WO2013132899A1 - Speed-change control apparatus and speed-change control method for continuously variable transmission - Google Patents

Abstract

A frictional engagement element control unit is provided with: a target slip rotational speed setting unit for setting a target slip rotational speed for the frictional engagement element; an engaging force control unit for controlling the engaging force of the frictional engagement element so that an actual slip rotational speed of the frictional engagement element corresponds to the target slip rotational speed; and a target slip rotational speed changing unit that sets, when a deviation between the actual slip rotational speed and a first target slip rotational speed is large, a second target slip rotational speed with a small deviation from the actual slip rotational speed, instead of the first target slip rotational speed.

Description

Speed change control device and speed change control method for continuously variable transmission

The present invention relates to shift control of a continuously variable transmission.

A transmission is known that includes a variator that changes the rotation of an engine, which is a driving force source, and a frictional engagement element that is arranged in series with the engine and the variator. When the excessive torque is input from the engine side or the drive wheel side, the transmission suppresses the slip of the variator belt by slipping the frictional engagement element and buffering the impact for the purpose of mitigating this. A so-called clutch fuse is used to prevent damage to the variator due to belt slip. As a result, in a belt-type continuously variable transmission that shifts with a belt wound around a pulley, the belt and the pulley can be prevented from being damaged due to the slip of the belt.

In order to perform such control, JP10-2390A controls that the transmission capacity of the frictional engagement element is smaller than the transmission capacity between the belt and the pulley in a vehicle with a belt type continuously variable transmission. It is known that when the frictional engagement element slips, the frictional engagement element is controlled so as to have a transmission capacity before slipping.

In the conventional transmission, after excessive torque is input and the clutch (friction engagement element) slips, the engagement force is increased and the clutch is engaged again. Such control can prevent the belt and pulley from being damaged due to excessive torque, but there is a possibility that a fastening shock will occur in the subsequent re-fastening control.

¡After the clutch engaged with the fastening force capable of transmitting the engine torque slips, the fastening force is increased for re-engagement, so that the engagement state is suddenly changed from the slip state, so that a fastening shock is generated. This shock has the problem of discomforting the driver.

This invention is made in view of such a problem, and it aims at providing the control apparatus of the continuously variable transmission which can prevent the shock at the time of re-engagement of a friction engagement element.

According to one embodiment of the present invention, a continuously variable transmission that is mounted on a vehicle and continuously outputs a rotational speed of a driving force source to driving wheels and is connected in series to the driving force source and the continuously variable transmission. And a frictional engagement element control unit that controls the engagement state of the frictional engagement element, and the frictional engagement element control unit includes a target slip of the frictional engagement element. A target slip rotation speed setting unit for setting the rotation speed, a fastening force control unit for controlling the fastening force of the friction engagement element so that the actual slip rotation speed of the friction engagement element matches the target slip rotation speed, and the actual slip rotation speed When the deviation between the first slip slip rotation speed and the first target slip rotation speed increases, a target slip rotation speed that sets a second target slip rotation speed that reduces the deviation from the actual slip rotation speed instead of the first target slip rotation speed. Characterized in that it comprises a flop rotational speed changing unit.

According to another embodiment of the present invention, a continuously variable transmission that is mounted on a vehicle and continuously outputs the rotational speed of a driving force source to driving wheels, and is connected in series to the driving force source and the continuously variable transmission. A variable speed control method for a continuously variable transmission, comprising: a frictional engagement element to be connected; and a frictional engagement element control unit that controls an engagement state of the frictional engagement element, wherein the frictional engagement element control unit is a target of the frictional engagement element. The slip rotation speed is set, the fastening force of the friction engagement element is controlled so that the actual slip rotation speed of the friction engagement element matches the target slip rotation speed, and the deviation between the actual slip rotation speed and the first target slip rotation speed Is increased, instead of the first target slip rotation speed, a second target slip rotation speed that reduces the deviation from the actual slip rotation speed is set.

According to the above-described embodiment, when the actual fuse rotation speed is increased because the clutch fuse function is exhibited, the second target is set so as to reduce the deviation from the actual slip rotation speed instead of the first target slip rotation speed. By setting the slip rotation speed, the fastening force of the friction element is prevented from becoming excessive, and the fastening shock can be prevented.

Embodiments of the present invention and advantages of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of a vehicle equipped with a continuously variable transmission according to the present embodiment. FIG. 2 is an explanatory diagram showing an example of the configuration of the transmission controller according to the embodiment of the present invention. FIG. 3 is an explanatory diagram illustrating an example of a shift map according to the embodiment of this invention. FIG. 4 is an explanatory diagram of clutch fuse control according to a reference example of the present invention. FIG. 5 is an explanatory diagram of clutch fuse control according to the embodiment of the present invention. FIG. 6 is a flowchart at the time of clutch fuse control executed by the transmission controller according to the embodiment of the present invention. FIG. 7 is a flowchart for calculating the heat generation amount of the frictional engagement element, which is executed by the transmission controller according to the embodiment of the present invention. FIG. 8 is an explanatory diagram of clutch fuse control according to a modification of the embodiment of the present invention. FIG. 9 is an explanatory diagram of clutch fuse control according to another modification of the embodiment of the present invention. FIG. 10 is an explanatory diagram of clutch fuse control of still another modified example of the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the “transmission ratio” of a transmission mechanism is a value obtained by dividing the input rotational speed of the transmission mechanism by the output rotational speed of the transmission mechanism. “Lowest gear ratio” means the maximum gear ratio of the transmission mechanism, and “Highest gear ratio” means the minimum gear ratio of the transmission mechanism.

FIG. 1 is a schematic configuration diagram of a vehicle equipped with a continuously variable transmission according to the present embodiment. The vehicle includes an engine 1 as a power source. The output rotation of the engine 1 is via a torque converter 2 with a lock-up clutch, a first gear train 3, a continuously variable transmission (hereinafter simply referred to as "transmission 4"), a second gear train 5, and a final reduction gear 6. Is transmitted to the drive wheel 7. The second gear train 5 is provided with a parking mechanism 8 that mechanically locks the output shaft of the transmission 4 at the time of parking.

