JPH0697066B2 - Reverse shift control method for automatic transmission for vehicle - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control method for an automatic transmission used in a vehicle such as an automobile, and in particular, it has two reverse shift stages, a high-speed reverse stage and a low-speed reverse stage. The present invention relates to a reverse shift control method for an automatic transmission for a vehicle.

2. Description of the Related Art An automatic transmission for a vehicle, which has a low-speed reverse gear and a high-speed reverse gear and is configured such that the reverse gear can be switched between these two reverse gears, is disclosed in Japanese Patent Laid-Open No. 57-37140. Has been done. In the automatic transmission for a vehicle described in this patent publication, a main gear transmission including two sets of planetary gear mechanisms and a friction engagement device such as a clutch and a brake is selected as the friction engagement device. Mechanically engaging or disengaging to provide three forward gear ratios and one reverse gear ratio, and a sub-gear transmission having a set of planetary gear mechanism, clutch, and brake provides engagement between the clutch and brake. Two gear ratios are provided by reversing the disengagement, and these main gear transmission and auxiliary gear transmission are connected in series, so that the auxiliary gear transmission is provided for each of the three forward gear ratios by the main gear transmission. By changing the gear ratio of the two gears to two, a total of six forward gears are provided, and by changing the gear ratio of the auxiliary gear transmission to the two gear ratio with respect to the reverse gear ratio of the main gear transmission. Low speed reverse speed and high speed It adapted to provide a Susumudan. Switching between the low speed reverse speed and the high speed reverse speed in this vehicle automatic transmission follows the conventional control mode in the automatic vehicle transmission by this type of gear transmission, and the accelerator pedal depression amount is changed. (Or the throttle opening corresponding to this) As the vehicle speed increases, the upshift from the low-speed reverse gear to the high-speed reverse gear is automatically performed, and the vehicle speed increases in comparison with the accelerator pedal depression amount. As it decreases, a downshift from the high-speed reverse gear to the low-speed reverse gear is automatically performed according to the shift characteristics that are shifted to the low speed side somewhat compared to the characteristics of the accelerator pedal depression amount at the time of upshifting to the vehicle speed so that hysteresis is given It is presumed that the automatic gear shift control is performed in the above manner.

Upshift and downshift of automatic transmission for vehicles are
Generally, as described above, the control is performed based on the comparison between the accelerator pedal depression amount (or the corresponding throttle opening) and the vehicle speed. When the vehicle is stopped, the vehicle is started by depressing the accelerator pedal, and the vehicle speed gradually increases while overcoming the inertia. As the vehicle speed increases beyond the predetermined limit value for the same accelerator pedal depression amount, an upshift to a higher speed stage is performed sequentially, and the vehicle speed limit value is In general, the higher the accelerator pedal depression amount, the higher the value.Therefore, the vehicle speed is on the horizontal axis, and the accelerator pedal depression amount or throttle opening is on the vertical axis. If shown, it is generally represented as a rising line. The downshift limit line for switching the gear transmission from the high speed stage to the low speed stage is usually a line obtained by slightly shifting the rough upshift limit line to the low vehicle speed side.

As described above, in the forward driving of the vehicle, the limit of upshift and downshift in the graph in which the horizontal axis is the vehicle speed and the vertical axis is the depression amount of the accelerator pedal or the throttle opening degree as described above. The line is a line that rises to the right as a whole, and in a state where the vehicle speed gradually increases even if the accelerator pedal depression amount is relatively small, that is, in a flat and smooth or extremely gentle downward slope. When the vehicle speed gradually increases with a small depression of the accelerator pedal, such as when the vehicle is slowly starting, the gear transmission is upshifted to the next gear when the vehicle speed increases slightly. Often, this allows the engine speed to be kept to the required minimum, improving fuel economy and reducing operating noise.

However, when driving a vehicle in reverse, the attention to the rear of the vehicle is not fully reached, and for many drivers, steering in reverse is generally not as easy as in forward, so the accelerator pedal is relatively small. The situation in which the vehicle gradually increases in reverse speed due to depression, that is, the road surface is flat and smooth, or the vehicle gently inclines rearward, and the engine is slightly accelerated from the idle state due to a light depression of the accelerator pedal. In a situation where the vehicle gradually increases its speed in the rearward state, the gear transmission automatically changes to the low speed reverse drive stage due to the increase in the reverse drive speed even if the accelerator pedal depression amount is constant. When switching to a higher-speed reverse gear, the effect of engine braking when the accelerator pedal is released is reduced due to the reduction in the reduction ratio, and therefore the driver reverses. Also to stop the depression of the accelerator pedal in an attempt to finish, vehicle and there is a possibility that the situation too much down to the rear takes place against the will of the driver.

