JP3147741B2 - 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 a gear ratio and a gear ratio corresponding to the target input revolution number are set. There is known a device which continuously controls so as to be controlled.

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.

In order to reduce frequent braking operations during coasting on a downhill, a downhill is detected from the acceleration of the vehicle or the like, and an engine braking mode different from a normal target input speed is set. Switching is known. In this engine brake mode, the target input speed is set according to the vehicle speed and the throttle opening in the same manner as in normal shift control, but a lower speed ratio than normal is selected. (For example, JP-A-6-81932)

[0005]

However, in the above-described conventional shift control device, even if the brake is operated during coasting while the engine brake is applied on a downhill, the speed ratio is not affected by the brake operation. In order to maintain a value corresponding to a downhill, for example, as shown in FIG.
When traveling downhill at a speed of 60Km / h in the engine braking mode, if keep up the preceding vehicle traveling at a speed of 40 Km / h, per hour to operate the brakes from time t ₁ 40 Km /
and it will be decelerated to h or less, to release the brake at time t _2,
Since the gear ratio (input shaft speed Ni / output shaft speed No) is the same as before braking, the target input speed (input shaft speed Ni) decreases according to the vehicle speed VSP (∝output shaft speed No). However, at the lowered target input rotation speed (Ni), the engine braking force according to the slope of the downhill is insufficient, so that the vehicle starts accelerating again and approaches the preceding vehicle. For this reason, the driver must adjust the speed of the preceding vehicle while frequently operating the brakes, and in addition to reducing the drivability due to the complicated brake operation, the ride comfort also decreases due to repeated acceleration and deceleration. There was a problem. It is also conceivable that a plurality of speed ratios are set in advance in the engine brake mode, and the speed ratio on the downshift side is appropriately selected according to the operation of the brake, but a shock occurs when the speed ratio is switched. However, there is a problem that the driver is uncomfortable.

Accordingly, the present invention has been made in view of the above problems, and when the braking device is operated during coasting with the accelerator pedal released, the engine braking force is smoothly increased, and frequent braking is performed. It is an object of the present invention to provide a shift control device of a continuously variable transmission that can easily follow a low-speed front vehicle without giving a driver a feeling of strangeness or discomfort without requiring any operation.

[0007]

According to the present invention, as shown in FIG. 17, a speed ratio changing means 5 for changing a speed ratio of a continuously variable transmission 2 and a continuously variable transmission 2 according to a driving state of a vehicle. And a shift control means 50 for controlling the speed ratio changing means 5 so that the input shaft speed matches the target input speed. In the shift control device, an acceleration detecting means 51 for detecting an acceleration generated in the vehicle, an opening detecting means 52 for detecting an operation state of an accelerator pedal, and the opening detecting means 52
When an accelerator pedal release is detected, an engine brake correction value setting means 53 for setting a correction value of a target input rotational speed so that the acceleration falls within a predetermined range, and a brake for detecting an operation state of a vehicle braking device. State detecting means 55;
While the engine brake correction value setting means 53 corrects the target input rotational speed, the target input shaft rotational speed maintaining means for maintaining the correction value while the braking state detecting means 55 detects the operation of the braking device. 54 and the shift control means 50
Controls the speed ratio changing means 5 based on the correction value of the target input rotation speed.

[0008]

Therefore, the speed change control means controls the speed ratio changing means so that the input shaft speed of the continuously variable transmission coincides with the target input speed according to the driving state of the vehicle. When the coasting is started by releasing the vehicle, the target input rotation speed is corrected so that the acceleration of the vehicle is within a predetermined range.For example, when the alcel pedal is released and the coasting is performed on a downhill, the engine brake is applied. Then, coasting while maintaining a predetermined acceleration range is started. During the coasting in which the target input speed is corrected, while the braking device is in operation, the correction value of the target input speed is maintained, and the input shaft speed is corrected immediately before the start of braking. It becomes the target input speed. The output shaft speed of the continuously variable transmission also decreases in accordance with the decrease in vehicle speed due to braking.However, since the input shaft speed maintains the value before the start of braking, the speed ratio of the continuously variable transmission continuously increases. As a result, the engine braking force can be increased. Then, when the braking is released, it is possible to continue the coasting while maintaining the predetermined acceleration range while applying the engine brake again, particularly when the vehicle catches up with the low-speed front vehicle during the coasting while downhill. When the braking device is operated once to decelerate to the speed of the preceding vehicle and the braking device is released, the vehicle resumes coasting to maintain the predetermined acceleration range after the release of braking, and Acceleration / deceleration is suppressed, and the vehicle can follow the low-speed front vehicle without frequently operating the braking device.