The vehicle includes an oil pump 10 that is driven using a part of the power of the engine 1, a hydraulic control circuit 11 that regulates the hydraulic pressure from the oil pump 10 and supplies the hydraulic pressure to each part of the transmission 4, and hydraulic control A transmission controller 12 that controls the circuit 11 is provided.

The transmission 4 includes a continuously variable transmission mechanism (hereinafter referred to as “variator 20”) and an auxiliary transmission mechanism 30 provided in series with the variator 20. “To be provided in series” means that the variator 20 and the auxiliary transmission mechanism 30 are provided in series in the same power transmission path. The auxiliary transmission mechanism 30 may be directly connected to the output shaft of the variator 20 as in this example, or may be connected via another transmission mechanism or a power transmission mechanism (for example, a gear train).

The variator 20 is a belt-type continuously variable transmission mechanism that includes a primary pulley 21, a secondary pulley 22, and a V-belt 23 that is wound around the pulleys 21 and 22. Each of the pulleys 21 and 22 includes a fixed conical plate, a movable conical plate that is arranged with a sheave surface facing the fixed conical plate, and forms a V-groove between the fixed conical plate, and a rear surface of the movable conical plate. And hydraulic cylinders 23a and 23b for displacing the movable conical plate in the axial direction. When the hydraulic pressure supplied to the hydraulic cylinders 23a, 23b is adjusted, the width of the V groove changes, the contact radius between the V belt 23 and each pulley 21, 22 changes, and the speed ratio vRatio of the variator 20 changes steplessly. To do.

The auxiliary transmission mechanism 30 is a transmission mechanism having two forward speeds and one reverse speed. The sub-transmission mechanism 30 is connected to a Ravigneaux type planetary gear mechanism 31 in which two planetary gear carriers are connected, and a plurality of friction elements connected to a plurality of rotating elements constituting the Ravigneaux type planetary gear mechanism 31 to change their linkage state. Fastening elements (Low brake 32, High clutch 33, Rev brake 34) are provided. When the hydraulic pressure supplied to each friction engagement element 32, 33, 34 is adjusted and the engagement / release state of each friction engagement element 32, 33, 34 is changed, the gear position of the subtransmission mechanism 30 is changed. For example, if the Low brake 32 is engaged and the High clutch 33 and the Rev brake 34 are released, the gear position of the subtransmission mechanism 30 is the first speed. If the high clutch 33 is engaged and the low brake 32 and the rev brake 34 are released, the speed stage of the subtransmission mechanism 30 becomes the second speed having a smaller speed ratio than the first speed. When the Rev brake 34 is engaged and the Low brake 32 and the High clutch 33 are released, the gear position of the subtransmission mechanism 30 is reverse.

As shown in FIG. 2, the transmission controller 12 includes a CPU 121, a storage device 122 including a RAM and a ROM, an input interface 123, an output interface 124, and a bus 125 that interconnects them.

The input interface 123 includes an output signal of an accelerator opening sensor 41 that detects an accelerator pedal opening (hereinafter referred to as “accelerator opening APO”), an input rotational speed of the transmission 4 (= the rotational speed of the primary pulley 21). , Hereinafter referred to as “primary rotational speed Npri”), an output signal from the rotational speed sensor 42, an output signal from the vehicle speed sensor 43 that detects the traveling speed of the vehicle (hereinafter referred to as “vehicle speed VSP”), The output signal of the oil temperature sensor 44 for detecting the oil temperature of the oil and the output signal of the inhibitor switch 46 for detecting the position of the select lever are input.

The storage device 122 stores a shift control program for the transmission 4 and a shift map used in the shift control program. The CPU 121 reads out and executes a shift control program stored in the storage device 122, performs various arithmetic processes on various signals input via the input interface 123, generates a shift control signal, and generates the generated shift control program. The control signal is output to the hydraulic control circuit 11 via the output interface 124. Various values and calculation results used by the CPU 121 in the calculation processing are appropriately stored in the storage device 122.

The hydraulic control circuit 11 includes a plurality of flow paths and a plurality of hydraulic control valves. Based on the shift control signal from the transmission controller 12, the hydraulic control circuit 11 controls a plurality of hydraulic control valves to switch the hydraulic pressure supply path, and prepares the necessary hydraulic pressure from the hydraulic pressure generated by the oil pump 10, Is supplied to each part of the transmission 4. As a result, the gear ratio vRatio of the variator 20 and the gear position of the auxiliary transmission mechanism 30 are changed, and the transmission 4 is changed.

FIG. 3 shows an example of a shift map stored in the storage device 122 of the transmission controller 12.

On the shift map, the operating point of the transmission 4 is determined based on the vehicle speed VSP and the primary rotational speed Npri. The overall shift obtained by multiplying the transmission ratio of the transmission 4 (the transmission ratio vRatio of the variator 20 by the transmission ratio subRatio of the subtransmission mechanism 30) is obtained by the inclination of the line connecting the operating point of the transmission 4 and the zero point of the lower left corner of the transmission map Ratio, hereinafter referred to as “through transmission ratio Ratio”). Similar to the shift map of the conventional belt type continuously variable transmission, a shift line is set for each accelerator opening APO, and the shift of the transmission 4 is selected according to the accelerator opening APO. This is done according to the shift line. For simplicity, FIG. 3 shows a full load line (shift line when accelerator opening APO = 8/8), partial line (shift line when accelerator opening APO = 4/8), coast line (accelerator opening). Only the shift line when the degree APO = 0 is shown.

When the transmission 4 is in the low speed mode, the transmission 4 has a low speed mode lowest line obtained by maximizing the transmission ratio vRatio of the variator 20, and a low speed mode highest line obtained by minimizing the transmission ratio vRatio of the variator 20. You can shift between them. At this time, the operating point of the transmission 4 moves in the A region and the B region. On the other hand, when the transmission 4 is in the high speed mode, the transmission 4 has the maximum low speed line obtained by maximizing the transmission ratio vRatio of the variator 20 and the maximum high speed mode obtained by minimizing the transmission ratio vRatio of the variator 20. You can shift between the lines. At this time, the operating point of the transmission 4 moves in the B region and the C region.

