JP2003200748A - Automatic transmission of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accelerate a vehicle with a good acceleration feeling when engine rotation speed extremely decreases during constant speed running control. <P>SOLUTION: An automatic transmission of the vehicle comprises a constant speed running control means for performing the constant speed running control by controlling a fuel injection quality of an engine to match an actual car speed with a set car speed, and a shift down control means for performing shift down control of the transmission when the engine rotation speed decreases to a rotation speed that does not provide sufficient driving wheel torque in consideration of the driving state of the vehicle during the constant speed running control (Ne<Nes in the step 104). Thanks to this shift down, the engine rotation speed increases, the sufficient driving wheel torque is provided, and the vehicle can be accelerated with the good feeling. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle automatic transmission, and more particularly to a vehicle automatic transmission provided with a constant speed traveling control device (so-called auto cruise system) for realizing constant speed traveling of the vehicle.

[0002]

2. Description of the Related Art Recently, in order to reduce the load on the driver, there are many cases in which an automatic clutch and an automatic transmission are adopted even in a relatively large vehicle such as a tractor or a large truck, and a constant operation without an accelerator operation is performed. There are many examples of equipping a constant-speed traveling control device to realize traveling at high speed.

In the case of executing these cooperative controls, it is preferable to downshift the automatic transmission when the actual vehicle speed is lower than a predetermined value by a driver arbitrarily set by the driver. As a result, even if the drive wheel torque is insufficient on an uphill road and the actual vehicle speed gradually falls below the set vehicle speed, a high drive wheel torque is obtained by downshifting and the vehicle is accelerated to set the actual vehicle speed. It is possible to immediately return to near the vehicle speed.

[0004]

By the way, in recent years,
Even in large vehicles, the reduction gear ratio of the final gear tends to decrease for the purpose of improving fuel efficiency, and the engine speed during constant speed running control (auto cruise) tends to decrease. Therefore, although there is no problem if a high drive wheel torque such as a flat road is not required, when a relatively high drive wheel torque is required when approaching an uphill road or the like, before the shift down vehicle speed condition is satisfied, As the actual vehicle speed decreases, the engine speed decreases significantly, and the control to accelerate the vehicle by forcibly increasing the fuel injection amount to increase the engine torque while maintaining the current gear position is performed. Will be done. In this case, what is called engine knocking occurs, and there is a problem that the acceleration feeling is extremely poor.

Therefore, the present invention was devised in view of the above problems, and an object thereof is to accelerate a vehicle with a good acceleration feeling when the engine speed significantly decreases during constant speed running control. Especially.

[0006]

SUMMARY OF THE INVENTION An automatic transmission apparatus for a vehicle according to the present invention executes constant speed traveling control by controlling a fuel injection amount of an engine so that an actual vehicle speed matches a set vehicle speed. The control means and the shift-down control for executing the shift-down control of the transmission when the engine rotation speed drops to a rotation speed at which sufficient driving wheel torque cannot be obtained in view of the driving condition of the vehicle during the constant-speed traveling control. And a control means.

Here, the downshift control means may execute downshift control of the transmission when the engine speed drops below a predetermined speed slightly higher than the idle speed. .

Further, the downshift control means executes downshift control of the transmission when the fuel injection amount of the engine is a value indicating a state in which the vehicle is being accelerated. May be.

Further, the downshift control means may perform a downshift control of the transmission when the engine speed after downshift is predicted and calculated, and the value is less than a predetermined value. .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an automatic transmission for a vehicle according to this embodiment. Here, the vehicle is a tractor towing a trailer, and the engine 1 is a diesel engine equipped with an electronic governor 1d. As shown, the engine 1
A transmission 3 is attached to the vehicle via a clutch 2, and an output shaft 4 (see FIG. 2) of the transmission 3 is connected to a rear wheel (not shown) which is a driving wheel via a propeller shaft (not shown) or the like. To be done. The engine 1 is an engine control unit (E
It is electronically controlled by the CU) 6. That is, the ECU 6
The target fuel injection amount is calculated according to the map of FIG. 8 based on the values of the engine speed and the accelerator opening detected mainly by the engine rotation sensor 7 and the accelerator opening sensor 8, and is equal to this target fuel injection amount. The electronic governor 1d of the fuel injection pump 1a so that a certain amount of fuel injection is actually performed.
To control.

As shown in FIG. 2, the flywheel 1b is attached to the crankshaft of the engine, and the ring gear 1c is formed on the outer periphery of the flywheel 1b.
The engine rotation sensor 7 outputs a pulse each time the tooth c passes, and the ECU 6 counts the number of pulses per unit time to calculate the engine rotation speed.