Therefore, when the vehicle is moved backward on a flat and smooth road surface or on a gentle rear slope that will increase the vehicle speed even if the engine output is not increased much by lightly pressing down the accelerator pedal, immediately when the accelerator pedal is released. It is desired that the gear transmission remains in the low speed reverse gear stage so that the engine brake works.

In view of the above circumstances, the present invention automatically switches the gear transmission from a low speed reverse speed to a high speed reverse speed in response to an increase in vehicle speed during reverse operation performed by depressing the accelerator pedal relatively widely, but it is flat and smooth. When the vehicle can be operated in reverse even on a rough road surface or on a gentle downslope without increasing the engine output so much, it is possible to use a vehicle automatic transmission that allows reverse operation with good engine braking when the accelerator pedal is stopped. An object is to provide a method for reverse shift control.

Means for Solving the Problems According to the present invention, there is provided a reverse shift control method for an automatic transmission for a vehicle having a low-speed reverse gear and a high-speed reverse gear, in which the accelerator pedal depression amount and the vehicle speed are changed. Accordingly, the low speed reverse gear and the high speed reverse gear are automatically switched,
At that time, when the accelerator pedal depression amount is less than or equal to the first depression amount, and when the vehicle speed increases beyond the relatively high first vehicle speed, an upshift from the low speed reverse gear to the high speed reverse gear is performed. , When the accelerator pedal depression amount is between the first depression amount and a second depression amount that is larger than the first depression amount, when the vehicle speed increases beyond a predetermined vehicle speed lower than the first vehicle speed This is achieved by a method characterized by performing an upshift to a high speed reverse gear.

EFFECTS AND EFFECTS OF THE INVENTION According to the reverse shift control method for an automatic transmission for a vehicle as described above, the driver removes his / her foot from the brake pedal and depresses the accelerator pedal lightly so that the vehicle can be used on a flat and smooth road surface or on a gentle rear slope. When the vehicle is moved backward, even if the vehicle speed is increased to some extent after the vehicle is started, the gear transmission is maintained in the low speed reverse speed state, and the accelerator pedal is released to prevent the accelerator pedal from rushing. The vehicle is braked by the engine braking effect without any change from the brake pedal to the brake pedal, so that a comfortable reverse drive operation is performed. On the other hand, when the accelerator pedal is depressed with a magnitude exceeding the above first depression amount, the gear transmission automatically shifts from the low speed reverse gear to the high speed reverse gear at a relatively early timing as the reverse speed of the vehicle increases. It is possible to avoid the generation of noise that has been generated when the vehicle is reversely driven at a high speed.

Example Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 schematically shows the structure of a general automatic transmission for a vehicle. The automatic transmission 1 includes a three-element one-stage two-phase general hydraulic clutch-equipped direct torque clutch 2 having a pump impeller 3, a turbine impeller 4, a stator impeller 5, and a direct coupling clutch 6, and an auxiliary transmission device. A pump impeller 3 which is an input member of the fluid torque converter 3 and is connected to an output shaft 101 of the internal combustion engine 100, and a turbine blade which is an output member of the fluid torque converter 2. The vehicle 4 is drivingly connected to an input shaft 9 of a gear transmission 7, and an output shaft 8 of the gear transmission 7 is drivingly connected to a drive wheel (not shown) of the vehicle via a differential gear unit.

The gear transmission 7 includes a sub gear transmission 10 and a main gear transmission 11
And are in series with each other.

The sub gear transmission 10 includes a sun gear 12, a ring gear 13 concentric with the sun gear 12, a sun gear 12, and a ring gear.
Planetary pinion between 13 and meshed with both
14, a carrier 15 that rotatably supports the planetary pinion 14, a one-way clutch (F ₀ ) 16 that blocks the left rotation of the carrier 15 with respect to the sun gear 12, and an OD clutch that selectively connects the sun gear 12 and the carrier 15. (C ₀ ) 17 and
Includes an OD brake (B ₀ ) 18 that selectively locks the sun gear 12 to the transmission case,
15 is drivingly connected to the input shaft 9, and is selectively engaged between the OD clutch 17 and the OD brake 18 so that the gear can be switched between two shift speeds.

The main gear transmission 11 includes a front sun gear 20 and a rear sun gear 21 that are connected to each other by an intermediate shaft 19, and a front ring gear 22 that is provided concentrically with the front sun gear 20.
And a rear ring gear provided concentrically with the rear sun gear 21
23, a front planetary pinion 24 between the front sun gear 20 and the front ring gear 22 and meshing with them, a rear planetary pinion 25 between the rear sun gear 21 and the rear ring gear 23 and meshing with both, and a front planetary gear. A front carrier 26 that rotatably supports a pinion 24, a rear carrier 27 that rotatably supports a rear planetary pinion 25, a front ring gear 22 that is an input member for forward traveling of the main gear transmission 11, and a sub gear transmission. Forward clutch (C ₁ ) 28 that selectively connects to the ring gear 13 that is the output member of 10 in a torque transmission relationship
And a direct clutch (C ₂ ) 29 for selectively connecting the intermediate shaft 19 and the ring gear 13 in a torque transmission relationship, and the intermediate shaft 19
Shift brake (B ₁ ) 30 that selectively locks the rear carrier 27 to the transmission case, another shift brake (B ₂ ) 31 that selectively locks the rear carrier 27 to the transmission case, and the rear carrier 27 It has a one-way clutch (F ₁ ) 32 for locking left rotation, and a front carrier 26 and a rear ring gear 23 are drivingly connected to the output shaft 8, and the plurality of clutches and the plurality of brakes are respectively provided. By engaging and disengaging in a predetermined combination, the gears can be switched between a plurality of shift stages of three forward gears and one reverse gear.

The gear transmission 7 includes a sub gear transmission 10 and a main gear transmission 11
The plurality of clutches and the plurality of brakes are engaged and disengaged according to the table shown below, so that the auxiliary gear transmission 10 and the main gear transmission 11 cooperate with each other to move forward including an overdrive stage. A plurality of shift speeds, five speeds and two reverse speeds, are selectively achieved. In this case, when the main gear transmission 11 is in the reverse gear state and the auxiliary gear transmission 10 is switched between the direct coupling gear and the speed increasing gear, the low speed reverse gear and the high speed reverse gear are selectively obtained.

In this table, a circle indicates that the clutch or brake is engaged, a cross indicates that the clutch or brake is released, and a triangle indicates that the one-way clutch is on the internal combustion engine side. It is shown that it is engaged (locked) when the engine is driven to drive the drive wheels, and released (free) when the engine is braked when the internal combustion engine is driven from the drive wheel side.

In the L range, the upshift to the second speed is not performed, and only the downshift from the second speed to the first speed is performed.

Clutch 17, 2 of auxiliary gear transmission 10 and main gear transmission 11
8, 29 and the brakes 18, 30, 31 are hydraulically actuated ones that are driven by a hydraulic servo device to selectively engage and operate, and a hydraulic control device that controls the supply and discharge of hydraulic pressure to and from the hydraulic servo device. Under the control of an electronic control unit including a microcomputer for instructing switching of an oil passage of the hydraulic control unit, the clutch and the brake are operated according to a shift pattern determined according to a vehicle speed and a throttle opening for each manual shift range. The gear stage of the gear transmission 7 is switched and set by engaging and disengaging in the combination as described above.

FIG. 2 shows an embodiment of a control device used for carrying out the reverse shift control method according to the present invention. The control device includes an overdrive control valve 40 that controls switching of the auxiliary gear transmission 10 between the direct connection stage and the speed increasing stage. The overdrive control valve 40 is switched according to the oil pressure supplied to the oil chamber 41, and is located at the first switching position when the oil pressure in the oil chamber 41 is below a predetermined value, and the oil pressure supply port a is connected to the clutch port. c
And the drain port b is connected to the brake port d, and when the hydraulic pressure larger than a predetermined value is being supplied to the oil chamber 41, the hydraulic pressure supply port a is located at the second switching position. And the drain port b is connected to the clutch port c. The clutch port c is connected by an oil passage 42 to the oil chamber 43 of the hydraulic servo device of the OD clutch 17, and the port d is connected by an oil passage 44.
The OD brake 18 is communicatively connected to the oil chamber 45 of the hydraulic servo device. The hydraulic pressure supply port a is connected to the line hydraulic pressure output port of the line hydraulic pressure control valve 60 via the oil passages 46 and 47, and the line hydraulic pressure is supplied from this.

