JPH11230293A - Speed change controller of continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure shift hunting and correct the control range of a continuously variable transmission so that an appropriate transmission ratio range is ensured by absorbing any production dispersion in its precess cam if any. SOLUTION: A continuously variable transmission 2 has a precess cam with a high-pitched region of different inclinations at one or both ends. A means 5 is provided which includes a high-pitched region (shift hunting) detector and corrects a transmission ratio limiter such that it narrows the transmission ratio range if any shift hunting is detected. The means 5 gets further effective when designed to have a mode in which the transmission ratio limiter related to shift hunting generated is corrected to narrow the transmission ratio range and the other transmission ratio limiter is corrected to widen the transmission ratio range, or the transmission ratio limiters are changed gradually to widen the transmission ratio range by a preset transmission ratio until any shift hunting is just generated.

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.

[0002]

2. Description of the Related Art As a continuously variable transmission, a toroidal type continuously variable transmission using a precess cam having an inclined cam surface in a feedback system for feeding back a transmission ratio to a transmission control valve is known. This type of toroidal-type continuously variable transmission includes an input disk, an output disk, and a pair of friction rollers (power rollers) arranged in a toroidal groove formed by both disks so as to make frictional contact with both disks. A roller support member (trunnion) rotatably supporting the friction roller and being rotatable and movable in the axial direction; a hydraulic cylinder capable of driving the roller support member in the axial direction; Speed control means for controlling the oil pressure so as to obtain a speed change ratio, a precess cam having a slope which rotates integrally with the roller support member to feed back an actual speed ratio to the speed change control means, and a slope of the precess cam. And a link that can swing by the rotation of the precess cam in contact with the precess cam. Here, the shift control means can be configured to include a shift control valve as a hydraulic leveling valve and a step motor for driving a shift control valve for giving a gear ratio command value. Motion such as tilting of the friction roller can be fed back to the shift control valve via the contacting link.

[0003] In such a speed change control device for a continuously variable transmission, the response delay is small from when a speed ratio command is given until the friction roller reaches a corresponding tilt angle, while the friction roller tilt angle (speed ratio) is reduced. It is preferable that the number of vibrations, that is, so-called hunting, until the gear ratio command value (target gear ratio) settles is small. Generally, as a shift control valve, an overlap type shift control valve (in a balanced state of the shift control valve after a shift is completed, a sleeve valve body (for example, FIG. 2; 251A)
) And a feedback spool valve element (also see FIG. 251B) with a shift control valve having a configuration in which the valve port components overlap (fit) with each other. Even when the valves are in a balanced state, the operating oil used for the hydraulic control does not continue to leak, and the energy loss of the engine (also see FIG. 1; see FIG. 1) that drives the oil pump (see FIG. 1; 29) is reduced. This is advantageous in that the hunting tends to occur relatively easily (see JP-A-5-39).
No. 850). Also, in general, if the inclination of the cam slope formed on the precess cam is set to be too steep, hunting tends to occur easily because the feedback gain is large, and the cam inclination is usually set so that such a state does not occur, The feedback control gain is tuned in accordance with the cam inclination. In addition, the area other than one end or both ends of the precess cam is a moderately inclined area, that is, a normal cam inclined area that is not so steeply inclined as described above, and at one end or both ends, the normal cam inclined area is It is conceivable to provide a steeply inclined region having a different inclination. However, when such a precessed cam with a slope having a steeply inclined region and a gentlely inclined region at least at one end is used, the following reasons are caused by the steeply inclined portion. This may cause a shift hunting.

[0004]

FIG. 3 is a diagram which will be referred to also in the following description. When a precess cam having a steeply inclined region at both ends is used, the number of steps of a step motor for giving a speed ratio command is determined. The relationship between the friction roller tilt angle (speed change ratio), the variation in the processing of the precess cam, the hunting occurrence area, and the like is shown. As shown in the drawing, if the characteristics of the solid line (nominal) are different from the processing accuracy of the precess cam due to the processing variation and the like, and if the individual used precess cams vary within the variation width as shown by the broken line, in this case, The principle of hunting and the like can be explained as follows. That is, (1) For example, taking the variation on the high (Hi) side as an example, if the vehicle enters the steep slope region earlier than the nominal (design value), the number of steps of the step motor (STEP) in STEP 1 shown in FIG. It can be seen that the position is insufficient to achieve the target desired gear ratio (the gear ratio Hi in the design gear range), and the gear ratio does not reach the gear ratio as it is and does not reach Hi. Therefore, at this time (that is, even when the vehicle enters the steeply inclined region at the end of the precess cam), in order to obtain the gear ratio Hi by feedback control, up to the position of STEP 2 shown on the right side of the broken line characteristic in FIG. I have to send more. Here, the control amount difference of "STEP2-STEP1" is very large with respect to the normal speed change range, and when the downshift is performed to the low side at the next moment, the delay becomes "lag", and at the same time, the feedback control step number difference Is large ("Tilt angle / STEP" is small)
Therefore, hunting is accompanied by feedback control. (2) Since the feedback control gain is usually tuned in accordance with the cam inclination, if the vehicle enters a steeply inclined surface, hunting occurs in excessive gear shifting. Therefore, it is necessary to set a shift range within the normal cam range by setting a limit on the shift range to avoid a region where hunting occurs (a steeply inclined region). However, if there is an individual difference in the normal cam area due to processing variation or the like, the shift range must be set in anticipation of the individual difference, and the shift range becomes narrower than the normally set shift range. In this figure, if the shift range is set so as not to enter the steep slope region due to the precess cam machining accuracy or the like, the shift range of the nominal value (the “design shift range” indicated by the vertical arrow on the right side in the figure) is set as shown in the figure. This results in a narrow shift range (“shift range in anticipation of variation” indicated by a vertical arrow on the left side in the figure).
Therefore, in order to obtain the required shift range, that is, the conventional method as described above (a method of setting the shift range in anticipation of variations in individual differences, etc.), and the required shift range can be obtained. Then, the precess cam itself must be made large. Further, in reality, there is a limit to the tilt angle, and when a shift range is designed in consideration of variations, it becomes difficult to obtain a speed ratio width required for a transmission. The present applicant has previously described Japanese Patent Application Laid-Open No. 5-2
No. 6317 (Literature 1) proposes a technique in which a precess cam having a steeply inclined region having different inclinations at both ends is used and a torque shift prevention region is provided. In this steeply inclined region, hunting occurs due to a large feedback gain. Occur. In order to prevent this hunting, it is necessary to set the shift range of the continuously variable transmission within the normal cam inclination region other than the steep inclination region as described above. However, the shift range that can be set in the normal cam inclination region in anticipation of the processing variation of the slope of the precess cam is extremely narrow. Further, since the cutting process is different for each cam inclination, there is a possibility that the speed ratio at the steeply inclined position varies from part to part. Similarly, as shown in FIG. There is still room for improvement in that the transmission ratio width of the transmission range becomes narrower.