As shown in FIG. 1, here, the clutch 2 and the transmission 3 are automatically controlled based on a control signal of a transmission control unit (TMCU) 9.
The ECU 6 and the TMCU 9 are connected to each other via a bus cable or the like and can communicate with each other.

As shown in FIGS. 1, 2, and 3, the clutch 2 is a mechanical friction clutch, and the flywheel 1b on the input side, the driven plate 2a on the output side, and the driven plate 2a are connected to the flywheel 1a. It is composed of a pressure plate 2b which is pressed against or separated from. The clutch 2 operates the pressure plate 2b in the axial direction by the clutch booster 10 and is basically automatically connected / disconnected to reduce the load on the driver. On the other hand, in order to enable delicate clutch work at the time of a slight low speed reverse and quick clutch disconnection in an emergency, manual disconnection / connection by the clutch pedal 11 is also possible here. This is a so-called selective auto clutch configuration. A clutch stroke sensor 14 for detecting the stroke of the clutch itself (that is, the position of the pressure plate 2b) and a clutch pedal stroke sensor 16 for detecting the stepping stroke of the clutch pedal 11 are provided and connected to the TMCU 9.

As shown in FIG. 3, the clutch booster 10
Is connected to the air tank 5 through two lines of pneumatic passages a and b indicated by the solid line, and operates with the air pressure supplied from the air tank 5. One passage a is for automatic clutch connection / disconnection, and the other passage b is for clutch manual connection / disconnection. One passage a
Is bifurcated, one of which is provided with solenoid valves MVC1 and MVC2 for automatic connection and disconnection in series, and the other is provided with an emergency solenoid valve MVCE. A double check valve DCV1 is provided at the branch / merge portion. The other passage b
And a hydraulically operated valve 12 attached to the clutch booster 10.
Is provided. A double check valve DCV2 is also provided at the confluence of both passages a and b. The double check valves DCV1 and DCV2 are differential pressure operated three-way valves.

The solenoid valves MVC1, MVC2 and MVCE
ON / OFF control is performed by TMCU9. When ON, the upstream side communicates with the downstream side, and when OFF, the upstream side is shut off and the downstream side is opened to the atmosphere. First, the automatic side will be explained. Solenoid valve MVC
1 is ON / OFF simply according to ON / OFF of the ignition key
It is only done. Ignition key is OFF, that is, it is OFF when the vehicle is stopped to shut off the air pressure from the air tank 5. The solenoid valve MVC2 is a proportional control valve and can freely control the amount of supplied or discharged air. This is for controlling the connecting / disconnecting speed of the clutch. Solenoid valve MVC1, MVC2
When both are ON, the air pressure of the air tank 5 is supplied to the clutch booster 10 by switching between the double check valves DCV1 and DCV2. This disconnects the clutch. Only MVC2 is OFF when the clutch is connected
As a result, the air pressure of the clutch booster 10 becomes MVC.
2 is discharged and the clutch is connected.

If an abnormality occurs in the solenoid valve MVC1 or MVC2 while the clutch is disengaged and either of them is turned off, the clutch is suddenly engaged against the driver's intention. Therefore, when such an abnormality is detected by the abnormality diagnosis circuit of the TMCU 9, the solenoid valve MVCE is immediately turned on.
Then, the air pressure passing through the solenoid valve MVCE switches the double check valve DCV1 in the opposite direction, and the clutch booster 10
To maintain the disengaged state of the clutch and prevent the clutch from coming into close contact.

Next, the manual side will be described. The master cylinder 1 is operated according to the depression / return operation of the clutch pedal 11.
The hydraulic pressure is supplied to and discharged from 3 and is supplied to the hydraulically operated valve 12 via the hydraulic passage 13a shown by the broken line. As a result, the hydraulically operated valve 12 is opened and closed, and the clutch booster 10 is opened.
The air pressure is supplied to and discharged from, and the clutch 2 is manually connected and disconnected. When the hydraulically actuated valve 12 opens, the air pressure passing therethrough switches the double check valve DCV2 and reaches the clutch booster 10. When the automatic connection and disconnection of the clutch interferes with the manual connection and disconnection, the manual connection and disconnection is prioritized.

As shown in detail in FIG. 2, the transmission 3 is basically a constant mesh type so-called multi-stage transmission, which is capable of shifting to 16 forward gears and 2 reverse gears. Further, the transmission 3 itself has the same structure as the manual transmission. The transmission 3 is provided with a splitter 17 and a range gear 19 as an auxiliary transmission on the input side and the output side, respectively, and a main gear stage 18 between them. Then, the engine power transmitted to the input shaft 15 is sequentially sent to the splitter 17, the main gear stage 18, and the range gear 19 and output to the output shaft 4.

