JP3230422B2 - Transmission control device for continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a shift control device for a continuously variable transmission mounted on a vehicle.

[0002]

2. Description of the Related Art Conventionally, a V-belt type or a toroidal type (friction wheel type) has been known as a continuously variable transmission used for vehicles such as automobiles, and a transmission control device for such a continuously variable transmission. Then, based on the throttle opening of the engine (or the accelerator opening, the same applies hereinafter) and the vehicle speed, a target value of the number of revolutions input to the continuously variable transmission is set, and the gear ratio according to this target number of revolutions is obtained. Such a control is known.

In the above-described transmission control apparatus for a continuously variable transmission, as the throttle opening is smaller, the gear ratio is set to a higher speed side (the target input rotation speed is smaller). Since the ratio is set to the low speed side (the target input rotation speed is large), the throttle opening decreases when the driver releases the accelerator pedal during downhill running, and the gear ratio is set to the high speed side to set the target speed. Since the input speed decreases, the engine brake is controlled in a direction in which it does not work. For this reason, the driver may feel an extra feeling of acceleration despite releasing the accelerator pedal, and the frequency of the brake operation may increase during downhill traveling, which may increase the consumption of the braking device. Conceivable.

Japanese Patent Application Laid-Open No. 6-819 discloses a technique for reducing frequent brake operations during coasting on a downhill.
No. 32 is known, which is to set the lower limit value of the target input rotation speed of the continuously variable transmission in accordance with the increase of the absolute value of the weight gradient resistance of the vehicle, and to positively apply the engine brake. Is operated.

[0005]

However, in the above-mentioned conventional shift control device, the lower limit of the target input rotational speed is set to a large value in accordance with the increase in the absolute value of the weight gradient resistance of the vehicle. When the coasting is performed with the accelerator pedal released on a downhill that is not the target, the target input speed frequently fluctuates according to the change in the gradient, so in addition to the engine speed constantly fluctuating, if the gradient decreases The engine brake suddenly decreases, and if the gradient increases, the engine brake rapidly increases, and the deceleration changes abruptly and stepwise according to the gradient, which may cause discomfort or discomfort to the driver. as shown in the downhill as gradient increases, when coasting in a state of releasing the accelerator pedal, the time t target input rotational speed in ₁ gradient changes is surge stepwise However, there is a problem that the deceleration also suddenly increases, which causes a shock to the driver. There was a problem that the ride quality was reduced.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a continuously variable transmission capable of coasting smoothly on a downhill with a changing gradient without giving a driver an uncomfortable feeling or discomfort. It is an object to provide a shift control device.

[0007]

According to a first aspect of the present invention, as shown in FIG. 18, a speed ratio changing means 5 for changing a speed ratio of a continuously variable transmission 2 and a continuously variable transmission according to a driving state of a vehicle. Continuously variable transmission comprising: a target input rotation speed of an input shaft of the machine 2; and a shift control means 50 for controlling the speed ratio changing means 5 so that the input shaft rotation speed matches the target input rotation speed. In the shift control device of the machine, an acceleration detecting means 51 for detecting an acceleration of the vehicle, an opening degree detecting means 52 for detecting an operation state of an accelerator pedal, and a state where the opening degree detecting means 52 detects the release of the accelerator pedal. An acceleration comparing means 53 for comparing the detected acceleration with a preset constant velocity region, and a predetermined unit time per unit time for correcting the target input rotational speed when the acceleration exceeds a preset constant velocity region . Acceleration of correction amount The shift control means 50 includes a correction amount calculating means 54 for calculating in accordance with the detected value, and a correction target input rotation speed setting means 55 for adding the correction amount to the target input rotation speed. The gear ratio changing means 5 is controlled based on the rotation speed.

In a second aspect based on the first aspect, the correction amount calculating means increases the correction amount per predetermined unit time according to the magnitude of the acceleration.

In a third aspect based on the first or second aspect, the correction amount calculating means sets the correction amount per predetermined unit time to zero or substantially zero when the acceleration is equal to or less than a predetermined value. .

In a fourth aspect based on the first aspect, the correction amount calculating means calculates a correction amount per predetermined unit time set in advance according to the magnitude of the acceleration.

[0011]

According to the first aspect of the present invention, the transmission control means controls the transmission ratio changing means such that the input shaft rotation speed of the continuously variable transmission matches the target input rotation speed according to the driving state of the vehicle. However, when the driver releases the accelerator pedal, if the acceleration of the vehicle exceeds a preset constant velocity range , a correction amount per predetermined unit time is calculated according to the acceleration, and the correction amount is calculated. The gear ratio is changed according to the target input rotational speed thus set. Since the target input rotation speed changes continuously with the correction amount per unit time added, if the correction amount is increased according to the magnitude of the acceleration generated in the vehicle, the engine braking force will be continuously changed according to the acceleration. When the vehicle is coasting down a slope with a changing gradient while the accelerator pedal is released, the driver can suppress excessive fluctuations in engine speed and sudden changes in deceleration. By continuously changing the engine braking force in accordance with the expectation, it is possible to perform a smooth coasting without a sense of discomfort.

According to a second aspect of the present invention, the correction amount calculating means increases the correction amount per a predetermined time according to the magnitude of the acceleration. When coasting, when the gradient increases sharply and the acceleration increases, the corrected target input rotation speed can be increased quickly, and the speed at which the engine braking force is increased can be increased. A reliable braking force can be obtained while changing the force.