FIG. 16 is also referred to in the embodiment of the present invention described later. As shown in FIG. 16, the characteristics are shifted laterally as shown by adjusting the speed ratio, and the nominal line shown by a broken line is compared with the nominal line shown by a solid line. Step direction (horizontal axis direction) like characteristics
In some cases, deviations may occur. As a result, even if the same step number is output as the step motor step number, the speed ratio may enter a steep slope region, and the speed change hunting occurs in the same manner as described above.
Therefore, also in this case, when the conventional method of setting the shift range in consideration of such variations and anticipating the variation is used, there is a similar problem that the shift range becomes narrower than the normally set shift range.

The present invention is based on the above considerations and the following considerations, and seeks to make improvements in these respects. Even if there is a manufacturing variation of the precess cam, it is absorbed. In order to ensure an appropriate gear ratio width, the problem is solved by measuring the gear shift hunting and correcting the control area. More specifically, the present invention does not set the shift range that has been set in the past, but does so in a wide range or without considering variations, and sets or corrects the gear ratio width when shift hunting occurs. Things.

[0007]

According to the present invention, there is provided the following shift control device for a continuously variable transmission. That is, the present invention provides an input disk, an output disk, a pair of friction rollers disposed in frictional contact with both disks in a toroidal groove formed by both disks, and rotatably rotating the friction rollers. A roller supporting member that is supported, rotatable and axially movable, a hydraulic cylinder capable of driving the roller supporting member in the axial direction, and controlling a hydraulic pressure so as to obtain a target gear ratio for the hydraulic cylinder. And a slope having at least one end having a steeply inclined region that is steeper than a centrally inclined region at least at one end thereof, and that is integrally rotated with the roller support member so as to feed back an actual gear ratio to the transmission control unit. Speed control of a continuously variable transmission having a precessed cam with a link and a link abutting on a slope of the precessed cam and swinging by rotation of the precessed cam. In the device, a steep slope region detecting means for detecting a shift hunting generated by the link abutting on the steep slope region of the precess cam; and, when the shift hunting is detected based on the steep slope region detecting means, the shift is performed. A shift range limiting means for limiting the range in a direction in which the range becomes narrower is provided (claim 1).

Further, the steeply inclined region is provided at both ends of the precess cam, and when a steeply inclined region at one end of the both ends causes shift hunting, and when this is detected by the steeply inclined region detecting means, the speed ratio is reduced. The shift range is limited in the direction in which the shift range is narrowed by the shift range limiting means on one side of the shift side or the large gear ratio side where the shift hunting has occurred, and the other of the small gear ratio side or the large gear ratio side is selected. In the second aspect, the limitation of the shift range of the shift range limiting means is corrected in the direction in which the shift range is widened (claim 2).

Further, the present invention provides an input disk, an output disk, a pair of friction rollers arranged in a toroidal groove formed by the two disks so as to make frictional contact with the two disks, and A roller support member rotatably supported and rotatable and movable in the axial direction, a hydraulic cylinder capable of driving the roller support member in the axial direction, and a target gear ratio transmitted to the hydraulic cylinder. Shift control means for controlling oil pressure, and a steeply inclined area which is integrally rotated with the roller supporting member for feeding back an actual gear ratio to the shift control means, and which is steeply inclined at least at one end from a gentle inclined area at the center. Continuously variable transmission having a precessed cam having a slope, and a link abutting on the slope of the precess cam and swinging by rotation of the precess cam. In the shift control device, and the steep area detection means for detecting a shift hunting phenomenon in which the link is generated by contacting a steep area of the precess cam,
A shift range limiting means capable of limiting the shift range to a predetermined state, and limiting the shift range limiting means immediately before shift hunting occurs and the shift hunting is detected based on the steep slope region detecting means. A changing means for changing the speed change range in a direction in which the speed change range is widened by a predetermined amount of gear ratio up to a predetermined speed ratio is provided (claim 3).

The steep slope region detecting means estimates a hunting frequency based on one of an input rotation speed, an output rotation speed, a control command line pressure, and an actual line pressure of the continuously variable transmission, and calculates a measured rotation speed. Alternatively, when the measured gear ratio and the measured tilt angle are hunting at this frequency, it is determined that hunting occurs in the steeply inclined region (claim 4).

Further, the hunting is determined at a vehicle speed set for each gear ratio or higher.

[0012]

According to the present invention, the speed change range in the normal cam inclination region is not set as in the prior art, and is widened (or narrowed (claim 3)), or the speed is changed without considering variations. Each time hunting occurs, the shift range can be corrected. Therefore, the control area can be corrected by measuring the shift hunting, and the problem of the conventional method of setting the shift range in anticipation of manufacturing variations and the like as described at the beginning can be appropriately solved. Even if there is variation in the use precess cam, regardless of the variation of each individual use individual, while avoiding shift hunting as much as possible,
In addition, it is possible to use the normal inclination region other than the hunting occurrence region as effectively as possible, and to realize appropriate shift control.

[0013] In particular, in the first aspect, even if it is initially set wide, that is, the shift range according to the conventional method which must be narrowed in advance as indicated by, for example, the left vertical arrow in FIG. Even if the shift hunting is detected, even if the shift hunting is detected, even if the shift hunting is detected, the shift range is appropriately set and corrected when the shift hunting occurs. it can. Therefore, as compared with the conventional case, the shift range must be set in anticipation of individual differences and the like, so that the shift range is narrower than the normally set shift range, and the shift range that can be set within the normal cam inclination region is a very narrow range. There is no disadvantage such that the precess cam itself has to be large in order to obtain the required shift range.

