JPH11210872A - Controller for power train - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent hunting in transmission route change caused by fluctuation of the final gear ratio in a power train constituted to use a different transmission route in response to the final gear ratio of a continuously variable transmission. SOLUTION: The final gear ratio G is attained upto the minimum value GL in a low mode route and upto the maximum value GH in a high mode route, and the same final gear ratio G is duplicaredly attained for the both modes in the range between the critical values GL and GH. When the final gear ratio G is changed from a GS attainable only in the low mode to a G2 attainable in the both modes, the mode is not changed over in a shift point P to move to a high mode condition ϕ, but it is maintained even after passing through the point P to move to a low mode condition H2 . The number of times and a frequency for mode change are surely reduced to prevent hunting in change-over by utilizing the duplicated range between the critical values GL and GH.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control apparatus for a power train having a continuously variable transmission, and more particularly, to a power train control apparatus having a plurality of power transmission paths, the power transmission paths corresponding to the final speed ratio of the continuously variable transmission. The present invention belongs to the technical field of a power train control device that is configured to switch over.

[0002]

2. Description of the Related Art In recent years, a speed change ratio between an input rotation from an engine side and an output rotation to a drive wheel side is steplessly changed by being disposed on a power transmission path between an engine and drive wheels. 2. Description of the Related Art A vehicle equipped with a continuously variable transmission configured to drive a vehicle in a power train has been put to practical use. As this type of continuously variable transmission, a belt-type transmission has been known, but Japanese Patent Application Laid-Open Nos. 3-223555 and 6-101754.
As disclosed in Japanese Patent Laid-Open Publication No. H07-209, an input disk to which rotation from the engine side is input and an output disk to which rotation to the driving wheel side is output are coaxially arranged, and between these disks, A roller for transmitting power between the two disks is interposed in a press-contact state, and by tilting the roller, the contact position between the roller and each disk is changed in the radial direction. There is also known a toroidal type continuously variable transmission configured to continuously change the speed ratio of the toroidal transmission.

[0003] The above publication further discloses a geared neutral start system that enables the vehicle to start without using a clutch, a torque converter, or the like. This starting method uses a combination of a continuously variable transmission mechanism and a planetary gear mechanism, and a route in which rotation from the engine side is input to the planetary gear mechanism via the continuously variable transmission mechanism, and without using a continuously variable transmission mechanism. By adopting a power transmission path having two routes, a route directly input to the planetary gear mechanism, and controlling the speed ratio of the continuously variable transmission mechanism in this state, from the planetary gear mechanism to the drive wheel side. A geared neutral state in which the output rotation of the planetary gear mechanism is reduced to zero by realizing a geared neutral state where the output rotation of the planetary gear mechanism becomes zero, and increasing or decreasing the speed ratio of the continuously variable transmission mechanism from the geared neutral state. It is.

In such a geared neutral starting system, a path for transmitting the driving torque of the engine to the driving wheels via the planetary gear mechanism is adopted. This is disadvantageous in increasing the speed of output rotation to the driving wheel side, and causes problems such as an overspeed of the engine. In particular, in the case of a toroidal type continuously variable transmission, if there is only one power transmission path, the speed ratio (final speed ratio) of the entire continuously variable transmission is
Due to the correlation with the speed ratio (toroidal speed ratio) of the toroidal-type continuously variable transmission mechanism, the range of the roller tilt angle becomes larger, the roller becomes excessively inclined with respect to the disk, and the power transmission efficiency decreases. Failure occurs.

Therefore, in order to cope with such a problem, the above-described path for transmitting the driving torque of the engine to the driving wheels via the planetary gear mechanism in order to realize the geared neutral state is set to the low mode. In addition to this, a high-mode power transmission path that transmits the drive torque of the engine to the drive wheels only through the continuously variable transmission mechanism without passing through the planetary gear mechanism is provided separately,
It is common practice to selectively switch the power transmission path between the low mode and the high mode and use the power transmission path. An example of such a switching operation of the power transmission path is specifically described by taking a toroidal type continuously variable transmission as an example. Generally speaking, it is as follows.

That is, as shown in FIG. 9, for example, the roller is limitedly tilted so as not to be excessively tilted with respect to the disc between the lower limit tilt angle θmin and the upper limit tilt angle θmax. The toroidal speed ratio H is increased as the roller tilt angle θ increases, and the toroidal speed ratio H becomes the minimum value Hmin when the roller tilt angle θ is the lower limit tilt angle θmin, and the upper limit tilt Angle θmax
In such a case, the maximum value Hmax is obtained.

In the low-mode power transmission path, as the roller tilt angle θ increases and the toroidal speed ratio H increases (decelerates), the final speed ratio G of the entire continuously variable transmission increases. The gear ratio becomes smaller (increases speed), the gear ratio neutral state GN in which the final speed ratio G is infinite from the reverse direction is passed, and then in the forward direction, the roller tilt angle θ becomes the upper limit tilt angle θmax and the toroidal speed ratio H becomes the maximum. At the time of the value Hmax, the final speed ratio G becomes the minimum value GL achievable in the low mode, while in the power transmission path of the high mode, the roller tilt angle θ increases and the toroidal speed ratio H increases. As the speed decreases, the final speed ratio G increases (decelerates). When the roller tilt angle θ is equal to the upper limit tilt angle θmax, the toroidal speed ratio H is equal to the maximum value Hmax. Configured to final speed ratio G is the maximum value GH achievable in the high mode when.