[0009]

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 drive 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
SRREV is calculated, and the target speed ratio DSRRTO (= Ni / N) is sent to the speed ratio changing means 5 constituted by an actuator or the like so that the input shaft speed Ni = engine speed Ne matches the control target input speed DSRREV.
o) to transmit the driving force from the engine 1 to the drive shaft 3 coupled to the output shaft (not shown).

In this embodiment, a case is shown in which the engine 1 and the input shaft of the continuously variable transmission 2 are directly connected, 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 shift 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 shift 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 control controller 6 controls the supercharging pressure in addition to the fuel injection control from the fuel injection nozzle 4 and the ignition timing control according to the driving state of the vehicle. The control is the throttle opening TV
O, the engine speed Ne, the amount of intake air, etc. are performed, and in addition to the air-fuel ratio feedback control, the fuel is cut at a predetermined engine speed or more when the throttle is fully closed, and the fuel is injected when the throttle is fully closed. It controls recovery and the like. 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 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 shows the state at predetermined time intervals, for example, 5 ms.
FIG. 3 shows a subroutine for performing engine brake correction control during downhill traveling or the like. FIG. 3 and subsequent drawings show a subroutine for performing engine brake correction control. The brake correction control 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 rotation 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 should be further strengthened or weakened. 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 (correction target value) is calculated, and step S15
Then, after newly setting the corrected target input rotation speed DSRENBR as the control target input rotation speed DSRREV, the process returns to the main routine after step S4, and the control target input rotation speed DSRRE to which the engine brake correction has been added.
The target speed ratio DSRRTO is calculated from V.

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 according to the vehicle speed VSP is set in advance using the throttle opening (or the accelerator opening) TVO as a parameter. What is stored.

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.

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 set to 0.06 G in the low vehicle speed range according to the driver's perceived acceleration.
On the other hand, in the high vehicle speed range, the deceleration is increased to secure the engine braking force, and the engine braking force is set so that the vehicle acceleration when the accelerator pedal is released is in a constant speed range which is a predetermined acceleration range. Is changed continuously. In FIG. 12, the area above the constant velocity area is set as an acceleration area where the driver experiences the acceleration of the vehicle, and the area below the constant velocity area is set as a deceleration area where the driver experiences the deceleration of the vehicle.
The boundaries between the constant velocity region, the acceleration region, and the deceleration region are set as the above-described threshold values VSPOVLM and VSPUDLM. In the present embodiment, these threshold values VSPO
Although VLM and VSPUDLM are used as maps, they may be handled as functions.

An example in which the idle switch 15 is used as the opening degree detecting means for detecting the operation state of the accelerator pedal will be described. In a premixed 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.

Thus, 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 within a predetermined low speed range, 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 which} is five cycles before (50 msec before) the current vehicle speed VSP.
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, at step S113, the vehicle acceleration TKRAMS6 is compared with the acceleration-side threshold value VSPOVLM obtained at step S103 to determine the vehicle acceleration TKR.
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.

At 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 Setting of Target Input Rotational Speed Correction Amount, Mode Classification 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 D for increasing the target input speed per unit time to increase the engine braking force.
On the other hand, when the vehicle acceleration TKRAMS6 is negative, the upshift correction amount DDSRUUP for reducing the target input rotational speed per unit time is selected in order to reduce the engine braking force. Here, the unit time indicates the execution interval of the processing, and in this case, 5 msec
The figure shows the target input rotation speed correction amount for each.

The map shown in FIG. 13 is set in advance based on experiments conducted by the applicant of the present invention. When the vehicle is coasting downhill, the map shown in FIG. The setting is made in accordance with the change in the perceived acceleration expected by the driver when shifting to.

As the vehicle acceleration increases, the correction amount of the target input rotation speed per unit time is increased, and the driver dislikes a rapid increase due to a sudden increase in the slope or the like. In the case where the acceleration is approximately zero, the driver may feel uncomfortable if the target input rotation speed is frequently changed, so the correction amount is set to approximately zero.

From the map shown in FIG. 13, the downshift correction amount DDSRDN or the upshift correction amount DDSRUP is changed according to the magnitude of the acceleration of the vehicle, and the speed at which the engine braking force is increased or decreased is changed. The generated engine braking force smoothly occurs and converges to the constant velocity region shown in FIG. The map according to the acceleration is stored in a ROM (not shown) of the shift control controller 7.
And the like.

