JP5880831B2 - Shift control device for automatic transmission - Google Patents

Description

  The present invention relates to a shift control device for an automatic transmission, and more particularly to a shift control device for quickly and appropriately executing a downshift on an uphill road or a downhill road.

  2. Description of the Related Art In recent years, automatic transmissions that automatically switch gear positions according to the amount of accelerator operation by a driver, vehicle speed, and the like have become widespread not only in passenger cars but also in large vehicles such as trucks and buses. As this type of automatic transmission, for example, an automatic transmission in which a planetary gear mechanism is combined with a torque converter, a continuously variable transmission such as a belt type, or the like, a conventional mechanical manual transmission is used as a base. There is an automatic transmission in which clutch operation associated with operation and shift is automated by an actuator.

In such an automatic transmission based on a manual transmission, a target shift stage is calculated from the accelerator opening and the vehicle speed based on a predetermined shift map during traveling of the vehicle, and an appropriate clutch is applied to achieve the target shift stage. The gear stage of the transmission is switched while connecting and disconnecting. For example, when the vehicle goes from a flat road to an uphill road, the target gear position on the low-speed gear side is calculated from the shift map in accordance with the decrease in vehicle speed, and the vehicle driving force required on the uphill road by downshifting based on the target gear stage Is secured. In addition, when the vehicle moves from a flat road to a downhill road, it is switched to a downhill road shift map on the condition that the downhill road is determined based on the estimation of the road surface gradient or the accelerator operation is stopped, and the target gear position on the low-speed gear side is changed. The engine brake required on the downhill road is ensured by downshifting based on the target shift speed.
On the other hand, there is a technique disclosed in Patent Document 1 as a technique focusing on shift control on an uphill road or a downhill road. The technology of Patent Document 1 relates to a constant speed traveling control device. During constant speed traveling control, for example, when the vehicle reaches an uphill road and the actual vehicle speed decreases and falls below a set vehicle speed by exceeding a predetermined value, the downshift is performed. Is running.

JP 2003-200249 A

  By the way, although depending on the speed of the uphill and downhill roads, the delay of the downshift causes a decrease in vehicle speed and an increase in vehicle speed against the driver's intention. For example, if the downshift is delayed on the uphill road, the vehicle driving force is insufficient on the uphill road, so the vehicle speed decreases, and the vehicle stops when it is severe. Further, if the downshift is delayed on the downhill road, the engine speed is insufficient for the downhill road, the vehicle speed increases, and the driver is forced to operate an extra footbrake.

FIG. 3 is a time chart showing a downshift situation on the uphill road by the shift control based on the shift map of the prior art, and the case of the uphill road will be described in detail below based on this figure.
When the vehicle reaches an uphill road, the vehicle speed V begins to decrease (point a), but the target shift speed cannot be switched as long as it is within the current shift speed range on the shift map. When the vehicle speed V decreases to a predetermined vehicle speed V0 corresponding to the shift-down line on the shift map (point b), the target gear position is switched to the gear position on the low-speed gear side and the engine is shifted down on condition that the engine does not overspeed. Is allowed.

Engine overspeed is determined based on the overrun speed Ne0 set in advance slightly lower than the engine allowable speed. If the engine speed Ne after the downshift is equal to or lower than the overrun speed Ne0, the engine is immediately shifted. Down is allowed. On the other hand, as shown by a broken line in FIG. 3, when the engine speed Ne after the downshift exceeds the overrun speed Ne0, the engine speed Ne decreases with the vehicle speed V and becomes equal to or lower than the overrun speed Ne0. At this point, downshifting is permitted (point c).
When the downshift is permitted, the clutch in the connected state starts to be operated in the disconnection direction, and switching to the target gear position is executed after the disconnection of the clutch is completed (point d). Since the so-called torque loss occurs in which the transmission of the driving force to the driving wheel is interrupted by the clutch disengagement, the vehicle speed decrease after the point c becomes more rapid. After the shift stage is changed, the clutch is controlled in the connecting direction and connected through a half-clutch starting point (point e) (point f). For this reason, the engine rotational speed Ne increases to the value after the downshift, and the vehicle speed V once decreased by the driving force transmission through the shift stage on the low speed gear side is recovered.