According to a second aspect of the present invention, in addition to the same operation and effect as described above, the precess cam to be used is made as small as possible with respect to a deviation due to a variation in the stepping direction of the stepping motor as shown in FIG. The control area can be corrected by making the best use of the control area. In this case, it is preferable when there is such a variation, and similarly,
At the time when the shift hunting occurs, the shift range is corrected to be narrower on one side, and is corrected to be wider on the other side. As a result, the shift range is maintained.

A third aspect of the present invention is similar to the first aspect, except that the shift range is not set or the variation is not taken into account when the shift hunting occurs. Can be appropriately corrected, and the same aim can be realized. In this case, contrary to the above, even if the initial setting is narrow (for example, FIG. 18), until the shift hunting occurs,
The shift range is gradually expanded in a direction in which the shift range is widened, so that the normal inclination region other than the hunting occurrence region can be used as effectively as possible, and appropriate shift control can be realized. So, if you do this,
As a result of being able to change and correct such a change, regardless of the manufacturing variation of the used precess cam, the gear ratio width can be ensured, so that the cam is more effectively used as much as possible, so that the cam becomes more effective. .

Further, in the present invention, the detection of the steeply inclined region can be suitably carried out by a mode in which this is determined as hunting due to the steeply inclined region, and such a method of judging hunting is used. In this case, there is no need for a mechanism or means for directly detecting the steeply inclined region at one end or both ends of the precess cam, and there is an additional effect that it can be realized by software processing. Preferably, when hunting is determined as described in claim 5, in this case, the same operation as described above can be more appropriately realized in consideration of the vehicle speed.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a system configuration according to an embodiment of the present invention, in which the present invention is applied to a toroidal type continuously variable transmission. In the figure, 1 is an engine (internal combustion engine),
2 is a toroidal type continuously variable transmission (CV) as a continuously variable transmission.
T) are shown respectively.

As shown, the CVT 2 includes a torque converter 21, a forward / reverse switching mechanism 22, a toroidal transmission unit 23, a hydraulic control device 25, and a step motor 26.
And the like. The hydraulic control device 25 includes a PL duty solenoid 27, an L / U duty solenoid 28, an oil pump 29, and the like, and further includes a later-described transmission control valve (FIG. 2).

In this embodiment, the toroidal transmission unit 23
Is a double-cavity type using two units of an input / output cone disk (input / output disk) and two power rollers (friction wheels). In this case, the output disks are back-to-back with each other. The unit may be arranged coaxially before and after the input / output disk rotation axis.

Here, the toroidal transmission unit includes a pair of power rollers arranged in frictional contact with the two disks in a toroidal groove formed by both the input disk and the output disk, and rotates the power rollers. A roller support member that is freely supported, rotatable and movable in the axial direction, a hydraulic cylinder that can drive the roller support member in the axial direction, and controls a hydraulic pressure so that a target gear ratio is obtained for the hydraulic cylinder. Speed change control means,
In order to feed back the actual speed ratio to the speed change control means, a precess cam having a slope that rotates integrally with the roller support member, and a link that is in contact with the slope of the precess cam and that can swing by the rotation of the precess cam may be provided. it can.

FIG. 2 shows the toroidal transmission unit 2.
3, an outline of a peripheral structure including a servo piston portion that controls shift control is illustrated on the trunnion 232 (power roller support member) side with the precess cam 235, and the sleeve 2 of the shift control valve 251 is also illustrated.
The configuration of 51A, spool 251B and step motor 26 is shown.

A servo piston 234 is attached to a shaft 233 of the trunnion 232 that supports the power roller 231, and a precess cam 23 is attached to a lower end of the shaft 233.
5

The precess cam 235 is provided with a speed change link 236.
(X2) to control the offset amount of the power roller trunnion 232 in the oscillating axis direction (Y) and the tilt angle (θ) amount around the axis. The feedback is provided to the valve 251 in the device 25. The shift control object is a spool 251 of a shift control valve 251 (hydraulic leveling valve) by a step motor 26.
The position B is controlled (X1). Basically, the speed ratio RTO is uniquely determined by the control position of the step motor 26. The Y-θ hydraulic servo shown in FIG. 1 includes a feedback system using the servo piston 24 and the precess cam 235.

In this embodiment, the precess cam 235 to be applied is a precess cam having a steeply inclined region having different inclinations at both ends, as described in the above-mentioned document 1, and therefore, within the range of the design rotation angle. It has a normal slope area, and both ends are slopes of a steep slope area where the slope is steeper than the slope in the normal slope area. Therefore, by this, the feedback gain of the speed ratio when the rotation angle of the power roller trunnion 232 around the axis exceeds the limit value of the design range or a value near the limit value is made higher than those in other cases. As a result, as described above, when the design exceeds the normal inclination region as described above, the operation amount for returning to the target state is increased (the movement amount of the spool 251B is increased by the increased inclination). And the change in flow rate acting on the piston 234 by the shift control valve 251 increases), the aim described in the document is realized, and the target state can be quickly returned to. In addition, the precess cam 235 to be applied may be a precess cam in a mode in which a steeply inclined region having a different inclination is set only on one end side instead of both ends, in addition to the above-described configuration.

Returning to FIG. 1, the step motor 26 and the solenoids 26 and 27 serve as an electronic control unit for the transmission.
Controlled by the VT control unit (C / U) 5,
Here, the control unit 5 detects information on the throttle opening TVO and the engine (engine) speed Ne from the engine electronic control device 6 which can communicate with the control unit, and the transmission input shaft speed Nt. A signal from the input rotation sensor 31, a signal from the output rotation sensor 32 for detecting the transmission output shaft rotation speed No (a value corresponding to the vehicle speed Vsp), and the like are input. Here, the control unit 6 further includes a signal from a selector switch (SW) 33 provided in association with the selector 4, a signal from a low switch (SW) 34, a signal from an oil temperature sensor 35, A signal from the brake switch (SW) 36, a signal from the snow switch (SW) 36, and the like can be input.
Low μ road signal (Fsnw) from the control unit 5
Can be received.

The transmission control unit 6 includes a microcomputer. Here, the input signal waveforms from various sensors and the like are shaped, and an analog signal value is converted into a digital signal value by A / D conversion. An input detection circuit having a function of: an arithmetic processing circuit (CPU);
A shift control program executed by the arithmetic processing circuit;
ON / OFF of L / U clutch of torque converter 21
A storage circuit (RAM, ROM) for storing various control programs, such as an L / U control program and a line pressure control program, as well as calculation results and other information, and a drive circuit for driving the step motor 26 and the solenoids 26 and 27. It can be composed of an output circuit for transmitting a control signal and the like.