The gear ratio of each gear stage of the sub-transmission mechanism 30 is such that the gear ratio corresponding to the low speed mode highest line (low speed mode highest high gear ratio) corresponds to the high speed mode lowest line (high speed mode lowest gear ratio). It is set to be smaller than that. Accordingly, a low speed mode ratio range that is a range of the through speed ratio Ratio of the transmission 4 that can be taken in the low speed mode and a high speed mode ratio range that is a range of the through speed ratio Ratio of the transmission 4 that can be taken in the high speed mode are partially obtained. When the operating point of the transmission 4 is in the B region sandwiched between the high-speed mode lowest line and the low-speed mode highest line, the transmission 4 can select either the low-speed mode or the high-speed mode. ing.

The transmission controller 12 refers to the shift map, and sets the through speed ratio Ratio corresponding to the vehicle speed VSP and the accelerator opening APO (the driving state of the vehicle) as the reaching through speed ratio DRatio. The reached through speed ratio DRatio is a target value that the through speed ratio Ratio should finally reach in the driving state. Then, the transmission controller 12 sets a target through speed ratio tRatio that is a transient target value for causing the through speed ratio Ratio to follow the reached through speed ratio DRatio with a desired response characteristic, and the through speed ratio Ratio is the target. The variator 20 and the subtransmission mechanism 30 are controlled so as to coincide with the through speed ratio tRatio.

On the shift map, a mode switching shift line (1-2 shift line of the subtransmission mechanism 30) for performing the shift of the subtransmission mechanism 30 is set to overlap the low speed mode highest line. The through speed ratio corresponding to the mode switching speed line (hereinafter referred to as “mode switching speed ratio mRatio”) is equal to the low speed mode maximum High speed ratio.

When the operating point of the transmission 4 crosses the mode switching speed line, that is, when the through speed ratio Ratio of the transmission 4 changes across the mode switching speed ratio mRatio, the transmission controller 12 performs the mode switching speed control. Do. In the mode switching shift control, the transmission controller 12 shifts the subtransmission mechanism 30, and changes the transmission ratio vRatio of the variator 20 in a direction opposite to the direction in which the transmission ratio subRatio of the subtransmission mechanism 30 changes. I do.

In the coordinated shift, when the through speed ratio Ratio of the transmission 4 is changed from a larger state to a smaller state than the mode switching speed ratio mRatio, the transmission controller 12 changes the speed of the subtransmission mechanism 30 from the first speed to the second speed. (Hereinafter referred to as “1-2 shift”), and the gear ratio vRatio of the variator 20 is changed to the higher gear ratio side. Conversely, when the through speed ratio Ratio of the transmission 4 changes from a state smaller than the mode switching speed ratio mRatio to a larger state, the transmission controller 12 changes the gear position of the subtransmission mechanism 30 from the second speed to the first speed. While changing (hereinafter referred to as “2-1 speed change”), the speed ratio vRatio of the variator 20 is changed to the lower speed ratio.

The reason why the cooperative shift is performed at the time of the mode switching shift is to suppress the driver's uncomfortable feeling due to the change in the input rotation caused by the step of the through speed ratio Ratio of the transmission 4. The mode change gear shift is performed when the gear ratio vRatio of the variator 20 is the highest gear ratio. In this state, the torque input to the auxiliary transmission mechanism 30 is the minimum under the torque input to the variator 20 at that time. This is because the shift shock of the subtransmission mechanism 30 can be alleviated by shifting the subtransmission mechanism 30 in this state.

According to the speed change map, when the vehicle stops, the speed change ratio vRatio of the variator 20 is the lowest speed speed change ratio, and the speed change stage of the auxiliary speed change mechanism 30 is the first speed.

Next, the operation when excessive torque is input in the continuously variable transmission of the present invention configured as described above will be described.

If the vehicle suddenly decelerates due to sudden braking, etc., the vehicle moves from a low μ road surface to a high μ road surface, and when the drive wheel 7 transitions from a slip state to a grip state, the drive wheel 7 rides on a step. In such a case, the rotational speed of the drive wheel 7 changes abruptly, so that excessive torque is input to the transmission 4 from the drive wheel 7 side.

After completion of stepping of the drive wheels 7 or when the engine 1 is excessively increased due to excessive fuel injection due to a failure in the engine 1, the transmission 4 from the engine 1 side that is the drive source. An excessive torque is input to. That is, the “excessive torque” means a large torque input from the drive wheels 7 at the time of sudden deceleration or a torque larger than the torque intended by the driver due to an abnormality in the engine 1 such as an abnormality in the fuel injection amount. The torque input from the engine 1 in response to the accelerator operation that is the driver's intention to travel, for example, the large torque that is input when the driver depresses the accelerator pedal for the purpose of kicking down or the like is excessive torque. Is not called.

When such an excessive torque is input to the variator 20 of the transmission 4, the following problems may occur. When excessive torque is input to the variator 20 that controls the transmission ratio by the V belt 23 held between the pulleys 21 and 22, the pulleys 21 and 22 and the V belt 23 may slip. The slip of the V belt 23 may damage the pulleys 21 and 22 or the V belt 23.

On the other hand, a so-called clutch fuse that buffers excessive torque by slipping a frictional engagement element coupled to the front stage or the rear stage of the variator 20 is conventionally performed.

In the embodiment of the present invention, by slipping the frictional engagement elements (Low brake 32, High clutch 33, Rev brake 34) of the auxiliary transmission mechanism 30 connected in series to the rear stage of the variator 20 that is a continuously variable transmission, It functions as a clutch fuse.

In order to make the clutch fuse function more effective, a differential rotation between the input rotational speed and the output rotational speed of the frictional engagement element can be generated to control to always generate a slight slip in the frictional engagement element.

Next, the conventional problems with the clutch fuse will be described.

