JP4340434B2 - Shift control device for continuously variable transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shift control device for a vehicle including a continuously variable transmission.
[0002]
[Prior art]
In conventional transmission control of a continuously variable transmission, a shift pattern according to the vehicle speed and the amount of accelerator operation is stored as a map of the target input shaft speed, and the target speed ratio is determined from the target input shaft speed according to the driving state. (See Japanese Patent Laid-Open No. 4-54371).
[0003]
In this conventional example, even if a kick-down operation is performed to increase the accelerator operation amount suddenly with the intention of sudden acceleration from a steady running state where the vehicle is traveling at a substantially constant vehicle speed with a relatively small accelerator operation amount, the accelerator operation amount at this time is reduced. Since it takes some time for the actual gear ratio to reach the corresponding target gear ratio, the driving force does not increase despite the engine speed increasing immediately, and the engine seems to be blown in the meantime. The driver feels uncomfortable.
[0004]
As a countermeasure, it is conceivable to suppress a change in the gear ratio when the acceleration request is large. For example, there is proposed a method in which the gear ratio is fixed when the throttle opening exceeds a threshold value (Japanese Patent No. 2593432). etc). This means that the fixed gear ratio is determined by the gear ratio on the shift map when the throttle opening is the threshold value. In this way, by fixing the gear ratio before reaching a large gear ratio, an increase in engine rotation causes an increase in driving force quickly, so the time delay from when the throttle increases until a feeling of acceleration is obtained is shortened. As a result, the sense of incongruity is reduced and the acceleration response in terms of experience is improved.
[0005]
[Patent Document 1]
JP-A-4-54371 [Patent Document 2]
Japanese Patent No. 2593432 [0006]
[Problems to be solved by the invention]
However, in such a method for determining a constant gear ratio, the throttle opening is kept at a constant gear ratio unless the throttle opening is returned from the threshold and hysteresis settings, and the driver's initial acceleration intention is satisfied. Since the change of the gear ratio does not occur even after being done, this will cause a sense of incongruity. In other words, in order to generate a gear ratio change, an operation of intentionally returning the accelerator pedal to a large degree is required.
[0007]
Therefore, the present invention has been made in view of the above-described problems, and an object thereof is to reliably provide a driving feeling according to the driver's intention to accelerate at the time of kickdown acceleration.
[0008]
[Means for Solving the Problems]
The first invention is a driving state detecting means for detecting a driving state of a vehicle including a vehicle speed and an accelerator operation amount, a speed ratio determining means for determining a gear ratio according to the vehicle speed and the accelerator operation amount, and the determined In a transmission control device for a continuously variable transmission comprising a control means for controlling the transmission ratio of the continuously variable transmission based on the transmission ratio, an acceleration request determining means for determining the magnitude of the acceleration request, and the magnitude of the acceleration request Acceleration shift characteristic determining means for respectively determining a shift characteristic of a downshift and a shift characteristic of an upshift based on the length, and when the acceleration request is greater than a preset reference value, And an acceleration control means for performing an upshift based on the upshift speed characteristic after downshifting to a speed ratio that is suppressed by a speed ratio determined by the speed ratio determining means. The upshift characteristic, the shift amount of the shift to the smaller side of the gear ratio is set smaller the larger the acceleration request in accordance with the increase of the vehicle speed from the gear ratio after the downshift.
[0009]
In a second aspect based on the first aspect, the acceleration speed change characteristic determining means selects one of a plurality of downshift speed characteristics preset according to the magnitude of the acceleration request, One is selected from a plurality of preset upshift characteristics according to the magnitude of the acceleration request.
[0012]
According to a third invention, in the first or second invention , the acceleration request determination means detects an accelerator operation speed based on an accelerator operation amount, and accelerates based on the accelerator operation speed and the accelerator operation amount. Determine the size of the request.
[0013]
In a fourth aspect based on any one of the first to third aspects, the acceleration control means changes a reference value for comparing the acceleration requests according to a vehicle speed and an accelerator operation amount.
In a fifth aspect based on any one of the first to fourth aspects, the acceleration control means increases the amount of downshift as the acceleration request is larger, based on the downshift speed change characteristic. Thus, the suppressed gear ratio is set.
