanism 4. The hydraulic pressure of the combined element is controlled according to the traveling state.
The hydraulic control device 7 may be provided with other electromagnetic valves for lock-up clutch control and line pressure control in addition to the three electromagnetic valves 21 to 23 for shift control.

A shift lever 24 that can be switched to each range such as P, R, N, and D is provided on the side of the driver's seat. The shift lever 24 is provided with a shift position sensor 25 for detecting each range position and an OD switch 26. The signals from these sensors 25 and 26 are input to the AT controller 20. The AT controller 20 also receives signals such as engine speed, turbine speed (input speed), throttle opening (accelerator opening), and vehicle speed.

The memory of the AT controller 20 stores a power on / power off determination value map as shown in FIG. 6 in addition to a known shift map. The AT controller 20 selects the optimum gear position based on the input signal and the shift map, and controls the solenoid valves 21 to 23 based on the power on / off map, thereby optimizing the hydraulic pressure control of the engagement element. It can be performed.

FIG. 2 shows an example of the speed change mechanism 4.
The speed change mechanism 4 includes an input shaft 10 to which engine power is transmitted via a torque converter 3, three clutches C1 to C3 and two brakes B1 and B2, which are engaging elements, a one-way clutch F, a Ravigneaux type planetary gear A mechanism 11 and a differential device 14 are provided.

The forward sun gear 11a and the input shaft 10 of the planetary gear mechanism 11 are connected via a C1 clutch, and the rear sun gear 11b and the input shaft 10 are connected via a C2 clutch. The carrier 11c is connected to the center shaft 15, and the center shaft 15 is connected to the input shaft 10 via a C3 clutch. The carrier 11c is connected to the transmission case 16 via a B2 brake and a one-way clutch F that allows only forward rotation (engine rotation direction) of the carrier 11c. The carrier 11c supports two types of pinion gears 11d and 11e, the forward sun gear 11a meshes with a long pinion 11d having a long axial length, and the rear sun gear 11b meshes with the long pinion 11d via a short pinion 11e having a short axial length. . A ring gear 11f that meshes only with the long pinion 11d is coupled to the output gear 12. The output gear 12 is connected to the differential device 14 via the intermediate shaft 13.

The transmission mechanism 4 achieves four forward speeds and one reverse speed as shown in FIG. 3 by operating the clutches C1, C2, C3, the brakes B1, B2, and the one-way clutch F. In FIG. 3, ● represents the action state of hydraulic pressure. The B2 brake is engaged at the time of reverse and the first speed in the L range. FIG. 3 also shows the operating states of the first to third solenoid valves (SOL1 to SOL3) 21 to 23. ○ indicates an energized state, and x indicates a non-energized state. This operation table shows the operation in a steady state.

The first solenoid valve 21 is for B1 brake control, the second solenoid valve 22 is for C2 clutch control, and the third solenoid valve 23 is for both C3 clutch control and B2 brake control. The reason why the third solenoid valve 23 serves both for C3 clutch control and B2 brake control is that the B2 brake does not operate in the D range, but is used only in the engine brake control in the L range and the transient control in the R range. This is because it does not interfere with the C3 clutch operated in the D range.
Since the first to third solenoid valves 21 to 23 need to perform delicate hydraulic control, a linear solenoid valve or a duty solenoid valve is used. Here, a linear solenoid valve is used. In this embodiment, the first electromagnetic valve 21 is a normally closed type, and the second and third electromagnetic valves 22 and 23 are normally open types.

FIG. 4 shows the speed change of the present invention when a power-on upshift from the third speed to the fourth speed is instructed immediately after the power-off downshift from the fourth speed to the third speed is instructed by ON / OFF switching of the OD switch 26. An example of a control method is shown. Here, changes over time in the hydraulic pressure of the engagement element B1 and the command current of the B1 control electromagnetic valve 21, the hydraulic pressure of the engagement element C2, the command current of the C2 control electromagnetic valve 22, and the turbine speed are shown. The engagement element B1 is engaged at the fourth speed and released at the third speed, and the engagement element C2 is released at the fourth speed and engaged at the third speed.
The rattling of the engagement element C2 is performed from the time when the power-off downshift command is issued at time t1 to time t2, the initial pressure is output to the engagement element C2 at time t2, and the hydraulic pressure is gradually increased from time t3. Raise. On the other hand, for the engagement element B1, when the shift command is issued at time t1, the B1 current is almost zero. Therefore, when a power-on upshift is commanded at time t4, the hydraulic pressure of the engagement element B1 is considerably low. The hydraulic pressure of the engagement element C2 is increased only to a low hydraulic pressure. The operation from time t1 to t4 is the same as the conventional one.
Next, when a power-on upshift is commanded at time t4, the hydraulic pressure of the engagement element B1 is increased again. However, since the hydraulic pressure of the engagement element B1 is almost fully released, the engagement is performed next. Even if the command is issued, the rise of the hydraulic pressure is slow, and the increase in turbine speed is delayed. Therefore, almost simultaneously with the upshift command, it is determined that it is apparently synchronized with the rotational speed of the high speed stage (fourth speed).
Therefore, in the present invention, when the synchronization determination is made, the instruction current to the B1 control electromagnetic valve 21 at the time of the synchronization determination is compared with the instruction current corresponding to the normal engagement initial pressure, and the instruction current is the normal engagement. When the current is lower than the command current corresponding to the combined initial pressure, the command current corresponding to the predetermined initial engagement pressure is forcibly output.
As a result, the engagement initial pressure is immediately supplied to the engagement element B1. The initial engagement pressure is a hydraulic pressure for starting engagement after filling, and is a minimum hydraulic pressure at which the piston presses the clutch plate. By gradually increasing the hydraulic pressure from the initial engagement pressure, the hydraulic pressure of the engagement element B1 rises quickly, the engine blow-up is suppressed, and the occurrence of a shock due to a sudden decrease in the turbine speed can be prevented.
Time t5 is the start of drawing-in of the turbine speed due to engagement of the engagement element B1, and time t6 is the engagement completion command. Turbine rotation speed pull-in start t5 is earlier than in the prior art (see FIG. 7), and engagement completion t6 is also earlier.