As described above, in the shift control based on the conventional shift map, the target shift speed is not switched unless the vehicle enters the uphill road and the vehicle speed V actually decreases (point b), and the target shift speed is switched. In some cases, the downshift is delayed until the condition regarding the engine overspeed is satisfied (point c). Therefore, the period of points a to f is very long from reaching the uphill road until the driving force transmission is resumed due to the completion of the downshift. For this reason, the vehicle speed V is greatly reduced by the completion of the shift and the driving feeling is deteriorated. When the vehicle speed is extremely low, the vehicle may stop (indicated by an arrow in the figure) on the uphill road. .
The same applies to downhill roads. Since the target gear cannot be switched unless the vehicle reaches the downhill road and the vehicle speed V actually increases, the vehicle speed V greatly increases until the downshift is completed, and the running feeling is improved. Getting worse. In some cases, the vehicle speed increases during shifting, and the engine speed Ne after downshifting exceeds the overrun speed Ne0 and cannot be downshifted. Therefore, the driver performs an extra footbrake operation for vehicle deceleration. I will be forced.

The constant speed traveling control device disclosed in Patent Document 1 is also different from the prior art in FIG. 3 in that the shift down is performed based on the decrease in the vehicle speed on the uphill road. there were.
The present invention has been made to solve these problems, and the object of the present invention is to be able to complete a downshift quickly and appropriately on an uphill or downhill road. It is an object of the present invention to provide a shift control device for an automatic transmission that can avoid a deterioration in running feeling due to a significant increase in vehicle speed on a slope.

In order to achieve the above-mentioned object, the invention according to claim 1 is an automatic control system that sets a target shift stage based on a vehicle speed and an accelerator operation amount according to a preset shift map, and shift-controls the automatic transmission of the vehicle based on the target shift stage. In a transmission control device for a transmission, an ascending / descending road judging means and an ascending / descending road judging means for judging whether an uphill road or a downhill road exists within a predetermined distance on the course of the vehicle based on map information When the presence of an uphill road or downhill road is determined, regardless of the target gear position based on the shift map, the target gear position that sets the target gear position on the low-speed gear side before the vehicle reaches the uphill road or downhill road. and setting means, and downshift execution means for executing a downshift based on the target shift stage set by the target shift speed setting means, the presence of an uphill road by uphill-downhill determination means The vehicle deceleration during downshifting on the uphill road is calculated based on the slope of the uphill road obtained from the map information at least before the vehicle reaches the uphill road, and the vehicle deceleration and the target speed change are determined in advance. The vehicle speed reduction amount during downshifting is calculated based on the shift required time set in accordance with the gear position, and the engine speed reduction amount during shifting, which is converted from the vehicle speed reduction amount to the rotational speed based on the gear ratio of the target gear stage, is calculated in advance. And a correction means for correcting the increase by adding to the overrun rotation speed set for preventing the rotation, and the shift down execution means corrects the engine rotation speed after the shift down based on the target shift stage by the correction means. When the overrun speed is exceeded, the shift speed decreases when the engine speed after downshifting decreases with the vehicle speed and falls below the overrun speed. It is intended to run down.

The invention of claim 2 is characterized in that, in claim 1, when the target gear position setting means determines the presence of the uphill road by the uphill / downhill road determination means, the road surface gradient of the uphill road is calculated based on the map information, Based on the road gradient, the target shift speed is set as a shift speed that can secure a driving force that allows the vehicle to travel on the uphill road without significantly reducing the vehicle speed.
The invention of claim 3 is the invention according to claim 2, wherein when the target gear position setting means determines the presence of the downhill road by the uphill / downhill road determination means, the road surface gradient of the downhill road is calculated based on the map information, The target shift stage is set as a shift stage that can secure an engine brake that allows the vehicle to travel without greatly increasing the vehicle speed on a downhill road based on the road gradient.

As described above, according to the shift control device for an automatic transmission of the first aspect of the present invention, when it is determined that an uphill road or a downhill road exists within a predetermined distance on the course of the vehicle based on the map information, the shift map Regardless of the target shift speed based on the above, the target shift speed on the low-speed gear side is set before the vehicle reaches the uphill or downhill road.
In addition, before the vehicle reaches the uphill road, the vehicle deceleration during the downshift on the uphill road is calculated based on the road slope of the uphill road, and the downshift is performed based on the vehicle deceleration and the required shift speed of the target gear stage. The amount of decrease in vehicle speed is calculated by adding the amount of decrease in rotation during conversion, which is converted to rotation speed, to the overrun rotation speed to prevent engine overspeed, and the engine speed after downshifting is Shift shift down is now executed when the overrun speed after the increase correction is reduced.
Even if the engine speed after the downshift is limited at the original overrun speed, the vehicle speed decreases during the downshift on the uphill road, so the rotation is actually limited in a lower speed range. . Since the overrun rotational speed is increased by the amount of decrease in engine rotational speed that occurs during downshifting (rotational speed reduction during shifting), it is possible to limit the engine rotational speed at the time of completion of downshifting to approximately match the overrun rotational speed. For this reason, the start timing of the downshift can be accelerated as much as possible while preventing the engine from over-rotating.