According to the third aspect of the present invention, the correction amount per unit time is set to zero or almost zero when the acceleration is equal to or less than a predetermined value. The number hardly increases, and the engine brake is hardly effective.However, when the vehicle is coasting on a gentle slope with the acceleration below a predetermined value with the accelerator pedal released, the driver must release the engine brake. By suppressing the fluctuation of the target input rotation speed without increasing, it is possible to realize coasting as expected by the driver.

According to a fourth aspect of the present invention, when the vehicle is coasting downhill with the accelerator pedal released, the acceleration (or deceleration) required by the driver differs according to the magnitude of the acceleration. By presetting the correction amount of the target input speed in accordance with the perceived acceleration, etc., it is possible to smoothly change the engine braking force according to the driver's expectation in accordance with the change in the gradient, and to achieve smooth inertia. Driving can be realized.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, a continuously variable transmission 2 (C in the figure)
VT) is set to a predetermined speed ratio according to the driving state of the vehicle by the speed ratio changing means 5 controlled by the speed change controller 7. The continuously variable transmission 2 is, for example, a V-belt type or a toroidal type. It is composed of expressions.

The shift control controller 7 is mainly composed of a microprocessor or the like, and has a vehicle speed sensor 8 for detecting a vehicle speed VSP, a throttle opening sensor 9 for detecting a throttle opening TVO, a driving wheel rotation sensor 11, a braking device. Brake switch 12 for detecting the operating state of the vehicle, a vehicle acceleration sensor 14 for detecting the longitudinal acceleration G of the vehicle, an idle switch 15 for detecting the released state of the accelerator pedal, and detecting the rotational speed No of the output shaft of the continuously variable transmission 2. As means for detecting the output shaft rotation sensor 13 and the input shaft rotation speed Ni of the continuously variable transmission 2, the driving is performed based on a signal indicating the driving state of the vehicle input from the engine rotation sensor 10 which detects the engine rotation speed Ne. Control target input rotation speed D according to state
In addition to calculating SRREV, a target gear ratio DSRRTO is instructed to a gear ratio changing means 5 composed of an actuator or the like so that the input shaft rotational speed = engine rotational speed Ne matches the target input rotational speed. The driving force from the engine 1 is transmitted to the drive shaft 3 coupled with the drive shaft 3.

In this embodiment, the case where the engine 1 is directly connected to the input shaft of the continuously variable transmission 2 is shown, and the engine speed Ne is equal to the input shaft speed Ni. When a speed reduction mechanism, a torque converter, or the like is interposed between the transmission 2 and the input shaft, an input shaft rotation sensor may be provided, and the detected value may be set as the input shaft rotation speed Ni.

The transmission control controller 7 is also connected to an engine control controller 6 for controlling the engine 1 according to the driving state of the vehicle, and sends a transmission ratio control signal and the like from the transmission control controller 7 to the engine control controller 6. On the other hand, various operation information such as fuel injection cut-off is transmitted from the engine controller 6 and the engine 1
And the speed change controller 7 constitute an integrated control system that is controlled synchronously.

The engine controller 6 performs supercharging pressure control and the like in addition to fuel injection control from the fuel injection nozzle 4 and ignition timing control in accordance with the operating state of the vehicle. The control is the throttle opening TV
O, engine speed Ne, intake air amount, etc.
In addition to the air-fuel ratio feedback control, when the throttle is fully closed, fuel cut is performed at a predetermined engine speed or higher, and when the throttle is fully closed, control such as fuel injection recovery is performed. In the present embodiment, a case is shown in which the engine 1 is configured by a spark ignition type internal combustion engine.

An example of the control performed by the shift control controller 7 is shown in the flowcharts of FIGS. 2 to 10, and the details of the control will be described in detail with reference to these flowcharts.

Here, FIG. 2 is a diagram showing a state where the time is predetermined, for example, 5 ms.
An outline of a main routine of the shift control executed for each ec is shown. FIG. 3 and subsequent drawings show a subroutine for performing an engine brake correction during downhill traveling or the like. Will be described in detail.

[1. Shift control] In the main routine of FIG. 2, first, in step S1, the operating state of the vehicle is read from the above-described sensors and the like, and in step S2, the throttle opening TVO and the vehicle speed V read in step S1 are read.
Based on the SP, a control target input rotation speed DSRREV which is a target value of the input shaft rotation speed Ni (= engine rotation speed Ne) of the continuously variable transmission 2 is calculated from the shift map shown in FIG.

In step S3, a later-described step S1 is executed.
0, the control target input rotation speed DSRRE when the engine brake is operated according to the longitudinal acceleration G applied to the vehicle.
V is corrected.

In step S4, the control target input rotational speed DSRREV after the correction by the engine brake is performed.
And the target speed ratio DS so that the input shaft speed Ni matches.
RRTO is calculated, and in step S5, a control signal is output to the speed ratio changing means 5 of the continuously variable transmission 2 so that the continuously variable transmission 2
Control the transmission gear ratio.

[2. Engine Brake Correction Control] The flowchart of FIG. 3 shows the outline of the subroutine of the engine brake correction control performed in step S3, and the details of this subroutine are configured as shown in the flowcharts of FIGS. First, the outline of the engine brake correction control will be described.

In step S10, the control target input rotational speed DSRRE obtained in step S2 of the main routine is determined.
V, the input shaft speed Ni of the continuously variable transmission 2 (hereinafter, referred to as Ni).
(Hereinafter simply referred to as the input shaft rotation speed) is determined.