[0014]
【The invention's effect】
Therefore, according to the first and fifth aspects of the present invention, when the acceleration request is large (for example, at the time of kickdown acceleration), the downshift with the downshift transmission characteristic that is suppressed more than the normal shift determined by the transmission ratio determining means is performed. By performing a shift and then performing an upshift to the lower side of the gear ratio by the upshift transmission characteristics, an excessive increase in engine rotation speed and a decrease in vehicle acceleration during acceleration are suppressed, and a rise in vehicle acceleration is achieved. The vehicle acceleration according to the driver's acceleration intention can be reliably obtained by balancing the depression.
In addition, since the upshift speed change characteristic has set the shift amount from the speed ratio after the downshift to the smaller side of the speed ratio according to the increase in the vehicle speed, it is possible to suppress a drop in vehicle acceleration during the upshift after the downshift, Acceleration growth can be provided.
In addition, the greater the acceleration request, the smaller the shift amount to shift to the lower gear ratio in accordance with the increase in the vehicle speed, so the engine rotation speed is increased according to the magnitude of the acceleration intention, and the driver expectation The corresponding vehicle acceleration can be obtained.
[0015]
In the second aspect of the present invention, one of the plurality of downshift transmission characteristics and the plurality of upshift transmission characteristics is selected as the acceleration transmission characteristic. It is possible to realize a shift according to the speed.
[0018]
In the third aspect of the invention, since the magnitude of the acceleration request is determined based on the accelerator operation speed and the accelerator operation amount, the driver's intention to accelerate can be accurately determined.
[0019]
In the fourth aspect of the invention, the reference value for comparing the acceleration requests is changed according to the vehicle speed and the accelerator operation amount. Therefore, the downshift can be performed according to the driver's intention to accelerate regardless of the change in the driving state. it can.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
[0021]
FIG. 1 shows a schematic configuration of a vehicle to which the present invention is applied. An engine 11 is connected to a continuously variable transmission 10 provided with a torque converter 12 to an engine 11 so that an optimum driving state is obtained in accordance with a running state. The controller 1 which controls the output of 11 and the gear ratio of the continuously variable transmission 10 is provided. As the continuously variable transmission mechanism of the continuously variable transmission 10, a V-belt type or a toroidal type can be adopted.
[0022]
The controller 1 performs fuel injection amount control, ignition timing control, and the like of the engine 11 according to the operating state, and controls the speed ratio steplessly according to the operating state. The controller 1 is an integrated control device having both engine control means and shift control means.
[0023]
The controller 1 includes an accelerator sensor 5 that detects an accelerator pedal operation amount APO (or an accelerator operation amount), a vehicle speed sensor 4 that detects a traveling speed of the vehicle (hereinafter referred to as a vehicle speed VSP), and an engine rotation that detects a rotational speed Ne of the engine 11. The sensor 2 and the input shaft rotation sensor 3 for detecting the input shaft rotation speed Nt of the continuously variable transmission 10 are connected to detect the driving state of the vehicle. Here, the vehicle speed sensor 4 detects the output shaft rotational speed OutRev of the continuously variable transmission 10, and multiplies it by a constant (ratio of tire radius, etc.) according to the final reduction ratio and the vehicle specifications. And
[0024]
FIG. 2 is a flowchart showing an example of the shift control according to the present invention, which is executed periodically (for example, every several tens of milliseconds) by the microcomputer of the controller 1.
[0025]
In this control, a change in the gear ratio is suppressed when a predetermined acceleration condition (kick-down acceleration) is satisfied from a control mode (hereinafter referred to as “normal mode”) in which the gear ratio is variably controlled according to the driving state. The mode is shifted to a control mode (hereinafter referred to as “linear mode”).
[0026]
Although not shown in the figure, in the background of these routines, the accelerator operation amount APO and the vehicle speed VSP are detected as the driving state. In the following description, numerals indicated by reference sign S correspond to the processing steps in FIG.
[0027]
First, in step S1, it is determined whether the previous control mode is the normal mode or the linear mode with reference to the control flag F. If the previous control mode is the normal mode, the kickdown in step S2 is performed. On the other hand, if the previous control mode is the linear mode, the process proceeds to step S4, where it is determined whether the linear mode release condition is satisfied. The control flag F indicates, for example, a linear mode when it is 1, and a normal mode when it is 0.