After obtaining the correction amount DDSRDN or DDSRUP for correcting the target input rotational speed per unit time in this manner, in steps S123 to S131, the change of the previous and current values of the operation state of the accelerator pedal is used to determine the driver's The intention of acceleration / deceleration is estimated 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 processing (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 both the previous time and the present time, 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 depression state of the accelerator pedal has changed from the previous value, and the current state of the idle switch 15 is changed to OLDIDLE = in step S127. 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 accelerator pedal depressed state 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, the change in the depression state of the accelerator pedal is determined in step S.
The target input rotational speed is corrected in each of the three cases of 140, S150, and S160, and these steps S1
Steps after 40 correspond 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 flow 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.
In BR, the control target input rotation speed DSRREV by the normal shift control obtained in step S2 of FIG. 2 is set, 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, and if the current vehicle acceleration is within the deceleration range of the map shown in FIG. 12, the process proceeds to step S147. Otherwise, the process proceeds to step S170.

In step S147, it is determined whether or not the brake is being depressed based on the signal of the brake switch 12.

The signal from the brake switch 12 turns on when the brake is depressed, and turns off when the brake is released, and the transmission control controller 7 sets the brake flag BRK to 1 when the brake switch 12 is on. The brake flag BRK is set to 0 when the brake flag BRK is OFF, and in this step S147, the brake flag BRK is set.
= 0, and if the brake is not depressed (BRK = 0), the process proceeds to step S148 to perform the correction process in the deceleration range, while if the brake is depressed (BRK = 1). Goes to step 170 without correcting the deceleration range even in the deceleration range where the engine brake needs to be weakened, in order to prohibit the target input rotation speed from being corrected small and give priority to the driver's braking operation. move on.

In step S148, the upshift correction amount DDSRUP obtained in step S122 in FIG. 6 is used to reduce the engine brake so that the engine brake is weakened to increase the speed from the deceleration range shown in FIG. 12 to the constant speed range.
The target input rotational speed is gradually decreased in addition to the previous value of BR (the upshift correction amount DDSRUP becomes a negative value, and by adding this to the previous 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 under the correction control to change the engine brake, and the correction control in which NOWCNT = 1 is being performed. Sometimes, the process proceeds to step S152, in which the engine brake correction control is shifted to the normal shift control (control according to the map in FIG. 11).
On the other hand, if not, the process proceeds to step S153 to perform normal shift control.

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 rotational speed DSRENBR _-1 and slightly lowering the target input rotational speed is set as the present corrected target input rotational speed DSRENBR as follows. .

DSRENBR = DSRENBR ₋₁ −1 In this case, every predetermined time (5
msec), the correction target input rotation speed DSRENBR is reduced by a fixed subtraction value, for example, 1 rpm, and the correction target input rotation speed D
Control SRENBR at a predetermined rate of change and control target input speed DS
The control target input rotation speed DSRREV is gradually changed from the correction target value of the engine brake correction control to the control target input rotation speed by the normal shift control.

At this predetermined rate of change, the corrected target input rotational speed D
The subtraction value for decreasing the SRENBR is the previous corrected target input rotation speed DSRENBR _-1 and the current corrected target input rotation speed D
SRENBR difference is set to be equal to or less than a predetermined value,
The predetermined value is set in advance so that a change in the gear ratio during acceleration does not give a feeling of strangeness to the driver.

The process of shifting from the engine brake correction control to the normal shift control is performed in step S152 until the previous corrected target input rotation speed DSRENBR- ₁ becomes equal to the control target input rotation speed DSRREV.

Then, the process proceeds to step S 171 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
In order to perform normal shift control, the corrected target input rotational speed D
The control target input rotational speed DSRREV obtained in step S2 is stored in SRENBR, and the process proceeds to step S2 as described above.
Go to 171.

[2.6 When the Accelerator Pedal is Released] Steps S160 to S164 in FIG. 9 are executed at steps S160 to S164 of the target input 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 the rotational speed is equal to or lower than the upper limit input rotational 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 lower 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 in-progress flag NOWCNT is reset to 0 to end the correction control, and then step S177 is performed. Proceed to.

On the other hand, in the determination of 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], the process proceeds 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. Overall operation] In the engine brake correction control, the vehicle acceleration TKRAMS6 deviates from the constant velocity region of the map shown in FIG. 12 to become an acceleration region or a deceleration region (steps S113 and S114), and the accelerator pedal is continuously released. It is started on the condition that it is performed (step S129, step S140 and subsequent steps).

