JP4496714B2 - Transfer mode switching control device for transfer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a transfer drive in which drive mode position switching control is executed when a predetermined switching condition is satisfied, including a condition that an automatic transmission is in a neutral range position, during a drive mode switching operation by a driver's operation. It belongs to the technical field of mode switching control devices.
[0002]
[Prior art]
Conventionally, a drive mode switching control device for a part-time transfer that switches power from a transmission between two-wheel drive and four-wheel drive and switches a four-wheel drive state between a high mode position and a low mode position is a high mode position. For the purpose of improving safety when switching between the vehicle and the low mode position, the transmission is in neutral, the brake operating state is ON, the vehicle speed is below a predetermined vehicle speed, Switching of the drive mode is permitted only when the engine rotational speed is equal to or lower than the predetermined rotational speed (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
JP 2001-280491 A (page 7, paragraph)
[0004]
).
[0005]
[Problems to be solved by the invention]
However, in the conventional transfer drive mode switching control device, the switching operation torque commanded to the shift actuator is given by a constant torque (= a constant current value) regardless of the friction torque of the automatic transmission. Therefore, a large current value is applied so that the switching operation can be ensured even in the situation where the friction torque of the automatic transmission is the largest. There is a problem that fuel consumption will worsen by increasing.
[0006]
By the way, the friction torque of the automatic transmission is the addition of the torque due to the frictional resistance at each bearing, etc. to the drag torque between the plates due to residual hydraulic oil when the frictional engagement element is released with the automatic transmission at the neutral range position. Caused by. The friction torque accounts for a large proportion of the total torque, and the magnitude of the friction torque varies considerably, for example, when the hydraulic oil of the automatic transmission is at a low oil temperature and at a high oil temperature.
[0007]
The present invention has been made paying attention to the above problems, and ensures reliable switching operation regardless of the magnitude of friction torque of the automatic transmission, and improvement of fuel consumption by reducing energy consumption in the shift actuator. It is an object of the present invention to provide a transfer drive mode switching control device capable of achieving both.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention,
Drive that outputs a drive mode switching operation command to the shift actuator when the drive mode is switched by a driver's operation and satisfies a predetermined switching condition including a condition that the automatic transmission is in the neutral range position In the transfer drive mode switching control device including the mode switching control means,
Friction torque estimating means for estimating the friction torque when the automatic transmission is in the neutral range position is provided,
The drive mode switching control means sets a switching operation torque commanded to the shift actuator at the time of switching between the high mode position and the low mode position by a variable torque according to the estimated friction torque. And a switching operation torque setting unit that sets the switching response time target value in advance and sets the actual switching response time based on the relational characteristic between the friction torque and the switching operation torque determined to be the switching response time target value. As a means.
[0009]
Here, the “friction torque estimating means” means, for example, means for estimating that the friction torque is larger as the oil temperature detected by the oil temperature sensor for detecting the hydraulic oil temperature of the automatic transmission is lower.
[0010]
【The invention's effect】
Therefore, in the drive mode switching control device of the transfer according to the present invention, the switching operation torque commanded to the shift actuator at the time of switching between the high mode position and the low mode position in the drive mode switching control means, Since the variable torque is set according to the estimated friction torque, reliable switching operation is ensured regardless of the friction torque of the automatic transmission, and fuel consumption is improved by reducing energy consumption in the shift actuator. , Both can be achieved.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment for realizing a transfer drive mode switching control device of the present invention will be described based on a first example shown in the drawings.
[0012]
(First embodiment)
First, the configuration will be described.
FIG. 1 is an overall system diagram showing a transfer drive mode switching control apparatus according to a first embodiment. In FIG. 1, the structure of the drive system will be described. 1 is an engine, 2 is an automatic transmission, 3 is an automatic transmission output shaft, 4 is a transfer, 5 is a rear propeller shaft, 6 is a rear differential, and 7 is a left rear wheel drive. Shaft, 8 is the right rear wheel drive shaft, 9 is the left rear wheel, 10 is the right rear wheel, 11 is the front propeller shaft, 12 is the front differential, 13 is the left front wheel drive shaft, 14 is the right front wheel drive shaft, and 15 is the left A front wheel, 16 is a right front wheel.
[0013]
When 2WD is selected in the transfer 4, the driving force that has passed through the engine 1 and the automatic transmission 2 is transferred to the transfer 4 → the rear propeller shaft 5 → the rear differential 6 → the left and right rear wheel drive shafts 7 and 8 → the left and right rear wheels 9 and 10. The rear wheel drive state transmitted to is realized.
[0014]
When 4WD is selected by the transfer 4, the driving force that has passed through the engine 1 and the automatic transmission 2 is transmitted to the left and right rear wheels 9, 10, and the front propeller shaft 11 → the front differential 12 → the left and right front wheel drive shafts 13,14. → A rigid 4WD state in which a driving force by equal distribution is transmitted to the left and right rear wheels 9 and 10 and the left and right front wheels 15 and 16 is transmitted to the left and right front wheels 15 and 16.
[0015]
The transfer 4 includes a drive motor 20, a high gear-low gear switching mechanism 21, a 2WD-4WD switching mechanism 22, and a shift motor 23 that performs switching operation of both the switching mechanisms 21 and 22 by an external control command. Actuator).