The control unit 6 basically calculates a target gear ratio based on various input information and executes control for the step motor 26 so that the gear ratio becomes the target value. Shift control can be performed. In addition to this, the precess cam 2 is controlled so that appropriate shift control is performed while suppressing shift hunting.
In addition to providing a steep slope region (shift hunting) detection function related to 35, when a shift hunting occurs, a control region correction control for correcting the speed ratio limiter in a direction to reduce the speed ratio width is also executed. That is, FIG.
The power roller tilt angle characteristic with respect to the number of control steps of the step motor is shown. In this case, the correction control is also executed in order to absorb the influence of the manufacturing variation of the precess cam 235 in the hunting occurrence area.

In this case, the functions of the CVT control unit 6 include a gear ratio measuring unit, a hunting determining unit,
It can be understood that the target speed ratio correction unit, the target speed ratio calculation unit, and the target control amount calculation unit have respective functions. The control unit 6 preferably estimates the hunting frequency due to the steep inclination based on any of the CVT operating state, the input rotation speed, the output rotation speed, the control command line pressure, or the actual line pressure. If the rotational speed, the measured gear ratio, and the measured tilt angle are hunting at this frequency, it is determined that hunting occurs in the steeply inclined region. Preferably, the hunting determination is performed at a vehicle speed set for each gear ratio or higher.

Hereinafter, a more specific description will be given with reference to FIGS. FIG. 4A shows a D range target rotation map T.
Nt. The horizontal axis is the vehicle speed Vsp, and the vertical axis is the target input shaft rotation speed RREV00 (map search target rotation speed). The target input shaft rotation speed RREV00 is searched based on the throttle opening TVO and the vehicle speed Vsp. The highest design (Hi) gear ratio is TNthi, and the lowest design (Low) gear ratio is TNtlo.
w. The map characteristics can be applied to the processing in the following control program (Step S201 in FIG. 10). FIG. 6B shows the D range target rotation limiters TNtlow and TNthi. Similarly, the horizontal axis is the vehicle speed Vsp, and the vertical axis is the target rotation map of the target input shaft speed. When hunting occurs, the low-side corrected speed ratio limit value RTO and the Hi-side corrected speed ratio limit value RTO are set.
The gear ratio limiters on the Low and Hi sides are changed with H as a limit.

FIGS. 5 to 11 also include a control area correction process executed by the transmission control unit (C / U) 5 to correct the gear ratio limiter in the direction of decreasing the gear ratio width when the gear hunting occurs. 5 is an example of a shift control program. For any of these, a certain period of time (eg, 1
This is a routine for performing control (processing) every 0 msec) (periodic interruption).

Here, the basic processing is performed from three functional parts (processing parts) of a signal measurement unit (FIG. 5), a signal output unit (FIG. 6), and a shift control unit (CVT control unit) (FIG. 8). It is represented as In this example program,
A reading process (RAM with backup) when the backup power supply is turned on, as shown in FIG. 7, can be added to this.

FIG. 5 shows a process of measuring signals to be measured in the shift control. In the signal measurement unit, first, as shown in FIG. 5, based on input information from the corresponding sensors 31, 32, etc., the throttle opening TVO at the time, the engine (engine) speed Ne,
The input shaft rotation speed Nt and the output shaft rotation speed No are measured (step S1).

In the following step S2, the vehicle speed Vsp,
The calculation is executed for the gear ratio RTO and the estimated input torque Tin. Here, the vehicle speed Vsp is the output shaft speed No.
X The conversion ratio A is calculated by the product of the conversion coefficients A, and the gear ratio RTO is calculated by the input shaft speed Nt / the output shaft speed No. Also, regarding the estimated input torque Tin, the engine torque map (T
In step e), an engine torque Te is searched for based on the engine speed Ne and the throttle opening TVO, and a value Tin is calculated as a product of the engine torque Te and a torque converter torque ratio t (Nt / Ne). Here, in an engine torque characteristic map as exemplified in FIG. 12, a Te value is searched from the engine torque map using Ne and TVO as parameters, and further, a torque converter speed ratio e
(= Nt / Ne) as torque parameter t (e)
From the product of, Te (TVO, Ne) × t (Nt / Ne)
Then, the input torque Tin is searched.

FIG. 6 shows a control signal output program for outputting the step number (step motor control step number ASTP) of the step motor 26 obtained by calculation as described later in step S3. The signal output unit executes the output process every time the step S3 is executed by a periodic interruption every predetermined time.

Further, in this example of the program, the read processing shown in FIG. 7 is executed for the RAM with backup in the control unit 5 when the backup power supply is turned on. That is, once the backup power supply is turned on, by executing step S4 in FIG. 7, LmtLow (corrected lowest speed ratio) ← designed lowest speed ratio RTOMAX, LmtHi.
(Maximum Hi gear ratio after correction) ← Design maximum Hi gear ratio RTOMI
The process as N is performed.

FIG. 8 is a shift control program for determining the number of step motor control steps.
It comprises a hunting determining section (step S5), a shift determining section (step S6), and a shift control section (step S7). In step S5, a steep inclination region (shift hunting) of the precess cam 235 is detected, and a process of changing the speed ratio limiter when shift hunting occurs is performed. Step S
In step 5 and step S7, what kind of shift should be performed, that is, calculation about the target gear ratio and calculation of the step motor control step number based on the calculation are executed. These can be the following processing contents, respectively.

FIG. 9 shows an example of the processing performed by the hunting judgment section (step S5) of FIG. Here, for the hunting detection target, there are a method of measuring the gear ratio RTO and the tilt angle (rotation angle), and others. For example, if this is performed using the speed ratio RTO, the hunting determination unit holds the fluctuation of the speed ratio RTO as a max value (max value) and / or a min value (minimum value), and holds the change between the hold values. Time, and take the reciprocal of this as the hunting frequency FRTO:

## EQU1 ## FRTO ← FFT (RTO) where FFT; hunting frequency can be calculated (step S101).

FIG. 13 shows the contents of one method of determining shift hunting by the control unit (C / U) 5. Since the hunting frequency is about 10 Hz or less, the cycle is 62.5 msec or more, for example, when the higher frequency is 16 Hz. On the other hand, if the lower hunting is 4 Hz, the cycle is 250 ms.
c, and it is necessary to suppress hunting in this cycle.