A gear shift unit GSU is provided for automatically shifting the transmission 3, and comprises a splitter actuator 20, a main actuator 21, and a range actuator 22, which are in charge of shifting the splitter 17, the main gear stage 18, and the range gear 19, respectively. . Like the clutch booster 10, these actuators are pneumatically operated and controlled by the TMCU 9. The current gear stage of the transmission 3 is detected by the gear position switch 23 (see FIG. 1). The rotation speed of the counter shaft 32 is detected by the counter shaft rotation sensor 26, and the rotation speed of the output shaft 4 is detected by the output shaft rotation sensor 28. These detection signals are sent to TMCU9.

In this automatic transmission, a manual mode is set, and manual shifting based on a driver's shift change operation is also possible. In this case, as shown in FIG. 1, the engagement / disengagement control of the clutch 2 and the gear shift control of the transmission 3 are performed in response to a signal from a shift lever device 29 provided in the driver's seat. That is, the shift lever device 29 has a built-in shift switch (not shown) that outputs a signal in response to a manual operation of the shift lever 29a. When the driver shifts the shift lever 29a, the signal is sent to the TMCU 9. Based on this, the TMCU 9 appropriately operates the clutch booster 10, the splitter actuator 20, the main actuator 21, and the range actuator 22 to execute a series of gear shift operations. TMC
U9 displays the current gear on the monitor 31. In this way, as far as the manual mode is limited, such an automatic transmission is a remote-operated type manual transmission in which the shift control is performed by the TMCU 9 based on the output signal of the shift switch. That is, the manual transmission is automatically shifted to the driver's instruction stage without using a mechanical connecting means such as a shift cable.

In the shift lever device 29 shown in FIG. 1, R is reverse, N is neutral, D is drive,
UP means upshift, and DOWN means downshift, and when the shift lever 29a is operated to each position, a signal corresponding to those positions is output.
Further, the driver's seat is provided with a mode switch 24 for switching the shift mode between automatic and manual, and a skip switch 25 for switching between shifting one shift at a time and skipping one shift.

In the automatic shift mode, the shift lever 29
If a is set in the D range, the gear shift is automatically performed according to the vehicle speed and the like. Also in this automatic shift mode, manual upshifting or downshifting is possible if the driver operates the shift lever 29a to UP or DOWN. In this automatic speed change mode, if the skip switch 25 is OFF (normal mode), the speed change is performed step by step. This is effective when the load is relatively large, such as when the trailer is towed. Also, the skip switch 25 is turned on.
In the (skip mode), shifting is performed by skipping one gear.
This is effective when the trailer is not towed or when the load is light.

On the other hand, in the manual shift mode, shifting completely complies with the driver's intention. Shift lever 29a
When is in the D range, gear shifting is not performed, the gear is currently held, and the driver is positively willing to shift the shift lever 29a to U.
Only when operated to P or DOWN, shift up or down is performed. Also at this time, similarly to the above, if the skip switch 25 is OFF, the gear shift is performed step by step, and if the skip switch 25 is ON, the gear shift is skipped by one step.

An emergency shift switch 27 is provided in the driver's seat so that when the solenoid valve of the GSU or the like fails, the switch 27 can be manually switched to shift gears.

As shown in FIG. 2, in the transmission 3,
The input shaft 15, the main shaft 33, and the output shaft 4 are arranged coaxially, and the counter shaft 32 is arranged below them in parallel. The input shaft 15 is connected to the driven plate 2 a of the clutch 2, and the input shaft 15 and the main shaft 33 are connected.
And are supported for relative rotation.

First, the configurations of the splitter 17 and the main gear stage 18 will be described. Split high gear SH on input shaft 15
Is rotatably mounted. Also the main shaft 33
Also, from the front, main gears M4, M3, M2, M1,
The MR is rotatably mounted. Gear S excluding MR
H, M4, M3, M2 and M1 are counter gears CH, C4, C3 fixed to the counter shaft 32, respectively.
It is always meshed with C2 and C1. The gear MR is constantly meshed with the idle reverse gear IR, and the idle reverse gear I
R is a counter gear C fixed to the counter shaft 32
Always meshed with R.