At this time, the minimum value GL of the final speed ratio G achievable in the low mode is set to be higher than the maximum value GH of the final speed ratio G achievable in the high mode. The maximum value GH of the achievable final gear ratio G is set on the deceleration side from the minimum value GL of the achievable final gear ratio G in the low mode, so that the achievable final gear ratio G in each path is reduced. The characteristic line of both modes overlaps in the range between the two limit values GL and GH, and the characteristic line of both modes is that the final speed ratio G is an intermediate value GP between these two limit values GL and GH, the roller tilt angle θ is θP,
And the toroidal speed ratio H intersects at a point P which is HP. Therefore, switching of the power transmission path between the low mode and the high mode is performed at this point P.
In this case, the final speed ratio G can be continuously and smoothly changed, and it is possible to reduce the occurrence of shock due to switching of the mode or the power transmission path.

In this case, the roller inclination angle θP, the toroidal speed ratio HP and the final speed ratio GP at the switching point P are mechanically constant, but the vehicle speed VP at the switching point P changes depending on the engine speed. . In general, the vehicle speed is thus affected by both the engine speed and the final speed ratio. For example, when the engine speed is constant, the vehicle speed directly reflects the change in the final speed ratio. Then, as shown in FIG.
The vehicle speed V is changed so as to increase as the final speed ratio G decreases in the forward direction.

Here, the operation of changing the vehicle speed will be described more specifically as follows. That is,
Generally, in this type of continuously variable transmission, for example, FIG.
As shown in FIG. 5, a characteristic map indicating a correlation between parameters such as a vehicle speed V, an engine speed N, an opening degree (throttle opening degree) T of an engine throttle valve, and a final speed ratio G is set in advance. The target vehicle speed determined based on the driving state of the vehicle, such as the amount of depression of the accelerator pedal by the driver (accelerator opening), the rate of change thereof (accelerator opening change rate), or the current vehicle speed, is applied to the map. , A control parameter N for realizing the target vehicle speed,
G or the like is obtained, and the engine or the continuously variable transmission is controlled so that the engine speed and the final transmission ratio become the target values.

For example, in the high mode, when the final speed ratio G is controlled to GS and the throttle opening T is controlled to TS, and the engine speed N is Nc and the current vehicle speed is VS, the state of the symbol a is assumed. If a target vehicle speed Vo lower than the current vehicle speed VS is determined, the target vehicle speed Vo is realized by controlling either or both of the engine speed N and the final gear ratio G as described above. Can be. And, for example, the current engine speed Nc
Is an engine speed excellent in fuel efficiency, and in a case where the engine speed N is to be maintained at the current engine speed Nc (economy mode), the engine speed N is fixed to the constant value Nc. Only the final gear ratio G is changed to the current gear ratio G
The target vehicle speed Vo can be realized by increasing the value from S to Go and shifting to the state indicated by the symbol b. At this time, the throttle opening T is controlled to To in order to keep the engine speed N constant at Nc.
In this case, since the state b after the change in the vehicle speed is still on the high mode side, the switching of the mode or the power transmission path does not occur.

On the other hand, for example, as indicated by reference character c, even in the same economy mode, the target vehicle speed is determined to be a lower value Vo ', and as a result, the target final gear ratio for realizing this target vehicle speed Vo' is obtained. Is further deceleration direction G
o ′, the engine speed N is increased when the state c after the change of the vehicle speed moves to the low mode side or when the target vehicle speed Vo is realized as indicated by reference numeral d in FIG. As a result of the accompanying control (power mode), the target final gear ratio for realizing the target vehicle speed Vo is further determined as Go 'in the deceleration direction so as to cancel out the increase in the engine speed N, When the state d after changing the vehicle speed moves to the low mode side or the like, the power transmission path is switched from the high mode to the low mode.

In other words, the switching of the mode or the power transmission path depends on the target final speed ratio for realizing the target vehicle speed in relation to the engine speed, not on what value the target vehicle speed is determined. It may or may not occur depending on what value is required. In the conventional example, the switching is performed while the final speed ratio G is being changed from the GS before the vehicle speed change to the target speed ratio Go ′.
Is performed at a point in time when the vehicle crosses the switching point speed ratio GP. As a result, as described above, the final speed ratio G continuously and smoothly changes, and the shock accompanying the mode or path switching is suppressed.

[0014]

The target vehicle speed or the target final gear ratio is determined one after another in a predetermined control cycle according to the change of the driving state by the driver as described above. For example, the vehicle speed V or the final gear ratio G is determined. In the state near the switching point P, the target vehicle speed or the target final gear ratio is alternately set to the other mode side with the switching point P interposed therebetween due to frequent forward / reverse accelerator operation of the driver or the like. Things can happen.

In this case, if the mode is switched each time the final speed ratio G crosses the switching point speed ratio GP or the switching point P as described above, hunting of the mode switching occurs. Switching between the low mode and the high mode frequently occurs, and the engagement and disengagement operation of the friction elements such as the clutch for switching the power transmission path repeatedly occurs, so that the control of the speed ratio or the control of the vehicle speed does not converge well. Failure occurs.