[0016]
The configuration of the drive mode switching control system for controlling the shift motor 23 will be described with reference to FIG. 1. 24 is a drive mode switch, 25 is a drive mode position sensor, 26 is a transfer control unit (drive mode switching control means), and 27 is An indicator 28 is a warning lamp.
[0017]
The drive mode changeover switch 24 is disposed at a position that can be operated by the driver, such as an instrument panel position in the passenger compartment, and a two-wheel drive high mode position (2H) and a four-wheel drive high position by a switch changeover operation by the driver. Switching between the mode position (4H) and the four-wheel drive low mode position (4LO) can be performed.
[0018]
The drive mode position sensor 25 is provided on a shift motor output shaft 23a, which will be described later, and includes a two-wheel drive high mode position (2H), a four-wheel drive high mode position (4H), a neutral position (N), and a four-wheel drive low mode. The position (4LO) is constituted by four shift actuator position switches SW1, SW2, SW3, SW4 that are determined by a combination of switch signals within a set rotation range.
[0019]
The transfer control unit 26 starts the operation of the shift motor 23 after confirming the switching condition when the driving mode switching signal is input by the driving mode switching switch 24, and after the switching by the driving mode position sensor 25. Electronic control means for stopping the shift motor 23 using the signal at the drive mode position as a stop signal.
[0020]
In addition to the information from the drive mode changeover switch 24 and the drive mode position sensor 25, the transfer control unit 26 includes a brake operation signal from the brake switch 31, a right rear wheel speed from the right rear wheel speed sensor 32, and a left rear wheel. Left rear wheel speed from speed sensor 33, right front wheel speed from right front wheel speed sensor 34, left front wheel speed from left front wheel speed sensor 35, engine speed from engine speed sensor 36, A / from inhibitor switch 37 Information such as the T position (range position), the A / T output shaft rotational speed from the output shaft rotational speed sensor 38, and the A / T hydraulic oil temperature from the oil temperature sensor 39 is input.
[0021]
The indicator 27 is disposed at a position where the driver can visually recognize the instrument panel position or the like in the vehicle interior, and the drive mode selected by the transfer 4 is displayed by a command from the transfer control unit 26.
[0022]
The warning lamp 28 is disposed at a position where the driver can visually recognize the position of the instrument panel or the like in the vehicle interior, and when a 4WD system such as the 2WD-4WD switching mechanism 22 fails or a speed change system such as the high gear-low gear switching mechanism 21. When a failure occurs, it is turned on or blinked according to a command from the transfer control unit 26.
[0023]
FIG. 2 is a sectional view showing a transfer to which the drive mode switching control device of the first embodiment is applied. FIG. 3 is a cylindrical cam turning diagram of the apparatus of the first embodiment. In FIG. 2, 40 is a transfer case, 41 is a transfer input shaft, 21 is a high gear-low gear switching mechanism, 42 is a transfer rear output shaft, 22 is a 2WD-4WD switching mechanism, 43 is an input side chain sprocket, and 20 is a drive transmission chain. , 44 is an output side chain sprocket, 45 is a transfer front output shaft, 46 is a slide shaft, 47 is a cylindrical cam shaft, and 48 is a cylindrical cam.
[0024]
The high gear-low gear switching mechanism 21 includes a sun gear 21a formed integrally with the transfer input shaft 41, a ring gear 21b fixed to the transfer case 40, and a carrier 21c that supports a pinion that meshes with both the gears 21a and 21b. The two-stage transmission gear is constituted by a single type planetary gear train having Then, a high gear portion 21d disposed on the side portion of the sun gear 21a, a low gear portion 21e disposed on the side portion of the carrier 21c, and a first coupling that is slidably fitted to the transfer rear output shaft 42. A sleeve 21f, a first shift fork 21g engaged with the first coupling sleeve 21f, a first slide sleeve having one end fixed to the first shift fork 21g and the other end movably provided on the slide shaft 46 A gear switching mechanism is configured by 21h and the first pin 21i fixed to the first slide sleeve 21h. The slide shaft 46 is disposed in parallel with the transfer rear output shaft 42 and is capable of reciprocating with respect to the transfer case 40.
That is, when the first coupling sleeve 21f is in the position shown in FIG. 2, the high gear (gear ratio 1) that directly connects the transfer input shaft 41 and the transfer rear output shaft 42 via the sun gear 21a and the first coupling sleeve 21f. ) Is obtained. Further, when the first coupling sleeve 21f is at the position stroked to the right from the position shown in FIG. 2, the transfer input shaft 41 and the transfer rear output shaft 42 are connected to the sun gear 21a, the pinion, the carrier 21c, and the first coupling sleeve. A low gear (a reduction gear ratio is a ratio of the number of sun gear teeth to the number of ring gear teeth) coupled through 21f is obtained.