.. attached to the input shaft 15 and the main shaft 33 are integrally provided with splines 36 so that the gears can be selected. Adjacent to the splines 36 are the splines 36 and the main shaft 33. Shaft 3
The first to the fourth splines 37 to 40 are fixedly installed at the position 3. The first to fourth sleeves 42 to 45 are provided so as to be always engaged with the first to fourth splines 37 to 40 and slidable in the front-rear direction (shift direction). By appropriately selecting and slidingly moving the first to fourth sleeves 42 to 45, and engaging and disengaging with the gear side spline 36, gear insertion and gear removal can be performed. The splitter actuator 20 moves the first sleeve 42, and the main actuator 21 moves the second to fourth sleeves 43 to 45.

As described above, the splitter 17 and the main gear stage 18 are of a constant mesh type which can be automatically shifted by the actuators 20 and 21. In particular, the spline portion of the splitter 17 has a normal mechanical synchronizing mechanism, but the spline portion of the main gear stage 18 does not have a synchronizing mechanism. For this reason, when the main gear stage 18 is shifted, synchro control is performed to adjust the engine rotation and the gear speed so that they can be synchronized without the synchro mechanism. Here, in addition to the main gear stage 18, the splitter 17 is also provided with a neutral position to prevent so-called rattling noise (see Japanese Patent Application No. 11-319915).

Next, the structure of the range gear 19 will be described. The range gear 19 employs a planetary gear mechanism 34 and can be switched to either a high position or a low position. The planetary gear mechanism 34 includes a sun gear 65 fixed to the rear end of the main shaft 33, a plurality of planetary gears 66 meshed with the outer periphery of the sun gear 65, and a ring gear 67 having inner teeth meshed with the outer periphery of the planetary gear 66. Become.
Each planetary gear 66 is rotatably supported by a common carrier 68, and the carrier 68 is connected to the output shaft 4. The ring gear 67 integrally has a pipe portion 69, and the pipe portion 69 is relatively rotatably fitted to the outer periphery of the output shaft 4 and constitutes a double shaft together with the output shaft 4.

The fifth spline 41 is provided integrally with the pipe portion 69. An output shaft spline 70 is integrally provided on the output shaft 4 adjacent to the rear side of the fifth spline 41. A fixed spline 71 fixed to the mission case side is provided adjacent to the front of the fifth spline 41. The fifth sleeve 4 is always engaged with the fifth spline 41.
6 is provided so as to be slidable back and forth. Fifth sleeve 46
Is moved by the range actuator 22. A synchro mechanism exists in each spline portion of the range gear 19.

When the fifth sleeve 46 moves forward, it engages with the fixed spline 71, and the fifth spline 41 and the fixed spline 71 are connected. As a result, the ring gear 67 is fixed to the mission case side, and the output shaft 4 is rotationally driven at a reduction ratio greater than 1. This is the low position.

On the other hand, when the fifth sleeve 46 moves rearward, this engages with the output shaft spline 70, and the fifth spline 41 and the output shaft spline 70 are connected. As a result, the ring gear 67 and the carrier 68 are fixed to each other, and the output shaft 4 is directly driven at a reduction ratio of 1. This is the high position.

As described above, in the transmission 3, on the forward side, it is possible to shift to two stages of high / low by the splitter 17, four stages of the main gear stage 18, and two stages of high / low by the range gear 19. It is possible to shift to 2 × 4 × 2 = 16 steps. On the reverse side, the splitter 17 alone can switch between high and low to shift gears in two steps.

Next, each actuator 20, 21, 22
Will be described. These actuators are composed of a pneumatic cylinder that operates by the pneumatic pressure of the air tank 5, and a solenoid valve that switches between supplying and discharging pneumatic pressure to the pneumatic cylinder. Then, these electromagnetic valves are selectively switched by the TMCU 9 to selectively operate the pneumatic cylinders.

The splitter actuator 20 comprises a pneumatic cylinder 47 having a double piston and three solenoid valves MV.
It is composed of H, MVF, and MVG. MVH / ON, MVF / OF when the splitter 17 is set to neutral
F, MVG / ON. MVH / OFF, MVF / OFF, MVG / O when turning the splitter 17 high
N. MVH when splitter 17 goes low
/ OFF, MVF / ON, MVG / OFF.

The main actuator 21 is a pneumatic cylinder 4 having a double piston and in charge of the operation on the select side.
8 and a pneumatic cylinder 49 having a single piston and in charge of the shift side operation. Three solenoid valves MVC, MVD, MVE and MVB, M for each pneumatic cylinder
VA is provided.

The select side pneumatic cylinder 48 is MVC /
When it is OFF, MVD / ON, MVE / OFF, it moves to the lower part of the figure, and 3rd, 4th or N3 of the main gear can be selected, MVC / ON, MVD / OFF, MVE / O.
When it is N, it becomes neutral as shown in the figure and the 1st of the main gear,
2nd or N2 can be selected, MVC / ON, MVD
When / OFF or MVE / OFF, it moves to the upper part of the figure and Rev or N1 of the main gear can be selected.