The present invention addresses the above-described problem in a power train configured to selectively switch a plurality of power transmission paths in accordance with the final speed ratio of a continuously variable transmission. It is an object of the present invention to effectively avoid hunting of the switching of the route or the mode even when the vehicle crosses the route switching point.

[0017]

In order to solve the above problems, the present invention uses the following means.

First, the invention described in claim 1 of the present application (hereinafter, referred to as "first invention") is a method of shifting between input rotation from the engine side and output rotation to the drive wheel side. A control device for a power train having a continuously variable transmission configured such that a ratio changes steplessly, wherein a plurality of power transmission paths are provided between the engine and the drive wheels, and each of the paths can be achieved. The speed ratio of the continuously variable transmission overlaps within a predetermined range, and running state detecting means for detecting a running state of the vehicle; and a target shift of the continuously variable transmission based on a detection result of the detecting means. Target speed ratio setting means for setting a ratio, and transmission path switching means for selectively switching the path according to the speed ratio of the continuously variable transmission, wherein the switching means is set by the setting means. As long as the target gear ratio can be achieved on the current route Even if the target gear ratio is in the overlapping range, the power transmission path is not switched, and the target gear ratio is achieved only when the target gear ratio deviates from the overlapping range and cannot be achieved on the current path. Switching to a possible power transmission path, and the switching is performed after a predetermined standby time has elapsed after the target gear ratio not achievable on the current path is set. Features.

The invention according to claim 2 (hereinafter referred to as “second
Invention ". In the first aspect, the speed ratio of the continuously variable transmission is maintained at the speed ratio closest to the target speed ratio among the speed ratios achievable on the current path until the standby time elapses. Features.

According to a third aspect of the invention (hereinafter referred to as a "third invention"), the transmission ratio of the continuously variable transmission is changed by the transmission path switching after the standby time has elapsed. Means for changing the power transmission path to the same achievable speed ratio between the paths to be switched, wherein the switching means switches the power transmission path when the speed ratio of the continuously variable transmission reaches the same speed ratio. And the engine speed is controlled such that a change in vehicle speed due to the change of the speed ratio to the same speed ratio is suppressed.

On the other hand, the invention according to claim 4 (hereinafter referred to as “fourth
Invention ". In the first aspect of the present invention, there is provided acceleration request determination means for determining the presence or absence of a driver's acceleration request based on the detection result of the traveling state detection means, and the determination means determines that there is a driver's acceleration request. When the determination is made, the standby time is shorter than when the determination is not made.

Further, the invention according to claim 5 (hereinafter referred to as the "fifth invention") is characterized in that in the first invention, the standby time is made longer in a cold state than in a warm state. And

By using the above means, the following effects can be obtained according to each invention of the present application.

According to the first aspect of the present invention, in a power train having a continuously variable transmission, a plurality of power transmission paths are provided between an engine and driving wheels, such as the low mode and high mode power transmission paths described above. In this case, the speed ratio of the continuously variable transmission that can be achieved in each path is a predetermined value, such as a range between the minimum speed ratio GL in the low mode and the maximum speed ratio GH in the high mode. Range. Therefore, within this overlapping range, there is a speed ratio that is the same between these paths, such as the speed ratio GP at the above-mentioned switching point P, and the speed ratio of the continuously variable transmission is the same speed ratio. By switching the power transmission path at that point, a smooth mode or path switching without shock can be achieved.

These paths are selectively switched by the transmission path switching means in accordance with the speed ratio of the continuously variable transmission, and the running state of the vehicle such as the accelerator opening, the accelerator opening change rate, and the vehicle speed is controlled. The target speed ratio of the continuously variable transmission is set by the target speed ratio setting device based on the detection result. Therefore, the switching of the plurality of power transmission paths is performed according to the target speed ratio of the continuously variable transmission set based on the traveling state of the vehicle.

In this case, first, as long as the target gear ratio of the continuously variable transmission can be achieved on the current path, the power transmission path is switched even if the target gear ratio is in the overlapping range. Only when the target speed ratio deviates from the overlapping range and cannot be achieved on the current route, switching from the current route to another power transmission route capable of achieving the target speed ratio is performed. Is being done.

That is, in the low mode described above,
In the overlapping range (between GL and GH), a region between the speed ratio GP and the minimum speed ratio GL, which is provided on the high mode side beyond the switching point speed ratio GP, is used. In the high mode, similarly, within the overlapping range (between GL and GH), a region between the speed ratio GP and the maximum speed ratio GH provided on the low mode side beyond the switching point speed ratio GP. , The speed ratio G on the other mode side, which exceeds the above-mentioned switching point speed ratio GP, respectively.
By using these regions, as long as the target speed ratio of the continuously variable transmission can be achieved on the current path, the shift from the current speed ratio to the target speed ratio can be achieved. All gear ratios in the course of changing the ratio can likewise be achieved on the current path, so that the current path or the current mode can be maintained, thereby changing the gear ratio towards the target gear ratio. Thus, even if the speed ratio passes the above-mentioned switching point speed ratio GP, it is possible to prevent the path from being switched every time, thereby suppressing the hunting of mode or path switching.

Further, even when the target speed ratio deviates from the overlapping range and cannot be achieved on the current route and the power transmission route is switched, for example, the target speed ratio that cannot be achieved on the current route is set. At this time, the path is not switched immediately, but the path is switched after a predetermined standby time has elapsed after the target gear ratio is set.