FIG. 4 is an explanatory diagram of the clutch fuse control of the reference example of the present invention, and explains the problems of the conventional clutch fuse.

In FIG. 4, the output torque of the engine 1, the excessive torque input to the transmission 4, the actual slip rotation speed Nr (solid line) of the friction engagement element, the target slip rotation speed (dotted line), the actual clutch hydraulic pressure to the friction engagement element ( A solid line) and a clutch command oil pressure (dotted line) are shown as time charts with time on the horizontal axis.

FIG. 4 shows an operation when an excessive torque is input at timing t1 when the output torque of the engine is substantially constant and the vehicle is traveling.

The transmission controller 12 instructs the clutch instruction hydraulic pressure so that the friction engagement element satisfies the target slip rotation speed. On the other hand, the actual clutch hydraulic pressure is supplied to the friction engagement element, and the relative rotation between the input side and the output side of the friction engagement element is controlled to the actual clutch slip rotation speed.

Here, when an excessive torque is input at the timing t1, a slip is generated in the frictional engagement element, and the excessive torque is buffered so as not to be directly input to the variator 20.

At this time, the actual slip rotation speed Nr of the frictional engagement element increases, and the deviation between the target slip rotation speed set by the transmission controller 12 and the actual slip rotation speed Nr increases.

At this time, the transmission controller 12 determines the clutch instruction oil pressure based on the deviation between the target slip rotation speed and the actual slip rotation speed Nr, and instructs the oil pressure control circuit 11. The hydraulic control circuit 11 supplies the actual clutch hydraulic pressure to the frictional engagement element based on the clutch command hydraulic pressure.

By this control, the friction engagement element promptly shifts to the target slip rotation speed based on the supplied actual clutch hydraulic pressure in order to cause the actual slip rotation speed Nr to quickly follow the target slip rotation speed.

At this time, a fastening shock is generated by the rapid fastening of the frictional engagement element (timing t2). The fastening shock is unintended by the driver and gives the driver discomfort.

Furthermore, since the clutch command hydraulic pressure is increased by F / B control in order to reduce the deviation between the target slip rotation speed and the actual slip rotation speed Nr, the deviation between the actual slip rotation speed Nr and the target slip rotation speed is less. In spite of being small or zero, the command clutch hydraulic pressure is excessive with respect to the clutch hydraulic pressure required to make the actual slip rotation speed Nr the target slip rotation speed. As a result, the actual clutch hydraulic pressure becomes excessive. As a result, the fastening force of the frictional fastening element becomes excessive. Therefore, when an excessive torque is further input immediately after the timing t2, there is a possibility that the clutch fuse function of the frictional engagement element cannot be exhibited.

When the driver depresses the accelerator pedal and the driving force of the engine 1 increases while the clutch fuse is exerted and the frictional engagement element is slipping, the driving force is not transmitted due to the frictional engagement element slipping. At this time, the frictional engagement element is fastened so as to have a transmission capacity before slipping when the driver feels uncomfortable and returns the accelerator pedal. Even in this case, a fastening shock occurs. The same situation also occurs when the driver feels a sense of discomfort when the driver feels discomfort when excessive fuel injection occurs due to engine 1 failure and the engine speed Ne increases excessively.

On the other hand, in the embodiment of the present invention, the following control can prevent the engagement shock in the clutch fuse, and can prevent the situation where the engagement force of the friction engagement element becomes excessive and the clutch fuse function cannot be exhibited. It was configured as follows.

FIG. 5 is an explanatory diagram of clutch fuse control according to the embodiment of the present invention.

In FIG. 5, the output torque of the engine 1, the excessive torque input to the transmission 4, the actual slip rotation speed Nr (solid line) of the friction engagement element, the target slip rotation speed (dotted line), the actual clutch hydraulic pressure to the friction engagement element ( A solid line) and a clutch command oil pressure (dotted line) are shown as time charts with time on the horizontal axis.

FIG. 5 shows the operation of the transmission controller 12 when an excessive torque is input at timing t11 when the vehicle is running with the engine output torque being substantially constant.

As described above, the transmission controller 12 sends the clutch command hydraulic pressure to the hydraulic control circuit 11 so that the actual slip rotation speed Nr becomes the first target slip rotation speed dNr1 in order to generate a slight slip in the friction engagement element. And the actual clutch hydraulic pressure is supplied to the frictional engagement element.

The first target clutch rotational speed is set to, for example, several to several tens [rpm]. The actual slip rotation speed Nr is a difference between the input rotation speed and the output rotation speed of the friction engagement element in the auxiliary transmission mechanism 30, and is calculated from the primary rotation speed Npri, the vehicle speed VSP, and the current through speed ratio Ratio.

By such control, the fastening force of the frictional engagement element becomes smaller than the clamping force of the belt 23 of the variator 20. Therefore, when excessive torque is input, the frictional engagement element slips and the belt 23 in the variator 20 is slipped. Prevent slipping.

Here, when an excessive torque is input to the transmission 4 at the timing t11, a large slip is generated in the frictional engagement element to buffer the excessive torque from being directly input to the variator 20.

Since the frictional engagement element slips at the first target slip rotation speed dNr1, slipping easily occurs when an excessive torque is input. This prevents large fluctuations in rotational speed due to excessive torque from being transmitted to the transmission 4 (particularly the variator 20) due to slipping.

When the actual slip rotation speed Nr of the frictional engagement element increases, the deviation between the first target slip rotation speed dNr1 and the actual slip rotation speed Nr increases. When the deviation increases, as described above with reference to FIG. 4, conventionally, the transmission controller 12 causes the frictional engagement element to perform the actual slip rotation in order to cause the actual slip rotation speed Nr to follow the first target slip rotation speed dNr1. A clutch command oil pressure is commanded based on a deviation between the speed Nr and the first target slip rotation speed dNr1. For this reason, the fastening force of the frictional fastening element is excessive.