The shift side pneumatic cylinder 49 is an MVA / O.
When N and MVB / ON, it becomes neutral and N of main gear
1, N2 or N3 can be selected, MVA / ON, MV
When B / OFF, move to the left side of the figure, 2n of the main gear
Selectable d, 4th or Rev, MVA / OF
When F, MVB / ON, it moves to the right side of the figure, and 1st or 3rd of the main gear can be selected.

The range actuator 22 includes a pneumatic cylinder 50 having a single piston and two solenoid valves MV.
I and MVJ. Pneumatic cylinder 50 is MV
When I / ON or MVJ / OFF, the range gear is moved to the right side, and the range gear is set to high. When MVI / OFF or MVJ / ON, the range gear is moved to the left side, and the range gear is set to low.

By the way, in order to brake the counter shaft 32 during the above-mentioned synchro control, the counter shaft 3
A counter shaft brake 27 is provided at 2. The counter shaft brake 27 is a wet multi-plate brake and operates by the air pressure of the air tank 5. A solenoid valve MV BRK is provided to switch between supply and discharge of this pneumatic pressure. When the solenoid valve MV BRK is ON, air pressure is supplied to the counter shaft brake 27, and the counter shaft brake 27
Is activated. When the solenoid valve MV BRK is off, air pressure is discharged from the counter shaft brake 27, and the counter shaft brake 27 is deactivated.

Next, the contents of the automatic shift control will be described. T
The MCU 9 stores the shift-up map shown in FIG. 4 and the shift-down map shown in FIG.
9 executes the automatic shift according to these maps in the automatic shift mode. For example, in the shift-up map of FIG. 4, the shift-up diagram from the gear stage n (n is an integer from 1 to 15) to n + 1 is the accelerator opening (%) and the output shaft (output shaft) rotation speed (rpm).
) Is determined by the function. Then, on the map, only one point is determined from the current accelerator opening (%) and output shaft speed (rpm). During vehicle acceleration, the rotation speed of the output shaft 4 connected to the drive wheels gradually increases. Therefore, in the normal automatic shift mode, every time one current point exceeds each diagram, the gear is shifted up one step. At this time, if the mode is the skip mode, the lines are alternately skipped one by one and upshifted by two steps.

Similarly, in the shift-down map of FIG. 5, gears n + 1 (n is an integer from 1 to 15) to n
The shift-down diagram for is determined by the function of accelerator opening (%) and output shaft speed (rpm). And on the map, the current accelerator opening (%) and output shaft speed (rpm)
) And only one point is decided. Since the rotation speed of the output shaft 4 gradually decreases during deceleration of the vehicle, in the normal automatic transmission mode, the gear is downshifted by one step each time one current point exceeds each diagram. In the skip mode, the charts are alternately skipped one by one and downshifted by two steps.

On the other hand, in the manual mode, the driver can freely shift up / down regardless of these maps. In the normal mode, one shift change operation allows one speed change, and in the skip mode, one shift change operation allows two speed change.

The current accelerator opening is detected by the accelerator opening sensor 8, and the current output shaft rotation speed is detected by the output shaft rotation sensor 28. In particular, the TMCU 9 converts the current vehicle speed from the current output shaft rotation speed value and displays it on the speedometer. That is, the vehicle speed is indirectly detected from the output shaft rotation speed, and the output shaft rotation speed and the vehicle speed correspond to each other.

Next, this device is equipped with a constant speed traveling control device for realizing constant speed traveling of the vehicle. Here, the cruise controller 6a that controls the control is also used as the ECU 6.

First, the contents of the basic control of the constant speed traveling control are shown in FIG.
This will be described with reference to 0. When the driver sets the set vehicle speed, the fuel injection amount of the engine is controlled so that the actual vehicle speed matches the set vehicle speed.

That is, as shown in FIG. 9, the difference Vr-Vs between the actual vehicle speed Vr and the set vehicle speed Vs is calculated, and based on this difference, the proportional term and the integral gain are obtained from the corresponding maps. , A proportional term × difference and a sum Vt of the integral gain × difference integrated value, from a map different from the map shown in FIG. 8, a target fuel injection amount for constant speed traveling control (hereinafter referred to as “cruise Q”). Is calculated. The electronic governor 1d is controlled so that fuel injection equal to this cruise Q is actually performed. Such a cruise Q is calculated for a predetermined time (for example,
It is repeated every 32 msec).