Therefore, the next target gear ratio is set during the standby time, and the next target gear ratio is set again to a gear ratio achievable on the current route due to a change in the driving state by the driver. In this case, the current path can be maintained as it is, and as a result, there is no need to switch the power transmission path at all. On the other hand, as described above, when such a standby time is not provided and the route is switched immediately when the target speed ratio that cannot be achieved on the current route is set, the next target speed ratio becomes When the speed ratio is set to be achievable with the above, the power transmission path is switched again. Therefore, according to the first aspect, the number or frequency of switching of the mode or the power transmission path is reliably reduced, and hunting of the switching is effectively suppressed.

According to the second invention, in particular, the speed ratio of the continuously variable transmission cannot be achieved on the current route among the speed ratios achievable on the current route until the standby time elapses. Is held at the gear ratio closest to the target gear ratio of
Even if the target speed ratio is not achieved during this standby time, and therefore the target vehicle speed is not realized, the deviation from the target vehicle speed can be made as small as possible, and the engine speed is adjusted so as to cancel the deviation. Even when the number is controlled to increase or decrease, the control amount, that is, the increase or decrease amount of the engine speed can be reduced as much as possible, which is advantageous.

Further, according to the third aspect of the present invention, the path in which the speed ratio of the continuously variable transmission can be switched to each other like the speed ratio GP at the switching point P, particularly after the standby time has elapsed. The power transmission path is switched when the speed ratio of the continuously variable transmission becomes the same speed ratio, so that the smooth transmission mode without shock as described above can be achieved. Since the path can be switched and the engine speed is controlled so that the change in the vehicle speed that occurs with the change of the speed ratio to the same speed ratio in that case is controlled, for example, the target vehicle speed Although the vehicle speed has been determined to be higher than the current vehicle speed, the vehicle speed has decreased during the vehicle speed change control, and conversely, the vehicle speed change control has been performed despite the target vehicle speed being determined to be lower than the current vehicle speed. Car on the way There is avoided as or increased, thereby preventing such discomfort to the driver.

On the other hand, according to the fourth invention, the presence or absence of a driver's acceleration request is determined based on the detection result of the running state of the vehicle. When it is determined that there is a driver's acceleration request for a reason such as being larger than the value, the waiting time is shortened compared to when it is not determined, so that the period during which the target vehicle speed is not realized during the waiting time is shortened. As a result, the target vehicle speed is realized early, and it is possible to appropriately respond to the acceleration request.

Further, according to the fifth aspect, for example, when the operating oil temperature or the engine water temperature is low, or when the engine is started in a cold period in which the time is short, the standby time is made longer than in the warm state. In addition, it is possible to appropriately cope with a response delay occurring in the operation of changing the tilt angle of the roller during a cold time when the viscosity of the hydraulic oil increases, that is, in the control operation of the gear ratio and the switching operation of the clutch.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by describing an embodiment of a power train having a toroidal type continuously variable transmission as a continuously variable transmission with reference to the drawings.

FIG. 1 is a skeleton diagram showing a mechanical configuration of a toroidal type continuously variable transmission according to the present embodiment, and FIG. 2 is a system configuration diagram. An input shaft 11 connected to the output shaft 2 via a torsional damper 3, a hollow primary shaft 12 loosely fitted to the outside of the shaft 11, and a secondary shaft arranged in parallel to these shafts 11, 12. And a shaft 13.
However, both are arranged so as to extend in the lateral direction of the vehicle.

In the continuously variable transmission 10, the toroidal first and second transmission mechanisms 20 are disposed on the axis of the input shaft 11 and the primary shaft 12.
30 and a loading cam 40, and a planetary gear mechanism 50, a low mode clutch 60 and a high mode clutch 70 are provided on the axis of the secondary shaft 13. A low-mode gear train 80 and a high-mode gear train 90 are provided between the axis of the input shaft 11 and the primary shaft 12 and the axis of the secondary shaft 13.

The first and second transmission mechanisms 20 and 30 have substantially the same configuration, and each of the input and output disks 21 and 31 and the output disks 22 and 3 has a toroidal surface.
2 between the opposed surfaces,
Two rollers 23, 33 for transmitting power between the two and between 31, 32, respectively, are interposed.

In the first transmission mechanism 20 arranged farther from the engine 1, the input disk 21 is arranged on the opposite side to the engine, the output disk 22 is arranged on the engine side, and the first transmission mechanism 20 is arranged closer to the engine 1. Second transmission mechanism 30
Indicates that the input disk 31 is on the engine side and the output disk 3
2 is disposed on the opposite side to the engine, the input disks 21 and 31 of both transmission mechanisms 20 and 30 are respectively coupled to both ends of the primary shaft 12, and the output disks 22 and 32 are integrated, It is rotatably supported by an intermediate portion of the primary shaft 12.

A first gear 81 constituting the low mode gear train 80 is connected to an end of the input shaft 11 on the side opposite to the engine, and the first gear 81 and an input disk of the first transmission mechanism 20 are connected. A loading cam 40 is interposed between the output disc 2 and the output disc 2 integrated with the first and second transmission mechanisms 20 and 30.
A first gear 91 that constitutes the high-mode gear train 90 is provided on the outer periphery of each of the gears 2 and 32 (hereinafter, referred to as the “integrated output disk 34”).