FIG. 5 shows an example of the control flow of the engagement side engagement element B1 during upshifting.
When the control starts, it is first determined whether or not it is on-up (step S1). If it is not on-up, off-up control is performed (step S2). If it is on-up, it is next determined whether or not it is a multiple shift (step S3). The multiple shift referred to here is a case where an off-down command is issued before the on-up command and an on-up command is issued during the off-down shifting period. If it is not a multiple shift, the backlash is output and normal shift control is performed (step S4). In the case of multiple shifts, it is determined whether or not synchronization is detected (step S5). If synchronization is not detected, the shift control is continued after outputting the initial pressure (step S6).
If synchronization is detected, it is next determined whether or not the engagement hydraulic pressure (current value) is greater than or equal to the initial pressure (step S7). If the engagement hydraulic pressure is higher than the initial pressure, the hydraulic pressure is increased by sweeping from the current value (step S8). On the other hand, if the engagement hydraulic pressure does not output the initial pressure or higher, the shift control is continued after the initial pressure is output, as in step S6.
After detecting the synchronization as described above (step S5), it is determined whether or not the engagement hydraulic pressure outputs an initial pressure or higher (step S7). If the initial pressure or higher is not output, the initial pressure is output first. Then, since the control is shifted to the sweep control, the response delay of the hydraulic pressure of the engagement element B1 can be reduced, and the occurrence of the shock can be suppressed.

In the above-described embodiment, the example of the power-off downshift → power-on upshift at the time of the 4th speed → the 3rd speed → the 4th speed has been described. It is possible to apply.
Further, the manual switching means in the present invention is not limited to the OD switch, but may be a manual transmission means in the D range called an up switch or a down switch.
Of course, the automatic transmission to which the present invention is applied is not limited to the automatic transmission having the structure shown in FIG.

It is a system diagram carrying the automatic transmission for vehicles in the present invention. FIG. 2 is a skeleton diagram of a transmission mechanism of the automatic transmission of FIG. 1. 3 is an operation table of each friction engagement element and electromagnetic valve of the speed change mechanism shown in FIG. 2. FIG. 5 is a time chart showing a shift control method according to the present invention when a power-on upshift is commanded after a poweroff downshift command. It is a flowchart figure which shows an example of the flow of control of engagement side engaging element B1 at the time of upshift. It is a map figure which shows a power on / off determination value. FIG. 10 is a time chart showing a conventional shift control method when a power-on upshift is commanded after a poweroff downshift command.

Explanation of symbols

B1 Engaging element C2 Disengaging element 20 AT controller 21 B1 Electromagnetic valve for brake control 22 C2 Electromagnetic valve for clutch control 23 Shift lever 26 OD switch

Claims (1)

The power-on upshift region and the power-off downshift region are set so as to partially overlap, and downshift from N speed to N-1 speed and N-1 to N speed by manual switching means The up-shift to the up-shift can be manually switched, and the first engagement element is released and the second engagement element is engaged at the time of the down-shift from the N-speed to the N-1 speed. In an automatic transmission that engages a first engagement element and releases a second engagement element during an upshift from the first speed to the Nth speed,
Detecting by the manual switching means that a power-on upshift from N-1 to N is commanded during a shift-off period of a power-off downshift from N to N-1 ,
A step of performing synchronization determination when the input rotational speed at the time of the power-on upshift command is in the vicinity of the input rotational speed at the N-speed stage;
Forcibly supplying a predetermined initial engagement pressure to the first engagement element when the hydraulic pressure of the first engagement element at the time of the synchronization determination is lower than the normal initial engagement pressure;
And a step of gradually increasing the hydraulic pressure of the first engagement element from the initial engagement pressure.

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