Therefore, as shown in FIG.
Hold the highest and lowest values during 0 msec, and
The maximum value (max1, max2,...) And the minimum value (min
The time (t1) between (1, min2,...) Is measured, and the hunting period is specified twice as long. The hunting is based on the premise that the difference between the max value and the min value is equal to or greater than a certain value. In the illustrated example, min1 is the highest (Hi) value in the shift state. 125msec after min1
The maximum value between them is defined as the max2 value (however, min1 + R
TOTH1 ≦ max2).

The hunting can be determined by a method of performing the above-described computer software processing or a method of performing the FFT (hunting frequency calculation) processing by a circuit or a computer, and the present invention can employ any of these methods.

The hunting frequency FRTO in step S101 is within a predetermined range (FRToh>FRTO>
When it is in (FRTOl) (when the answer in step S102 is affirmative (Yes)), a hunting determination timer TMRf (hunting erroneous detection prevention timer) composed of, for example, an up counter is operated, and the value is incremented by one. Then, time measurement is executed (step S104). Here, FRToh is a predetermined upper limit of a predetermined hunting determination frequency, and FRTOl is a predetermined lower limit of a predetermined hunting determination frequency. On the other hand, at other times, that is, when the answer to step S102 is negative (N
In the case of o), the timer TMRf is cleared every time the step is executed in step S103.

When the value of the timer TMRf exceeds a predetermined value TIMf (hunting erroneous detection prevention time) in the course of execution of the process from step S102 to step S104, it is determined that hunting has occurred (step S105). Is yes), and then, in this example of the program, an area determination (hunting area determination) is performed. This prevents erroneous detection of hunting. Step S10
If the answer to 5 is No, this routine is terminated as it is, and the process proceeds to FIG.

In this program example, the steeply inclined region of the precess cam 235 having the steeply inclined region having an inclination different from that of the normal inclined region at the end (therefore, the detection of the shift hunting) can be detected, and this can be detected by mistake. It is possible to appropriately realize while preventing detection.

Here, the hunting area determination is performed on both the Low side and the Hi side so as to correspond to the precess cam 235 in which a steeply inclined area is set at each end of the applicable precess cam (steps S106 to S106). S108).

In step S106, RTO0 (target speed ratio after hunting limit) and RTOL (predetermined predetermined Low-side corrected speed ratio limit value (constant); FIG. 4 (B)) are compared and compared. RTO0> RTO
When it is determined whether L is satisfied (whether it is on the Low side) or not, in step S107, the gear ratio Low limiter LmtLow is changed and the corrected gear ratio is set as the corrected lowest gear ratio. That is, in the hunting in the Low-side region, the speed ratio Low limiter LmtLow is reduced by the limit correction unit amount dltRto. At the same time, the timer TMRf is cleared (step S10).
7). Then, the process proceeds to the following (FIG. 10). Here, the obtained value LmtLow is used in step S208 described later.
Is applied to the arithmetic processing in.

If the answer in Step S105 is No, then in Step S108, RTOH (a predetermined Hi-side corrected speed ratio limit value (constant);
Referring to FIG. 4B), it is determined whether or not RTO0 <RTOH is satisfied (whether or not Hi-side). If the answer to step S108 is No, the process proceeds to the following process, while the answer is Yes.
If so, in step S109, the speed ratio Hi limiter LmtHi is changed, and this is set as the corrected highest Hi speed ratio. That is, in the hunting in the Hi-side region, the speed ratio Hi limiter LmtHi is increased by dltRto. At the same time, the timer TMRf is cleared, and the process proceeds to the following (FIG. 10). Here, the obtained value LmtL
ow is applied to the arithmetic processing in step S208 described later.

Thus, the shift hunting can be measured and the control area can be corrected. As a result, the subsequent shift determination → shift control → step motor control step number signal output (FIG. 1)
When the processing of (0, 11, 6) is executed, the problem described at the beginning of the specification can be properly solved by correcting the gear ratio limiter in the direction in which the gear ratio width becomes narrower. Can be. Even if there is a variation (individual difference) in the used precess cams, the shift hunting is avoided as much as possible and the normal inclined area other than the hunting occurrence area is maximized regardless of the individual use individuals (precess cams 235). Appropriate shift control can be realized by using the gear effectively.

As shown in FIG. 3, in the case of the CVT in which the control area correction processing is not adopted, if the shift range is set so as not to enter the steep slope area due to the precision of the process of the precess cam, as shown in FIG. Although the gear ratio becomes narrower than the gear shift range and the gear ratio width of the gear shift range in anticipation of the variation with respect to the designed gear shift range is narrowed, such disadvantages can be avoided. Since the cutting process is different for each cam inclination in the setting of the above, there is a possibility that the transmission ratio of the steeply inclined position may vary from part to part. The precess cam 235 having such a steeply inclined area is also provided with the steeply inclined area. The precess cam 235 can be satisfactorily handled while making use of the aforementioned advantages.

FIG. 10 is a flow chart showing the shift judging section (step S) in FIG.
An example of the processing content of 6) is shown. Step S201 is a target input rotation RREV00 map search process, which is described in FIG.
Based on the target rotation map of (A), the target input rotation speed map value RREV00 is calculated based on the vehicle speed Vsp and the throttle opening TV.
O can be searched as a parameter. In the following step S202, a limiter reading process is executed, and the maximum L is set by the rotation speed Low-side limiter TNtlow (Vsp).
The ow limiter RREVL (design low limit target rotation speed) is changed. Also, the rotation speed Hi-side limiter TNth
The highest Hi limiter RREVH is changed by i (Vsp). In FIG. 4B, the hunting determination vehicle speed (RT
As also illustrated as O0), the hunting determination is performed at a vehicle speed set for each gear ratio or higher.

Next, step S203 is a limiter setting process, in which the map value target rotation speed RREV00 is calculated using the limiters RREVL, RRE obtained in step S202.
A limiter is set within the range of VH. Here, for example, “RREV0 ← min (RREV00, RREV
L) selects the smaller of the value RREV00 in step S201 and the value RREVL in step S202,
It means to substitute for RREV0 (target rotational speed after design limiter correction).

The following step S204 is a target rotation speed change amount determination process, and step S205 is a time constant setting process. In step S204, the previous control value target rotation speed RRE is set.
V is set as the target rotation speed RREVold one cycle before. In step S205, the time constant Kr of the target rotational speed is set to K
Set to 1 (shift time constant (reciprocal of time constant)). These RREVold value and Kr value are
Next first-order lag target rotation speed calculation process (step S206)
Applied to

In step S206, the first-order lag target rotation speed is calculated by using the values obtained in the above-described steps S203 to S205, by using (RREV0 + RREVold × Kr) /
(Kr + 1).
V.

After the target rotational speed RREV is obtained, a process for calculating the target speed ratio will be described below. Here, first, in step S207, the target speed ratio RTO00 before the hunting limit is calculated from the ratio between the target speed RREV and the output speed No by RREV / No. Next, the post-limiter target speed ratio RTO0 is calculated by multiplying the Hi and Low speed ratio limiters as follows (step S208).

## EQU2 ## TMP ← max (RTO00, LmtHi) RTO0 ← min (TMP, LmtLow)

Here, when shifting hunting occurs,
If this is the case, LmtHi and LmtLow changed in step S107 or step S109 in FIG. 9 are applied, and this is appropriately reflected in the setting of the target gear ratio as in the above equation. In the case of such a correction of the gear ratio, the provision of the gear ratio limiter as described above may be performed by providing a value corresponding to the gear ratio limiter to the target rotational speed.

Further, as described above, the target speed ratio RT
When O0 is obtained, the number of control steps of the step motor 26 is calculated and output so that the actual gear ratio becomes the target, and here, as described above, the step motor 2 is controlled.
Since the gear ratio is determined by the control position of No. 6, it is also possible to adopt a method in which a limiter equivalent value is provided in the number of control steps to absorb the above-described manufacturing variation of the precess cam in the same manner as described above. it can.

FIG. 11 shows the transmission control section (step S) of FIG.
An example of the processing content of 7) is shown. Step S301 is TS
This is a (torque shift) compensation speed ratio RTO search process. FIG. 14 shows a map used in this step. This is a map TRT for correcting the CVT torque shift characteristics.
At O, a corrected target gear ratio RTO1 is searched from the target gear ratio RTO0 and the estimated input torque Tin. Here, based on the characteristics of FIG. 14, the estimated input torque Tin obtained in step S2 of FIG. 5 and the target value RTO0 of the speed ratio obtained in step S208 of FIG. Search for RTO1 (actual target gear ratio). The next step S302 is a control step search process. Here, the control step DSRS
For TP (target step number), the value RTO1 is searched for as a parameter based on the map of FIG. 15 showing the relationship between the target gear ratio and the step motor control amount.

However, in the present program example, the following processing (steps S303 to S306) is further taken into account. That is, the step motor control unit defines the control speed because the step motor 26 cannot instantaneously achieve the target position. Therefore, the target number of steps D
When SRSTP is smaller than the current control amount ASTP (the number of control steps) (the answer to step S303 is Ye
s) includes a unit control amount DST from the current control amount ASTP.
P (Step motor control unit amount) is reduced and
The TP value is set (step S307). And then,
The calculated value ASTP is compared with the value DSRSTP (step S308), and the calculated value ASTP is compared with the value DSRSTP.
If it is smaller than (the answer to step S308 is Yes), the value DSRSTP is set as the ASTP value (step S306).

Also, except when the target step number DSRSTP is smaller than the current control amount ASTP (step S
If the answer to step 303 is No), the unit control amount DSTP is increased from the current control amount ASTP, and this is used as the ASTP value (step S304). Then, further, the calculated value AS
TP is compared with the value DSRSTP (step S305),
If the calculated value ASTP is larger than the value DSRSTP (the answer to step S305 is Yes), the process proceeds to step S305.
306 is executed, the value DSRSTP is set to the ASTP value, and the program ends.

Thus, the above steps S304 and S30
6 or S307 is output as the number of control steps ASTP for the step motor 26 in the current loop every time the step S3 in FIG. 6 is executed. As a result, the CVT 2 has the speed ratio In this case, as described above, by correcting the control region when appropriate, regardless of the manufacturing variation of the precess cam,
Depending on the individual use precess cam 235, the function of each individual can be extracted to the maximum, and a wider gear ratio range can be secured as compared with the case where the gear range is set narrower in advance considering uniformity and variation. Gear shift control is executed. As described above, the shift range can be corrected every time the shift hunting occurs, without setting the shift range in the normal cam inclination region as in the related art, without considering the wide range or the variation. In the present embodiment, the control area can be corrected by measuring the shift hunting, and the problem of the conventional method of setting the shift range in anticipation of manufacturing variations and the like can be appropriately solved. Even if the shift hunting is initially set, if the shift hunting is detected, the shift range is limited to a narrower direction, and the shift hunting can be appropriately set and corrected when the shift hunting occurs. Therefore, as compared with the conventional case, the shift range must be set in anticipation of individual differences and the like, so that the shift range is narrower than the normally set shift range, and the shift range that can be set within the normal cam inclination range is a very narrow range. There is no disadvantage such as becoming, and while avoiding shift hunting as much as possible,
Appropriate shift control can be realized by maximally and effectively using the central inclined region other than the hunting occurrence region. Note that, in the above description, providing a shift range limit is the same as providing a gear ratio limiter equivalent value to the target rotational speed, and providing a shift range limit is equivalent to providing a limiter equivalent value to the number of control steps. It is the same as the provision, and the present invention includes such an embodiment (these points are the same in other embodiments).

Next, another embodiment of the present invention will be described. The present embodiment is a shift control device in a toroidal CVT 2 including a precess cam having different inclinations at both ends and a steeply inclined region (shift hunting) detecting device as in the above-described embodiment (first embodiment). When this occurs, the speed ratio limiter on the side where the speed change hunting has occurred is to be corrected in a direction in which the speed ratio width becomes narrower. At the same time (also), the other gear ratio limiter is intended to be corrected in the direction in which the gear ratio width increases.