According to the shift control device for an automatic transmission of the invention of claim 2, in addition to claim 1, when the presence of an uphill road is determined, the vehicle speed is greatly reduced based on the road slope of the uphill road calculated from the map information. The target gear position that can be driven without being set is set.
Although it is necessary to set the target shift speed before reaching the uphill road, the optimum target shift speed can be set for the uphill road by using the road surface gradient obtained from the map information as an index.
According to a shift control apparatus for an automatic transmission according to a third aspect of the present invention, in addition to the second aspect, when the presence of a downhill road is determined, the vehicle speed is greatly increased based on the road surface gradient of the downhill road calculated from the map information. The target gear position that can be driven without being set is set.
Although it is necessary to set the target shift speed before reaching the downhill road, the optimum target shift speed can be set for the downhill road by using the road surface gradient obtained from the map information as an index.

1 is an overall configuration diagram showing a track drive system to which a shift control device for an automatic transmission according to an embodiment is applied. It is a time chart which shows the downshift situation on the uphill road by the shift control based on GPS information and map information of 1st and 2nd embodiment. It is a time chart which shows the downshift condition in the uphill road by the shift control based on the shift map of a prior art.

[First Embodiment]
A first embodiment of a shift control apparatus for an automatic transmission embodying the present invention will be described below.
FIG. 1 is an overall configuration diagram showing a track drive system to which a clutch control device for an automatic transmission according to this embodiment is applied.
A vehicle is equipped with a diesel engine (hereinafter referred to as an engine) 1 as a driving power source. An input shaft 3a of an automatic transmission (hereinafter simply referred to as a transmission) 3 is connected to an output shaft 1b of the engine 1 via a clutch device 2. The rotation of the engine 1 is transmitted to the transmission 3 when the clutch device 2 is connected. It has come to be. The transmission 3 is based on a manual transmission having six forward speeds and one reverse speed. As described below, the gear shifting operation and the connecting / disconnecting operation of the clutch device 2 accompanying the gear shifting are automated. It is a thing.

The clutch device 2 is configured as a friction clutch that is connected to the flywheel 4 by press-contacting the clutch plate 5 with a pressure spring 6 and is disconnected by separating the clutch plate 5 from the flywheel 4. An air cylinder 8 is connected to the clutch plate 5 via an outer lever 7, and an air tank 11 filled with compressed air is connected to the air cylinder 8 via an air passage 10 in which an electromagnetic valve 9 is interposed.
When the solenoid valve 9 is opened, compressed air is supplied from the air tank 11 to the air cylinder 8 (shift down execution means) through the air passage 10, and the air cylinder 8 is activated to move the clutch plate 5 through the outer lever 7 to the flywheel. The clutch device 2 is switched from the connected state to the disconnected state. On the other hand, when the solenoid valve 9 is closed, the air cylinder 8 stops operating due to the stop of the supply of compressed air, so that the clutch plate 5 is pressed against the flywheel 4 by the pressure spring 6, and thereby the clutch device 2 is released from the disconnected state. Switch to connected state. As described above, the air cylinder 8 is operated in accordance with the opening and closing of the electromagnetic valve 9 so that the clutch device 2 can be automatically connected and disconnected.

  The transmission 3 is provided with a gear shift unit 14 for switching the gear stage. Although not shown, the gear shift unit 14 (shift down execution means) operates a plurality of shift forks corresponding to the respective gear stages in the transmission 3. Air cylinders and a plurality of solenoid valves for operating the air cylinders. The gear shift unit 14 is connected to the above-described air tank 11 through the air passage 12, and compressed air from the air tank 11 is supplied to the corresponding air cylinder according to opening and closing of each solenoid valve, and the air cylinder is operated. When the corresponding shift fork is switched, the gear position of the transmission 3 is switched according to the switching operation. As described above, the air cylinder is operated in accordance with the opening / closing of the electromagnetic valve of the gear shift unit 14, and the transmission 3 can be automatically operated for shifting.

In the passenger compartment, an input / output device (not shown), a storage device (ROM, RAM, etc.) for storing control programs and control maps, an ECU (control unit) equipped with a central processing unit (CPU), a timer counter, etc. 21 is installed, and comprehensive control of the engine 1, the clutch device 2, and the transmission 3 is performed.
On the input side of the ECU 21 are an engine rotation speed sensor 22 that detects the rotation speed Ne of the engine 1, a clutch rotation speed sensor 23 that detects the rotation speed (clutch rotation speed Nc) of the input shaft 3a of the transmission 3, and a driver's seat. A lever position sensor 24 that detects the switching position of the provided change lever 13, a gear position sensor 25 that detects the gear position of the transmission 3, an accelerator sensor 27 that detects the operation amount Acc of the accelerator pedal 26, and the output of the transmission 3 A vehicle speed sensor 28 provided on the shaft 3b for detecting the output shaft rotation speed Vss (correlating with the vehicle speed V), a brake switch 30 for detecting the operation of the foot brake 29, and a stroke sensor 31 for detecting the clutch stroke ST of the clutch device 2. Sensors such as navigation unit 32 (uphill / downhill road judging means) are connected.
The navigation unit 32 receives a GPS signal from an artificial satellite via the GPS antenna 33, while map information including altitude is stored in advance in a built-in storage device, and the GPS information and map information are stored in the ECU 21. Can be read arbitrarily.