Therefore, in the embodiment of the present invention, a threshold value is set in advance, and the transmission controller 12 determines that the deviation between the actual slip rotation speed Nr of the friction engagement element and the first target slip rotation speed dNr1 exceeds the threshold value. Then, the current actual slip rotation speed Nr is set as the second target slip rotation speed dNr2 (timing t12).

By this control, the deviation between the second target slip rotation speed dNr2 and the actual slip rotation speed Nr becomes substantially zero. The transmission controller 12 commands a clutch command oil pressure to be commanded to the frictional engagement element based on a deviation (substantially zero) between the second target slip rotation speed dNr2 and the actual slip rotation speed Nr. The clutch command hydraulic pressure is the same as the state where there is no deviation between the first target slip rotation speed dNr1 and the actual slip rotation speed Nr (before timing t11), and the clutch command hydraulic pressure does not change.

Therefore, since the actual clutch hydraulic pressure does not increase from the timing t12 to t13 regardless of the increase in the actual slip rotation speed Nr, it is possible to prevent the engagement force of the friction engagement element from becoming excessive.

After that, when the clutch fuse function is exerted and the excessive torque is buffered, the actual slip rotation speed Nr of the frictional engagement element is changed from increasing to decreasing (timing t13).

At this time, the transmission controller 12 sets the second target slip rotation speed dNr2 so that the actual slip rotation speed Nr gradually decreases toward the first target slip rotation speed dNr12, and a clutch instruction based on the second target slip rotation speed dNr2 The hydraulic pressure is instructed to the hydraulic pressure control circuit 11.

More specifically, the transmission controller 12 sets a value obtained by adding a predetermined value to the actual slip rotation speed Nr as the second target slip rotation speed dNr2.

The predetermined value is set according to the change speed (decrease gradient) of the actual slip rotation speed Nr. The steeper shock increases as the slope of the actual slip rotation speed Nr decreases. In order to prevent this, the second slip rotation speed is set by setting a larger predetermined value to be added as the decrease gradient of the actual slip rotation speed Nr is larger. The larger the actual slip rotation speed Nr with respect to the input of excessive torque, the larger the predetermined value to be added is set to set the second slip rotation speed. As a result, sudden engagement at the actual slip rotation speed Nr can be suppressed, and engagement shock can be reduced.

By setting the second target slip rotation speed dNr2 in this way, the transmission controller 12 commands a clutch command oil pressure based on the deviation between the second target slip rotation speed dNr2 and the actual slip rotation speed Nr. The hydraulic control circuit 11 supplies the actual clutch hydraulic pressure based on the clutch command hydraulic pressure to the friction engagement element. The deviation is substantially equal to the above-mentioned predetermined value, and the second target slip rotation speed dNr2 is larger than the actual slip rotation speed Nr. Therefore, the values of the clutch instruction oil pressure and the actual clutch instruction oil pressure are negative values, and the friction engagement element The fastening force will not be excessive.

Thereafter, when the excessive slip is buffered and the actual slip rotation speed Nr gradually decreases, and the actual slip rotation speed Nr decreases to such an extent that the engagement shock can be permitted even if the frictional engagement element is rapidly engaged (timing t15). ), The second target slip rotation speed dNr2 is set to the first target rotation speed. The actual clutch rotational speed gradually approaches the first target slip rotational speed dNr1. At the timing t16, the friction engagement element becomes the first target slip rotation speed dNr1.

By such control, after the shock is input, the fastening force of the frictional fastening element does not become excessive and the fastening shock can be prevented.

FIG. 6 is a flowchart of clutch fuse control executed by the transmission controller 12 according to the embodiment of the present invention.

The transmission controller 12 determines whether a large driving force is required for the engine 1 (S101). For example, when the accelerator opening APO of the accelerator pedal is depressed more than a predetermined opening, it is determined that a large driving force is required for the engine 1. When the driving force is requested, the process proceeds to step S102. If it is determined that the driving force is not requested, the process proceeds to step S103.

When the engine 1 requires a large driving force, the slip amount of the frictional engagement element changes depending on the driving force from the engine. At this time, when the actual slip rotation speed Nr increases beyond the threshold value described above, if the clutch fuse as described above is exhibited, the efficiency with which the driving force is transmitted from the transmission 4 to the driving wheel 7 is reduced, and the driving is performed. The driving force required by the person cannot be satisfied.

Therefore, when a large driving force is required for the engine 1, the threshold value of the actual slip rotation speed Nr is changed (S102). Specifically, the slip amount that cannot be generated by the driving force requested by the driver is set as the threshold value. The threshold value may be set only for a scene in which excessive torque is input, but in particular, input of excessive torque from the drive wheel 7 (for example, sudden braking, or when the drive wheel 7 shifts from a slip state to a grip state, It is difficult to predict when, for example, the driving wheel 7 has climbed a step. Therefore, it is necessary to always set the threshold value. Since the threshold value is always set as described above, it is necessary to change the threshold value so that the slip amount cannot be generated by the driving force requested by the driver as described above in a scene where the driving force is required. .

Next, the transmission controller 12 determines whether or not the excessive torque is inputted and the slip amount of the friction engagement element is increased, and the actual slip rotation speed Nr of the friction engagement element exceeds the threshold value (S103). If the actual slip rotation speed Nr of the frictional engagement element does not exceed the threshold value, the process returns to step S101.

If it is determined that the actual slip rotation speed Nr of the frictional engagement element has exceeded the threshold, the transmission controller 12 sets the actual slip rotation speed Nr at this time as the second target slip rotation speed dNr2 (S104).

In step S104, by setting the actual slip rotation speed Nr as the second target rotation speed, the deviation between the actual slip rotation speed Nr and the second target slip rotation speed dNr2 in the frictional engagement element becomes substantially zero. The transmission controller 12 commands a clutch command oil pressure to be commanded to the frictional engagement element based on a deviation (substantially zero) between the second target slip rotation speed dNr2 and the actual slip rotation speed Nr.

Next, the transmission controller 12 determines whether the rate of change of the actual slip rotation speed Nr of the frictional engagement element is increasing or decreasing (step S105). If the change rate of the actual slip rotation speed Nr is increasing, the process returns to step S104. When the change rate of the actual slip rotation speed Nr starts to decrease, the process proceeds to step S106, and the second target slip rotation speed dNr2 is set so that the frictional engagement element is gradually engaged.