While the accelerator pedal continues to be released and the vehicle is coasting downhill, if the vehicle acceleration enters an acceleration range or a deceleration range according to the vehicle speed VSP as shown in FIG. 12 (steps S117 and S116), From the 13 maps, step S
Based on the downshift correction amount DDSRDN or the upshift correction amount DDSRUP obtained in accordance with the magnitude and sign of the vehicle acceleration in 121 and S122, the corrected target input rotational speed DSRENBR is changed at the speed at which the engine braking force is increased or decreased (the target per unit time). The input rotation speed correction amount is continuously corrected (S143, S148), and the engine braking force is smoothly changed in accordance with the slope of the downhill to converge the vehicle acceleration to the constant velocity region shown in FIG. , Realizes a sense of deceleration according to the driver's expectations.

When the vehicle is coasting downhill by continuously releasing the accelerator pedal, for example, if the downhill gradient increases,
Since the target input rotation speed is set according to the previous gentle gradient, the vehicle acceleration increases and the vehicle speed VSP tends to increase from the constant velocity region shown in FIG. 12 to the acceleration region. For this reason, it is necessary to increase the engine braking force.

Therefore, when the vehicle enters the acceleration range, the downshift correction amount DDSRD according to the vehicle acceleration is obtained from the map shown in FIG.
N is obtained, the correction amount DDSRDN is added to the previous value of the corrected target input rotation speed DSRENBR, and this value is used as the control target input rotation speed DSRREV as the target gear ratio DSRR.
TO is changed.

The downshift correction amount DDSRDN is:
It is obtained at predetermined time intervals (5 msec) in accordance with the vehicle acceleration at that time, and is also obtained at the previous correction target input rotation speed DSREN.
The control target input rotation speed DSRREV is added to BR.
Increases continuously without giving the driver any discomfort.
According to the change in the vehicle acceleration, the engine braking force is smoothly increased, and the vehicle acceleration converges to the constant velocity region shown in the map of FIG. A feeling of deceleration can be obtained.

Conversely, when the descending gradient decreases and becomes gentler, the target input speed is set higher according to the previous gradient, so that the vehicle acceleration decreases and the constant speed region shown in FIG. And the vehicle speed VSP is about to decrease. Therefore, it is necessary to weaken the engine braking force.

Therefore, when the vehicle enters the deceleration range, the upshift correction amount DDSRU according to the vehicle acceleration is obtained from the map shown in FIG.
P, the correction amount DDSRDN is subtracted from the previous value of the correction target input rotation speed DSRENBR (a negative correction amount is added), and the target speed ratio DSRRTO is changed using this value as the control target input rotation speed DSRREV.

The upshift correction amount DDSRUP is also
It is obtained at predetermined time intervals (5 msec) in accordance with the vehicle acceleration at that time, and is also obtained at the previous correction target input rotation speed DSREN.
Control target input rotation speed DSRRE because it is subtracted from BR
V is continuously reduced, the engine braking force is smoothly reduced according to the change in the vehicle acceleration without giving the driver a sense of incongruity, and the vehicle acceleration is reduced according to the decreased slope of the downhill as shown in FIG. The vehicle converges to the constant velocity region shown in the map, and a feeling of deceleration according to the driver's expectation can be obtained.

Thus, the accelerator pedal is continuously released,
When coasting downhill and catching up with the preceding vehicle whose vehicle speed is lower than that of the own vehicle, the brakes are activated to decelerate, but during this braking, the following control is performed. Will be

For example, as shown in FIG. 15, when the own vehicle is coasting at a speed of 60 km / h, if the vehicle catches up with the preceding vehicle traveling at a speed of 40 km / h, the brake is activated from time t ₁ to activate the speed per hour. Decelerate to 40 km / h or less.

At this time, since the vehicle is coasting downhill, the engine brake correction control from step S140 is continued (NOWCN in step S142).
T = 1), since the brake operates and the deceleration increases,
The vehicle acceleration enters the deceleration range of FIG.
PMNS = 1, and an attempt is made to enter the deceleration range correction for weakening the engine brake from step S145.

However, since the brake is operated and the brake flag BRK = 1, the correction of the deceleration range is prohibited, and the corrected target input speed DSRENBR maintains the previous value.