  Further, the electromagnetic valve 9 of the clutch device 2 and the electromagnetic valves of the gear shift unit 14 are connected to the output side of the ECU 21, and the fuel injection valve of the engine 1 is connected (not shown). . In addition, you may make it provide ECU for exclusive use of engine control separately from ECU21, for example, without controlling comprehensively by single ECU21 in this way.

For example, the ECU 21 calculates a fuel injection amount to each cylinder of the engine 1 from a map (not shown) based on the engine rotation speed Ne detected by the engine rotation speed sensor 22 and the accelerator operation amount Acc detected by the accelerator sensor 27. At the same time, the fuel injection timing is calculated from a map (not shown) based on the engine rotational speed Ne and the fuel injection amount. Based on these calculated values, the engine 1 is operated while driving the fuel injection valves of the respective cylinders.
In addition, the ECU 21 stores in advance an overrun rotational speed Ne0 for suppressing excessive rotation of the engine 1. The overrun rotational speed Ne0 is set in advance as a value slightly lower than the allowable rotational speed of the engine 1, and the ECU 21 makes the engine rotational speed Ne unexpectedly due to some factor during the operation of the engine 1. Even if the engine speed increases, the engine speed increase is limited to the overrun speed Ne0 to prevent engine damage due to overspeed.

Further, the ECU 21 executes the automatic transmission mode when the lever position sensor 24 detects that the change lever 13 is switched to the D range, and based on the accelerator operation amount Acc and the vehicle speed V detected by the vehicle speed sensor 28, the ECU 21 The target gear position is calculated from the shift map that is not. Then, while opening and closing the electromagnetic valve 9 of the clutch device 2 and connecting and disconnecting the clutch device 2 by the air cylinder 8, the predetermined electromagnetic valve of the gear shift unit 14 is opened and closed and the corresponding shift fork is switched by the air cylinder. Thus, the shift stage is switched to the target shift stage, and thereby the vehicle is always driven with an appropriate shift stage.
For example, when the vehicle travels from a flat road to an uphill road, the ECU 21 calculates a target gear position on the low-speed gear side from the shift map in accordance with a decrease in the vehicle speed V, and executes a downshift based on the target gear speed to increase the uphill road. The vehicle driving force required in the above is secured. Also, when the vehicle goes from a flat road to a downhill road, switching to a downhill road shift map and setting the target gear position on the low-speed gear side on condition that the downhill road is judged based on the estimation of the road surface gradient or the accelerator operation is stopped. The engine brake required on the downhill road is secured by calculating and executing a downshift based on the target shift speed.

  When the downshift is executed, the engine rotational speed Ne may exceed the overrun rotational speed Ne0. Therefore, the overrun rotational speed Ne0 is applied even during a shift assuming such a case. For example, when downshifting is performed on an uphill road, if it is estimated that the engine speed Ne after the downshift exceeds the overrun speed Ne0, the downshift is prohibited. After that, the engine speed Ne decreases as the vehicle speed decreases on the uphill road, and when the engine speed Ne after the shift down becomes equal to or lower than the overrun speed Ne0, the shift down is permitted. Running downshift.

In the shift control based on the shift map described above, the target shift speed cannot be switched unless the vehicle enters the uphill road or the downhill road and the vehicle speed V actually decreases, and even if the target shift speed is switched, the engine speed cannot be changed. In some cases, the downshift is delayed until the conditions for rotation are met. Therefore, as described in [Problems to be Solved by the Invention], the period from the arrival at the uphill road to the resumption of driving force due to the completion of the shift becomes very long, and various problems such as deterioration of the running feeling, etc. A problem will occur.
The present inventor has noted that the cause of such a problem is that the timing at which the target gear position is switched to the low-speed gear side is late based on the shift map. GPS information and map information at an earlier timing before the vehicle reaches the uphill road or downhill road without being based on the target shift stage obtained from the shift map for downshift on the uphill road or downhill road Based on the above, it was found that recognizing uphill and downhill roads and switching the target shift speed would solve the problem. Hereinafter, the shift control executed by the ECU 21 based on this viewpoint will be described.