In step S11, the longitudinal acceleration of the vehicle (hereinafter referred to as "the vehicle acceleration") is determined in order to determine whether the engine brake needs to be further strengthened or needs to be weakened.
(Hereinafter simply referred to as acceleration).

In step S12, the acceleration generated in the vehicle is detected, and the magnitude of the acceleration is compared with the threshold value obtained in step S11 to determine whether the engine brake is to be further strengthened or further reduced. Is determined based on the operation state of the accelerator pedal.

In step S13, a correction amount of the target input rotational speed per unit time, which is a speed at which the engine braking force is changed, is calculated according to the magnitude of the acceleration obtained in step S12.

Then, in step S14, step S
13, a corrected target input rotation speed DS for generating an engine braking force corresponding to the acceleration based on the correction amount obtained in step 13.
RENBR is calculated, and in step S15, the corrected target input rotation speed DSRENBR is changed to the control target input rotation speed DSRRE.
After newly setting V, the process returns to the main routine after step S4, and the target speed ratio DSRRTO is calculated from the control target input rotation speed DSRREV to which the engine brake correction has been added.

Hereinafter, the details of the engine brake correction control will be described with reference to the flowcharts of FIGS.

[2.1 Determination of Correction Range of Control Target Input Rotational Speed and Acceleration Threshold] FIG. 4 shows a subroutine process performed in step S3 shown in the main routine of FIG. 2, and steps S101 to S104. Corresponds to steps S10 and S11 in the outline shown in FIG.

In step S101, based on the vehicle speed VSP read in step S1, the upper limit input rotation speed DSR which is the upper limit value of the correction control range is obtained from the map shown in FIG.
Calculate HLMT. The map shown in FIG. 11 is a map in which the input rotation speed corresponding to the vehicle speed VSP is set in advance using the throttle opening TVO as a parameter, and is stored in a storage means such as a ROM (not shown) of the shift control controller 7. .

On the other hand, in step S102, similarly,
Lower limit input rotation speed DSRHL which is the lower limit value of the correction control range
MT is calculated based on the vehicle speed VSP.

Next, in steps S103 and S104, in order to determine whether the engine brake needs to be further strengthened or needs to be further weakened, FIG.
Based on the map shown in FIG. 2, a threshold VSPOVLM on the acceleration side and a threshold VSPUDL on the deceleration side
M is calculated according to the vehicle speed VSP.

The map shown in FIG. 12 is set in advance according to the sensible acceleration expected by the driver when the accelerator pedal is released (idle switch 15 = ON), and changes according to the speed. The constant velocity region is set around a constant velocity region having a predetermined acceleration range. This constant velocity region does not indicate a physical constant velocity (acceleration = 0 G), and when the accelerator pedal is released, the driver Is an area where the driver feels that the vehicle is traveling at a substantially constant speed. An acceleration area in which the driver experiences the acceleration of the vehicle above the constant velocity area, and a driver experiences the deceleration of the vehicle below the constant velocity area. The deceleration range is defined, and the boundary between the constant speed range and the acceleration range is the acceleration-side threshold VSPOVLM.
The boundary between the constant speed range and the deceleration range is the deceleration side threshold VSPUDLM.
It is.

An example in which an idle switch 15 is used as an opening degree detecting means for detecting an operation state of an accelerator pedal will be described. In a spark ignition type internal combustion engine such as a gasoline-powered car or a gas-fueled car, the throttle opening TVO is used. Thus, the release state of the accelerator pedal may be detected.

As described above, in steps S101 to S104, the upper limit input speed DSRHLMT, the lower limit input speed DSRLLMT of the correction control range, and the acceleration / deceleration threshold value VSPO
After setting VLM and VSPUDLM, the process proceeds to the acceleration / deceleration determination process in step S110 shown in FIG.

[2.2 Acceleration / Deceleration Judgment Processing] In steps S110 to S118 of FIG. 5, it is determined in which area the current vehicle acceleration is in the map of FIG. Step S12.

First, in step S111, it is determined whether or not the vehicle speed VSP read in step S1 is in a predetermined low-speed region, for example, 10 km / h or less. Acceleration TKRAM
While S6 is set to 0, if not, the process proceeds to step S112.

In step S112, the vehicle acceleration is calculated from the difference between the current vehicle speed VSP and the vehicle speed VSP _-5 a predetermined time before, for example, five cycles (50 msec before).
Find KRAMS6. In addition, as the acceleration detecting means,
Although the case where the differential value of the vehicle speed VSP is used is shown, the differential value of the detection value G of the vehicle acceleration sensor 14 or the detection value of the drive wheel rotation sensor 11 may be used.

Next, in step S113, the vehicle acceleration TKRAMS6 is compared with the acceleration-side threshold value VSPOVLM obtained in step S103, and the vehicle acceleration TKR is calculated.
If AMS6 is larger than threshold value VSPOVLM, it is determined that the current vehicle acceleration TKRAMS6 is in the acceleration region where the engine brake needs to be increased in the map shown in FIG. 12, and the process proceeds to step S117.
The acceleration flag VSPPLS is set to 1; otherwise, the process proceeds to step S114 to determine whether the vehicle is in the deceleration range.

In step S114, the vehicle acceleration TKRA
If MS6 is smaller than the deceleration side threshold VSPUDLM obtained in step S104, step S11
The routine proceeds to step 6, where 1 is set to the deceleration flag VSPMNS. If not, it is determined that the vehicle is in the constant velocity region of FIG. 12, and the routine proceeds to step S115 to set 1 to the constant velocity flag VSPEQS. In step S118, the vehicle acceleration TK
Also in the case of the low speed range where RAMS6 = 0, step S
At 115, the constant speed flag is set to 1.