More specifically, as described above, the transmission controller 12 sets the second target slip rotation speed dNr2 so that the actual slip rotation speed Nr gradually decreases. That is, a value obtained by adding a predetermined value to the actual slip rotation speed Nr is set as the second target slip rotation speed dNr2.

The predetermined value is set according to the change speed (decrease gradient) of the actual slip rotation speed Nr. The steeper shock increases as the slope of the actual slip rotation speed Nr decreases. In order to prevent this, the second slip rotation speed is set by setting a larger predetermined value to be added as the decrease gradient of the actual slip rotation speed Nr is larger. The larger the actual slip rotation speed Nr with respect to the input of excessive torque, the larger the predetermined value to be added is set to set the second slip rotation speed. As a result, sudden engagement at the actual slip rotation speed Nr can be suppressed, and engagement shock can be reduced.

The transmission controller 12 commands the clutch control oil pressure to the oil pressure control circuit 11 based on the deviation between the actual slip rotation speed Nr and the first or second target slip rotation speed dNr2, and sets the actual clutch oil pressure to the friction engagement element. Supply.

After the process of step S106, the process of this flowchart is complete | finished.

In this way, the transmission controller 12 controls the hydraulic pressure supplied to the friction engagement element based on the actual slip rotation speed Nr and the first target slip rotation speed dNr1 or the second target slip rotation speed dNr2. By controlling the fastening force of the fastening element, a friction fastening element control unit is configured.

The first target slip rotation speed dNr1 is stored in advance in the transmission controller 12, and the target slip rotation speed setting unit is configured by setting the second target slip rotation speed dNr2 by the transmission controller as described above. Is done.

When the deviation between the actual slip rotation speed Nr and the first target slip rotation speed dNr1 exceeds the threshold, the transmission controller 12 replaces the first target slip rotation speed dNr1 with the second target slip rotation speed dNr2. Is set as a target slip rotation speed changing unit.

FIG. 7 is a flowchart for calculating the amount of heat generated by the frictional engagement element, which is executed by the transmission controller 12 according to the embodiment of the present invention.

When the frictional engagement element slips at the actual slip rotation speed Nr after the clutch fuse function is exhibited as described above, the frictional engagement element generates heat. In particular, when the state where the actual slip rotation speed Nr is high continues for a long time, the frictional engagement element may generate heat more than allowable. Since heat generation may damage the frictional engagement element, if the frictional engagement element is likely to generate more heat than allowed, even if the engagement shock is allowed regardless of the actual slip rotation speed Nr, It is necessary to fasten the frictional fastening elements.

The transmission controller 12 determines whether or not an excessive torque is input (S201). As described above, it can be determined that an excessive torque is input when the deviation between the actual slip rotation speed Nr and the first target slip rotation speed dNr1 exceeds the threshold value. The input of excessive torque may be determined by other means.

If it is determined that excessive torque has been input, the transmission controller 12 starts a timer (S202).

Next, the transmission controller 12 acquires the actual slip rotation speed Nr and the magnitude of the excessive torque (S203). And based on these acquired values and the elapsed time after starting a count by step S202, the emitted-heat amount of a friction engaging element is calculated (S204).

Next, the transmission controller 12 determines whether or not the heat generated by the frictional engagement element is equal to or greater than the upper limit calorific value (S205). When the heat generation amount of the friction engagement element becomes equal to or greater than the upper limit heat generation amount, control is performed so that the friction engagement element is immediately engaged (S206).

Specifically, the second target slip rotation speed dNr2 is set to the first target slip rotation speed dNr1, and the hydraulic control is performed based on the deviation between the actual slip rotation speed Nr and the first target slip rotation speed dNr1. A clutch command oil pressure is commanded to the circuit 11 to supply the actual clutch oil pressure to the friction engagement element. Thereby, the frictional engagement element is immediately engaged. Instead of setting the second target slip rotation speed dNr2 to the first target slip rotation speed dNr1, the second target slip rotation speed dNr2 may be set to zero.

By performing such control, priority can be given to preventing the influence of durability due to heat generation of the frictional engagement element over the occurrence of a shock that the frictional engagement element is engaged.

As described above, in the embodiment of the present invention, the transmission 4 that is mounted on a vehicle and continuously outputs the rotational speed of the engine 1 as a driving force source to the drive wheels 7 and outputs the engine 1 or the transmission. 4, and a transmission controller 12 serving as a friction engagement element control unit that controls the engagement state of the friction engagement element. The transmission controller 12 includes a target slip rotation speed setting unit that sets a target slip rotation speed (first target slip rotation speed dNr1, second target slip rotation speed dNr2) of the friction engagement element, and an actual slip of the friction engagement element. A hydraulic control circuit 11 as a fastening force control unit that controls the fastening force of the frictional engagement element so that the rotational speed Nr matches the target slip rotational speed, the actual slip rotational speed Nr, and the first target slip rotational speed dNr1. And a target slip rotation speed changing unit that sets a second target slip rotation speed dNr2 that reduces the separation instead of the first target slip rotation speed dNr1.

With this configuration, even when the clutch fuse function is exerted and the actual slip rotation speed Nr increases, the second target slip rotation speed dNr2 is set, so that the engagement force of the friction element becomes excessive. This prevents the fastening shock.

Since the target slip rotation speed changing unit sets the actual slip rotation speed Nr as the second target slip rotation speed dNr2, the deviation between the actual slip rotation speed Nr and the second target slip rotation speed dNr2 is substantially zero. Therefore, the fastening force of the friction element is prevented from becoming excessive, and a fastening shock is prevented.

The target slip rotation speed changing unit sets the actual slip rotation speed Nr as the second target slip rotation speed dNr2 when the deviation between the first target slip rotation speed dNr1 and the actual slip rotation speed Nr is equal to or greater than a threshold value. Therefore, it can be detected that the actual slip rotation speed Nr is increased by the clutch fuse function being exhibited.