While the vehicle is traveling, the ECU 21 sequentially reads GPS information and map information around the vehicle from the navigation unit 32, specifies the current position of the vehicle (own vehicle) on the map, and then on the road on which the current vehicle is traveling. It is determined whether or not an uphill road or a downhill road exists within a predetermined distance (for example, 100 m) (hereinafter referred to as on the course of the vehicle) (uphill / downhill road judging means). When there is no uphill road or downhill road on the course of the vehicle, the vehicle is driven while appropriately switching the gear position of the transmission 3 by shift control based on the shift map as usual.
Then, when the presence of an uphill road or a downhill road is determined on the course of the vehicle, it is obtained from the shift map before the vehicle reaches the uphill road or the downhill road, for example, at a timing a predetermined distance before the arrival timing. The target shift stage of the shift control is switched to the shift stage on the low-speed gear side without being based on the target shift stage (target shift stage setting means).

For this purpose, the ECU 21 estimates the slope of the climbing road on the course of the vehicle based on the altitude information included in the map information, estimates the vehicle weight including the load, and climbs the slope based on the road slope and the vehicle weight. An optimum shift speed for traveling on the road is calculated and set as the target shift speed.
Specifically, for example, in the case of an uphill road, a gear stage that can secure a driving force that can travel without greatly reducing the vehicle speed even when entering the uphill road, and more preferably a driving force that can maintain a substantially constant speed is provided. Calculate as the target gear. Also, in the case of downhill roads, the target gear stage is a gear stage that can secure an engine brake that can travel without significantly increasing the vehicle speed even if it enters the downhill road, and more preferably an engine brake that can maintain a substantially constant speed. calculate. In either case, the shift stage on the low-speed gear side is calculated and set as the target shift stage as compared with the current shift stage on the flat road.

That is, in the shift control based on the shift map, the target shift stage is automatically switched according to the vehicle speed change on the uphill road or downhill road, but in this embodiment in which the target shift stage is set before reaching the uphill road or downhill road. , Need another indicator for setting. Therefore, the road surface gradient obtained from the map information and the vehicle weight are used as indices, thereby setting the optimum target shift stage for the uphill road and downhill road.
The vehicle weight is estimated based on the driving force of the vehicle, the longitudinal acceleration of the vehicle, and the like when the vehicle starts to travel. However, since it is a known estimation method, detailed description thereof is omitted here. .

  As described above, the road surface gradient and the vehicle weight are requirements that directly correlate with the driving force required on the uphill road and the engine brake required on the downhill road. The target shift speed may be calculated in consideration of the length. When the uphill and downhill roads are short, the vehicle speed decreases and the vehicle speed increases little, so it is possible to run even at gears on the high gear side (closer to flat roads) than the original gears on the low speed gear side. Because. Further, in a passenger car or the like, the vehicle weight does not change so much even if the number of passengers increases or decreases, so the target shift speed may be calculated based on only the road surface gradient without considering the vehicle weight.

The timing for switching the target shift speed is set based on the following viewpoints.
As will be described later, there is a case (Ne ≦ Ne0) in which the actual shift stage is switched in the downshifting direction simultaneously with the target shift stage switching. At this time, the low-speed gear side on the flat road before reaching the uphill or downhill road The vehicle will travel at the gear position. For this reason, it is desirable to make the target gear stage switching timing as late as possible from the standpoint of fuel economy, but it is desirable that the shift (shift down) is completed when reaching the uphill road or downhill road.

Therefore, the shift required time for each shift stage is set from a test performed in advance, the shift required time corresponding to the calculated target shift stage is converted into a distance based on the current vehicle speed V, and the preceding distance L is calculated. The target gear stage is switched at the timing when the vehicle reaches a point just before the preceding distance L from the uphill road or downhill road.
Further, the operation of rotation synchronization by the synchro mechanism of the transmission 3 is affected by the oil temperature, and as the oil temperature is lower, the shift required time tends to be prolonged. Therefore, the shift required time according to the oil temperature of the transmission 3 is extended. The preceding distance L may be corrected. However, the timing for switching the target gear stage is not limited to this, and it is sufficient that the target gear stage is switched at least before the vehicle reaches the uphill road or downhill road.

The ECU 21 repeatedly executes the above-described processing related to the change of the target shift stage while the vehicle is traveling. When it is determined that an uphill road or a downhill road is present on the course of the vehicle, the target gear stage is switched and shifted according to the following procedure. Run down.
FIG. 2 is a time chart showing a downshift situation on an uphill road by shift control based on GPS information and map information of the present embodiment.
The figure mainly shows the case where the engine rotational speed Ne after the downshift exceeds the overrun rotational speed Ne0 when the target gear stage is switched, and the engine rotational speed Ne after the downshift is the overrun rotational speed. In the case of Ne0 or less, only the relationship of the engine rotational speed Ne to the road gradient is shown in the second row from the bottom. Hereinafter, the execution state of the downshift will be described in detail with reference to this figure, taking the case of an uphill road as an example.

First, a description will be given of the case where the engine speed Ne after the downshift is equal to or lower than the overrun speed Ne0 when the target gear stage is switched.
When it is determined that an uphill road is present on the course of the vehicle, the target gear stage is switched to the low gear side gear stage at a point just before the preceding distance L from the uphill road, as indicated by a broken line in the figure (point) A). Since the engine speed Ne after the downshift indicated by the broken line is equal to or lower than the overrun speed Ne0, the downshift is immediately permitted and started at this point. Although details are not shown in FIG. 2, the downshift is completed through the disengagement operation of the clutch device 2, the shift gear switching operation, and the clutch device 2 connection operation (shift down execution means). Reach the uphill road (point B).
Therefore, power is transmitted from the beginning when the vehicle enters the uphill road through the shift stage after the downshift, and the vehicle continues running on the uphill road with almost no decrease in vehicle speed, and on the downhill road without significant increase in vehicle speed. Will continue.

Next, the case where the engine speed Ne after the downshift exceeds the overrun speed Ne0 at the time of switching the target gear stage will be described.
When the target shift speed is switched (point A), the engine speed Ne after the downshift indicated by the broken line exceeds the overrun speed Ne0, and therefore the downshift is prohibited at this point. When the vehicle reaches the uphill road (point B), the engine rotational speed Ne gradually decreases together with the vehicle speed V, and accordingly, the engine rotational speed Ne after the downshift also gradually decreases. When the engine speed Ne after downshifting becomes equal to or lower than the overrun speed Ne0, downshifting is permitted (point C), and downshifting is started based on this permission determination.

  First, the clutch device 2 in the connected state starts to be operated in the disconnection direction, and after the disconnection of the clutch device 2 is completed, the gear position is switched to the target gear position (point D). The clutch device 2 starts to be controlled in the connecting direction after the shift speed is changed, and the engine rotational speed Ne gradually increases and matches the value after the downshift (point E). The clutch device 2 is connected through the half-clutch starting point to complete the downshift (point F), the driving force transmission to the driving wheel side is resumed, and the once reduced vehicle speed V is recovered. Therefore, although a slight decrease in the vehicle speed occurs temporarily immediately after the vehicle enters the uphill road, the vehicle speed V quickly increases upon completion of the downshift, and the vehicle travels on the uphill road without causing a large decrease in the vehicle speed. Is done.

As described above, in the prior art shown in FIG. 3, the target shift speed is not switched unless the vehicle speed is reduced due to entry into the uphill road. In this embodiment, the vehicle corresponds to the uphill road before the vehicle reaches the uphill road. To change the target gear. For this reason, when the condition regarding engine overspeed is satisfied at the time of switching of the target gear stage (Ne ≦ Ne0), the downshift has already been completed when the uphill road is reached, and the condition regarding engine overspeed is reached. Even if no is seen (Ne> Ne0), the downshift is completed immediately after entering the uphill road.
Therefore, since the downshift can be completed quickly and appropriately on the uphill road, the period from reaching the uphill road to the resumption of driving force due to the completion of the shift can be greatly shortened. The traveling feeling of the vehicle can be improved by avoiding the stop of the vehicle.

On the other hand, as in the case of the uphill road described above, when it is determined that a downhill road is present on the course of the vehicle, the target gear stage is switched to the low gear side gear stage at a point just before the downhill road by a preceding distance L. . Although the time chart showing the downshift state on the downhill road is not shown, if the engine speed Ne after the downshift is equal to or lower than the overrun speed Ne0 at the time of switching the target shift stage, the downshift is immediately permitted and started. Is done.
Accordingly, the vehicle reaches the downhill road almost simultaneously with the completion of the downshift, and the engine brake is applied from the beginning of entering the downhill road through the shift stage after the downshift. In this way, downshifts can be completed quickly and properly on the downhill road, so that a significant increase in vehicle speed on the downhill road can be avoided in advance and the vehicle's driving feeling can be improved. It is also possible to avoid a situation where the brake operation is forced.