On the other hand, a second gear 82 constituting the low mode gear train 80 is rotatably supported at an end of the secondary shaft 13 on the side opposite to the engine.
3 and is connected to the first gear 81 via
The planetary gear mechanism 50 is disposed at an intermediate portion of the secondary shaft 13. And, the planetary gear mechanism 50
A low mode clutch 60 for connecting or disconnecting the pinion carrier 51 and the second gear 82 of the low mode gear train 80 is interposed between the pinion carrier 51 and the second gear 82 of the low mode gear train 80.

On the engine side of the planetary gear mechanism 50, a first gear 91 of a high mode gear train 90 provided on the outer periphery of the integrated output disk 34 of the first and second transmission mechanisms 20 and 30 meshes. A second gear 92 is rotatably supported, and the second gear 92 and the sun gear 5 of the planetary gear mechanism 50 are supported.
2 and the internal gear 53 of the planetary gear mechanism 50 is connected to the secondary shaft 13.
A high mode clutch 70 for connecting or disconnecting the second gear 92 of the high mode gear train 90 and the secondary shaft 13 is provided.

A differential device 5 is connected to an end of the secondary shaft 13 on the engine side via an output gear train 4 including first and second gears 4a and 4b and an idle gear 4c. Power is transmitted to the left and right drive wheels 7 and 8 from the differential device 5 via drive shafts 6a and 6b extending left and right.

By changing the tilt angle of the rollers 23, 33, the rollers 23, 33 are connected to the input,
The contact position between the two output disks 21, 31, 34 changes in the radial direction. As a result, the rotation of the input disks 21, 31 is continuously changed and transmitted to the integrated output disk 34.

In this case, the rollers 23 and 33 are supported by trunnions 14... 14 movably provided in a direction orthogonal to the rotation axes of the disks 21, 31 and 34.
By controlling the amount of movement of the trunnions 14... 14 in the same direction, tilt angle control of the rollers 23 and 33, that is, gear ratio control is performed.

In particular, as shown in FIG.
3, 33, the rollers 23, 33 are horizontal,
When the contact positions with the input and output disks 21, 31, and 34 are the same in the radial direction, that is, when the toroidal speed ratio is 1, the contact position with the output disk 34 is reduced from this state as shown. Is input disk 2
The inclination in the direction that becomes larger in the radial direction as compared with the contact position with the output disks 34, i.e., the direction in which the toroidal speed ratio becomes larger is positive (+ θ), and conversely, the contact position with the output disk 34 is the input disks 21, 31. The inclination in the direction that becomes smaller in the radial direction as compared with the contact position, ie, the direction in which the toroidal speed ratio becomes smaller is the negative direction (−θ).

The vehicle is provided with a control unit 100 that integrally controls the engine 1 and the continuously variable transmission 10 that constitute a power train. The control unit 100 includes a depression amount of an accelerator pedal 15 (accelerator opening). Acceleration sensor 1 for detecting
6, a signal from an engine speed sensor 17 for detecting the engine speed input to the continuously variable transmission 10, a signal from a vehicle speed sensor 101 for detecting the speed output to the differential device 5, A signal from an oil temperature sensor 104 for detecting a temperature, a signal from a water temperature sensor 105 for detecting an engine water temperature, and the like are input, and based on these signals, an intake passage 1 leading to a combustion chamber of the engine 1.
The throttle valve 19 is provided on the upstream side of the combustion chamber 8 and controls the amount of intake air drawn into the combustion chamber. Fuel injection valve 102 for supplying fuel
, 102, the ignition timing of the ignition plugs 103,... Installed in the combustion chamber, and the trunnions for supporting the rollers 23, 33 in the toroidal transmission mechanisms 20, 30, of the continuously variable transmission 10. The control of the speed ratio through the control of the amount of movement of the disks 14, 14, 14 with respect to the disks 21, 31, 34 and the control of the engagement / release operation of the low mode clutch 60 and the high mode clutch 70 are performed.

Here, the continuously variable transmission 1 having the above-described configuration is described.
0, first, a state in which the low mode clutch 60 is engaged and the high mode clutch 70 is released while the vehicle is stopped,
In other words, in the low mode state, the rotation from the engine 1 starts from the end of the input shaft 11 on the side opposite to the engine, the first gear 81, the idle gear 83, and the second gear 8.
The transmission is transmitted to the secondary shaft 13 side through a low mode gear train 80 made up of 2 and further input to the pinion carrier 51 of the planetary gear mechanism 50 via the low mode clutch 60.

The rotation of the engine 1 input to the input shaft 11 is transmitted from the first gear 81 of the low mode gear train 80 to the input disk 21 of the first transmission mechanism 20 via the loading cam 40 adjacent thereto.
And transmitted to the integrated output disk 34 via the rollers 23, 23, and at the same time, the input disk 2
1 through the primary shaft 12
2 is also input to the input disk 31 of the second transmission mechanism 30 disposed at the end of the first transmission mechanism 20 on the engine side.
Similarly to the above, the power is transmitted to the integrated output disk 34 via the rollers 33 and 33.

The first and second transmission mechanisms 20, 3
0, the rotation of the integrated output disk 34
Is transmitted to the sun gear 52 of the planetary gear mechanism 50 via a high mode gear train 90 including a first gear 91 provided on the outer periphery of the first gear 91 and a second gear 92 on the secondary shaft 13.

Therefore, the planetary gear mechanism 50 includes:
The rotation is input to the pinion carrier 51 and the sun gear 52. At this time, the ratio of the rotation speeds is set to a predetermined ratio by the speed ratio control of the first and second transmission mechanisms 20, 30. As a result, the rotation of the internal gear 53 of the planetary gear mechanism 50, that is, the rotation input from the secondary shaft 13 to the differential device 5 via the output gear train 4 becomes zero, that is, the vehicle speed becomes zero, and the transmission 10 Becomes geared neutral.

From this state, the speed ratio of the first and second transmission mechanisms 20 and 30 is changed to change the ratio between the input rotation speed to the pinion carrier 51 and the input rotation speed to the sun gear 52. For example, the internal gear 53 or the secondary shaft 13 rotates in the forward or reverse direction in a state where the speed ratio of the transmission 10 as a whole, that is, the final speed ratio is large, that is, in the low mode, and the vehicle starts. Will be.

Next, an example of the specific operation of the vehicle speed change control for realizing the target vehicle speed performed by the control unit 100 and the switching control between the low mode and the high mode accompanying the gear ratio control executed by the control. 3 and 4
This will be described according to the control program shown in the flowchart. In this embodiment, the vehicle speed change control is performed in the economy mode in which the engine speed is maintained as high as possible with excellent fuel efficiency and the target vehicle speed is realized not by controlling the engine speed but by controlling the gear ratio exclusively. It is supposed to be.

First, in step S0, all of the various detection signals used in the previous control and variables such as a standby time α, which will be described later, are all initialized. Then, various signals are read again for the current control in step S1, and then in step S1.
In 2, the target vehicle speed Vo is determined from the vehicle speed, the accelerator opening, that is, the depression amount of the accelerator pedal 15, and the accelerator opening change rate. In this case, the target vehicle speed Vo is determined according to the driver's acceleration request. For example, it is considered that the driver's acceleration request is larger as the accelerator opening and the accelerator opening change rate are larger, so the target vehicle speed Vo is higher. Determined by the value.
Further, since the acceleration request at the time of high vehicle speed is considered to be temporary such as overtaking, the target vehicle speed Vo is set to a relatively small value compared to the acceleration request at the time of low vehicle speed. More specifically, the operation of determining the target vehicle speed Vo is to obtain a deviation amount of the vehicle speed to be added to the current vehicle speed.

Next, at step S3, the vehicle speed VP at the switching point P is determined from the engine speed. That is, since the final speed ratio GP at the switching point P is mechanically determined, the switching point vehicle speed VP when the engine speed N is maintained at the current engine speed based on the map shown in FIG. You decide.

Next, in step S4, the above-mentioned step S
From the target vehicle speed Vo determined in step 2, the final speed ratio G, the toroidal speed ratio H, and the tilt angles of the rollers 23 and 33 (hereinafter simply referred to as “tilt angles”) for realizing the target vehicle speed Vo.
θ, that is, the target final speed ratio Go, the target toroidal speed ratio Ho, and the target tilt angle θo are obtained. That is, based on the map shown in FIG. 10, the target final speed ratio Go is determined from the target vehicle speed Vo and the engine speed, and further, the final speed ratio G, the toroidal speed ratio H, and the tilt angle θ
Is mechanically determined, the target toroidal speed ratio Ho or the target tilt angle θo is determined from the target final speed ratio Go and the current mode based on the map shown in FIG. 9 described above.

In this embodiment, since the toroidal type continuously variable transmission is used as the continuously variable transmission, the tilt angle can be obtained. However, in general, for example, a belt type continuously variable transmission and the like are included. The final speed ratio as the entire continuously variable transmission or the speed ratio as the continuously variable transmission mechanism is required.

Next, in step S5, it is determined whether or not the predetermined standby time α is larger than zero. And when NO, that is, when the standby time α is not set,
Proceeding to step S6, the standby time α is set based on the accelerator opening, the oil temperature, the vehicle speed, etc., and if YES,
That is, if the standby time α has already been set, the process proceeds to step S7, and the standby time α is decremented by 1, and then proceeds to step S8.

In this case, in step S6,
As shown in FIGS. 5 and 6, for example, the standby time α is determined to be smaller as the accelerator opening and the rate of change of the accelerator opening are larger, that is, as the driver's acceleration request is larger. The lower the temperature or the engine water temperature, or the shorter the elapsed time after starting the engine, that is, the colder the temperature, the larger the required value. Further, the standby time α may be set to a smaller value as the vehicle speed increases. The effects obtained by these will be described later.

Next, at step S8, the current tilt angle θ
Is determined to pass from the switching point P to the target tilt angle θo. That is, in the vehicle speed change control or the speed ratio control for realizing the target vehicle speed Vo, for example, when the current tilt angle θ is in a state as indicated by a in FIG. 7 (final speed ratio GS, toroidal speed ratio HS), Whether the target tilt angle θo is before the switching point P as shown by the symbol A (final speed ratio G1, toroidal speed ratio H1) or is it at the switching point P as shown by the symbol o (final speed ratio GP) , Toroidal gear ratio HP) or whether it is on the other side of the switching point P as shown by the symbol c (final gear ratio G
2. The toroidal speed ratio H2) is determined.