[0102] Thus, in FIG. 15, between the time t ₁ that stepping on the brake of t _2, the vehicle speed V by the braking
The SP decreases and the output shaft rotation speed No of the continuously variable transmission 2 also decreases. On the other hand, the correction target input rotation speed DSRENBR (= control target input rotation speed DSRREV) maintains the value immediately before the start of braking. Is increased, and the engine braking force can be continuously increased. Therefore, the engine braking force can be rapidly and continuously increased according to the braking operation of the driver, and the vehicle can be quickly decelerated.

On the other hand, the time t when the brake pedal is released
_{From 2} onward, the engine brake correction control after step S140 is performed to maintain the target input speed immediately after the brake is released, and the vehicle does not accelerate again and approach the preceding vehicle as in the conventional example. In addition to preventing the frequent brake operation and acceleration / deceleration associated with the brake operation as described above, a sense of deceleration according to the driver's expectation is realized, and in addition, the engine braking force according to the operation of the braking device is reduced. Can be strengthened smoothly.

In this way, when the accelerator pedal is released and the vehicle is coasting downhill and catching up with the preceding vehicle at a lower speed than the own vehicle to apply braking, once the brake operation is performed and the vehicle speed becomes equal to that of the preceding vehicle, the braking is performed. Even after the release of the vehicle, it is possible to prevent excessive acceleration of the vehicle as in the conventional example, greatly reduce frequent brake operations, and prohibit the change of the target input rotation speed during the brake operations. A smooth increase (shift down) promotes the braking operation, and after the braking operation is completed, the smooth coasting is realized again without giving the driver any uncomfortable feeling or discomfort, and the continuously variable transmission is realized. Drivability and riding comfort of the equipped vehicle can be greatly improved.

In the above embodiment, the braking state is determined according to the operation state of the brake pedal. However, although not shown, in a vehicle equipped with an auxiliary braking device such as an exhaust brake or a retarder, the operation state of the auxiliary braking device is determined. May be used to determine the braking state.

[0105]

As described above, according to the present invention, the correction value of the target input rotational speed is maintained while the braking device is operated during coasting by the engine brake correction control for converging to a predetermined acceleration range. The input shaft speed is fixed to the target input speed corrected immediately before the start of braking, while the output shaft speed of the continuously variable transmission decreases in accordance with a decrease in vehicle speed due to braking. The speed change ratio of the vehicle can be continuously increased to increase the engine braking force to promote the braking effect. In particular, when the vehicle catches up with the preceding vehicle that is slower than the own vehicle and applies the braking, the braking device is operated once. If the vehicle decelerates to approximately the same speed as the preceding vehicle, after the braking state is released, the engine brake correction control that converges to a predetermined acceleration range prevents the vehicle from over-accelerating and facilitates coasting at the speed of the preceding vehicle. To do Frequent braking operation as in the conventional example can be greatly reduced, driving operation can be reduced, and smooth coasting can be realized without giving the driver a feeling of discomfort or discomfort. It is possible to greatly improve the drivability and riding comfort of a vehicle equipped with the vehicle.

[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 a process for shifting from engine brake correction control to normal shift control 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 a relationship between a deceleration expected by a driver during coasting and a vehicle speed VSP.

FIG. 15 is a graph showing the behavior of the vehicle when braking is performed during coasting downhill according to the present invention.

FIG. 16 is a graph showing a conventional example, and showing behavior of the vehicle when braking is performed during coasting on a downhill.

FIG. 17 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 Transmission control means 51 acceleration detection means 52 opening degree detection means 53 engine brake correction value setting means 54 target input shaft rotation speed maintaining means 55 braking state detection means

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-6-81932 (JP, A) JP-A-58-203258 (JP, A) JP-A-1-106742 (JP, A) JP-A 62-819 166121 (JP, A) JP-A-3-18964 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48

Claims (1)

(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 coincides with a target input rotation speed; an acceleration detection unit that detects an acceleration generated in the vehicle; Opening degree detecting means for detecting an operation state of the engine, and engine brake correction for setting a correction value of a target input rotational speed such that the acceleration falls within a predetermined range when the opening degree detecting means detects release of an accelerator pedal. Value setting means, braking state detecting means for detecting an operation state of a braking device of the vehicle, and wherein the engine braking correction value setting means corrects the target input rotational speed while the braking state detecting means detects a braking device. While detecting the operation of (i), the target input shaft speed maintaining means for maintaining the correction value, and the shift control means controls the speed ratio changing means based on the target input speed correction value. A shift control device for a continuously variable transmission, comprising: