JP3257454B2 - 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 a shift control device for a continuously variable transmission, and more particularly to a device for appropriately controlling the speed of a continuously variable transmission when the vehicle is suddenly decelerated.

[0002]

2. Description of the Related Art A continuously variable transmission typified by a V-belt type continuously variable transmission and a toroidal type continuously variable transmission calculates a target speed ratio from an engine required load and a vehicle speed, for example. Shift control is performed so that the actual speed ratio becomes the target speed ratio in accordance with the deviation. Therefore, during acceleration in which the driver depresses the accelerator pedal to increase the required engine load, the target gear ratio is changed to be larger (to be a lower speed gear ratio), and the continuously variable transmission is set to the increased target gear ratio. During a low-load operation in which the gear ratio is downshifted and the driver returns the accelerator pedal to reduce the required engine load,
The target gear ratio is changed to be smaller (to be a higher gear ratio), and the continuously variable transmission is upshifted to the reduced target gear ratio.

However, such a shift is inevitable that a response delay occurs in the progress of the shift from when the target gear ratio is commanded until the gear ratio actually matches the target gear ratio. When the vehicle is suddenly decelerated by braking, the following problem occurs. Figure 5 shows the change tendency of the vehicle speed VSP is the target speed ratio i ^* and the actual speed ratio i of the time of rapid deceleration to decrease with a time course as shown, the normal target speed ratio i ^* is 2 points by the reduction of the The shift is determined as indicated by the chain line, and the shift progresses so that the actual speed ratio i follows the shift response delay as indicated by the two-dot chain line.

However, the above-mentioned shift response delay is caused by the vehicle speed VS
When the vehicle stops at P = 0, the actual gear ratio i cannot be set to the lowest gear ratio (maximum gear ratio). When the vehicle restarts after sudden deceleration, the actual gear ratio i is changed to a higher gear ratio than the lowest gear ratio. I have to start. This means that after restarting at the high-speed side gear ratio, the continuously variable transmission is immediately brought to the lowest speed ratio from the high-speed side gear ratio by a normal shift, and the speed ratio suddenly increases. It is inevitable that a shock will occur when restarting.

In order to solve this problem, conventionally, as described in Japanese Patent Application Laid-Open No. Sho 62-31726, when the vehicle deceleration is large, the target speed ratio is set to the lowest speed ratio.
It has been proposed to increase the shift speed by increasing the deviation between this and the actual gear ratio.

[0006]

By the way, even under the same rapid deceleration, when the vehicle is suddenly decelerated from a high vehicle speed, there is sufficient time until the vehicle stops at a vehicle speed of 0, and the vehicle stops even if there is a delay in the shift response. Sometimes the continuously variable transmission can surely complete the shift to the lowest speed ratio. Nevertheless, if the target gear ratio is set to the lowest gear ratio and the gear speed is increased as in the conventional device described above, the gear speed is too high at a high vehicle speed. As a result of the selection of the lowest speed ratio that does not match the running conditions long before, the engine speed is rapidly increased, causing a so-called engine idling.

The first aspect of the present invention increases the speed change speed by manipulating the target speed ratio based on the fact that the rapid deceleration region in which the speed change response delay is a problem becomes smaller as the vehicle speed increases. The control range is made variable in accordance with the vehicle speed, so that the shift to the minimum speed ratio of the continuously variable transmission is reliably completed when the vehicle stops, without causing the above-mentioned problems at high vehicle speeds that occurred with the conventional device. The main purpose is to be able to do so.

In the first invention, furthermore, at low vehicle speeds, the continuously variable transmission cannot return to the lowest speed gear ratio even in the above case, and the calculation of the gear ratio is difficult and the above-mentioned control becomes random. It is another object of the present invention to avoid the problem by maintaining the speed ratio at the time of the low vehicle speed.

According to a second aspect of the present invention, if the shift speed increase control according to the first aspect of the invention is performed while the input speed of the transmission is low, slippage occurs between the friction transmission elements of the continuously variable transmission. It is an object of the present invention to prevent the slipping problem from occurring by maintaining the speed ratio at the time when the transmission input rotation speed becomes low.

According to the third aspect of the present invention, when the vehicle deceleration is in the large deceleration range, the wheels are locked at the earliest.
Even when the vehicle is stopped, the continuously variable transmission cannot return to the lowest speed gear ratio by the shift speed increase control according to the first invention, and the calculation of the gear ratio is difficult, and the control according to the first invention is random.
It is an object of the present invention to avoid the adverse effects of the above by maintaining the gear ratio at the time of entering the large deceleration range.

According to a fourth aspect of the present invention, when the anti-skid control device is operated, the wheels are not locked, and the gear ratio fixing control according to the vehicle deceleration is not required. However, if the speed ratio is set to the lowest speed ratio under the control of the first invention during rapid deceleration, the rotational inertia of the wheels increases rapidly and the anti-skid control performance deteriorates. The purpose of the present invention is to prevent the speed ratio fixed control and the speed change control according to the speed from being performed, thereby preventing the speed ratio fixed control from being wasted and the anti-skid control performance from being reduced by the speed change control. And

A fifth object of the present invention is to propose an appropriate release range of the above-described fixed gear ratio control.

A sixth object of the present invention is to enable the release of the fixed gear ratio control in accordance with the vehicle speed to be properly performed without hunting of the control.

A seventh object of the present invention is to enable the release of the fixed gear ratio control in accordance with the vehicle speed and the transmission input rotation speed without hunting the control. I do.

[0015]

SUMMARY OF THE INVENTION To achieve these objects, a shift control device for a continuously variable transmission according to a first aspect of the present invention provides a shift control device for a continuously variable transmission in accordance with a deviation between a target speed ratio and an actual speed ratio determined by running conditions. In the continuously variable transmission in which the shift is advanced so as to eliminate the deviation, the deceleration region in which it is not possible to return to the minimum speed gear ratio before the vehicle stops due to a shift response delay of the continuously variable transmission, and the speed returns to the minimum speed gear ratio. At the time of rapid deceleration in which the vehicle deceleration exceeds the set deceleration that increases as the vehicle speed increases, indicating the boundary with the deceleration area that can be decelerated, the target gear ratio is set to be lower than the normal minimum gear ratio regardless of the running conditions. The gear ratio is also increased to increase the gear speed.

The shift control device for a continuously variable transmission according to the first aspect of the present invention further has a low speed range less than a minute set value such that the speed ratio cannot be returned to the minimum speed ratio until the vehicle stops even with the speed change speed increased as described above. During a certain period, the actual gear ratio when the vehicle enters the low vehicle speed range is set as the target gear ratio.

According to a second aspect of the present invention, there is provided a transmission control device for a continuously variable transmission according to the first aspect of the invention, wherein the input rotation speed of the continuously variable transmission is very small instead of the condition that the vehicle is in a low vehicle speed range less than a small set value. When the condition that the engine speed is in the low rotation speed range less than the set value is satisfied, the actual gear ratio when the vehicle enters the low rotation speed region is set as the target gear ratio.

According to a third aspect of the present invention, in the continuously variable transmission according to the first or second aspect, the vehicle deceleration is set to
During a large deceleration range exceeding a fixed set deceleration larger than a variable set deceleration that is increased as the vehicle speed increases, an actual speed ratio when the large deceleration range is entered is set as a target speed ratio. It is characterized by the following.

The shift control device for a continuously variable transmission according to the fourth invention is the shift control device for a continuously variable transmission according to any one of the first to third inventions, wherein the target gear ratio is maintained during the operation of the anti-skid control device regardless of the vehicle deceleration. Is determined according to the running conditions, and normal shift control is performed.

According to a fifth aspect of the present invention, in the transmission control apparatus for a continuously variable transmission according to the third or fourth aspect, when the polarity of the vehicle deceleration is reversed to the acceleration, the transmission ratio fixing control in the large deceleration range is released. The control is returned to the normal shift control.

According to a sixth aspect of the present invention, there is provided a transmission control device for a continuously variable transmission according to any one of the first to fifth aspects, wherein the release of the fixed gear ratio control in the low vehicle speed range is performed by setting the vehicle speed to be smaller than the minute set value. Is performed when a second minute set vehicle speed that is higher by the amount of hysteresis is reached.

According to a seventh aspect of the present invention, in the continuously variable transmission according to any one of the first to fifth aspects, the release of the fixed gear ratio control in the low vehicle speed range and the low rotation speed range is performed when the vehicle speed is reduced. A second minute input speed setting that reaches a second minute setting vehicle speed higher by the hysteresis amount than the minute setting value and that the input rotation speed of the continuously variable transmission is higher by the hysteresis amount than the minute setting value. It is characterized in that it is configured to be performed when the value reaches a value.

[0023]

According to the first aspect of the present invention, the continuously variable transmission normally shifts in accordance with the deviation between the target transmission ratio and the actual transmission ratio determined by the running conditions of the vehicle so that the deviation disappears. However, as the vehicle speed increases, the boundary between the deceleration region in which the speed change response of the continuously variable transmission cannot be returned to the minimum speed ratio before the vehicle stops and the deceleration region in which the speed ratio can return to the minimum speed ratio is shown. At the time of rapid deceleration in which the vehicle deceleration exceeds the increased set deceleration, the target gear ratio is set to a gear ratio larger than the normal minimum speed gear ratio regardless of the vehicle running conditions. Therefore, at the time of sudden deceleration, the deviation between the target speed ratio and the actual speed ratio increases, and the speed of shifting to the lowest speed ratio becomes faster. This eliminates such a situation that the shift to the ratio has not yet been completed.

In the first invention, in particular, since the above-mentioned set deceleration is increased as the vehicle speed increases, the following operation and effect can be obtained. In other words, the time required for the vehicle to stop at a vehicle speed of 0 due to deceleration becomes longer as the vehicle speed becomes higher. Therefore, as the vehicle speed becomes higher, the shift to the lowest gear ratio is still completed when the vehicle is stopped due to a shift response delay due to a sudden deceleration. The problem of not doing so is less likely. This means that the deceleration range that causes the problem becomes smaller as the vehicle speed increases, and the vehicle deceleration at which the above-described shift speed increasing operation according to the first invention should be started, that is, the set deceleration becomes higher as the vehicle speed increases. Should be larger. The setting of the set deceleration according to the first aspect of the present invention matches such a request, and the above-described shift speed increasing operation can be performed only when necessary. As a result, the speed change operation is not performed unnecessarily at the time of high vehicle speed, and the problem that has occurred in the above-described conventional device, that is, the lowest speed gear ratio that does not match the running conditions long before stopping is selected. As a result, while avoiding the problem that the engine speed is rapidly increased and so-called engine idling occurs, the above-mentioned operation and effect, that is, the shift to the lowest speed gear ratio is surely completed at the time of stoppage even at the time of sudden deceleration. The operation and effect described above can be achieved.

In the first aspect of the present invention, while the vehicle is in a low vehicle speed range less than a minute set value such that it is not possible to return to the minimum speed gear ratio before the vehicle stops even with the speed change speed increased as described above, the vehicle enters the low vehicle speed range. In order to set the actual speed ratio at the time of the shift as the target speed ratio, the following operation and effect can be obtained. In other words, in the low vehicle speed range, the continuously variable transmission cannot return to the minimum speed gear ratio when the vehicle is stopped even with the above-described shift speed increase control, and it is difficult to calculate the gear ratio, so that the above control becomes random. According to the further configuration of the first invention, that is, according to the configuration in which the continuously variable transmission is maintained at the speed ratio at the time when the vehicle speed is in the low vehicle speed range, the above-described adverse effects can be avoided.

In the second invention, instead of the condition in the first invention that the vehicle speed is in the low speed range less than the minute set value, the condition is that the input speed of the continuously variable transmission is in the low speed region in less than the minute set value. When the condition is satisfied, the following operation and effect can be obtained because the actual gear ratio when the vehicle enters the low rotation speed region is set as the target gear ratio. In other words, if the shift speed increase control according to the first invention is performed while the transmission input rotation speed is in the low rotation range, slippage occurs between the friction transmission elements of the continuously variable transmission. Since the speed change ratio of the stepped transmission is maintained at the time when the transmission input rotation speed enters the low rotation range, the problem of slippage can be avoided.

In the third invention, while the vehicle deceleration in the first invention or the second invention is in a large deceleration range exceeding a fixed set deceleration larger than a variable set deceleration which is increased as the vehicle speed increases, Since the actual gear ratio when the vehicle enters the large deceleration range is set as the target gear ratio, the following operation and effect can be obtained. That is, when the vehicle deceleration is in the above-described large deceleration range, the wheels are locked at the earliest, so that the continuously variable transmission cannot return to the minimum speed gear ratio when the vehicle is stopped even if the shift speed increases according to the first invention, and Although the calculation is difficult and the control according to the first invention is random, in the third invention, during the large deceleration range,
Since the actual gear ratio when the vehicle enters the large deceleration range is set as the target gear ratio, it is possible to avoid adverse effects due to these.

In the fourth invention, during the operation of the anti-skid control device, the target gear ratio is determined based on the vehicle running conditions regardless of the vehicle deceleration, and the normal gear shift control is performed. can get. In other words, if the anti-skid control device is operating, the wheels do not lock, so that the gear ratio fixing control according to the vehicle deceleration is not required. When the shift speed increase control is performed, the rotational inertia of the wheels increases quickly and the anti-skid control performance is degraded, but the anti-skid control is performed in accordance with the vehicle deceleration during the anti-skid control. If the gear ratio fixing control and the speed change control are not performed, it is possible to prevent the speed ratio fixing control from being wasted and the anti-skid control performance from being reduced by the speed change control.

In the fifth invention, when the polarity of the vehicle deceleration is reversed to the acceleration, the gear ratio fixing control in the large deceleration range is released and the normal gear ratio control is returned. Can be canceled.

In the sixth invention, the release of the fixed gear ratio control in the low vehicle speed range according to any one of the first invention to the fifth invention is performed by a second minute setting in which the vehicle speed is higher by a hysteresis than the minute setting value. Because it is performed when the vehicle speed is reached,
The release of the gear ratio fixed control according to the vehicle speed can be appropriately performed without causing hunting of the control.

In the seventh invention, the release of the fixed gear ratio control in the low vehicle speed range and the low rotation range in any one of the first invention to the fifth invention is performed by the second vehicle speed higher than the minute set value by a hysteresis. And the input speed of the continuously variable transmission reaches a second minute input speed setting value higher by the hysteresis than the minute setting value. The release of the gear ratio fixed control according to the input rotation speed can be appropriately performed without causing hunting of the control.

[0032]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a power train of a vehicle including a shift control device according to an embodiment of the present invention, and a control system thereof.
And the continuously variable transmission 2. The engine 1 includes a throttle valve 5 linked to an accelerator pedal 3 operated by a driver, and the throttle valve 5 has an opening increased by a depression of the accelerator pedal 3 by the driver to increase the engine output. It shall be.

The continuously variable transmission 2 is a well-known V-belt type continuously variable transmission, and includes a primary pulley 7 which is drivingly connected to an output shaft of the engine 1 via a torque converter 6 and a secondary pulley 8 which is aligned with the primary pulley 7. And a V-belt 9 stretched between these pulleys. Then, a differential gear device 11 is drive-coupled to the secondary pulley 8 via a final drive gear set 10, and the wheels (not shown) are rotationally driven by these.

For shifting of the continuously variable transmission 2, one of the flanges forming the V-grooves of the primary pulley 7 and the secondary pulley 8 is moved closer to the other fixed flange. The width of the V-groove can be reduced or the width of the V-groove can be widened by separating the two movable flanges to positions corresponding to the primary pulley pressure P _pri and the secondary pulley pressure P _sec from the control valve 12. Thus, the continuously variable transmission 2 can be continuously variable so that the actual gear ratio matches a target gear ratio described later. For this reason, the control valve 12 is provided with a step motor 14, which is rotated by the drive signal S _step and outputs a primary pulley pressure P _pri and a secondary pulley pressure P _sec to achieve a target gear ratio described later. It is assumed that the control valve 12 is operated as much as possible.

The step motor drive signal S _step is calculated and obtained by the controller 13. Therefore, the controller 13 has a signal from the G sensor 15 for detecting the vehicle acceleration / deceleration G and a throttle for detecting the throttle opening TVO. a signal from position sensor 16, the rotational speed of the primary pulley 7 (primary speed) and a signal from a primary pulley rotation sensor 17 for detecting the N _pri, the secondary pulley 8 rpm (secondary revolution speed) N _sec detection From the secondary pulley rotation sensor 18
A signal from a vehicle speed sensor 19 for detecting a vehicle speed VSP is input.

The controller 13 uses these input information based on the input information.
Then, the shift control shown in FIG. 2 is performed as follows. First
At step 21, the vehicle speed VSP and the throttle opening TV
O, primary rotation speed N_pri, Secondary speed
N_sec, And the vehicle acceleration / deceleration G are read. Next
In step 22, the primary rotation speed N_priWhen
Secondary rotation speed N _secThe actual transmission ratio i, which is the ratio of
N_pri/ N_secIs calculated by the following calculation.

In step 23, based on the vehicle speed VSP and the vehicle acceleration / deceleration G, the present invention for judging the speed change region based on the maps corresponding to FIGS. It is determined whether the gear area A is a sudden deceleration gear shift area where the target shift speed increase control is to be performed, the normal gear shift areas B and E where the normal gear shift control is to be performed, or the gear ratio fixed areas C and D where the gear ratio is to be fixed. . Specifically, if the anti-skid control device is not operating, the vehicle deceleration G is calculated based on FIG.
A rapid deceleration range A exceeding a variable set deceleration a that is set to increase as the vehicle speed increases is determined as a rapid deceleration shift range, and a region where the vehicle deceleration G is equal to or less than the set deceleration a (including the vehicle acceleration range). B is determined to be in the normal shift range. Here, set deceleration a
Is determined with the aim of a deceleration limit value at which the vehicle speed VSP can return to the minimum speed ratio by the time of stoppage due to shift response delay,
Therefore, the area A where the vehicle deceleration G exceeds the set deceleration a
Is an area in which it is not possible to return to the minimum speed gear ratio before the vehicle stops due to a shift response delay for each vehicle speed VSP.

In the deceleration range where the vehicle acceleration / deceleration G is a negative value, the vehicle speed VSP is also equal to the first minute set value VSP _1.
Speed ratio fixed range C when in low vehicle speed range (less than 3 km / h)
And a fixed gear ratio range D when the vehicle deceleration G is in a large deceleration range exceeding a fixed set deceleration -1 g larger than the variable set deceleration a. The former fixed speed ratio range C due to the low vehicle speed is a region where the continuously variable transmission cannot return to the lowest speed ratio when the vehicle is stopped by any measures and the calculation of the speed ratio is difficult and control is random. The gear ratio fixing control in this case will be described later in detail, but means control for maintaining the gear ratio when the vehicle enters the low vehicle speed range C. In the latter, the gear ratio fixed region D due to the large deceleration is such that the wheels are locked at the earliest, so that the infinitely variable transmission cannot return to the minimum speed gear ratio when the vehicle is stopped by any measures, and the calculation of the gear ratio is difficult. This is an area where the control is randomized, and the gear ratio fixing control in this case will be described later in detail, but means a control for maintaining the gear ratio when the vehicle enters the large deceleration region D.

If the anti-skid control device is in operation, the vehicle deceleration range other than the above-mentioned fixed speed ratio range C is set to the normal speed range over the entire range as indicated by E based on FIG. The reason is that the wheels are not locked during the operation of the anti-skid control device, so that the gear ratio fixing controls A and D according to the vehicle deceleration are unnecessary. This is because, when the speed change control for setting the speed change ratio is performed, the rotational inertia of the wheels increases rapidly, and the anti-skid control performance deteriorates.

The above area determination in step 23 of FIG.
If the result of the determination is that the normal shift range is B or E,
If so, the control proceeds to steps 24-27, and
Shift normally. In step 24, the vehicle speed VSP
Set in advance from the throttle opening TVO
4 based on the shift map of FIG._pri ^*
Search for. Then, at step 25, the target
Mali speed N_pri ^*Is the secondary rotation speed N_secRemoved by
Target gear ratio i according to the running state^*=
N_{pr i} ^*/ N_secIs calculated. Next, in step 26
And the target gear ratio i^*Ratio deviation between the speed ratio and the actual speed ratio i
Δi is calculated, and in step 27, the speed ratio deviation
Step motor drive signal that eliminates Δi from the predetermined gain
No. S_stepTo the step motor 14 in FIG. that's all
The control valve 12 sets the actual speed ratio i to a predetermined value.
In the target gear ratio i^*Primary
Relief pressure P_priAnd secondary pulley pressure P _secOutput
Then, normal shift control is executed.

If the result of the area determination in step 23 of FIG. 2 is that of the rapid deceleration shift area A shown in FIG. 3A, the control proceeds to steps 28, 26 and 27 and In this way, a shift different from the normal shift is performed. Step 2
At 8, the target gear ratio i ^* is set to a gear ratio larger than the normal lowest gear ratio as shown by the solid line in FIG.
Next, in step 26, a gear ratio deviation Δi between the large target gear ratio i ^* and the actual gear ratio i is calculated, and in step 27, a step motor drive signal S such that the gear ratio deviation Δi is not a predetermined gain is obtained. _Step is instructed to the step motor 14 shown in FIG. 1 to advance the downshift to the lowest speed ratio.

Therefore, during the rapid deceleration, the speed ratio deviation Δi calculated in step 26 increases, and the downshift speed to the lowest speed ratio is increased accordingly. For this reason, if normal shift control is performed with a shift response delay, even during a rapid deceleration in which the minimum speed shift ratio cannot be reached when the vehicle is stopped, it is apparent from the temporal change of the actual speed ratio i shown by the solid line in FIG. Thus, downshifting to the lowest speed ratio can be reliably completed when the vehicle is stopped.

By the way, as shown in FIG. 3A, since the variable set deceleration a is increased as the vehicle speed increases, the following operation and effect can be obtained. In other words, the time required for the vehicle to stop at a vehicle speed of 0 due to deceleration becomes longer as the vehicle speed becomes higher. Therefore, as the vehicle speed becomes higher, the shift to the lowest gear ratio is still completed when the vehicle is stopped due to a shift response delay due to a sudden deceleration. The problem of not doing so is less likely. This means that the deceleration region causing the problem becomes smaller as the vehicle speed increases, and the vehicle deceleration at which the above-described shift speed increasing operation should be started, that is, the set deceleration at which the shift speed increasing operation is started is high. Should be as high as vehicle speed. Since the variable set deceleration a in the present embodiment is increased as the vehicle speed increases, the shift speed increasing operation can be performed only when necessary in accordance with such a request. As a result, the speed change operation is not performed unnecessarily at the time of high vehicle speed, and the problem that has occurred in the above-described conventional device, that is, the lowest speed gear ratio that does not match the running conditions long before stopping is selected. As a result, while avoiding the problem that the engine speed is rapidly increased and so-called engine idling occurs, the above-mentioned operation and effect, that is, the shift to the lowest speed gear ratio is surely completed at the time of stoppage even at the time of sudden deceleration. The operation and effect described above can be achieved.

In the step 23 of FIG.
If so, the control proceeds to steps 29 to 32,
Control for fixing the gear ratio is performed as follows. Step 2
In step 9, the flag FLAG is set to 1 in step 31 when the vehicle enters the gear ratio fixed range, and is not shown, but is reset to 0 when a command to cancel the gear ratio fixed control described later is given. Is determined. Since FLAG = 0 at the first time after entering the gear ratio fixed range, the control is executed in step 3
Proceeds to 0,31, stores the actual gear ratio i of the instantaneous as gear ratio i _m at the time of entering the fixed gear ratio range, and sets the flag FLAG to 1 in step 32, entered the fixed gear ratio range to set the target speed ratio i ^* a gear ratio i _m at the time was. These steps 30 and 31 are executed only once by the above-mentioned setting of the flag FLAG.
Target speed ratio is set at 2 i ^* is held to the gear ratio i _m at the time of entering the fixed gear ratio range. Thereafter, step 26,
CVT by the same processing as above described in 27, so that the actual gear ratio i is held at the target gear ratio i ^* = i _m, i.e., gear ratio i _m at the time of entering the fixed gear ratio range Is controlled so as to be fixed at.