On the other hand, even during the constant speed running control, the target fuel injection amount is calculated as usual by the map shown in FIG.
When this value (referred to as "accelerator Q") exceeds the cruise Q, the accelerator Q becomes the final target fuel injection amount. The larger of the accelerator Q and the cruise Q is the final target fuel injection amount. During constant-speed running control, the accelerator is not normally depressed, so cruise Q
However, when the driver depresses the accelerator in order to accelerate, if the accelerator Q exceeds the cruise Q, the control is based on the accelerator Q.

Then, as shown in FIG. 10, when the actual vehicle speed falls below the set vehicle speed by more than a predetermined value due to approaching an uphill road during the constant speed traveling control, one downshift control of the transmission is performed. . The first downshift condition is set vehicle speed V
s> (actual vehicle speed Vr + predetermined value Vsd1 (here 3 km /
h)) is established. Since a larger drive wheel torque can be obtained by this downshift, the actual vehicle speed normally increases. Upshift condition: Set vehicle speed Vs ≤ (actual vehicle speed Vr + predetermined value Vsu (0.5km / here)
If h)) is satisfied, the transmission is upshifted by one gear to return the transmission to the original gear when the vehicle speed was set.

If the driving wheel torque becomes insufficient even after the first downshift and the actual vehicle speed further decreases, the following downshift condition: set vehicle speed Vs> (actual vehicle speed Vr + predetermined value Vsd2 (here 8 km / h)) is established, further downshift control of the first stage of the transmission is performed. In this way, the transmission automatically shifts down and up based on the speed difference between the actual vehicle speed and the set vehicle speed.

The shift control during the constant speed traveling control is performed when the shift mode is the automatic shift mode and is not performed when the shift mode is the manual mode. In addition, the shift down / up is 1 in both the skip mode and the normal mode.
It is performed step by step.

It should be noted that during the constant speed traveling control, the maps shown in FIGS. 4 and 5 are not used, and shift down / up is performed exclusively based on the difference between the actual vehicle speed and the set vehicle speed. This is shown in Figs.
This is because when the vehicle speed is set in the vicinity of the shift point (each line of the map), the shift down is performed with a slight change in the vehicle speed and the feeling is not good when the map is used. In particular, in the present embodiment, since the number of gears is multi, the difference between the gears is small, and the possibility that the vehicle speed is set in the vicinity of the shift point is higher than that of a vehicle having a normal gear number, such a method is preferable.

Next, FIG. 6 shows the structure of the constant speed traveling control device. The constant speed traveling control device 80 includes an ECU 6 (cruise controller 6a) and switches 81 to 8 connected to the ECU 6 (cruise controller 6a).
5 and each lamp 81a, 81b.

Reference numeral 81 denotes a main switch, which is turned on by a driver to enter a constant speed traveling control standby state, and the main lamp 81a in the cab is turned on. The standby state is released by turning off the main switch 81 or the key switch, and the main lamp 81a is turned off at the same time as the release. A set switch 82 is set by the driver at the same time when the set vehicle speed is set, the constant speed traveling control is started, and the set lamp 82a in the cab is turned on. Reference numeral 83 denotes a cancel switch, which is released by the driver to cancel the constant speed traveling control. Set lamp 82 at the same time when the constant speed running control is released
a is turned off. 84 is a coast switch, and while this is turned on by the driver, the cruise Q = 0 and the vehicle is coasting. When the coast switch 85 is turned off by the driver in this state, the actual vehicle speed at that time is updated and set as a new set vehicle speed. A resume switch 85 is turned on by the driver to restore the set vehicle speed to the initial value when the set switch is turned on.

Incidentally, as is well known, in order to release the constant speed traveling control, the main switch 81 is turned off, the brake pedal is depressed (brake switch is turned on), or the clutch pedal 11 is depressed (the clutch pedal stroke sensor 16 is activated). Value is a predetermined value or more).

By the way, the first downshift condition when the vehicle approaches an uphill road during the constant speed traveling control: set vehicle speed Vs>
Before the (actual vehicle speed Vr + predetermined value Vsd1) is satisfied, if the engine speed falls to such a speed that a sufficient driving wheel torque cannot be obtained in view of the driving condition of the vehicle,
Since the cruise Q is increased while the current gear position is maintained and the control forcibly accelerating the vehicle is performed halfway,
There is a problem that what is called engine knocking occurs and the acceleration feeling is extremely poor.

Therefore, in order to prevent this, the following shift-down control is executed in this embodiment.

FIG. 11 shows a flow chart of downshift control. This flow is executed by the TMCU 9 every predetermined time (for example, 32 msec).

First, in step 101, the TMCU 9 determines whether or not constant speed traveling control is being performed. If the constant speed traveling control is being performed, the process proceeds to step 102, and if the constant speed traveling control is not being performed, this flow ends.

In step 102, it is determined whether or not the final target fuel injection amount (the larger one of the cruise Q and the accelerator Q) Qtfnl is larger than a preset predetermined value Qs. That is, in this step 102, it is judged whether or not the vehicle is substantially in the state of being accelerated, and the predetermined value Qs is the minimum value indicating the state. In the present embodiment, the predetermined value Qs is set to Pq% of the maximum fuel injection amount (full Q) for each engine speed (3 in the present embodiment.
0%).

This will be described in more detail as follows. FIG. 7 is a diagram showing the relationship between the engine speed and the maximum torque for each engine speed. On the maximum torque diagram (solid line), the target fuel injection amount (accelerator Q) for each engine speed is shown. Is the value when the accelerator opening is 100%, that is, the maximum fuel injection amount (full Q). Therefore, on the control, the maximum fuel injection amount at the rotational speed Ne is read from the detected actual engine rotational speed Ne according to the map of FIG.
This is multiplied by Pq to determine the threshold value Qs, and this threshold value Qs is compared with the final target fuel injection amount Qtfnl.
When Qtfnl> Qs, it is considered that the vehicle is being accelerated, and the routine proceeds to step 103, where Qtf
When nl ≦ Qs, it is considered that such a state is not reached, and this flow is ended.

At step 103, the current gear is the predetermined gear G.
It is determined whether it is larger than s. In this embodiment, Gs =
It is 10th speed. If the current gear is higher than the 10th speed, the routine proceeds to step 104, and if the current gear is 10th speed or less, this flow ends.

Step 104 is the most characteristic part of the present invention. In this step, it is judged whether the current actual engine speed Ne is less than a predetermined threshold Nes. In the present embodiment, Nes = 700 (rpm), which is a constant value slightly higher than the idle rotation speed = 500 (rpm). If Ne <Ne, the process proceeds to step 105, where Ne
If ≧ Nes, this flow ends.

That is, when the engine speed drops below Nes, which is close to the idling speed, sufficient drive wheel torque is no longer obtained to maintain constant speed running, and fuel injection is performed with the current gear position maintained. If an attempt is made to accelerate the vehicle by increasing the amount, the above-mentioned problem arises, so that automatic downshifting of the transmission is executed. As a result, the engine speed increases, sufficient driving wheel torque is obtained, and the vehicle can be accelerated with a good feeling.

In step 105, the engine speed Neasd after downshifting is predicted and calculated. That is, the current rotation speed of the output shaft 4 is multiplied by the gear ratio of the entire transmission in the gear after the shift down, and this is set as the predicted value Neasd of the engine speed after the shift down.

Next, at step 106, this predicted value Neasd is compared with a predetermined threshold value Neasds. In this embodiment, Neasds = 1800 (rpm)
Is. Step 1 if Neasd <Neasds
The flow proceeds to 07, and when Neasd ≧ Neasds, the present flow ends. This determination is made because if the engine speed after downshifting is too high, the engine will be in an overrun state, which is not preferable.

In step 107, the target gear is set to a value that is one speed lower than the current gear. As a result, the present flow ends, and thereafter actual automatic downshift is executed according to another flow not shown.

In the above downshift control, bidirectional data communication between the ECU 6 and the TMCU 9 is appropriately performed. For example, data indicating whether or not constant speed traveling control is being performed in step 101, step 10
The data of the final target fuel injection amount Qtfnl in 2 and the data of the maximum fuel injection amount based on the map of FIG.
It is taken into TMCU9 from CU6.

As described above, according to the downshift control, when the vehicle approaches an uphill road or the like and the engine speed significantly decreases, the downshift is immediately performed regardless of whether or not the downshift vehicle speed condition is satisfied. Since the down can be executed, the control for forcibly increasing the fuel injection amount and accelerating the vehicle in the middle is prevented, and the so-called engine knocking state can be avoided. Thus, the vehicle can be accelerated with a good acceleration feeling. In particular, this downshift control is very effective for the large vehicles of recent years in which the reduction ratio of the final gear is small and the engine speed during constant speed running control tends to be low. As a result, the reduction ratio can be reduced, which contributes to the improvement of fuel efficiency.

In this embodiment, the engine speed threshold Nes is set to the idle speed (500 rpm).
A value in the vicinity, or more accurately, a constant value slightly higher (70
0 rpm) is set. This is because it is considered that the drive wheel torque will always be insufficient when the engine speed reaches such a value, and such a constant value provides sufficient effect with simple control. Is.

On the other hand, in actuality, it is conceivable that the drive wheel torque will be insufficient due to the load condition, vehicle speed, wind, etc., in addition to the road surface condition such as an uphill road. Therefore, the threshold N
es can be a function based on these parameters.

The present invention can take various other embodiments. For example, the engine may be diesel, gasoline, or the like. For diesel, a common rail system or the like can be considered, and for gasoline, a system in which the throttle opening or accelerator opening is controlled by a throttle or an accelerator actuator during constant speed traveling control is considered. It is also possible to execute the fuel injection control during the constant speed traveling control by using the pseudo accelerator opening and the normal map as shown in FIG. 8 without using the cruise Q based on another map. In this case, the condition in step 102 of FIG. 11 may be that the pseudo accelerator opening is larger than a predetermined value. The automatic transmission is not limited to the one described above, and at least an automatic transmission can be used without a manual shift mode or a skip mode. The vehicle is not limited to a large vehicle, but can be a small truck, a passenger car, or the like. The above numerical values are representative examples, and can be changed as appropriate.

[0074]

In summary, according to the present invention, there is an excellent effect that the vehicle can be accelerated with a good acceleration feeling even when the engine speed is remarkably reduced during the constant speed running control. To be demonstrated.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an automatic transmission for a vehicle according to an embodiment.

FIG. 2 is a skeleton diagram of the same.

FIG. 3 is a configuration diagram showing an automatic clutch device.

FIG. 4 is a shift-up map.

FIG. 5 is a shift-down map.

FIG. 6 is a configuration diagram of a constant speed traveling control device.

FIG. 7 is a diagram showing a method of comparing a final target fuel injection amount and a fuel injection amount threshold value.

FIG. 8 is a target fuel injection amount (accelerator Q) calculation map.

FIG. 9 is a block diagram showing a method of calculating a target fuel injection amount (cruise Q) during constant speed traveling control.

FIG. 10 is a time chart showing the contents of basic control of constant speed traveling control.

FIG. 11 is a flowchart showing the contents of downshift control according to the present invention.

[Explanation of symbols]

3 transmission 6 engine control unit (ECU) 6a cruise controller 7 engine rotation sensor 8 accelerator opening sensor 9 transmission control unit (TMC)
U) 20 Splitter actuator 21 Main actuator 22 Range actuator 28 Output shaft rotation sensor 80 Constant speed running control device GSU Gear shift unit Vr Actual vehicle speed Vs Set vehicle speed Vsd1, Vsd2, Vsu Predetermined value (speed difference) Ne Engine speed Nes Engine speed Threshold value Qtfnl final target fuel injection amount Qs threshold value of fuel injection amount Neasd predicted value of engine speed Neasds threshold value of predicted value

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 29/02 301 F02D 29/02 301C F16H 61/00 F16H 61/00 // F16H 59:02 59:02 59:34 59:34 59:42 59:42 F-term (reference) 3D041 AA32 AA39 AB02 AC02 AC11 AC17 AD02 AD07 AD09 AD10 AD20 AD31 AE07 AE16 AE32 AE45 AF01 3D044 AA01 AA45 AB01 AC05 AC16 AC19 AC22 AC26 AD06 AD17 AE04 AE21 3G093 A09 AB01 BA01 3G093 BA23 CA10 CB10 DA01 DA06 DA10 DB05 DB11 EA05 EB03 FA04 3J552 MA04 MA13 NA01 NB01 PA25 PA39 PA55 QA06C QA26C RA06 RB11 RC14 SA26 SB13 TB01 VA66Z VA70W VB01Z VC01W VC06W VD02Z VD11Z

Claims (4)

[Claims] 1. A constant speed running control means for executing a constant speed running control by controlling a fuel injection amount of an engine so that an actual vehicle speed matches a set vehicle speed, and an engine speed during the constant speed running control. , When the speed drops to a level where sufficient driving wheel torque cannot be obtained from the driving situation of the vehicle,
An automatic transmission device for a vehicle, comprising: a shift-down control unit that executes shift-down control of a transmission. 2. The downshift control means executes the downshift control of the transmission when the engine speed drops below a predetermined speed slightly higher than the idle speed. Automatic transmission. 3. The downshift control means executes downshift control of the transmission when the fuel injection amount of the engine is a value indicating a state in which the vehicle is being accelerated. Alternatively, the vehicle automatic transmission described in 2. 4. The downshift control means executes the downshift control of the transmission when the engine speed after the downshift is predicted and calculated and the value is equal to or less than a predetermined value. An automatic transmission device for a vehicle according to claim 1.