In this embodiment (second embodiment), as shown in FIG. 16, when the step-speed ratio or tilt angle characteristic of the step motor 26 is displaced in the step direction (horizontal axis direction), Since the speed ratio width does not change as in the case of FIG. 3, one of the speed ratio limits (highest Hi or low Lo)
This is based on the consideration that hunting may occur in w). That is, the characteristics are shifted laterally as shown in FIG. As a result, even if the same step number (ASTP) is output, the speed ratio RTO falls within the steep slope region. For example, if the vehicle enters the steeply inclined region on the Hi side, the speed ratio width does not change, so that the normal inclined region on the Low side is expanded.

Therefore, this embodiment takes into consideration such a deviation in the characteristic step direction, and the main part of this embodiment will be described below with reference to FIG. The other basic configurations are the same as in the first embodiment.

FIG. 17 is a program flowchart showing the processing contents of the hunting judgment unit in the control program in this embodiment. In the figure, steps S101 to S10
6 and S108 are the same processing contents as the corresponding steps in FIG. 9 of the first embodiment, and are performed in steps S107-1 and S107.
99-1 is different from the case of FIG. In FIG. 17, when the answer in step S106 is Yes and it is determined that the hunting is in the low-side region, the speed ratio limiter Lm
tLow is calculated as LmtLow ← LmtLow−DltRt
When correcting o, LmtHi ← LmtHi + D
The speed ratio width is maintained as ltRto (step S107-1). Similarly, step S108
Is determined to be hunting in the Hi-side region, the speed ratio limiter HiLow is changed to HiLow ← H.
When correcting to iLow + DltRto, Lmt
Hi ← LmtHi−DltRto so that the speed ratio width is maintained.

As described above, the present invention can be implemented by replacing the control program of FIG. 9 in the first embodiment with that of FIG. According to the present embodiment, similarly to the first embodiment, it is possible to correct the control area by measuring the shift hunting and to cope with the variation due to the shift in the characteristic step direction as shown in FIG.

Next, still another embodiment (third embodiment) of the present invention will be described. In the present embodiment, the speed ratio limiter is to be changed in a direction in which the speed ratio width is widened by a predetermined amount of speed ratio until immediately before the speed hunting occurs. For this reason, in the present embodiment, the control program of FIG. 7 in the first embodiment is replaced with the one shown in FIG. 18, and the control program of FIG. 9 is replaced with the one shown in FIG.

The main parts of this embodiment are described below with reference to FIGS.
In this embodiment, as shown in step S4A of FIG. 18, in the reading process when the backup power supply is turned on, LmtLow ← RTOL (Low-side corrected speed ratio limit value), LmtHi ← RTOH (Hi-side corrected speed ratio) As the limit value, a gear ratio limiter initial value is set.

On the other hand, the processing contents of the hunting judgment section are executed according to the flowchart shown in FIG. In the figure, steps S101 to S104 have the same processing contents as the corresponding steps in FIG. 9 of the first embodiment, and the subsequent steps are as follows. That is, step S135
In RTOMIN (design maximum H)
(i limit value) ≦ RTO0 <RTOH, and when the answer is Yes, step S136 having the same contents as step S105 in FIG. 9 is executed. When TMRf> TIMf is satisfied, step S137 is selected. The processing in step S137 having the same contents as step S109 in FIG. 9 is executed.

However, the hunting error detection prevention timer T
If hunting is not detected by MRf, step S1
Select the 38 side. Here, the second hunting erroneous detection prevention timer TMRs is used, and when TMRs> TIMs (predetermined second hunting erroneous detection prevention time) (the answer to step S138 is Yes), it is determined that hunting has not occurred. Then, the limiter is expanded as LmtHi ← LmtHi-dlTRto (step S139). At the same time, the hunting error detection prevention timer TMRs is cleared. On the other hand, when TMRs is other than TIMs (step S
138 is No) is the hunting error detection prevention timer T
MRs is incremented (step S140).

In this way, on the highest Hi side, the change of the highest Hi limiter in step S139 is executed until immediately before the occurrence of hunting on the Hi side by the loop of steps S135 → S136 → S138 → S139. can do.

It is assumed that these processes are performed similarly on the lowest side, and as shown in FIG.
Steps S141 to S146 on the lowest side corresponding to steps 140 and 140, respectively, are provided.
In this embodiment, the other configuration is the same as that of the first embodiment. Therefore, after the process of the hunting determination unit of FIG. 19, the processes of FIG. 10 and thereafter are executed.

According to the present embodiment, in the same manner as in the first and second embodiments, the shift hunting can be measured and the control area can be corrected.
By the processing of 36 → S138 → S139 and by the processing of steps S141 → S142 → S144 → S145, the gear ratio limiter is increased by a predetermined amount gear ratio until the gear ratio hunting occurs, so that the gear ratio width is increased. As a result of being able to change and correct, regardless of the manufacturing variation of the precess cam 235, it is possible to secure the speed ratio width, and to use it as effectively as possible. The present embodiment is applied not only to the case of the precess cam 235 having steeply inclined regions at both ends but also to a toroidal type CVT provided with a precess cam having a different inclination at one end and a shift hunting detection device, and is similarly implemented. Can be.

[Brief description of the drawings]

FIG. 1 is a control system diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a configuration of a speed change valve (spool, sleeve), a step motor, and the like, which can be applied to the same example.

FIG. 3 is a diagram for explaining a power roller tilt angle characteristic with respect to the number of control steps;

FIG. 4 is a Hi / Low limit, a gear ratio limiter RT.
FIG. 3 is a diagram provided for explaining a target rotation map and a target rotation limiter, including OL, RTOH, RTOMAX, and RTOMIN.

FIG. 5 is a flowchart of a control program executed by a control unit, showing an example of a signal measurement process.

FIG. 6 is a flowchart of a control program showing an example of a control signal output process.

FIG. 7 is a flowchart of a control program showing an example of a reading process when a backup power supply is turned on.

FIG. 8 is a flowchart showing a control program for hunting determination, shift determination, and shift control.

FIG. 9 is a flowchart of an example of a control program showing the contents of processing in a hunting determination unit.

FIG. 10 is a flowchart of an example of a control program showing the content of a process in a shift determination unit.

FIG. 11 is a flowchart of an example of a control program showing the contents of processing in a shift control unit.

FIG. 12 is a diagram provided for describing an example of an engine torque characteristic map applicable to a control program.