The operation and effect of the gear ratio fixing control will be described below. In the fixed gear ratio zone C, while the vehicle speed VSP is low vehicle speed range below the minute set value VSP ₁ = 3km / h, and the actual gear ratio i _m at the time of entering this low vehicle speed range and the target speed ratio i ^*, Since the continuously variable transmission is fixed at the gear ratio, the following operational effects can be obtained. That is, in the low vehicle speed range C, the continuously variable transmission cannot return to the minimum speed gear ratio when the vehicle is stopped even with the above-described shift speed increase control, and it is difficult to calculate the gear ratio. while the place to be, in this embodiment by fixing the gear ratio i _m at the time when the continuously variable transmission has become the low vehicle speed range C, it is possible to avoid these by negative effects.

Although not shown in the control program of FIG. 2 only in FIGS. 3 (a) and 3 (b),
The gear ratio fixed control in the condition that the primary rotational speed _Npri, which is the input rotational speed of the continuously variable transmission, is in the low rotational speed range of less than the minute set value 200 rpm, even if the vehicle speed conditions are not as described above. May be performed. Also in this case, the actual gear ratio when the vehicle enters the low rotation speed range is naturally set as the target gear ratio. In this case, if the above-described increase control of the shift speed is performed while the transmission input rotation speed (primary rotation speed _Npri ) is in the low rotation range, the V belt 9 (FIG. 1) which is a friction transmission element of the continuously variable transmission is used. ) Causes the slippage with respect to the pulleys 7 and 8, but fixes the continuously variable transmission to the speed ratio at the time when the transmission input rotation speed enters the low rotation range, thereby avoiding the slippage problem. can do.

Next, the operation and effect of the fixed gear ratio control in the fixed gear ratio region D of FIG. 3A will be described. The fixed speed ratio range D is a fixed set deceleration (-) where the vehicle deceleration G is larger than the variable set deceleration a that is increased as the vehicle speed increases.
1g), but this large deceleration range D
In the actual gear ratio i _m at the time of entering to the region as a target gear ratio i ^*, the continuously variable transmission because it is fixed to the gear ratio, operation and effect can be obtained or less. That is, the vehicle deceleration G
When the vehicle enters the above-mentioned large deceleration range, the wheels are locked at the earliest, so that the continuously variable transmission cannot return to the lowest speed ratio when the vehicle is stopped even by the above-mentioned speed change control, and it is difficult to calculate the speed ratio, and While the speed increase control is random, the continuously variable transmission is fixed at the actual gear ratio at the time of entering the large deceleration range while the large deceleration range D is in effect. Can be.

How to cancel the fixed gear ratio control in the fixed gear ratio ranges C and D shown in FIGS. 3A and 3B is omitted in the control program of FIG. 2 because it becomes complicated. However, the release of the fixed gear ratio control is performed when the conditions shown in FIG. First release of the fixed gear ratio control in the low speed range in the fixed gear ratio zone C, large by the hysteresis amount than the first micro-set value VSP ₁ the vehicle speed VSP is the as shown by F in FIG. 3 (c) first reaches a minute set value VSP _2, and, for the first time to perform when the transmission input rotational speed N _pri reaches only a high second set value 250rpm hysteresis amount than the minute setting value 200 rpm. For this reason, it is possible to avoid a hunting phenomenon in which execution and release of the gear ratio fixed control are frequently repeated.

Next, the release of the gear ratio fixed control in the large gear deceleration region in the gear ratio fixed region D will be described. This gear ratio fixed control is performed by the vehicle deceleration G as shown by H in FIG. Is released when the polarity is inverted from the deceleration value to the acceleration value, and the gear ratio fixing control can be appropriately released.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a power train of a vehicle equipped with a continuously variable transmission equipped with a shift control device according to an embodiment of the present invention, together with a control system thereof.