The oil chamber 41 of the overdrive control valve 40 includes an oil passage 48, a throttle 49,
It is connected to the line hydraulic pressure output port of the line hydraulic pressure control valve 60 via oil passages 50 and 47. The oil passage 48 is connected to an electromagnetic solenoid valve 51 on the way, and the electromagnetic solenoid valve 51 is opened when energized to connect the oil passage 48 to the drain passage 52. The passage 48 is separated by a drain passage 52.

As a result, when the electromagnetic solenoid valve 51 is energized, the overdrive control valve 40 is located at the first switching position, the line hydraulic pressure is supplied to the oil chamber 43 at the hydraulic servo position of the OD clutch 17, and the auxiliary gear The transmission 10 is set to direct connection,
On the other hand, when the electromagnetic solenoid valve 51 is not energized, the overdrive control valve 40 is located at the second switching position, the line hydraulic pressure is supplied to the oil chamber 45 of the hydraulic servo device of the OD brake 18, and the auxiliary pressure is reduced. The gear transmission 10 is set to the speed increasing stage.

The line hydraulic control valve 60 connects its hydraulic intake port to the oil passage 61.
Is connected to the oil pump 62, and the oil pressure is supplied from the oil pump 62 to regulate the oil pressure to a line oil pressure that matches the vehicle speed and the engine output (depression amount of the accelerator pedal).

The hydraulic output port of the line hydraulic control valve 60 is connected to the manual shift valve 64 by an oil passage 63. The manual shift valve 64 is switched by operating a manual manual shift range setting lever (not shown), and when the manual shift range is set to the R range, that is, the reverse range, the oil passages 65 and 66, the check valves 67 and The line hydraulic pressure is supplied to the oil chamber 69 of the hydraulic servo device of the direct clutch 29 via the oil passage 68, and the oil of the hydraulic servo device of the shift brake 31 is supplied via the oil passage 65, the oil passage 70, the check valve 71 and the oil passage 72. The line hydraulic pressure is supplied to the chamber 73 to set the main gear transmission 11 to the reverse gear.

Energization of the electromagnetic solenoid valve 51 is performed by the electronic control unit 80. The electronic control unit 80 includes a general microcomputer, and the internal combustion control information, which is information equivalent to the amount of depression of the accelerator pedal from the throttle opening sensor 82, is related to the manual shift range manually set by the shift position sensor 81. Information about the opening degree of the throttle valve of the engine 100, information about the vehicle speed is given from the vehicle speed sensor 83, and a shift pattern corresponding to each manual shift range is stored in a storage device such as a ROM. The energization of the electromagnetic solenoid valve 51 is controlled according to the information from each sensor and the shift pattern.

FIG. 3 is a shift diagram showing one embodiment of the shift pattern of the reverse gear for carrying out the reverse gear shift control method according to the present invention. The solid line in the illustrated graph shows the limit of upshifting from the low speed for reverse to the high speed for reverse in the graph with the vehicle speed on the horizontal axis and the slot opening on the vertical axis. The broken line in the middle shows the limit line where the downshift from the high speed gear for reverse drive to the low gear for reverse drive is performed. As shown in this figure, when the throttle opening is equal to or less than a relatively small _first depression amount such as Θ ₁ , the low-speed reverse gear is not reached until the vehicle speed increases beyond a relatively high _first vehicle speed such as V _1. When an upshift to a higher reverse speed is performed and the accelerator pedal depression amount is between the first depression amount Θ ₁ and the larger second depression amount Θ ₂ , the vehicle speed is the first vehicle speed V _An upshift limit line that defines the vehicle speed that increases in response to an increase in the throttle opening so that when the vehicle speed increases beyond a prescribed vehicle speed lower than ₁ , an upshift from the low speed for reverse drive to the high speed for reverse drive is performed. Is set. In the illustrated embodiment, when the throttle opening is Θ ₂ or more, the vehicle speed at which the upshift occurs is higher than V ₁ . As shown in the figure, the limit line for downshift is a line that is a little shifted from the limit line for upshift to the low vehicle speed side. Is given.

FIG. 4 is a flow chart showing an example of an implementation point of the reverse shift control method according to the present invention.

The routine of the flowchart shown in FIG. 4 is repeatedly executed every predetermined time or every predetermined crank angle.

In step 1, information from each sensor and switch is input. After step 1, the process proceeds to step 2.

In step 2, it is determined whether the manual shift range is the forward range such as the D range, the S range or the L range. When the manual shift range is the forward range, the process proceeds to a forward control step (not shown), while when the manual shift range is not the forward range, the process proceeds to step 3.

In step 3, it is determined whether or not the manual shift range is the R range. When the manual shift range is the R range, the routine proceeds to step 4, while when the manual shift range is not the R range, that is, when it is the P range or the N range, the routine proceeds to a neutral control step (not shown).