Thus, the threshold values VSPOVLM, VS
By comparing the PUDLM with the vehicle acceleration TKRAMS6, the region of the vehicle acceleration in the map of FIG. 12 is identified by the acceleration, deceleration, and constant speed flags. After that, the process proceeds to step S120 of FIG. The search for the correction amount of the target input rotation speed and the mode division according to the accelerator pedal operation are performed.

[2.3 Target Input Rotational Speed Correction Amount Setting, Mode Separation According to Driving Operation] Steps S120 to S120 in FIG.
In step S131, after setting the correction amount of the target input rotation speed according to the vehicle acceleration TKRAMS6, the operation state of the accelerator pedal, that is, the case according to the driver's intention is divided, and step S13 in the flowchart of FIG. Is equivalent to

In steps S121 and S122, FIG.
The correction amount of the target input rotation speed per unit time is obtained as the downshift correction amount DDSRDN or the upshift correction amount DDSRUP according to the magnitude and sign of the vehicle acceleration TKRAMS6 from the map shown in FIG.

When the vehicle acceleration TKRAMS6 is positive, the downshift correction amount DDSRDN in the direction of increasing the target input speed is used to increase the engine braking force.
However, in the negative case, to reduce the engine braking force,
The upshift correction amount DDSRUP in the direction of decreasing the target input rotation speed is selected, where the unit time indicates the execution interval of the process, and in this case, the downshift correction amount D
DSRUP and upshift correction amount DDSRUP each indicate a target input rotation speed correction amount every 5 msec, that is, a speed at which the target input rotation speed is changed.

The map shown in FIG. 13 is set in advance based on experiments conducted by the applicant of the present invention, as described later, and is stored in a storage means (not shown) of the shift control controller 7 such as a ROM.

Next, in steps S123 to S131,
The intention of the driver to accelerate or decelerate is estimated from the change between the previous value and the current value of the operation state of the accelerator pedal, and the cases are classified.

First, in step S123, it is determined whether or not the flag OLDIDLE indicating the status of the idle switch 15 is 0 in the previous process (5 msec before), that is, whether or not the accelerator pedal is depressed. If it is released to step S124, (OLDIDL
E = 1) Proceed to step S125.

In step S124, whether the flag IDLE indicating the current state of the idle switch 15 is 0,
That is, it is determined whether the accelerator pedal is depressed,
If it has been depressed, the process proceeds to step S126. If it has been released (IDLE = 1), the process proceeds to step S127.

In step S126, the accelerator pedal is continuously depressed in both the previous time and the present, and the idle switch 15 is in the OFF and OFF states, and the process proceeds to step S150 described later.

On the other hand, if it is determined in step S124 that the accelerator pedal is currently released, the depressed state of the accelerator pedal has changed from the previous value. In step S127, the current state of the idle switch 15 is changed to OLDIDLE = In step S128, the idle switch 15 is changed from OFF to ON, and it is determined that the accelerator pedal that has been depressed is released, and the process proceeds to step S160.

On the other hand, the previous idle switch 15 was turned on.
Also in step S125, similarly to the above, it is determined whether the flag IDLE indicating the current state of the idle switch 15 is 0, that is, whether the accelerator pedal is depressed, and if it is depressed, the process proceeds to step S130. If it has been released (IDLE = 1), the process proceeds to step S129.

In step S129, since the accelerator pedal is continuously released, step S1 is performed without changing the previous idle switch flag OLDIDLE.
Release 40 and proceed to processing.

On the other hand, if it is determined in step S125 that the accelerator pedal is currently depressed, the depression state of the accelerator pedal has changed from the previous value.
In step S130, the current status of the idle switch 15 is updated as OLDIDLE = 0, and step S131 is performed.
Then, the idle switch 15 changes from ON to OFF,
It is determined that the released accelerator pedal is depressed, and the process proceeds to step S150.

By comparing the previous value OLDIDLE of the idle switch 15 with the current value IDLE in this manner, the change in the depression state of the accelerator pedal is determined in step S.
The correction of the target input rotation speed is performed for each of the three cases of 140, 150, and 160, and these steps S140 are performed.
The following corresponds to step S14 in FIG.

Although the operation of the accelerator pedal is detected by the idle switch 15 in the above description, the operation may be performed based on the detection value TVO of the throttle opening sensor 9.

[2.4 When the accelerator pedal is continuously released] FIG. 7 shows that the idle switch 15
Step S141 shows a process of correcting the target input rotational speed when the accelerator pedal whose current value is ON is continuously released.
Then, it is determined whether or not the acceleration flag VSPPLS set in steps S110 to S118 is 1, and if it is 1, the current vehicle acceleration is in the acceleration range of the map in FIG. , 0, the process proceeds to step S142.

In step S143, the downshift correction amount DDSRDN obtained in step S121 in FIG. 6 is input to the correction target input in order to increase the engine braking force to reduce the vehicle acceleration from the acceleration range in FIG. 12 to the constant speed range. The target input speed is increased by adding to the previous value of the speed DSRENBR.

DSRENBR = DSRENBR ₋₁ + DDSRDN Note that “ ₋₁ ” indicates the previous value. The same applies hereinafter.

Then, in step S144, a correction control flag NOWCNT indicating that the correction control is being performed is set to 1, and the process proceeds to the rotation check in step S170.

On the other hand, if it is determined in step S141 that the vehicle is not in the acceleration range, the flow advances to step S142 to determine whether or not correction control is being performed.
The process proceeds to 45 to determine whether or not the vehicle is in the deceleration range. If the correction control is not being performed, the process proceeds to step S146.

In step S146, since it is not necessary to correct the target input rotation speed, the corrected target input rotation speed DSREN is used.
BR is set to the control target input rotation speed DSRREV obtained in step S2 of FIG. 2 and the process proceeds to step S170.

In step S145, it is determined whether or not the deceleration flag VSPMNS has been set in step S116 in FIG. 5 described above. If the current vehicle acceleration is in the deceleration range of the map shown in FIG. If not, the process proceeds to step S170.

In step S147, the output signal BRK of the brake switch 12 determines whether or not the brake is being depressed.
Determined by If the brake is not depressed (BR
K = 0), the process proceeds to step S148 to perform the correction process in the deceleration range, while the brake is being depressed (BR
In K = 1), even in the deceleration range where the engine brake needs to be weakened, the deceleration range is corrected in order to prohibit the target input rotation speed from being corrected small and give priority to the driver's braking operation. Instead, proceed to step 170.

In step S148, the upshift correction amount DDSRUP obtained in step S122 in FIG. 6 is used to correct the target input rotational speed DSREN in order to weaken the engine brake and increase the speed from the deceleration range shown in FIG. 12 to the constant speed range.
The target input rotational speed is gradually reduced in addition to the previous value of BR (since the upshift correction amount DDSRUP becomes a negative value, the corrected target input rotational speed DSRENBR is subtracted).

DSRENBR = DSRENBR ₋₁ + DDSRUP Then, the process proceeds to rotation check in step S 170.

[2.5 When the Accelerator Pedal is Depressed] Steps S150 to S155 in FIG. 8 are performed at the moment when the accelerator pedal at which the current value of the idle switch 15 is turned off is depressed or when the depression is continued. 4 shows a number correction process.

In step S151, it is determined from the state of the correction control in-progress flag NOWCNT whether or not the target input rotational speed is currently being subjected to correction control. If the correction control is being performed, the process proceeds to step S152. Proceed to step S153.

In step S152, the corrected target input rotation speed DSRENBR _{-1 of the} previous process and the current control target input rotation speed DSRREV obtained in step S2 of FIG.
When the control target input rotation speed DSRREV is equal to or less than the previous correction target input rotation speed DSRENBR _-1 , the process proceeds to step S154. Otherwise, the process proceeds to step S153.

In step S154, a value obtained by subtracting a predetermined value from the previous corrected target input speed DSRENBR _-1 and slightly lowering the target input speed is set as the current corrected target input speed DSRENBR as follows. , DSRENBR = DSRENBR _-1 -1 In this case, the correction target input rotational speed DSRENBR is set to 1 rp.
m, the corrected target input rotational speed DSRENBR is gradually approached to the control target input rotational speed DSRREV, and the process proceeds to step S171 without the rotation limiter.

On the other hand, in step S153, the correction control flag N is set to end the engine brake correction control.
After resetting OWCNT to 0, step S155
To the corrected target input rotational speed DSRENBR in step S
The control target input rotation speed DSRREV obtained in step 2 is stored,
The process proceeds to step S171 as described above.

[2.6 When the Accelerator Pedal is Released] Steps S160 to S164 in FIG. 9 correspond to the target input rotational speed at the moment when the accelerator pedal is released when the previous value of the idle switch 15 is OFF and the current value is ON. 4 shows a correction process.

In step S161, the correction target input rotation speed DSRENBR _{-1 of the} previous process and the upper limit input rotation speed DS of the correction control range obtained in step S101 of FIG.
RHLMT and the previous corrected target input rotational speed D
When SRENBR _-1 exceeds the upper limit input rotation speed DSRHLMT, the process proceeds to step S162, while when SRENBR _-1 is equal to or lower than the upper limit input rotation speed DSRHLMT, step S163 is performed.
Proceed to.

In step S162, the upper limit input rotation speed DSRHLMT of the correction control range is set as the correction target input rotation speed DSRENBR, and then the flow proceeds to the rotation check processing in step S170.

On the other hand, if it is equal to or lower than the upper limit input rotation speed DSRHLMT, it is determined in step S163 whether the correction control is being performed. If the correction control is not being performed, step S16 is performed.
In step S17, the control target input rotation speed DSRREV is set to the corrected target input rotation speed DSRENBR.
0, but if the correction control is being performed, step S1
Proceed to step 70.

[2.7 New Control Target Input Speed DSRR
EV setting] In this way, in the above 2.4 to 2.6, the operation state of the accelerator pedal is divided into three cases, and the corrected target input rotation speed DSRENBR is set, and then the process proceeds to step S170 or S171, and the engine is started. The setting of the control target input rotation speed DSRREV after the brake correction control is performed in and after step S170 in FIG.
Steps 170 and after correspond to step S15 in FIG.

When the process proceeds to the rotation checking process in step S170, it is determined in step S172 whether the corrected target input speed DSRENBR is equal to or less than the lower limit input speed DSRLLMT of the correction control range obtained in step S102 in FIG. If it is determined that the corrected target input rotation speed DSRENBR is equal to or lower than the lower limit input rotation speed, the process proceeds to step S173. Otherwise, the process proceeds to step S175.

In step S173, after the lower limit input rotation speed DSRLLMT of the correction control range is newly set as the correction target input rotation speed DSRENBR, the correction control flag NOWCNT is reset to 0 to end the correction control, and then step S177 is performed. Proceed to.

On the other hand, in step S172, the corrected target input speed DSRENBR is set to the lower limit input speed DSRL.
If it exceeds LMT, in step S175, the upper limit input rotational speed D of the correction control range obtained in step S101 described above.
It is determined whether or not SRHLMT has been exceeded, and if so, a new corrected target input rotational speed D is determined in step S176.
Upper limit input speed DS of correction control range as SRENBR
After setting the RHLMT, the process proceeds to step S177.

From the above process [2.5] to step S1
If the process has proceeded to the process 71 without the rotation limiter, the process directly proceeds to step S177.

In step S177, the correction target input rotation speed DSR set by the engine brake correction control is set.
ENBR is set as a new control target input rotation speed DSRREV, and the process returns to step S4 in FIG. Thus, the speed ratio changing means 5 of the continuously variable transmission 2 is driven such that the target speed ratio DSRRTO corresponding to the corrected target input rotational speed DSRENBR after the engine brake correction control is achieved.

[3. Setting of Downshift Correction Amount DDSRDN Map] Here, the downshift correction amount DDSRDN shown in FIG. 13 is not directly proportional to the vehicle acceleration, but is set by an experiment of the present applicant.

According to the experiment, when the vehicle is coasting downhill with the accelerator pedal released, the deceleration expected by the driver changes according to the magnitude of the vehicle acceleration.

In FIG. 14, an area where the vehicle acceleration is positive, an acceleration area A where the vehicle acceleration is very small, that is, an acceleration ≒ 0, and a medium acceleration area where the acceleration experienced by the driver gradually increases. B, and divided into three regions C in which the driver's bodily acceleration increases as if the vehicle were arbitrarily rushing, and the deceleration expected by the driver in each acceleration region = target input rotational speed. The amount of increase was considered.

3. A In the acceleration region A in which the acceleration is almost 0, the driver feels frequent changes in the engine speed (= target input speed) to be troublesome, and as shown by the broken line in the figure, the downshift correction amount is directly proportional to the acceleration. I feel uncomfortable. in addition,
In this region A, since the driver does not expect deceleration even when the accelerator pedal is released, the correction amount for increasing the target input rotation speed per unit time when the acceleration is equal to or less than a predetermined value near 0 is indicated by a broken line in the figure. The downshift correction amount DDSRDN is set to be zero or almost zero, greatly reduced from the directly proportional one shown.

3. B In the acceleration region B where the acceleration is moderate, the vehicle speed gradually increases, so the driver requests an increase in the engine brake immediately, and if the effect of the engine brake is delayed, the driver may feel impatient or kinky. , Downshift correction amount DD
In order to continuously increase the SRDN from almost zero in the acceleration area A and quickly apply the engine brake,
The downshift correction amount DDSRDN is continuously increased so as to become larger than the graph indicated by the broken line in the figure that is directly proportional to the acceleration.

3. C In the region C where the acceleration is large, the driver wants a large engine braking force because the vehicle speed increases sharply and the vehicle feels as if it is driving on its own. In this region, the driver does not feel uncomfortable even if the vehicle decelerates excessively, and on the contrary, feels uneasy if the vehicle is insufficiently decelerated.

Therefore, the downshift correction amount DDSRDN in the area C is set to be larger than the area B in direct proportion to the broken line in the figure.

In this way, the above 3. A-3. From C, the downshift correction amount DDSRDN is set so as to continuously change according to the driver's intention to decelerate, which changes according to the magnitude of the acceleration, and to the magnitude of the acceleration.
In the present embodiment, the downshift correction amount DDSRD
Although N is stored in the storage means of the shift control controller 7 as a map, it may be set as a function or the like.

[4. Overall action) Since the slope of a general slope is not constant, and there are irregularities on the road surface and subtle changes in the slope, if the accelerator pedal is continuously released and the vehicle is coasting downhill, the acceleration generated in the vehicle may fluctuate. For example, as shown in FIG. 15, on a downhill where the gradient suddenly increases, the acceleration rapidly increases at time t ₁ , and therefore, it is necessary to increase the engine brake.

When the acceleration increases and enters the acceleration range of the map shown in FIG. 12, an acceleration flag VS is set in step S117.
PPLS is set, and the corrected target input rotational speed DSREN is set.
In order to increase BR, a downshift correction amount DDSRDN, which is an increment value per unit time, is obtained from the map shown in FIG. 13 (step S121). Since the accelerator pedal is continuously released, the correction target input is performed in step S143. Correction amount DDSRD which is an incremental value to rotation speed DSRENBR
N is added, the control target input rotation speed DSRREV is increased every predetermined time (5 msec), and the vehicle acceleration is reduced as shown in FIG.
In the acceleration region B or C shown in FIG. 4, the speed at which the engine braking force is increased increases according to the magnitude of the acceleration.

Here, in order to increase the engine braking force, the correction amount of the downshift DDSRDN for increasing the target input rotation speed of the continuously variable transmission 2 depends on the acceleration generated in the vehicle as shown in FIGS. Is larger, the correction amount DDSRDN per unit time is set to be larger. Even if the acceleration generated in the vehicle changes abruptly, the correction amount DDSRDN per unit time only changes. The target input rotational speed DSRREV does not change abruptly and stepwise as in the conventional example, and as shown in FIG. 15, the engine braking force can be smoothly changed while responding to the change in acceleration. .