A driving force request detecting unit that detects a driving force request of the driver is provided, and the target slip rotation speed changing unit sets the minimum value of the slip rotation speed that cannot be generated by the driving force as the threshold value. When the actual slip rotational speed Nr is an abnormal rotational speed, the clutch fuse is prevented from being exhibited when the motor is required to satisfy the driving force required by the driver. It is possible to eliminate problems such as heat generation by buffering by function.

The target slip rotation speed changing unit sets a value obtained by adding a predetermined value to the actual slip rotation speed Nr as the second target slip rotation speed dNr2 when the change speed of the actual slip rotation speed Nr changes from increase to decrease. . The predetermined value is set larger as the decrease rate of the change in the actual slip rotation speed Nr is larger. The larger the actual slip rotation speed Nr, the larger the setting. As a result, the actual slip rotation speed Nr can be gently reduced to prevent the engagement shock of the friction engagement element.

The target slip rotation speed changing unit does not add a predetermined value when the actual slip rotation speed Nr is equal to or higher than a predetermined upper limit value, and therefore, when the situation affects the durability of the frictional engagement element such as heat generation. Can prevent this.

When the actual slip rotation speed Nr becomes equal to or lower than the predetermined rotation speed, the target slip rotation speed changing unit sets the first target slip rotation speed dNr1 instead of the second target slip rotation speed dNr2. After exhibiting the fuse function, it is possible to quickly return to the normal first target slip rotation speed dNr1.

A heat generation amount detection unit for detecting the heat generation amount of the frictional engagement element is provided, and the target slip rotation speed changing unit replaces the second target slip rotation speed dNr2 when the heat generation amount exceeds the upper limit heat generation amount. Since the target slip rotation speed dNr1 is set to 1, priority can be given to preventing the influence of the durability due to the amount of heat generated by the frictional engagement element rather than the occurrence of a shock that the frictional engagement element is engaged.

The calorific value detector detects the calorific value based on at least one of the magnitude of the torque, the elapsed time from the time of torque input, and the actual slip rotation speed Nr. Can be detected.

Next, a modification of the embodiment of the present invention will be described.

In FIG. 5 described above, the second target slip rotation speed dNr2 is set to the actual slip so that the actual slip rotation speed Nr gradually decreases when the actual slip rotation speed Nr of the frictional engagement element changes from increase to decrease. Control was performed to add a predetermined value that gradually increases to the rotational speed Nr.

On the other hand, when the actual slip rotation speed Nr changes from increasing to decreasing, the second target slip rotation speed dNr2 is set larger than the actual slip rotation speed Nr, and the second target slip at this time is set. Control may be made so that the deviation between the rotational speed dNr2 and the actual slip rotational speed Nr is increased to converge the actual slip rotational speed Nr of the frictional engagement element.

FIG. 8 is an explanatory diagram of clutch fuse control according to a modification of the embodiment of the present invention.

If excessive torque is input to the transmission 4 at timing t11, and the deviation between the actual slip rotation speed Nr and the first target slip rotation speed dNr1 exceeds the threshold at timing t12, the actual slip rotation speed Nr is set to the second slip. Is set as the target slip rotation speed dNr2.

Thereafter, when the actual slip rotation speed Nr changes from increasing to decreasing (timing t13), the second target slip rotation speed dNr2 is set to a value obtained by adding a predetermined value to the actual slip rotation speed Nr. The predetermined value at this time is preferably set to such a value that the actual slip rotational speed Nr does not fluctuate rapidly and the frictional engagement element does not suddenly engage.

The actual slip rotation speed Nr gradually decreases based on the second target slip rotation speed dNr2, and the second target slip rotation speed dNr2 is set to the first target rotation speed at timing t15. Thereafter, at timing t16, the frictional engagement element becomes the first target slip rotation speed dNr1.

FIG. 9 is an explanatory diagram of clutch fuse control of another modification of the embodiment of the present invention.

As described above, when the actual slip rotation speed Nr changes from increasing to decreasing (timing t13), the second target slip rotation speed dNr2 is set to a value obtained by adding a predetermined value to the actual slip rotation speed Nr. .

At this time, the larger the decreasing gradient of the actual slip rotation speed Nr, the larger the predetermined value to be added and set the second slip rotation speed. The example shown in FIG. 9 shows a case where the decrease gradient of the actual slip rotation speed Nr is larger than the example shown in FIG. 8, and in this case, the predetermined value is set to a larger value.

Thereafter, the actual slip rotation speed Nr gradually decreases based on the second target slip rotation speed dNr2, and the friction engagement element becomes the first target slip rotation speed dNr1 at timing t16.

FIG. 10 is an explanatory diagram of clutch fuse control according to still another modification of the embodiment of the present invention.

As described above, when the actual slip rotation speed Nr changes from increasing to decreasing (timing t13), the second target slip rotation speed dNr2 is set to a value obtained by adding a predetermined value to the actual slip rotation speed Nr. .

At this time, the larger the value of the actual slip rotation speed Nr, the larger the predetermined value to be added and set the second slip rotation speed. The example shown in FIG. 10 shows a case where the value of the actual slip rotation speed Nr is larger than the example shown in FIG. 8, and in this case, the predetermined value is set to a larger value.

Thereafter, the actual slip rotation speed Nr gradually decreases based on the second target slip rotation speed dNr2, and the friction engagement element becomes the first target slip rotation speed dNr1 at timing t16.

The embodiment of the present invention has been described above, but the above embodiment is merely one example of application of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. is not.

For example, in the above embodiment, a belt-type continuously variable transmission mechanism is provided as the variator 20, but the variator 20 is a continuously variable transmission mechanism in which a chain is wound around pulleys 21 and 22 instead of the V belt 23. There may be. Alternatively, the variator 20 may be a toroidal continuously variable transmission mechanism in which a tiltable power roller is disposed between the input disk and the output disk.