Although FIG. 7 illustrates the case where the mode is the low mode, it goes without saying that the situation is the same even when the mode is the high mode. Further, the above determination may be made more directly by using the toroidal speed ratio H or the final speed ratio G instead of the tilt angle θ.

If YES, that is, if the target tilt angle θo is on the other side of the switching point P as in the above state c or as indicated by the reference sign or d, the target tilt angle θo is further reduced in step S9. It is determined whether or not it is larger than the upper limit tilt angle θmax. In other words, it is determined whether or not the target final speed ratio Go for realizing the target vehicle speed Vo can be achieved in the current mode.

If YES, that is, the target vehicle speed V
If o cannot be achieved in the current mode, step S10
On the other hand, if NO in either step S8 or step S9, that is, if the target vehicle speed Vo can be achieved in the current mode including the overlapping range (the range of the final speed ratio between GL and GH) Then, the process proceeds to steps S16 to S18, in which the present tilt angle θ is changed to the target tilt angle θo without switching the mode in steps S16 to S18, and the processing is ended.

In other words, in FIG. 7, when the vehicle shifts from the state A before the vehicle speed change to the target A, the current mode (low mode) can be maintained because it is on the near side of the switching point P. Mode switching is not performed. Further, even if the target is in a state such as the signs o, c, d, and d, the range of the speed ratio achievable in any of the low mode and the high mode, that is, the overlapping range (the final speed ratio is GL and GL) GH), and without changing the mode, the state of each target e,
C, K and D can be realized. On the other hand, for example, in order to achieve the same final gear ratio G2 as in state c,
If the state of the code in another mode (high mode) is adopted, it is necessary to switch the mode at the switching point P during the shift control from the state A before the vehicle speed is changed to the target state. The number or frequency of switching of the transmission path increases, which may cause hunting.

On the other hand, if the target vehicle speed Vo cannot be attained in the current mode and the process proceeds to step S10, the process proceeds to step S1.
At 0, the tilt angle is kept at the upper limit tilt angle θmax. That is,
As shown by the reference numeral f in FIG. 7, if the target final speed ratio Go that cannot be achieved in the current mode (low mode) is G3 (the target toroidal speed ratio Ho is H3), the state of reference d is maintained. . As a result, the final gear ratio G in the state of the symbol d is GL, and this gear ratio GL
Is the value closest to the final speed ratio G3 at the target power among the speed ratios achievable in the current mode, so that the deviation from the target vehicle speed Vo can be made as small as possible, and the deviation of the vehicle speed is canceled. Therefore, even when the engine speed is controlled to increase or decrease, the amount of change in the engine speed can be made as small as possible, which is advantageous for the control in the economy mode.

Next, in step S11, it is determined whether or not the standby time α has become zero or less.
That is, when the standby time α has elapsed, the process proceeds from step S12 to
In S14, the tilt angle is returned to the switching point tilt angle θP.
That is, in FIG. 7, the state is shifted from the state of the symbol d to the state of the symbol e.

Then, in step S15, the low mode clutch 60 and the high mode clutch 70 are switched to switch the mode or the power transmission path. Then, in steps S16 to S18, the tilt angle is set to the target tilt angle. After changing to θo, the process ends. As a result, in FIG. 7 described above, the state changes from the state of the symbol o to the target power, and the target vehicle speed Vo is finally realized here.

On the other hand, if NO in step S11, that is, if the standby time α has not yet elapsed, the process returns to the first step S1, and the target vehicle speed Vo, the target final speed ratio Go, and the target toroidal speed ratio Ho are newly obtained. , And the target tilt angle θo, etc., the standby time α is subtracted, it is determined whether or not the target value can be achieved in the current mode, and control according to the result is performed.

Therefore, by the time the standby time α set in step S6 has elapsed for the first time, the next target is the current mode (low mode)
When set as achievable in, the state of d is transferred to those states again, and consequently,
No mode switching is performed.

On the other hand, even after the elapse of the standby time α, the step S12 is performed only when the next target is set as one that cannot be achieved in the current mode.
Proceeding below, the mode or the path is switched in step S15 on the way.

As a result, the number or frequency of mode or path switching between low and high is reliably reduced, and the possibility of hunting is effectively reduced.

In this case, the standby time α is
The smaller the value of the driver's acceleration request is, the smaller the value is. Therefore, the period during which the target vehicle speed is not realized during the standby time is shortened, whereby the target vehicle speed is realized early, and the acceleration request is appropriately responded to. Becomes possible.

Further, since the standby time α is required to be larger in a cold state, the operation of changing the tilt angles of the rollers 23 and 33 during a cold state in which the viscosity of the hydraulic oil becomes high, that is, the operation of controlling the gear ratio. Also, it is possible to appropriately cope with a response delay occurring in the switching operation of the clutches 60 and 70 and the like.

Further, when the standby time α is made smaller as the vehicle speed increases, the following operation is obtained. That is, when the vehicle speed is high, there is a high possibility that the target vehicle speed set next will be set to a value lower than the current vehicle speed of the high value, so that it is not necessary to switch the mode as a result. The probability of proceeding to increases. Therefore, there is a high possibility that the next target vehicle speed set on the current route can be achieved without taking the standby time α so long, so that the standby state is released early and the shift response to the next target vehicle speed is performed. It is more reasonable control to improve the performance.