[0028]
In step S2, it is determined whether or not a kick-down operation is performed. First, the accelerator operation speed dAPO is obtained from the difference between the detected accelerator operation amount APO and the previous value of the accelerator operation amount APO.
[0029]
Then, a reference value dAPOL serving as a threshold value of the accelerator operation speed is obtained from the current vehicle speed VSP and the accelerator operation amount APO from the map shown in FIG. 3, and if the accelerator operation speed dAPO exceeds the reference value dAPOL, the kick down is performed. If it is determined that it is an operation, the process proceeds to step S3, and if it is an accelerator operation other than kick-down, the process proceeds to step S20 to control the normal mode.
[0030]
In the map of the accelerator operation amount APO and the reference value dAPOL of the accelerator operation speed according to the vehicle speed VSP in FIG. 3, the accelerator operation amount APO is divided into a plurality of ranges, and the vehicle speed VSP is divided into a plurality of ranges. The reference value dAPOL is set for each range of the accelerator operation amount APO and the range of the vehicle speed VSP.
[0031]
Next, in step S3 determined to be a kick-down operation, after setting the control flag F = 1, the process proceeds to step S5 to determine the driver's acceleration intention (acceleration request).
[0032]
In step S5, the acceleration intention is searched from the map of FIG. 4 based on the accelerator operation speed dAPO and the accelerator operation amount APO obtained in step S2. In this map, when the accelerator operation amount APO is large, it is determined that the acceleration intention is large regardless of the accelerator operation speed dAPO, and the accelerator operation amount APO is in the intermediate region (for example, APO is 3/8 to 6 / In 5), if the accelerator operation speed dAPO is high, it is determined that the acceleration intention is medium, and if the accelerator operation speed dAPO is low, it is determined that the acceleration intention is low. A predetermined hysteresis is provided for the acceleration intention that changes in accordance with the magnitude of the accelerator operation amount APO to prevent control hunting.
[0033]
Next, in step S6, it is determined with reference to the mode flag Mf whether or not to switch between the downshift mode and the upshift mode in the linear mode.
[0034]
When the mode flag Mf is 0, switching from the downshift mode to the upshift mode has not been completed, so it is determined that there is a mode transition, and when the mode flag Mf = 1, the mode is changed from the downshift mode. Since the transition to the upshift mode has been completed, it is determined that there is no mode transition. If there is a mode transition, the process proceeds to step S7, whereas if there is no mode transition, the process proceeds to step S12.
[0035]
In step S7 where it is determined that there is a mode shift, it is determined whether the mode is the downshift mode or the upshift mode.
[0036]
Here, the downshift speed ratio DW_ratio (0) is not set, or the actual speed ratio (input shaft rotational speed impRev / output shaft rotational speed OutRev) has reached the downshift speed ratio DW_ratio (0). If not, it is determined as the downshift mode and the process proceeds to step S8.
[0037]
On the other hand, if the actual gear ratio has reached the downshift amount DW_ratio (0), it is determined that the mode is the upshift mode, and 1 is added to the mode flag Mf before the process proceeds to step S10.
[0038]
In step S8 of the downshift mode, a shift characteristic corresponding to the acceleration intention is selected from the map of FIG. 5 based on the acceleration intention determined in step S5.
[0039]
In step S9, the downshift speed ratio DW_ratio (0) is obtained from the speed change characteristic selected in step S8 according to the current vehicle speed VSP and stored.
[0040]
Thereafter, the process proceeds to step S14, and the target speed ratio Dratio is calculated from the following equation.
[0041]
Dratio = DW_ratio (0) −UP_ratio (0) + UP_ratio (n) (1)
However, UP_ratio (0) is an initial value of the upshift amount, and UP_ratio (n) is an upshift amount (a shift amount to the smaller side of the gear ratio) corresponding to an increase in the vehicle speed.
[0042]
It should be noted that at the time of proceeding from step S9 to step S14, the upshift amount initial value UP_ratio (0) and the upshift amount UP_ratio (n) are both 0, and the target gear ratio Datio = DW_ratio (0).