In the above embodiment, the sub-transmission mechanism 30 is a transmission mechanism having two speeds of first speed and second speed as the forward speed. However, the sub-speed change mechanism 30 has three or more speeds as the forward speed. A transmission mechanism having the same may be used.

The auxiliary transmission mechanism 30 is configured using a Ravigneaux type planetary gear mechanism, but is not limited to such a configuration. For example, the subtransmission mechanism 30 may be configured by combining a normal planetary gear mechanism and a frictional engagement element, or a plurality of power transmission paths configured by a plurality of gear trains having different gear ratios, and these powers You may comprise by the frictional engagement element which switches a transmission path.

Although the hydraulic cylinders 23a and 23b are provided as actuators for displacing the movable conical plates of the pulleys 21 and 22 in the axial direction, the actuators are not limited to those driven by hydraulic pressure but may be electrically driven.

With respect to the variator 20, the auxiliary transmission mechanism 30 may be in the front stage or the rear stage. For example, when the auxiliary transmission mechanism 30 is provided in the rear stage of the engine 1 and in the front stage of the variator 20, it is particularly effective against excessive torque from the engine 1. On the other hand, when the auxiliary transmission mechanism 30 is provided in the subsequent stage of the variator 20, it is particularly effective against excessive torque from the drive wheels 7. Furthermore, instead of the auxiliary transmission mechanism 30, a forward / reverse switching mechanism may be used.

The present invention is not limited to the embodiments described above, and various modifications and changes can be made within the scope of the technical idea, and it is obvious that these are also included in the technical scope of the present invention.

This application claims priority based on Japanese Patent Application No. 2012-53350 filed with the Japan Patent Office on March 9, 2012. The entire contents of these applications are incorporated herein by reference.

Claims (12)

1. A continuously variable transmission that is mounted on a vehicle and continuously outputs a rotational speed of a driving force source to driving wheels, and a frictional engagement element that is connected in series to the driving force source and the continuously variable transmission; A friction engagement element control unit that controls the engagement state of the friction engagement element, and a transmission control device for a continuously variable transmission,
   The frictional engagement element controller is
   A target slip rotation speed setting unit for setting a target slip rotation speed of the friction engagement element;
   A fastening force control unit that controls a fastening force of the frictional engagement element so that an actual slip rotational speed of the frictional engagement element matches the target slip rotational speed;
   When the deviation between the actual slip rotation speed and the first target slip rotation speed increases, the second target slip rotation reduces the deviation from the actual slip rotation speed instead of the first target slip rotation speed. A target slip rotation speed changing section for setting a speed;
   A transmission control device for a continuously variable transmission.
2. A transmission control device for a continuously variable transmission according to claim 1,
   The target slip rotation speed changing unit is a transmission control device for a continuously variable transmission that sets the actual slip rotation speed as the second target slip rotation speed.
3. A transmission control device for a continuously variable transmission according to claim 2,
   The target slip rotation speed changing unit sets the actual slip rotation speed as the second target slip rotation speed when a deviation between the first target slip rotation speed and the actual slip rotation speed is equal to or greater than a threshold value. Shift control device for continuously variable transmission to be set.
4. A transmission control device for a continuously variable transmission according to claim 3,
   Provided with a driving force request detection unit that detects a driving force request of the driver,
   The target slip rotation speed changing unit is a shift control device for a continuously variable transmission that sets, as the threshold value, a minimum value of a slip rotation speed that cannot be generated by the driving force.
5. A transmission control device for a continuously variable transmission according to any one of claims 1 to 4,
   The target slip rotation speed changing unit sets the second target slip rotation speed to a value larger than the actual slip rotation speed when the change speed of the actual slip rotation speed changes from increase to decrease. A shift control device for a step transmission.
6. A transmission control device for a continuously variable transmission according to claim 5,
   The target slip rotation speed changing unit is a transmission control device for a continuously variable transmission that sets the second target slip rotation speed to be larger as the decrease rate of the change in the actual slip rotation speed is larger.
7. A transmission control device for a continuously variable transmission according to claim 5,
   The target slip rotation speed changing unit is a transmission control device for a continuously variable transmission that sets the second target slip rotation speed to be larger as the actual slip rotation speed is higher.
8. A transmission control device for a continuously variable transmission according to any one of claims 5 to 7,
   The target slip rotation speed changing unit sets the actual slip rotation speed as the second target slip rotation speed when the actual slip rotation speed exceeds a predetermined upper limit value. A transmission control device for a transmission.
9. A transmission control device for a continuously variable transmission according to any one of claims 1 to 8,
   The target slip rotation speed changing unit sets the first target slip rotation speed instead of the second target slip rotation speed when the actual slip rotation speed is equal to or lower than a predetermined rotation speed. Gear shift control device.
10. A transmission control device for a continuously variable transmission according to any one of claims 1 to 9,
    A calorific value detection unit for detecting the calorific value of the frictional engagement element;
    The target slip rotation speed changing unit continuously sets the first target slip rotation speed in place of the second target slip rotation speed when the detected heat generation amount exceeds the upper limit heat generation amount. A transmission control device for a transmission.
11. A transmission control device for a continuously variable transmission according to claim 10,
    The heat generation amount detection unit is a shift control device for a continuously variable transmission that detects the heat generation amount based on at least one of a magnitude of torque, an elapsed time from the time of torque input, and an actual slip rotation speed.
12. A continuously variable transmission that is mounted on a vehicle and continuously outputs a rotational speed of a driving force source to driving wheels, and a frictional engagement element that is connected in series to the driving force source and the continuously variable transmission; A friction engagement element control unit for controlling the engagement state of the friction engagement element, and a transmission control method for a continuously variable transmission,
    The frictional engagement element controller is
    Setting a target slip rotation speed of the frictional engagement element;
    Controlling the fastening force of the friction engagement element so that the actual slip rotation speed of the friction engagement element matches the target slip rotation speed;
    When the deviation between the actual slip rotation speed and the first target slip rotation speed increases, the second target slip rotation reduces the deviation from the actual slip rotation speed instead of the first target slip rotation speed. A transmission control method for a continuously variable transmission that sets a speed.

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