FIG. 2 is a flowchart showing a shift control program executed by a controller in the embodiment.

FIG. 3A is a view showing a state where the anti-skid is not operated.
FIG. 4B is a region diagram of various types of shift control modes, and FIG. 4B is a region diagram of a shift control mode during an anti-skid operation;
FIG. 7 is a region diagram showing conditions for canceling the gear ratio fixed control in the gear shift control modes.

FIG. 4 is a shift pattern diagram illustrating a shift map used in a normal shift mode.

FIG. 5 is a time chart showing a shift operation at the time of rapid deceleration in comparison with a case where the shift speed increase control according to the present invention is performed and a case where it is not performed.

[Explanation of symbols]

 Reference Signs List 1 engine 2 continuously variable transmission 3 accelerator pedal 5 throttle valve 6 torque converter 7 primary pulley 8 secondary pulley 9 V belt 10 final drive gear set 11 differential gear device 12 control valve 13 controller 14 step motor 15 G sensor 16 throttle opening sensor 17 Primary pulley rotation sensor 18 Secondary pulley rotation sensor 19 Vehicle speed sensor

Continued on the front page (51) Int.Cl. ⁷ Identification code FI F16H 59:54 F16H 59:54 59:70 59:70 63:06 63:06 (72) Inventor Masahiro Yamamoto 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Address Nissan Motor Co., Ltd. (56) References JP-A-3-48061 (JP, A) JP-A-1-275947 (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 (7)

(57) [Claims] 1. A continuously variable transmission that shifts according to a deviation between a target transmission ratio and an actual transmission ratio determined by running conditions so as to eliminate the deviation, and a shift response delay of the continuously variable transmission. The deceleration range in which the vehicle deceleration cannot return to the minimum speed ratio before stopping and the deceleration region in which the speed reduction can return to the minimum speed ratio. At the time of exceeding rapid deceleration, the target speed ratio is set to a speed ratio larger than the normal lowest speed speed ratio regardless of the running conditions so that the speed change speed is increased. While the vehicle is in a low vehicle speed range below a minute set value such that it cannot return to the lowest speed gear ratio, the actual gear ratio when the vehicle enters the low vehicle speed region is set as the target gear ratio. Transmission control device for continuously variable transmission . 2. The condition according to claim 1, wherein the condition that the input rotation speed of the continuously variable transmission is in a low rotation speed range less than the minute set value is used instead of the condition that the vehicle speed is in a low vehicle speed range less than the minute set value. A shift control device for a continuously variable transmission, wherein when satisfied, an actual speed ratio when the vehicle enters the low rotation range is set as a target speed ratio. 3. The large deceleration range according to claim 1, wherein the vehicle deceleration is a large deceleration range that exceeds a fixed set deceleration that is larger than a variable set deceleration that is increased as the vehicle speed increases. A shift control device for a continuously variable transmission, wherein an actual speed ratio at the time of entering is set as a target speed ratio. 4. The normal gear shift control according to claim 1, wherein the target gear ratio is determined based on the running conditions regardless of the vehicle deceleration during the operation of the anti-skid control device. A shift control device for a continuously variable transmission, wherein the shift control device is configured to perform the following. 5. The vehicle according to claim 3, wherein when the polarity of the vehicle deceleration is reversed to the acceleration, the gear ratio fixing control in the large deceleration range is released to return to a normal gear shift control. Transmission control device for a continuously variable transmission. 6. The vehicle according to claim 1, wherein the release of the fixed gear ratio control in the low vehicle speed range is changed to a second minute set vehicle speed in which the vehicle speed is higher by a hysteresis than the minute set value. A shift control device for a continuously variable transmission, characterized in that the shift control device is configured to perform the shift operation when the shift is reached. 7. The method according to claim 1, wherein the release of the fixed gear ratio control in the low vehicle speed range and the low rotation range is performed by a second vehicle speed higher than the minute set value by a hysteresis. The control is performed when the vehicle speed reaches a minute set speed and the input rotational speed of the continuously variable transmission reaches a second minute input rotational speed set value which is higher by hysteresis than the minute set value. Transmission control device for continuously variable transmission.