In other words, when the vehicle is coasting on a downhill having a gradient that is not constant and the accelerator pedal is released, even if the acceleration generated in the vehicle fluctuates, the input rotational speed of the continuously variable transmission 2 rapidly changes. It is possible to realize a smooth coasting without giving a sense of discomfort or discomfort by preventing shock due to a sudden increase in engine brake and a gradual increase in deceleration that the driver does not intend. ,
It is possible to improve ride comfort and drivability.

In an acceleration state where the acceleration is very small but not equal to or less than a predetermined value other than 0, as shown in the acceleration region A of FIG. 14, the downshift correction amount DDSRDN becomes 0 or almost 0, but the driver does not have to. It can be said that the vehicle does not feel as if it is running on its own due to the speed increase, especially for the driver who has experienced the automatic transmission with the conventionally used torque converter, the creep of the torque converter Since the user is accustomed to the phenomenon, the user does not feel uncomfortable with the minute acceleration with the accelerator pedal released.
Thus, it is possible to prevent frequent changes in the engine speed, such as when the target input speed is increased and the engine braking force is increased, thereby preventing noise due to fluctuations in the engine speed and discomfort due to deceleration. As described above, the acceleration region A which is equal to or less than the predetermined value so that the driver does not feel uncomfortable even when the speed is increased.
Then, the downshift correction amount DDSRDN is set to 0 or almost 0.
By setting so that the engine brake is not effective, it is possible to realize more comfortable driving performance and riding comfort in coasting downhill.

Further, when the vehicle is coasting on a steep downhill, it is desired that the engine brake be applied slightly earlier than in the case of running down a gentle downhill. A sudden increase in the engine braking force in a stepwise manner gives the driver a sense of incompatibility.

On the other hand, in the present embodiment, the larger the acceleration is, as in the acceleration regions B and C in FIG. 14, the larger the correction amount DDSRDN per unit time is set. The speed at which the engine braking force is strengthened can be increased, and the engine braking force can be smoothly changed while responding to changes in the gradient, ensuring a deceleration that meets the driver's expectations. Thus, it is possible to reduce the frequency of brake operation during coasting downhill and suppress the wear of the braking device while significantly improving the drivability and ride comfort.

Further, the deceleration performed by the downshift correction amount DDSRDN set as described above does not converge to acceleration = 0 but is performed from the acceleration region shown in FIG. 12 to the constant velocity region. The constant velocity range is set by an experiment or the like by the present applicant.

Here, the outline of the acceleration / deceleration determination map shown in FIG. 12 will be described. The deceleration expected when the driver releases the accelerator pedal is almost independent of the vehicle speed VSP as shown in FIG. About 0.06G (acceleration =-
0.06 G) was found to be around 0.06 G) through experiments conducted by the present applicant. However, if the deceleration is simply set to ≒ 0.06 G, the driver's sensible acceleration may give an uncomfortable feeling because the engine braking force is too strong in a low vehicle speed range, while the engine braking force may be insufficient in a high vehicle speed range. .

Therefore, the target deceleration is reduced from 0.06 G in the low vehicle speed range according to the driver's perceived acceleration, while the deceleration is increased in the high vehicle speed range to secure the engine braking force. In addition, the engine braking force is continuously changed so that the vehicle acceleration when the accelerator pedal is released is in a constant speed range which is a predetermined acceleration range. In FIG. 12, an area above the constant velocity area is an acceleration area where the driver experiences the acceleration of the vehicle, and a part below the constant velocity area is set as a deceleration area where the driver experiences the deceleration of the vehicle. And the boundary between the acceleration region and the deceleration region are set as the threshold values VSPOVLM and VSPUDLM as described above.
In this embodiment, these threshold values VSPOVLM
And VSPUDLM are mapped, but may be treated as functions.

In this manner, when the vehicle is coasting on a slope having unevenness of the road surface or a slight change in gradient, the accelerator pedal is released and the input of the continuously variable transmission 2 is changed according to the magnitude of the acceleration generated in the vehicle. It is possible to continuously control the engine braking force by gradually changing the input rotation speed even on hills where the speed at which the rotation speed is corrected is changed continuously and the acceleration changes abruptly. On a downhill where the gradient suddenly increases as shown in FIG. 15, the engine braking force is prevented from increasing stepwise and suddenly as in the conventional example, and the engine braking force is smoothly increased, thereby satisfying the expectations of the driver. By performing the appropriate deceleration, the feeling of strangeness and discomfort as in the conventional example can be eliminated, and the drivability and riding comfort of the vehicle including the continuously variable transmission can be greatly improved.

[0104]

As described above, according to the first invention, when the vehicle is coasting on a downhill where the gradient changes, with the accelerator pedal released, if the acceleration exceeds a predetermined constant velocity range , the target is set to the target. Since the input rotation speed changes continuously with the correction amount per unit time added, the engine braking force can be changed continuously according to the change in acceleration, resulting in excessive fluctuations in engine speed and deceleration. The engine braking force according to the driver's expectation is generated while suppressing the rapid change of the vehicle speed, and the discomfort and discomfort due to the gradual and rapid increase of the deceleration are not given as in the above-described conventional example. This makes it possible to coast smoothly on a slope, and the drivability and riding comfort of a vehicle equipped with a continuously variable transmission can be greatly improved.