By the way, when the condition regarding the engine overspeed on the uphill road is not observed as described above (Ne> Ne0), the downshift is performed until the engine speed Ne is lowered to the overrun speed Ne0 or less together with the vehicle speed V. Did not start. During the downshift with torque loss, the vehicle speed V decreases due to the uphill road, and when the downshift is completed with the clutch connected, the engine speed Ne is a value corresponding to the decreased vehicle speed V, that is, a value lower than the overrun speed Ne0. It becomes. In this way, the substantial rotation limit at the time of downshifting is performed in a lower rotation range than the original overrun rotation speed Ne0, and this phenomenon can be shifted down more quickly by raising the rotation limit range. It means that there is room.
The inventor increases the overrun rotational speed Ne0 by the amount of decrease in the engine rotational speed Ne that occurs during downshifting (the rotational decrease amount during shift ΔNe described later), and the engine rotational speed Ne at the completion of the downshifting is exceeded. It has been found that it can be limited in accordance with the run rotational speed Ne0. Hereinafter, the shift control of the automatic transmission 3 based on this viewpoint will be described as a second embodiment.

[Second Embodiment]
The overall configuration of the shift control device of the automatic transmission 3 according to this embodiment is the same as that of the first embodiment shown in FIG. 1, and the difference is the overrun rotation speed on the uphill road as described above. Ne0 is set. Therefore, common constituent parts are denoted by the same member numbers, description thereof is omitted, and differences are mainly described.
First, the correction process of the overrun rotational speed Ne0 by the ECU 21 will be described. As described above, the shift required time of each gear stage is set for calculating the preceding distance L, and it is considered that the engine speed Ne is reduced within the required shift time (that is, during downshifting). On the other hand, the deceleration of the vehicle during the downshift differs depending on the road surface gradient and the vehicle weight. The steeper road surface gradient and the greater the vehicle weight, the higher the vehicle deceleration. The amount of decrease in the vehicle speed and the amount of decrease in the engine speed Ne that correlates with the amount of decrease in vehicle speed (hereinafter referred to as the amount of decrease in rotation during shifting ΔNe) increase.

Therefore, when the ECU 21 determines the presence of an uphill road on the course of the vehicle, the ECU 21 calculates the vehicle deceleration during downshifting (torque-out state) on the uphill road based on the road surface gradient of the uphill road and the vehicle weight. The vehicle deceleration is multiplied by the shift required time corresponding to the target shift speed to obtain the vehicle speed reduction amount during the downshift. The vehicle speed reduction amount is converted into the rotation reduction amount ΔNe during the shift based on the gear ratio of the target shift stage, and then added to the overrun rotation speed Ne0 to correct the increase (correction means).
Then, as shown in the lowermost stage in FIG. 2, when the target shift stage is switched to the shift stage on the low-speed gear side at a point just before the preceding distance L from the uphill road, the overrun rotational speed Ne0 is increased and corrected at the same time. (Point A). Initially, the engine speed Ne after the downshift exceeds the overrun speed Ne0, so that the downshift is prohibited. However, after reaching the uphill road, the engine speed Ne after the downshift is less than the overrun speed Ne0. At this point, downshifting is permitted (point C). At this time, the engine speed Ne after the downshift is higher than the original overrun speed Ne0 (before the increase correction), but the engine 1 is not actually rotated up to that speed range, so there is no problem. do not do.

It should be noted that the increase correction of the overrun rotational speed Ne0 does not necessarily have to be performed simultaneously with the switching of the target shift speed, and may be changed to an arbitrary timing at least before the vehicle reaches the uphill road.
A downshift is started based on the permission determination, and the downshift is completed through a disconnection operation of the clutch device 2, a shift speed switching operation, and a connection operation of the clutch device 2. The shift required time elapses from the start to the completion of the shift down, and during that time, the engine speed Ne after the shift down decreases by the rotation decrease amount ΔNe during the shift and substantially coincides with the original overrun rotation speed Ne0. Since the clutch device 2 is connected in this state, the engine rotational speed Ne is suppressed to the original overrun rotational speed Ne0 or less, and the engine 1 is prevented from over-rotating.
Then, by raising the overrun rotational speed Ne0 in this way, the start timing of the downshift is advanced as much as possible (point C). For this reason, the downshift can be completed more quickly on the uphill road, and thus the vehicle traveling feeling can be improved by avoiding a significant decrease in the vehicle speed and the stop of the vehicle on the uphill road.

As described above, in the present embodiment, the overrun rotation speed Ne0 is increased by the rotation decrease amount ΔNe during the shift down, but the present invention is not limited to this and can be arbitrarily changed. However, if the overrun rotational speed Ne0 is increased and corrected to be greater than or equal to the rotation reduction amount ΔNe during the shift, the engine rotational speed Ne after the completion of the shift down exceeds the original overrun rotational speed Ne0, and the engine may be damaged. Therefore, the overrun rotational speed Ne0 is preferably corrected to increase with the rotation reduction amount ΔNe during shifting as the upper limit.
In addition, the increase correction process for the overrun rotational speed Ne0 based on the rotation reduction amount ΔNe during the shift may be simplified. For example, the overrun rotational speed Ne0 may be increased by a predetermined amount when the vehicle deceleration during the downshift is greater than or equal to a predetermined value.