[0043]
Next, in step S15, the target input shaft rotational speed DsrRev is set to
DsrRev = Dratio × OutRev (2)
The process proceeds to step S16 to output the target speed ratio Dratio and control the speed ratio of the continuously variable transmission 10.
[0044]
On the other hand, in step S10 determined as the upshift mode in the determination in step S7, a shift characteristic corresponding to the acceleration intention is selected from the map of FIG. 6 based on the acceleration intention determined in step S5.
[0045]
In step S11, the upshift amount initial value UP_ratio (0) is obtained from the shift characteristic selected in step S10 according to the current vehicle speed VSP and stored.
[0046]
Then, the process proceeds to step S14, where the target speed ratio Datio is calculated from the above equation (1), and the target speed ratio Dratio is output in steps S15 and S16. However, when the routine proceeds from step S11 to step S14, the upshift amount UP_ratio (n) is 0, and the target gear ratio Datio = DW_ratio (0) −UP_ratio (0).
[0047]
Next, in step S12, in which it is determined in step S6 that there is no mode transition, a shift characteristic corresponding to the acceleration intention is selected from the map of FIG. 6 based on the acceleration intention determined in step S5.
[0048]
In step S13, the upshift amount UP_ratio (n) corresponding to the increase in vehicle speed is obtained from the shift characteristic selected in step S12 in accordance with the current vehicle speed VSP, and this upshift amount UP_ratio (n) is calculated from the next time onward. The process proceeds to step S14, where the target speed ratio Dratio is calculated from the above equation (1), and the target speed ratio Dratio is output in steps S15 and S16.
[0049]
Next, in step S4 which proceeds when the previous control mode is the linear mode in step S1, the accelerator operation amount APO is returned to a predetermined value such as 0/8 or less after the linear mode is set, and If a predetermined time has elapsed since the linear mode was entered, the linear mode is canceled and the process proceeds to step S20 to control the normal mode. When canceling the linear mode, the control flag F, the mode flag Mf, the downshift speed ratio DW_ratio (0), the upshift amount initial value UP_ratio (0), and the upshift amount UP_ratio (n) are reset to 0, respectively. To do.
[0050]
In the normal mode control, the target input shaft rotational speed DsrRev is obtained from the current vehicle speed VSP and the accelerator operation amount APO based on the shift map of FIG. 7 and is divided by the output shaft rotational speed OutRev to obtain the target speed ratio. After selecting “Dratio”, it is output in step S16.
[0051]
On the other hand, if the accelerator operation amount APO is maintained at a predetermined value or more, it is determined that the driver intends to continue acceleration, and the process proceeds to step S5 to continue the control in the linear mode.
[0052]
The effect | action by the said control is demonstrated below.
[0053]
When the accelerator is depressed and the accelerator operation speed dAPO exceeds the reference value dAPOL in FIG. 3 while traveling in the normal mode, the mode shifts to the linear mode and the intention of acceleration is determined from the map in FIG.
[0054]
First, since the mode flag Mf = 0 in the first control, the downshift speed ratio DW_ratio (0) is set in steps S8 and S9.
[0055]
Here, as shown in FIG. 5, the downshift speed ratio DW_ratio (0) is set for each vehicle speed, and the speed change characteristic varies depending on the intention of acceleration. It is set such that the greater the intention to accelerate, the greater the downshift amount (the amount of shift to the larger gear ratio).
[0056]
In steps S8 and S9, as shown in FIG. 8, the downshift speed ratio DW_ratio (0) at the time when the kickdown operation is performed is set.
[0057]
Next, when the actual speed ratio reaches the downshift speed ratio DW_ratio (0), as shown in FIG. 9, the initial upshift amount UP_ratio (0) at the completion of the downshift corresponding to the vehicle speed VSP during the down operation is obtained. Set and shift to upshift mode. Since the actual gear ratio at the completion of the downshift is the target gear ratio at the time of kickdown operation = downshift gear ratio DW_ratio (0), the initial upshift amount UP_ratio (0) is the target gear ratio at the time of kickdown operation. The value corresponds to the ratio.
[0058]
Here, as shown in FIG. 6, the upshift amount initial value UP_ratio (0) is set with an upshift amount for each vehicle speed, and with different speed change characteristics depending on the magnitude of the acceleration intention. The larger the intention is, the smaller the upshift amount corresponding to the vehicle speed is set.
[0059]
Thereby, the shift to the small (Hi) side of the gear ratio is started in accordance with the upshift amount from the above equation (1).
[0060]
Until the release condition of the linear mode is satisfied, the upshift amount UP_ratio (n) is updated according to the increase in the vehicle speed VSP every control cycle.
[0061]
In addition, the applicant of the present application has previously set two elements as a Japanese Patent Application No. 2001-182803, a downshift amount when a kickdown operation is performed and an upshift amount that determines a subsequent rotation rising locus (shift pattern). By defining on the map, we propose that the amount of downshift at the beginning of acceleration and the amount of upshift after downshifting are set according to the driver's intention to accelerate, and the gear is changed according to the driver's intention to accelerate. ing.
[0062]
However, in the prior application (Japanese Patent Application No. 2001-182803), when the kick down operation is performed, the downshift amount at the time of downshift and the upshift amount after the downshift are shown in FIG. Based on the same map that is set so that the gear ratio correction amount linearly decreases as the speed increases, the value of the gear ratio correction amount is changed using the magnitude of the acceleration request as a parameter. There is a problem that the degree of freedom in setting the ratio or the target input shaft rotational speed is low, and it is not always possible to obtain a driving sensation according to the driver's intention to accelerate depending on the driving state.
[0063]
In the present invention, as shown in FIG. 10, in the downshift mode after the kickdown operation, the amount of downshift is regulated as compared with the shift characteristic of FIG. 7 in the normal mode according to the shift characteristic according to the map of FIG. , The input shaft rotational speed impRev from point A to point B in the figure is suppressed to improve the vehicle acceleration height and vehicle acceleration response at the initial stage of acceleration.
[0064]
After reaching the downshift speed ratio DW_ratio (0), which is the target speed ratio of the downshift, the upshift amount UP_ratio corresponding to the increase in the initial value UP_ratio (0) equivalent to the kickdown operation and the vehicle speed VSP. From (n), the actual upshift amount UPratio is
UPratio = UP_ratio (0) −UP_ratio (n) (3)
This formula is the above formula (1),
Dratio = DW_ratio (0) − {UP_ratio (0) −UP_ratio (n)}
It is transformed like
Dratio = DW_ratio (0) -UP_ratio
It becomes.
[0065]
Thus, the value obtained by subtracting the actual upshift amount UP_ratio from the downshift speed ratio DW_ratio (0) becomes the target speed ratio, and in FIG. 10, after point B, gradually as shown by the solid line in the figure as the vehicle speed VSP increases. Thus, the gear ratio is changed to a smaller side, and an excessive increase in the engine rotation speed Ne during acceleration and a decrease in the vehicle acceleration can be suppressed to obtain a vehicle acceleration in accordance with the driver's acceleration intention.
[0066]
In FIG. 10, the wavy line in FIG. 10 is based on the prior application (Japanese Patent Application No. 2001-182803). According to this conventional example, the downshift amount is larger than the point B of the present invention, and then the shift to the smaller side is performed. However, it is excessive compared to the present invention.
[0067]
For this reason, as shown in FIG. 11, in the present invention indicated by the solid line in the figure, the arrival time to the maximum value of the vehicle acceleration is faster than the conventional example indicated by the wavy line in the figure, and the engine speed Ne at this time Is suppressed lower than the conventional example. For this reason, the magnitude of the vehicle acceleration and the arrival time to the maximum acceleration can be set optimally. Further, in the upshift mode, the reduction of the gear ratio is suppressed as compared with the conventional example, so that the increase of the engine rotation speed Ne is ensured. Thus, a drop in vehicle acceleration can be suppressed, and the acceleration can be experienced.
[0068]
And, during the kickdown operation, the shift characteristics according to the driver's intention to accelerate are set on the downshift side and the upshift side from the plurality of shift characteristics, so the engine can respond to the kickdown acceleration request for each vehicle speed. The degree of freedom of setting the rotational speed Ne can be obtained. In particular, by setting a plurality of speed change characteristics according to the acceleration intention, the balance between the rising and falling of the vehicle acceleration can be achieved while reducing the calculation load of the controller 1. This makes it possible to achieve good kickdown acceleration over a wide speed range.
[0069]
Also, in the upshift after the downshift, as shown in FIG. 6, the higher the intention of acceleration, the smaller the upshift amount corresponding to the vehicle speed is set, so the engine speed is increased along with the acceleration intention. Thus, the vehicle acceleration according to the driver's expectation can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a continuously variable transmission according to an embodiment of the present invention.
FIG. 2 is a flowchart showing an example of shift control performed by a controller.
FIG. 3 is a map of a reference value dAPOL of an accelerator operation speed dAPO corresponding to an accelerator operation amount APO and a vehicle speed VSP.
FIG. 4 is a map of acceleration intention according to an accelerator operation amount APO and an accelerator operation speed dAPO.
FIG. 5 is a map of a downshift speed ratio DW_ratio (0) corresponding to a vehicle speed with an acceleration intention as a parameter.
FIG. 6 is a map of the upshift amount according to the vehicle speed with the acceleration intention as a parameter.
FIG. 7 is a map of a target input shaft rotation speed according to a vehicle speed VSP using an accelerator operation amount APO used in a normal mode as a parameter.
FIG. 8 is a map of the downshift speed ratio according to the vehicle speed VSP showing how the downshift speed ratio DW_ratio (0) is determined.
FIG. 9 is a map of the upshift amount corresponding to the vehicle speed VSP showing how the upshift amount is determined.
FIG. 10 is a map of the input shaft rotational speed impRev according to the vehicle speed VSP when kickdown acceleration is performed, and the solid line in the figure shows the locus of the rotational speed impRev of the present invention, and the wavy line in the figure represents the rotational speed according to the conventional example. The trajectory of impRev is shown.
FIG. 11 is a graph showing the relationship between the accelerator operation amount APO, the engine rotation speed, the vehicle acceleration G (front-rear G) and time when kickdown acceleration is performed, and the solid line in the figure shows the present invention. A wavy line shows a conventional example.
FIG. 12 is a map showing a conventional example and determining a downshift amount and an upshift amount.
[Explanation of symbols]
1 controller 2 engine rotation sensor 3 input shaft rotation sensor 4 vehicle speed sensor 5 accelerator sensor 10 continuously variable transmission 11 engine

Claims (5)

Driving state detection means for detecting the driving state of the vehicle including the vehicle speed and the amount of accelerator operation;
Gear ratio determining means for determining a gear ratio according to the vehicle speed and the accelerator operation amount;
A transmission control device for a continuously variable transmission, comprising control means for controlling a transmission ratio of the continuously variable transmission based on the determined transmission ratio;
Acceleration request determination means for determining the magnitude of the acceleration request;
Acceleration shift characteristic determining means for determining a shift characteristic of a downshift and a shift characteristic of an upshift based on the magnitude of the acceleration request,
When the acceleration request is larger than a preset reference value, after downshifting to a speed ratio that is suppressed by a speed ratio determined by the speed ratio determining means based on the downshift speed characteristics, the upshift speed change is performed. Acceleration control means for upshifting based on characteristics,
The upshift speed change characteristic is set such that a shift amount for shifting from a speed ratio after a downshift to a smaller speed ratio according to an increase in vehicle speed is set smaller as the acceleration request is larger .
A transmission control apparatus for a continuously variable transmission.   The acceleration shift characteristic determining means selects one of a plurality of downshift transmission characteristics set in advance according to the magnitude of the acceleration request, and a plurality of upshifts preset in accordance with the magnitude of the acceleration request. 2. The transmission control device for a continuously variable transmission according to claim 1, wherein one is selected from the shift transmission characteristics. The acceleration request determining means detects an accelerator manipulation speed based on the accelerator operation amount, to claim 1 or 2, characterized in that determining the magnitude of the acceleration request based on the accelerator operating speed and the accelerator operation amount A transmission control device for a continuously variable transmission. The continuously variable transmission according to any one of claims 1 to 3 , wherein the acceleration control means changes a reference value for comparing the acceleration requests in accordance with a vehicle speed and an accelerator operation amount. Shift control device. Said acceleration control means, based on the downshift characteristic claims 1 to 4, characterized in that to set the acceleration demand is large enough speed ratio amount downshift is the suppressed so as to increase A transmission control device for a continuously variable transmission according to any one of the above.

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