[0025]
The 2WD-4WD switching mechanism 22 is disposed on the side of a 4WD gear portion 22a that is spline-fitted to the transfer output shaft 42, and an input side chain sprocket 43 that is rotatable with respect to the transfer output shaft 42. Or a 4WD input gear portion 22b, a second coupling sleeve 22c that engages with the 4WD gear portion 22a when 2WD is selected and engages with both gear portions 22a and 22b when 4WD is selected, and engages with the second coupling sleeve 22c. The second shift fork 22d, a second slide sleeve 22e having one end fixed to the second shift fork 22d and the other end fixed to the slide shaft 46, and a second pin 22f fixed to the second slide sleeve 22e And composed of
That is, when the second coupling sleeve 22c is in the position shown in FIG. 2, a two-wheel drive state (rear wheel drive state) in which the transfer output shaft 42 and the input side chain sprocket 44 are separated is obtained. When the sleeve 22c is in a position stroked to the right from the position shown in FIG. 2, the transfer rear output shaft 42 and the input side chain sprocket 44 connect the 4WD gear portion 22a, the second coupling sleeve 22c, and the 4WD input gear portion 22b. The four-wheel drive state which connects via this is obtained. In the four-wheel drive state, the driving force transmitted to the input side chain sprocket 44 is transmitted to the front propeller shaft 11 via the drive transmission chain 20, the output side chain sprocket 44, and the transfer front output shaft 45. Is done.
[0026]
The cylindrical cam shaft 47 is coaxially connected to the shift motor output shaft 23a of the shift motor 23, and rotates with the rotation of the shift motor output shaft 23a. A cylindrical cam 48 in which a high gear-low gear cam groove 48a in which the 1 pin 21i is fitted and a 2WD-4WD cam groove 48b in which the second pin 22f is fitted is formed on the cylinder is fixed.
[0027]
As shown in FIG. 3, the high gear-low gear cam groove 48 a is a straight cam groove perpendicular to the cylindrical cam shaft 47 from the two-wheel drive high mode position (2H) to the four-wheel drive high mode position (4H). A section from the four-wheel drive high mode position (4H) to a little before the four-wheel drive low mode position (4LO) is an inclined cam groove inclined to the cylindrical cam shaft 47, and the four-wheel drive low mode position (4LO) The front and rear sections are straight cam grooves orthogonal to the cylindrical cam shaft 47, and the end portions of the straight cam grooves are formed in the arc-shaped low side groove end portion 48a ′.
[0028]
As shown in FIG. 3, the 2WD-4WD cam groove 48 b is a linear cam orthogonal to the cylindrical cam shaft 47 in a section before and after the two-wheel drive high mode position (2H) from the arcuate 2WD side groove end portion 48 b ′. A section from the two-wheel drive high mode position (2H) to a four-wheel drive high mode position (4H) is formed as an inclined cam groove inclined to the cylindrical cam shaft 47, and the four-wheel drive high mode position (4H). A section from the four-wheel drive low mode position (4LO) to a little later than the four-wheel drive low mode position is defined as a straight cam groove orthogonal to the cylindrical cam shaft 47.
[0029]
FIG. 4 is a schematic diagram showing the drive mode position sensor 25 of the first embodiment apparatus, and FIG. 5 is a shift actuator position switch SW1, SW2, SW3, SW4 with respect to the cylindrical cam rotation angle of the drive mode position sensor 25 of the first embodiment apparatus. FIG. 6 is a diagram showing the correspondence between the drive mode changeover switch operation determination and the signal patterns of the shift actuator position switches SW1, SW2, SW3, SW4 in the first embodiment apparatus.
[0030]
As shown in FIG. 4, the drive mode position sensor 25 is fixed to the motor case and includes a switch board 25a having four annular switch circuits around the shift motor shaft 23a, and is fixed to the shift motor shaft 23a. And a movable switch portion 25b disposed at a radial position with respect to the annular switch circuit, and is configured by shift actuator position switches SW1, SW2, SW3, and SW4 that output four types of ON / OFF switch signals.
[0031]
As shown in FIG. 5, the shift actuator position switch SW1 outputs ON in the 2WD section, OFF in the 2WD-4H section, 4H section, 4H-N section and N section, and ON in the N-4LO section and 4LO section. .
[0032]
As shown in FIG. 5, the shift actuator position switch SW2 is OFF in the 2WD section, ON in the 2WD-4H section, OFF in the 4H and 4H-N sections, and most of the 4H-N sections. ON is output in N section, N-4LO section and 4LO section.
[0033]
As shown in FIG. 5, the shift actuator position switch SW3 outputs ON in the 2WD section, 2WD-4H section, and 4H section, and outputs OFF in the 4H-N section, N section, N-4LO section, and 4LO section.
[0034]
As shown in FIG. 5, the shift actuator position switch SW4 is OFF in most of the 2WD section and 2WD-4H section, ON in a few 2WD-4H sections, 4H sections and 4H-N sections, N section and N sections. Outputs OFF in -4LO section and ON in 4LO section.
[0035]
When the drive mode changeover switch 24 is switched from the two-wheel drive high mode position (2H) to the four-wheel drive high mode position (4H), the shift actuator position switch SW2 is changed from ON to OFF as shown in FIG. The operation of the 2H → 4H drive mode changeover switch can be determined.
[0036]
When the drive mode changeover switch 24 is switched from the four-wheel drive high mode position (4H) to the four-wheel drive low mode position (4LO), the shift actuator position switch SW4 is turned from OFF to ON as shown in FIG. It is possible to determine the operation of the 4H → 4LO drive mode changeover switch.
[0037]
When the drive mode changeover switch 24 is switched from the two-wheel drive high mode position (2H) to the four-wheel drive low mode position (4LO), as shown in FIG. 6, the shift actuator position switch SW1 is ON, and the shift actuator position switch SW3 Is OFF, and the shift actuator position switch SW4 is changed from OFF to ON, so that it is possible to determine the operation of the 2H → 4LO drive mode changeover switch.
[0038]
When the drive mode changeover switch 24 is switched from the four-wheel drive low mode position (4LO) to the four-wheel drive high mode position (4H), the shift actuator position switch SW3 is changed from ON to OFF as shown in FIG. The operation of the 4LO → 4H drive mode changeover switch can be determined.
[0039]
When the drive mode changeover switch 24 is switched from the four-wheel drive high mode position (4H) to the two-wheel drive high mode position (2H), or from the four-wheel drive low mode position (4LO) to the two-wheel drive high mode position (2H 6), the shift actuator position switch SW1 is turned from OFF to ON as shown in FIG. 6, so that it is possible to determine the operation of the 4H → 2H, 4LO → 2H drive mode changeover switch.
[0040]
Next, the operation will be described.
[0041]
[Drive mode switching control process]
FIG. 7 is a flowchart showing the flow of the drive mode switching control process executed by the transfer control unit 26, and each step will be described below.
[0042]
In step S1, it is determined whether or not the driver has performed an operation for switching the drive mode on the drive mode changeover switch 24. If YES, the process proceeds to step S2, and if NO, the confirmation of the mode switching operation is repeated. .
[0043]
In step S2, the drive mode switching operation performed in step S1 is a four-wheel drive high mode position (4H) and a four-wheel drive low mode position (4LO) for switching the gear ratio between the high side and the low side. Or when switching between the two-wheel drive high mode position (2H) and the four-wheel drive low mode position (4LO). The process proceeds to S3, and in the case of NO (when switching operation between the two-wheel drive high mode position (2H) and the four-wheel drive high mode position (4H) where the gear ratio is not switched between the high side and the low side) is step The process proceeds to S6.
[0044]
In step S3, it is confirmed whether or not the switching condition 1 is satisfied. If YES, the process proceeds to step S4, and if NO, the process returns to step S2 until it is satisfied.
Here, the “switching condition 1” is as follows: (1) the range position of the automatic transmission 2 is the neutral range position, (2) the wheel speed is 0 km / h, and (3) the engine speed is from 350 rpm. Four conditions, that is, up to 1600 rpm, and (4) the brake operation signal is ON.
[0045]
In step S4, based on the determination that the switching condition 1 in step S3 is satisfied, the A / T oil temperature from the oil temperature sensor 39 is detected, and the process proceeds to step S5 (friction torque estimating means).
[0046]
In step S5, the current value (= switching) applied to the shift motor 23 based on the A / T oil temperature from the oil temperature sensor 39 in step S4 and the transmission oil temperature-current value characteristic shown in FIG. Operating torque).
[0047]
In step S6, when the determination in step S2 is NO, that is, between the two-wheel drive high mode position (2H) and the four-wheel drive high mode position (4H) where the gear ratio is not switched between the high side and the low side. During the switching operation, it is confirmed whether or not the switching condition 2 is satisfied. If YES, the process proceeds to step S7, and if NO, the process returns to step S2 until it is satisfied.
Here, the “switching condition 2” is that the rotational speed difference between the front and rear wheels is equal to or less than a set speed difference (for example, a slight rotational speed difference that does not interfere with the 4WD side gear meshing operation in the 2WD-4WD switching mechanism 22). One condition of being.
[0048]
In step S7, the switching condition 1 in step S3 is satisfied, the current value determined in step S5, or the switching condition 2 in step S6 is satisfied, and the current value is determined by a predetermined constant value. The shift motor 23 is instructed to rotate in the direction to obtain the drive mode, and the process proceeds to step S8.
[0049]
In step S8, it is determined whether or not the elapsed time from the start of operation of the shift motor 23 exceeds the time limit. If YES, the process proceeds to step S12, and if NO, the process proceeds to step S9.
Here, the “time limit” is a maximum energization time (for example, 5 seconds) set to protect the shift motor 23.
[0050]
In step S9, if it is determined in step S8 that the time limit has not been exceeded, it is determined whether or not a stop signal (switch signal indicating that the drive mode after switching from the drive mode position sensor 25 has been switched) is being output. If YES, the process proceeds to step S10. If NO, the process returns to step S7, and the operation of the shift motor 23 is continued.
[0051]
In step S10, the shift motor 23 is stopped based on the output of the stop signal in step S9, and the process proceeds to step S11.
[0052]
In step S11, the motor rotation position of the shift motor 23 is replaced with the motor rotation position already stored in the motor rotation position memory, and is newly updated as the motor rotation position, and the process proceeds to return.
[0053]
In step S12, when the elapsed time from the start of operation of the shift motor 23 exceeds the time limit determined in step S8, the drive mode position sensor 25 that outputs a stop signal is broken or the shift motor 23 is stopped. Based on this failure diagnosis, a command to stop the shift motor 23 is output, and the process proceeds to step S13.
[0054]
In step S13, the current motor rotation position of the shift motor 23 is determined, the subsequent operation of the shift motor 23 is stopped, and the drive mode switching control is terminated.
[0055]
[Driving mode switching between 2H and 4H]
At the time of switching operation between the two-wheel drive high mode position (2H) and the four-wheel drive high mode position (4H) in which the gear ratio is not switched between the high side and the low side, step S1 → step S2 in the flowchart of FIG. → Proceed to step S6. In step S6, it is confirmed whether or not the switching condition 2 in which the rotational speed difference between the front and rear wheels is equal to or less than the set speed difference is satisfied. The flow from step S2 to step S6 is repeated.
[0056]
If the switching condition 2 is satisfied in step S6, the process proceeds from step S6 to step S7 → step S8 → step S9, and step S7 → step S8 → step S9 is repeated until a stop signal is input in step S9. A command is issued to rotate the shift motor 23 so as to shift from the drive mode position before the switching operation to the drive mode position after the switching operation.
[0057]
Then, since the drive mode switching control system is normal, the elapsed time from the start of operation of the shift motor 23 reaches the drive mode position after the switching operation within the time limit, and the drive mode position sensor 25 determines from step S9. When the stop signal is output, the process proceeds to step S10. In step S10, the shift motor 23 is stopped, and in the next step S11, the motor rotation position of the shift motor 23 is updated.
[0058]
Therefore, if the switching operation between the two-wheel drive high mode position (2H) and the four-wheel drive high mode position (4H) is performed by the drive mode switch 24 when the drive mode switching control system is normal, the rotation synchronization of the front and rear wheels is performed. The drive mode switching control is immediately executed only by satisfying the switching condition 2 which is a condition.
[0059]
Here, the switching condition 2 is the rotation synchronization condition for the front and rear wheels. When the second coupling sleeve 22c is stroked with the meshing of the gears, it is rotated by the left and right front wheels 15 and 16 together with the input side chain sprocket 44. This is because the 4WD input gear portion 22b and the 4WD gear portion 22a rotated together with the transfer output shaft 42 by the left and right rear wheels 9, 10 are required to be synchronized with each other.
[0060]
That is, when switching from the two-wheel drive high mode position (2H) to the four-wheel drive high mode position (4H), the second coupling sleeve 22c is moved to the right from the position 2H shown in FIG. The position of 4H is obtained by meshing the second coupling sleeve 22c meshed with the portion 22b with the 4WD gear portion 22a. Conversely, when switching from the four-wheel drive high mode position (4H) to the two-wheel drive high mode position (2H), the second coupling sleeve 22c is stroked to the left from the 4H position and meshes with the 4WD gear portion 22a. The position of 2H is obtained by meshing the second coupling sleeve 22c being engaged with the 4WD input gear portion 22b.
[0061]
[When drive mode switching control system fails]
When the drive mode switching operation is performed when the drive mode switching control system fails (when the drive mode position sensor 25 fails or when the shift motor 23 stops), in the flowchart of FIG. 7, step S1 → step S2 → step From S3 → step S4 → step S5 (or step S1 → step S2 → step S6) to step S7 → step S8 → step S9, until a stop signal is input in step S9, step S7 → step S8 → Step S9 is repeated, and a rotation operation command is issued to the shift motor 23.
[0062]
Here, for example, if the drive mode position sensor 25 is out of order, the time limit will be exceeded in step S8 without inputting a stop signal in step S9. If the shift motor 23 is in a stop failure, the shift motor 23 remains stopped even if a rotation operation command is issued to the shift motor 23, so that the stop signal is not input in step S9. The time limit will be exceeded.
[0063]
When the time limit is exceeded in step S8, the process proceeds from step S8 to step S12 to step S13. In step S12, the operation of the shift motor 23 is stopped, and in step S13, the motor rotational position is determined. Drive mode switching control is prohibited.
[0064]
Therefore, when the drive mode switching control system fails, even if the drive mode switching operation is performed, only a command to operate the shift motor 23 until the time limit is issued, and then the drive mode switching control is prohibited. The drive mode before operation is maintained as it is. When the drive mode switching control system fails, the warning lamp 28 is turned on or blinked to notify the occupant that a system failure has occurred.
[0065]
[Driving mode switching between 4H-4LO and 2H-4LO]
During a switching operation between the four-wheel drive high mode position (4H) and the four-wheel drive low mode position (4LO) for switching the gear ratio between the high side and the low side, or the two-wheel drive high mode position (2H) At the time of the switching operation between the four-wheel drive low mode position (4LO), the process proceeds from step S1 to step S2 to step S3 in the flowchart of FIG. 7. In step S3, the switching condition 1 (range position condition, vehicle speed condition, It is confirmed whether or not the engine speed condition and the brake operation condition are satisfied. If the condition cannot be confirmed, the flow from step S2 to step S3 is repeated until the switching condition 1 is satisfied.
[0066]
When the switching condition 1 is satisfied in step S3, the A / T oil temperature is detected in step S4, and in the next step S5, the A / T oil temperature detection value and the transmission oil temperature-current value characteristic (FIG. 4). (4)), the current value to be applied to the shift motor 23 is determined, the process proceeds from step S5 to step S7 → step S8 → step S9, and until the stop signal is input in step S9, step S7 → Step S8 → Step S9 is repeated, and a command to rotate the shift motor 23 with a current value determined so as to shift from the drive mode position before the switching operation to the drive mode position after the switching operation is issued.
[0067]
Then, since the drive mode switching control system is normal, the elapsed time from the start of operation of the shift motor 23 reaches the drive mode position after the switching operation within the time limit, and the drive mode position sensor 25 determines from step S9. When the stop signal is output, the process proceeds to step S10. In step S10, the shift motor 23 is stopped, and in the next step S11, the motor rotation position of the shift motor 23 is updated.
[0068]
Therefore, when the drive mode switching control system is normal, the switching operation between the four-wheel drive high mode position (4H) and the four-wheel drive low mode position (4LO) by the drive mode changeover switch 24, or the two-wheel drive high mode position. When switching operation between (2H) and the four-wheel drive low mode position (4LO) is performed, if the switching condition 1 based on the range position condition, the vehicle speed condition, the engine speed condition, and the brake operation condition is satisfied, A / T A current value to be applied to the shift motor 23 is determined according to the oil temperature, and drive mode switching control is executed based on the determined current value.
[0069]
[Drive mode switching action by switching gear ratio]
The automatic transmission 2 is moved to the neutral position (such as switching the drive mode between the four-wheel drive high mode position (4H) and the four-wheel drive low mode position (4LO) for switching the gear ratio between the high side and the low side. N) When the drive mode is switched under the switching condition, since the friction engagement element in the automatic transmission 2 is released, the engine driving force is theoretically applied from the automatic transmission 2 to the transfer 4. Although not transmitted, in actuality, the residual hydraulic oil in the automatic transmission 2 transmits torque (= dragging torque) due to plate dragging of the multi-plate clutch or the like to the transfer 4, and the automatic transmission 2 is mainly caused by this dragging torque. The switching operation torque required for switching the high gear-low gear switching mechanism 21 of the transfer 4 varies depending on the magnitude of the friction torque.
[0070]
Conventionally, when the drive mode is switched, a constant current value is applied to the shift motor, so when a high current value is set so that the high-low switching operation can be performed even with the maximum friction torque of the automatic transmission, When the A / T oil temperature is low and the friction torque is low, the current value is wasted and the fuel consumption is deteriorated. On the other hand, when the current value is set to be low so that the current value is not wasted, for example, when driving in a cold region where the A / T oil temperature is low, the switching operation is performed based on the friction torque of the automatic transmission. The torque becomes low, and the switching operation of the high gear-low gear switching mechanism cannot be secured.
[0071]
On the other hand, in the first embodiment apparatus, when a switching operation between 4H and 4LO that requires a switching operation of the high gear-low gear switching mechanism 21 or a switching operation between 2H and 4LO is performed, When the switching condition 1 based on the range position condition, the vehicle speed condition, the engine speed condition, and the brake operation condition is satisfied, the current value to be applied to the shift motor 23 is determined according to the A / T oil temperature, and the drive mode is determined by the determined current value. Since the switching control of the automatic transmission 2 is executed, it is possible to ensure both reliable switching operation and improved fuel consumption by reducing power consumption in the shift motor 23 regardless of the friction torque of the automatic transmission 2. Can do.
[0072]
Here, the reason why the engine speed was changed from 350 rpm to 1600 rpm as the engine speed condition will be described. First, since the gears are rotating relative to each other before being engaged by dragging the multi-plate clutch or the like in the automatic transmission 2, a structure that facilitates engagement is formed by forming an oblique tooth surface shape at the engagement start portion of the two gears that are engaged with each other. is doing. However, if the engine speed is lower than 350 rpm, it will be in an excessively stopped state in which the relative rotation hardly occurs. For example, when the tooth tops face each other, it is difficult to mesh the two gears. It depends. Further, when the engine speed is higher than 1600 rpm, the relative rotation becomes too large, and it becomes difficult to engage the two gears. In other words, the reason why the engine speed is set to 350 rpm to 1600 rpm is to surely achieve smooth two-gear engagement operation.
[0073]
[Transmission oil temperature-current value characteristics setting]
In step S5 of the flowchart of FIG. 7, the current value to be applied to the shift motor 23 is determined based on the A / T oil temperature detection value and the transmission oil temperature-current value characteristic. A description will be given of how to set the transmission oil temperature-current value characteristic indicated by ▼.
[0074]
First, looking at the relationship between the friction torque, current value, and switching response time of the automatic transmission 2, as shown in FIG. 8 (1), if the friction torque upper limit value obtained by experiments or the like is defined as a constant value, The switching response time is shorter as the current value is higher, and is longer as the current value is lower. Therefore, the point at which the maximum current value (5.0 A) characteristic and the friction torque upper limit characteristic intersect is set as the switching response time upper limit. The upper limit value of the switching response time is a time required for switching the driving mode when the oil temperature is extremely low and the maximum current is applied to the shift motor 23.
[0075]
Further, when the relationship between the impact load (shift shock) due to the gear meshing operation at the time of switching the drive mode and the switching response time is seen, as shown in FIG. 8 (2), the impact load is larger as the switching response time is shorter, The longer the switching response time, the smaller the impact load. Therefore, the impact load upper limit value is defined by a constant value, and the point at which the impact load characteristic and the impact load upper limit value intersect is defined as the switching response time lower limit value. This switching response time lower limit value is the minimum switching response time for suppressing the impact load to the upper limit value.
[0076]
Therefore, the time from the switching response time lower limit determined by the impact load to the switching response time upper limit determined by the friction torque and current value is set as the switching response time target value (for example, about 1 second). To do.
[0077]
On the other hand, as shown in FIG. 8 (3), the relationship between the A / T oil temperature and the friction torque of the automatic transmission 2 is such that the lower the A / T oil temperature, the higher the friction torque. The higher the oil temperature, the lower the friction torque.
[0078]
As described above, the switching response time target value is set in advance, the A / T oil temperature is used as friction torque estimation information, and the actual switching response time is determined to be the switching response time target value. 8 is a relationship characteristic of A / T oil temperature-current value shown in (4). By using this A / T oil temperature-current value relationship characteristic, when the drive mode is switched, the friction torque of the automatic transmission 2 is accurately estimated, and the maximum switching operation torque is required while keeping the impact load small. The switching operation can be ensured also in
The A / T oil temperature-current value relationship characteristic is not limited to the linear characteristic shown by the straight line in FIG. 8 (4), but is a combination characteristic of a linear characteristic and an inclined line characteristic, a stepped characteristic, and a nonlinear characteristic. Or the like.
[0079]
Next, the effect will be described.
In the transfer drive mode switching control apparatus of the first embodiment, the effects listed below can be obtained.
[0080]
(1) A high gear-low gear that is disposed at a position between the automatic transmission 2 and each of the wheels 9, 10, 15, 16 and can switch between a high mode position with a high gear ratio and a low mode position with a low gear ratio. Switching of the drive mode position when the transfer 4 having the switching mechanism 21 and the drive mode are switched by the operation of the driver and satisfying a predetermined switching condition including the condition that the automatic transmission 2 is in the neutral range position. In a transfer drive mode switching control device comprising a transfer control unit 26 for outputting an operation command to the shift actuator, friction torque estimating means for estimating the friction torque when the automatic transmission 2 is set to the neutral range position. The transfer control unit 26 has a high mode position and a low mode position. At the time of switching between the mode positions, the switching operation torque commanded to the shift actuator is set by a variable torque corresponding to the estimated friction torque, so that the automatic transmission 2 does not depend on the friction torque magnitude. Thus, it is possible to achieve both of ensuring a reliable switching operation and improving fuel efficiency by reducing energy consumption in the shift actuator.
[0081]
(2) Since the friction torque estimation means estimates that the friction torque is larger as the oil temperature detected by the oil temperature sensor 39 that detects the hydraulic oil temperature of the automatic transmission 2 is lower, the drag torque of the friction engagement element It is possible to accurately estimate the friction torque caused mainly by the hydraulic oil temperature of the automatic transmission 2.
[0082]
(3) The transfer control unit 26 sets the switching response time target value in advance, and sets it according to the relational characteristic between the friction torque and the switching operation torque determined so that the actual switching response time becomes the switching response time target value. Since the switching operation torque setting unit is provided, when the drive mode is switched, the switching response time based on the target value can be obtained almost regardless of the magnitude of the friction torque.
[0083]
(4) The switching operation torque setting unit includes a switching response time upper limit value determined by the friction torque upper limit value and the maximum switching operation torque of the automatic transmission, and a switching response time lower limit value determined by the impact load upper limit value at the time of switching. Since the time between and is set as the switching response time target value, the switching operation can be ensured even when the maximum switching operation torque is required while suppressing the impact load to a small value.
[0084]
(5) The transfer 4 is a high gear-low gear switch for switching between a two-wheel drive high mode position (2H), a four-wheel drive high mode position (4H), a neutral position (N), and a four-wheel drive low mode position (4LO). A mechanism 21 and a 2WD-4WD switching mechanism 22; the transfer control unit 26 has a range position condition in which the automatic transmission 2 is in a neutral range position and a wheel position during a switching operation between a high mode position and a low mode position. The oil temperature sensor 39 changes the speed when the vehicle speed condition that the speed is 0 km / h, the engine speed condition that the engine speed is 350 to 1600 rpm, and the brake condition that the brake is operating are all satisfied. The machine oil temperature is detected and applied to the shift motor 23 based on the transmission oil temperature detection value and the transmission oil temperature-current value characteristic. Regardless of the magnitude of the friction torque of the automatic transmission 2 estimated by the transmission oil temperature in order to determine the flow value, ensuring a reliable switching operation and improving the fuel consumption by reducing the power consumption in the shift motor 23, Both can be achieved.
[0085]
The transfer drive mode switching control device according to the present invention has been described based on the first embodiment. However, the specific configuration is not limited to the first embodiment, and each claim of the claims is described below. Design changes and additions are permitted without departing from the spirit of the invention according to the paragraph.
[0086]
For example, in the first embodiment, as a transfer, a high gear that switches between a two-wheel drive high mode position (2H), a four-wheel drive high mode position (4H), a neutral position (N), and a four-wheel drive low mode position (4LO). -Although the example which has a low gear switching mechanism and 2WD-4WD switching mechanism was shown, if it is a transfer which switches a high gear and a low gear, it will not be limited to the thing of an Example description.
[0087]
In the first embodiment, as the friction torque estimating means, an example of means for estimating based on the hydraulic oil temperature of the automatic transmission is shown. However, the friction torque is estimated by providing a torque sensor on the output shaft of the automatic transmission. Alternatively, the value estimated based on the hydraulic oil temperature of the automatic transmission may be obtained by correcting it with the engine torque or the transmission input torque.
[0088]
In the first embodiment, the example of prohibiting the switching of the drive mode after the failure diagnosis of the drive mode switching control system has been shown. However, among the failures of the drive mode switching control system, the shift is caused by the failure of the drive mode position sensor. When the actuator is normal, only switching between the two-wheel drive high mode position (2H) and the four-wheel drive low mode position (4LO) corresponding to both end positions where the operation stops mechanically may be permitted. .
[Brief description of the drawings]
FIG. 1 is an overall system diagram showing a transfer drive mode switching control apparatus according to a first embodiment;
FIG. 2 is a cross-sectional view showing a transfer to which the drive mode switching control device of the first embodiment is applied.
FIG. 3 is a development view of a cylindrical cam employed in a transfer in the first embodiment device.
FIG. 4 is a schematic diagram showing a drive mode position sensor of the first embodiment apparatus.
FIG. 5 is a diagram showing each signal pattern of a shift actuator position switch with respect to a cylindrical cam rotation angle of a drive mode position sensor of the first embodiment device.
FIG. 6 is a diagram illustrating a correspondence relationship between drive mode changeover switch operation determination and each signal pattern of a shift actuator position switch in the first embodiment apparatus;
FIG. 7 is a flowchart showing a flow of a drive mode switching control process executed by a transfer control unit in the first embodiment apparatus.
FIG. 8 is an explanatory diagram of a transmission oil temperature-current value characteristic setting method in the first embodiment device;
[Explanation of symbols]
1 engine
2 Automatic transmission
3 Automatic transmission output shaft
4 Transfer
20 Drive transmission chain
21 High gear-low gear switching mechanism
21i 1st pin
22 2WD-4WD switching mechanism
22f 2nd pin
23 Shift motor (shift actuator)
23a Shift motor output shaft
24 Drive mode switch
25 Drive mode position sensor
26 Transfer control unit (drive mode switching control means)
40 transfer case
41 Transfer input shaft
42 Transfer rear output shaft
43 Input side chain sprocket
44 Output side chain sprocket
45 Transfer front output shaft
46 Slide axis
47 Cylindrical camshaft
48 Cylindrical cam
48a High gear-low gear cam groove
48b 2WD-4WD cam groove
2H Two-wheel drive high mode position
4H 4-wheel drive high mode position
N Neutral position
4LO 4 wheel drive low mode position

Claims (4)

A transfer having a high gear-low gear switching mechanism that is disposed at a position between the automatic transmission and the wheels and capable of switching between a high mode position with a high gear ratio and a low mode position with a low gear ratio;
Drive that outputs a drive mode position switching operation command to the shift actuator when the drive mode is switched by the driver's operation and satisfies a predetermined switching condition including a condition that the automatic transmission is in the neutral range position. Mode switching control means;
In the drive mode switching control device of the transfer provided with
Friction torque estimating means for estimating the friction torque when the automatic transmission is in the neutral range position is provided,
The drive mode switching control means sets a switching operation torque commanded to the shift actuator at the time of switching between the high mode position and the low mode position by a variable torque according to the estimated friction torque , It has a switching operation torque setting unit that sets a switching response time target value in advance and sets the actual switching response time according to the relational characteristic between the friction torque and the switching operation torque determined so as to become the switching response time target value. A transfer drive mode switching control device. In the transfer drive mode switching control device according to claim 1,
The transfer drive mode switching control device according to claim 1, wherein the friction torque estimating means estimates that the friction torque is larger as the oil temperature detected by the oil temperature sensor for detecting the hydraulic oil temperature of the automatic transmission is lower. In the transfer drive mode switching control device according to claim 1 or 2 ,
The switching operation torque setting unit includes a switching response time upper limit value determined by a friction torque upper limit value and a maximum switching operation torque of the automatic transmission, and a switching response time lower limit value determined by an impact load upper limit value at the time of switching. A drive mode switching control device for a transfer, characterized in that a time between them is set as a switching response time target value. In the transfer drive mode switching control device according to any one of claims 1 to 3 ,
The transfer has a high gear-low gear switching mechanism and a 2WD-4WD switching mechanism for switching between a two-wheel drive high mode position, a four-wheel drive high mode position, a neutral position, and a four-wheel drive low mode position,
The drive mode switching control means includes a range position condition in which the automatic transmission is in the neutral range position, a vehicle speed condition in which the wheel speed is 0 km / h, and engine rotation during a switching operation between the high mode position and the low mode position. When satisfying all the switching conditions of the engine speed condition from 350 rpm to 1600 rpm and the brake operation condition that the brake is in operation, the transmission oil temperature is detected by the oil temperature sensor, the transmission oil temperature detection value and the transmission oil A transfer drive mode switching control device for determining a current value to be applied to a shift motor based on a temperature-current value characteristic.

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