In step 4, the direct coupling clutch 6 is released, and the process proceeds to the next step 5.

In step 5, it is determined whether or not the current vehicle speed V is lower than the downshift vehicle speed Vdown to the shift stage lower than the current reverse gear for the current throttle opening. When V≤Vdown, it is necessary to shift down. At this time, the process proceeds to step 6, and when V≤Vdown does not occur, the process proceeds to step 7.

In step 6, the electromagnetic solenoid valve 51 is energized to perform a downshift in which the reverse gear is switched to the low speed reverse gear.

In step 7, it is determined whether or not the current vehicle speed V is higher than the upshift vehicle speed Vup for a gear speed higher than the current gear speed with respect to the current throttle opening. V
When it is ≧ Vup, it is time to perform an upshift, and at this time, the process proceeds to step 8, where V ≧ Vu
When it is not p, it is reset when neither downshifting nor upshifting is necessary.

In step 8, an upshift is performed in which the energization of the electromagnetic solenoid valve 51 is stopped and the reverse gear is switched to the high-speed reverse gear.

In the above, the present invention has been described in detail with reference to specific embodiments, but the present invention is not limited to these.
It will be apparent to those skilled in the art that various embodiments are possible within the scope of the invention.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of an automatic transmission for a vehicle in which a reverse shift control method according to the present invention is implemented, and FIG.
FIG. 3 is a schematic configuration diagram showing one embodiment of a control device used for carrying out a reverse shift control method for an automatic transmission for a vehicle according to the present invention, and FIG. 3 is used for carrying out a reverse shift control method according to the present invention. FIG. 4 is a shift diagram showing an example of a reverse shift pattern, and FIG. 4 is a flowchart showing an example of an implementation point of the reverse shift control method according to the present invention. 1 …… Vehicle automatic transmission, 2 …… Fluid torque converter, 3 …… Pump impeller, 4 …… Turbine impeller, 5 …… Stator impeller, 6 …… Direct coupling clutch, 7 …… Gear transmission , 8 ...
Output shaft, 9 Input shaft, 10 Secondary gear transmission, 11 Main gear transmission, 12 Sun gear, 13 Ring gear, 14
… Planetary pinion, 15 …… Carrier, 16 …… One way clutch, 17 …… OD clutch, 18 …… OD brake, 19…
… Intermediate shaft, 20 …… Front sun gear, 21 …… Rear sun gear, 22 …… Front ring gear, 23 …… Rear ring gear, 2
4 …… front planetary pinion, 25 …… rear planetary pinion, 26 …… front carrier, 27 …… rear carrier, 28 …… forward clutch, 29 …… direct clutch, 30, 31 …… shift brake, 32 …… One-way clutch, 40 …… Overdrive control valve, 41 …… Oil chamber, 42 ……
Oil passage, 43 …… Oil chamber, 44 …… Oil passage, 45 …… Oil chamber, 46〜48 …… Oil passage, 49 …… Throttle, 50 …… Oil passage, 51 …… Solenoid solenoid valve, 52
…… Drain passage, 60 …… Line hydraulic control valve, 61 …… Oil passage, 6
2 …… Oil pump, 63 …… Oil passage, 64 …… Manual shift valve, 65, 66 …… Oil passage, 67 …… Check valve, 68 …… Oil passage, 69
…… Oil chamber, 70 …… Oil passage, 71 …… Check valve, 72 …… Oil passage, 73
...... Oil chamber, 80 ...... Electronic control unit, 81 ...... Shift position sensor, 82 …… Throttle opening sensor, 83 …… Vehicle speed sensor, 100 …… Internal combustion engine, 101 …… Output shaft

Claims (1)

[Claims] 1. A backward shift control method for an automatic transmission for a vehicle having a low-speed reverse gear and a high-speed reverse gear, wherein between the low-speed reverse gear and the high-speed reverse gear depending on the accelerator pedal depression amount and the vehicle speed. When the accelerator pedal depression amount is less than or equal to the first depression amount which is relatively small, the vehicle speed is relatively high and the vehicle speed increases beyond the first vehicle speed. When an upshift to a reverse gear is performed and the accelerator pedal depression amount is between the first depression amount and a second depression amount that is larger than the first depression amount, the vehicle speed increases beyond a predetermined vehicle speed that is lower than the first vehicle speed. The method further comprises upshifting from the low speed reverse gear to the high speed reverse gear.