FIG. 13 is a diagram provided for describing an example of a hunting determination method that can be similarly applied.

FIG. 14 is a diagram for explaining an example of applicable map characteristics.

FIG. 15 is a diagram for explaining an example of applicable map characteristics.

FIG. 16 is an explanatory diagram illustrating a relationship between the number of control steps and a gear ratio for explaining another embodiment of the present invention.

FIG. 17 is a program flowchart showing a main part of a control program in the same example and showing processing contents of a hunting determination unit.

FIG. 18 is a program flowchart showing a main part of a control program according to still another embodiment of the present invention and relating to a read processing portion when a backup power supply is turned on.

FIG. 19 is a program flowchart showing the processing performed by a hunting determination unit.

[Explanation of symbols]

Reference Signs List 1 engine (engine) 2 toroidal type continuously variable transmission (CVT) 4 selector 5 electronic control unit (transmission control unit (C /
U)) 6 Engine electronic control unit 21 Torque converter 22 Forward / reverse switching device 23 Toroidal transmission unit 25 Hydraulic control device 26 Step motor 27 Duty solenoid (PL) 28 Duty solenoid (LU) 29 Oil pump 31 Input rotation sensor 32 Output rotation ( Vehicle speed) sensor 33 Selector switch 34 Low switch 35 Oil temperature sensor 36 Brake switch 37 Snow (snw) switch 231 Power roller 232 Trunnion 233 Shaft 234 Servo piston 235 Precess cam 236 Shift link 251 Shift control valve (hydraulic copying valve) 251A Spool 251B Sleeve Variable: TVO Throttle opening Ne Engine rotation speed Nt Input rotation speed No Output rotation speed Vsp Vehicle speed RTO Gear ratio ASTP Step Motor control step number LmtLow Corrected lowest gear ratio LmtHi Corrected highest Hi gear ratio FRTO Hunting frequency TMRf Hunting error detection prevention timer RREV00 Map search target rotation speed RREVL Design low limit target rotation speed RREVH Design Hi limit target rotation speed RREV0 Design limit Corrected target speed RREVold One-cycle previous target speed RREV Target speed Kr Time constant coefficient RTO00 Target speed ratio before hunting limit RTO0 Target speed ratio after hunting limit Tin Estimated input torque RTO1 Torque shift compensation speed ratio DSRSTP Target step number TMRs Hunting False detection prevention timer constant; A Vehicle speed conversion coefficient RTOMAX Design low limit value RTOMIN Design hi limit value FRTO1 Han Lower limit of FR judgment frequency FRTOh Upper limit of hunting decision frequency TIMf Hunting erroneous detection prevention time RTOL Low side correction speed ratio limit value RTOH Hi side correction speed ratio limit value dltRto Limit correction unit amount K1 Shift time constant (reciprocal of time constant) DSTP step Motor control unit amount TIMs Hunting error detection prevention time function; FFT; Hunting frequency calculation TNt; Map value target rotation speed search TNtlow; Design low-side limit search TNthi; Design Hi-side limit search min; Minimum value calculation max; Max value calculation TRTO ; Torque shift compensation speed ratio search TFSTP; control step number search

Claims (5)

[Claims] 1. An input disk, an output disk, a pair of friction rollers disposed in a toroidal groove formed by both disks so as to make frictional contact with both disks, and rotatably supporting the friction rollers. A roller support member rotatable and movable in the axial direction, a hydraulic cylinder capable of driving the roller support member in the axial direction, and controlling a hydraulic pressure so as to obtain a target gear ratio for the hydraulic cylinder. A speed change control means, and a slope having a steep slope area which is integrally rotated with the roller support member to feed back an actual speed change ratio to the speed change control means and has a steep slope area at least at one end which is steeper than a gentle slope area at the center. Shift control of a continuously variable transmission having a precess cam and a link abutting on a slope of the precess cam and swinging by rotation of the precess cam A steep slope region detecting means for detecting a shift hunting caused by the link abutting on the steeply sloped region of the precess cam; and, when the shift hunting is detected based on the steeply sloped region detecting means, the shifting is performed. A shift control device for a continuously variable transmission, comprising shift range limiting means for limiting the range in a direction in which the range becomes narrower. 2. The method according to claim 1, wherein the steeply inclined region is provided at both ends of the precess cam, and a shift hunting occurs due to the steeply inclined region at one end of the both ends. The shift range is limited in the direction in which the shift range is narrowed by the shift range limiting means on one side of the shift side or the large gear ratio side where the shift hunting has occurred, and the other of the small gear ratio side or the large gear ratio side is selected. The shift control device for a continuously variable transmission according to claim 1, wherein, on the side of (1), the limitation of the shift range of the shift range limiting means is corrected in a direction in which the shift range increases. 3. An input disk, an output disk, a pair of friction rollers disposed in a toroidal groove formed by both disks so as to make frictional contact with both disks, and rotatably supporting the friction rollers. A roller support member rotatable and movable in the axial direction, a hydraulic cylinder capable of driving the roller support member in the axial direction, and controlling a hydraulic pressure so as to obtain a target gear ratio for the hydraulic cylinder. A speed change control means, and a slope having a steep slope area which is integrally rotated with the roller support member to feed back an actual speed change ratio to the speed change control means and has a steep slope area at least at one end which is steeper than a gentle slope area at the center. Shift control of a continuously variable transmission having a precess cam and a link abutting on a slope of the precess cam and swinging by rotation of the precess cam A steep slope region detecting means for detecting a shift hunting caused by the link abutting on the steep slope region of the precess cam; a shift range limiting means capable of limiting the shift range to a predetermined state; There is provided changing means for changing the limitation by the shift range limiting means in a direction in which the shift range is widened by a predetermined amount of gear ratio until immediately before shift hunting is detected and the shift hunting is detected based on the steep slope region detecting means. A shift control device for a continuously variable transmission. 4. The steeply inclined region detecting means according to claim 1, wherein:
The hunting frequency is estimated based on the output rotation speed, control command line pressure, or actual line pressure. If the measured rotation speed, measured gear ratio, and measured tilt angle are hunting at this frequency, a steep slope A shift control device for a continuously variable transmission, which determines hunting based on a region. 5. The shift control device for a continuously variable transmission according to claim 1, wherein the hunting determination is performed at a vehicle speed set for each gear ratio or higher.