By the way, although the above was demonstrated regarding the uphill road, a merit is acquired by switching overrun rotational speed Ne0 also on a downhill road.
As described above, a significant increase in vehicle speed can be avoided even on a downhill road by downshifting in advance. For example, if the road surface gradient of a downhill road that is running increases, further downshifting is required to suppress the increase in vehicle speed. On downhill roads, even if the downshift is permitted on the assumption that the engine speed Ne after the downshift is equal to or lower than the overrun speed Ne0, after the downshift with the vehicle speed V due to torque loss during the downshift (disappearance of the engine brake). Engine speed Ne may increase rapidly and exceed the overrun speed Ne0. At this time, since it is impossible to shift down and it is returned to the previous shift stage, as a result, only an unnecessary useless shift down is attempted, and only the adverse effect of increasing the vehicle speed during torque loss occurs.
Therefore, on the downhill road, an increase amount of the engine rotational speed Ne generated during the downshift may be calculated, and this rotational increase amount may be subtracted from the overrun rotational speed Ne0 to correct the decrease. Note that the amount of increase in rotation at this time corresponds to the amount of decrease in rotation ΔNe during shifting on the uphill road, and can be calculated by the same procedure. In this way, since downshifting is not permitted from the beginning, the above unnecessary useless downshifting trial is canceled and the running at the current shift stage is continued, and torque loss during downshifting is continued. It is possible to prevent an increase in vehicle speed due to the above.

This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, although applied to a truck in the above embodiment, the present invention is not limited to this and may be applied to a bus or a passenger car.
In the above embodiment, the automatic transmission 3 in which the shift operation and the clutch operation are automated based on the manual transmission is targeted. However, the type of the automatic transmission is not limited to this. For example, the present invention may be applied to a torque converter type automatic transmission provided with a planetary gear mechanism, and in this case as well, the same operation and effect as in the above embodiment can be obtained.

1 Engine 3 Transmission 8 Air cylinder (shift down execution means)
14 Gear shift unit (shift down execution means)
21 ECU (uphill / downhill road judging means, target gear position setting means,
Shift down execution means, correction means)
32 Navigation unit (uphill / downhill road judging means)

Claims (3)

In a shift control device for an automatic transmission that sets a target shift speed based on a vehicle speed and an accelerator operation amount according to a preset shift map and shift-controls an automatic transmission of the vehicle based on the target shift speed,
Uphill / downhill road judging means for judging whether an uphill road or downhill road exists within a predetermined distance on the course of the vehicle based on map information;
When the uphill / downhill road judging means determines the presence of the uphill road or downhill road, the low-speed gear side before the vehicle reaches the uphill road or downhill road regardless of the target shift stage based on the shift map. Target speed setting means for setting the target speed of
Downshift execution means for executing downshift based on the target shift speed set by the target shift speed setting means ;
When the uphill / downhill road judging means determines the presence of the uphill road, at least before the vehicle arrives on the uphill road, based on the road slope of the uphill road obtained from the map information, The vehicle deceleration during the downshift is calculated, the vehicle speed reduction amount during the downshift is calculated based on the vehicle deceleration and the shift required time set in advance corresponding to the target shift stage, and the vehicle speed reduction amount is calculated. Correction means for correcting the increase by adding the amount of rotation reduction during shift converted to the rotation speed based on the gear ratio of the target shift stage to an overrun rotation speed set in advance to prevent engine overspeed;
With
When the engine speed after the downshift based on the target shift speed exceeds the overrun speed after the increase correction by the correction means, the engine speed after the downshift decreases together with the vehicle speed. A shift control means for an automatic transmission , wherein shift downshifting is executed when the overrun rotational speed becomes lower than the above .   The target shift speed setting means calculates the road surface gradient of the uphill road based on the map information when the uphill / downhill road determination means determines the presence of the uphill road, and the vehicle operates based on the road surface gradient. 2. The shift control means for an automatic transmission according to claim 1, wherein the target shift stage is set as a shift stage capable of ensuring a driving force capable of traveling without greatly reducing the vehicle speed on an uphill road.   The target gear position setting means calculates the slope of the downhill road based on the map information when the uphill / downhill road judgment means determines the presence of the downhill road, and the vehicle is operated based on the road slope. 3. The shift control means for an automatic transmission according to claim 2, wherein the target shift stage is set as a shift stage capable of securing an engine brake capable of traveling on a downhill road without greatly increasing the vehicle speed.

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