Further, in the second invention, in order to increase the correction amount per predetermined unit time according to the magnitude of the acceleration, when the accelerator pedal is released, the vehicle is coasted on a downhill where the gradient changes. When the acceleration increases due to a rapid increase in the gradient, the corrected target input speed is rapidly increased, and the speed at which the engine braking force is increased can be smoothly increased, and the engine braking force is continuously increased. It is possible to obtain a reliable braking force while making it possible to realize a smooth coasting while obtaining a deceleration according to the driver's expectation while drastically reducing the frequency of brake operation. Drivability and riding comfort of the equipped vehicle can be greatly improved.

According to the third aspect of the present invention, the amount of correction per unit time is set to zero or almost zero when the acceleration is equal to or less than the predetermined value. Although it does not increase, the engine brake is hardly effective, but when the accelerator pedal is released, when coasting down such a downhill in the acceleration region, the driver does not like the increase of the engine brake,
The target input speed does not fluctuate frequently in accordance with the change in the gradient as in the conventional example, and unnecessary fluctuation of the engine speed and engine braking that is not expected by the driver are prevented, and smooth coasting is performed. Can be realized, and the drivability of the vehicle including the continuously variable transmission can be further improved.

According to the fourth aspect of the present invention, the acceleration (or deceleration) required by the driver when coasting downhill with the accelerator pedal released is different depending on the magnitude of the acceleration. By setting the correction amount in advance according to the perceived acceleration of the driver, etc., it is possible to smoothly control the engine braking force to the optimum one expected by the driver according to the change in the gradient, and the Drivability of the vehicle including the transmission can be further improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a shift control device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a main routine of control performed by a shift control controller.

FIG. 3 is a flowchart showing an outline of a subroutine of engine brake correction control.

FIG. 4 is a flowchart showing details of engine brake correction control and showing a search process of a correction control range and an acceleration / deceleration determination threshold value.

FIG. 5 is a flowchart showing acceleration calculation and acceleration / deceleration determination processing.

FIG. 6 is a flowchart showing a process of searching for a correction amount of a target input rotational speed and dividing a case according to an operating state.

FIG. 7 is a flowchart showing the setting of a corrected target input rotation speed DSRENBR when the accelerator pedal is continuously released.

FIG. 8 is a flowchart showing the setting of a corrected target input rotation speed DSRENBR when the accelerator pedal is depressed.

FIG. 9 is a flowchart showing the setting of a corrected target input rotation speed DSRENBR at the moment when the accelerator pedal is released.

FIG. 10 is a flowchart showing a rotation limit check process.

FIG. 11 shows the throttle opening TVO as a parameter.
4 is a shift map showing a control target input rotational speed DSRREV according to a vehicle speed VSP.

FIG. 12 is a map showing a relationship between a vehicle speed VSP and a threshold value of a vehicle acceleration.

FIG. 13 shows a downshift correction amount DDSRDN and an upshift correction amount DD per unit time according to vehicle acceleration.
Map showing SRUP.

FIG. 14 is a graph showing the setting of the downshift correction amount DDSRDN, and shows the relationship between the correction amount per unit time and acceleration.

FIG. 15 is an explanatory diagram showing a state of coasting downhill according to the present invention.

FIG. 16 is a graph showing the relationship between the deceleration expected by the driver during coasting and the vehicle speed VSP.

FIG. 17 is an explanatory view showing a state of coasting downhill according to a conventional example.

FIG. 18 is a diagram corresponding to claims of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 engine 2 continuously variable transmission 3 drive shaft 4 fuel injection valve 5 gear ratio changing means 6 engine control controller 7 shift control controller 8 vehicle speed sensor 9 throttle opening sensor 10 engine rotation sensor 12 brake switch 14 vehicle acceleration sensor 15 idle switch 50 Shift control means 51 acceleration detection means 52 opening degree detection means 53 acceleration comparison means 54 correction amount calculation means 55 correction target input rotation speed setting means

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ identification code FI F16H 63:06 F16H 63:06 (58) Investigated field (Int.Cl. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48

Claims (4)

(57) [Claims] A speed ratio changing means for changing a speed ratio of the continuously variable transmission; a target input speed of an input shaft of the continuously variable transmission calculated according to a driving state of the vehicle; A shift control device for a continuously variable transmission, the shift control device including: a shift control unit that controls the speed ratio changing unit so that the speed ratio matches a target input rotation speed; an acceleration detection unit that detects an acceleration of a vehicle; and opening detection means for detecting a situation, when the opening degree detecting means detects release of the accelerator pedal, an acceleration comparing means for comparing the constant velocity region previously set with the detected acceleration, the acceleration in advance Correction amount calculating means for calculating a correction amount per predetermined unit time for correcting the target input rotational speed when the speed exceeds a set constant velocity region in accordance with a detected value of acceleration; Number A shift target control unit for the continuously variable transmission, wherein the shift control unit controls the speed ratio changing unit based on the corrected target input speed. . 2. The shift control device for a continuously variable transmission according to claim 1, wherein said correction amount calculating means increases a correction amount per predetermined unit time according to the magnitude of acceleration. 3. The correction amount calculation means according to claim 1, wherein the correction amount per predetermined unit time is set to zero or substantially zero when the acceleration is equal to or less than a predetermined value.
3. The shift control device for a continuously variable transmission according to claim 1. 4. The transmission of a continuously variable transmission according to claim 1, wherein said correction amount calculating means calculates a correction amount per predetermined unit time set in advance according to the magnitude of acceleration. Control device.