By the way, as described above, even after the elapse of the standby time α, the target final speed ratio Go is set as
If a speed ratio that cannot be achieved in the current route is set, the route is switched as a result, but during this time, the final speed ratio G has not reached the target value Go and can be achieved in each route. After being held at the limit values GL and GH, the vehicle is returned to the switching point P, and thereafter, is finally changed to the target final gear ratio Go on the route after the switching. Therefore, during this time, if the control for changing the engine speed is not performed, the vehicle speed is determined only by the final speed ratio G, and as described above, it is difficult to obtain a vehicle speed that matches the driver's accelerator operation. On the contrary, during the period in which the final speed ratio G is returned from the limit values GL and GH to the switching point P, a phenomenon occurs such that the speed is reduced when the speed should be increased, and the speed increases when the speed should be reduced. It makes you feel uncomfortable.

Therefore, the control unit 100
Is designed to control the engine speed to solve such a problem at a minimum and in a limited manner as long as the effect of the economy mode is not impaired. Next, the engine control will be described with reference to the time charts of FIG. 7 and FIG.

That is, in this case, in FIG.
From the state of the sign a, the state is sequentially shifted to the states of the signs d, o, and f, and as shown in FIG.
Increases from AS to AE at time t1. Then, the state of the power is determined as the final target according to the accelerator opening AE and the like.

The toroidal speed ratio H exceeds the switching point speed ratio HP from the initial HS and reaches the maximum value Hm from time t2.
After the standby time α has elapsed at time t3, the gear ratio is returned to the switching point gear ratio HP at time t4, and changes to the target value H3 at time t5.

Then, along with this, the final speed ratio G exceeds the switching point speed ratio GP from the initial GS and exceeds the time t2.
After the standby time α has elapsed at time t3, the switching point gear ratio G at time t4.
It is returned to P, and changes to the target value G3 at time t5.

In this case, the speed ratios H and G do not reach the target values H3 and G3 from the time t2 to the time t5, so that the engine speed N is fixed at the initial speed NS. In this case, for example, as shown by a chain line in FIG.
From time t4 to time t4, and time t after the mode switch.
The vehicle speed suddenly increases from 4 to t5, and a smooth change in vehicle speed is not realized.

To cope with this, the engine speed N is set to be equal to the time t2 so as to cancel the above-mentioned change in vehicle speed.
From time t3 to time t3, at a larger increase rate from time t3 to time t4, and is returned to the original rotational speed NS between time t4 and time t5 after the mode switching. Thus, the change in the vehicle speed due to the final speed ratio G is corrected by the change in the vehicle speed according to the engine speed N, and as a result, the smooth vehicle speed V is linearly and smoothly changed from the initial VS to the target vehicle speed Vo.

In the above description, the case where the target vehicle speed is determined to be higher than the current vehicle speed and the mode is switched from low to high has been described. However, the present invention is not limited to this. For example, the target vehicle speed may be higher than the current vehicle speed. It is needless to say that the present invention is applicable even when the mode is switched from high to low, for example, when the mode is determined to be a low value.

[0082]

As described above, according to the present invention,
A plurality of power transmission paths are provided between the engine and the drive wheels. In this case, these paths are provided such that the speed ratio of the continuously variable transmission achievable in each path overlaps within a predetermined range. Therefore, by using the overlapping range, the number or frequency of the switching of the path or the mode can be reduced, and the hunting of the switching can be suppressed.

Further, even when the target transmission ratio deviates from the overlapping range and cannot be achieved on the current path and the power transmission path is switched, the path is switched after a predetermined standby time has elapsed. If the next target speed ratio is set to a speed ratio achievable again on the current route during the standby time, the current route can be maintained as it is, and as a result, the power transmission route is completely switched. This eliminates the need to perform the switching, thereby making it possible to more reliably reduce the number or frequency of path or mode switching, and to suppress hunting of the switching more effectively.

[Brief description of the drawings]

FIG. 1 is a skeleton diagram showing a mechanical configuration of a toroidal continuously variable transmission of a power train according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the configuration of the system.

FIG. 3 is a flowchart illustrating specific operations of vehicle speed change control and mode switching control.

FIG. 4 is also a flowchart.

FIG. 5 is a characteristic diagram used for the control.

FIG. 6 is also a characteristic diagram.

FIG. 7 is an explanatory diagram of an operation obtained by the control.

FIG. 8 is a time chart showing a change over time of each parameter in the control.

FIG. 9 is a characteristic diagram showing a relationship among parameters in the toroidal type continuously variable transmission.

FIG. 10 is another characteristic diagram.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 10 Toroidal type continuously variable transmission 16 Accelerator opening sensor 17 Engine speed sensor 20, 30 Continuously variable transmission mechanism 21, 31 Input disk 22, 32 Output disk 23, 33 Roller 50 Planetary gear mechanism 60 Low mode clutch 70 High Mode clutch 100 control unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F16H 63:06

Claims (5)

[Claims] 1. A control device for a power train having a continuously variable transmission configured such that a gear ratio between an input rotation from an engine side and an output rotation to a drive wheel side changes steplessly. A plurality of power transmission paths are provided between the engine and the drive wheels, and the speed ratios of the continuously variable transmission achievable in the respective paths overlap within a predetermined range, and a traveling state of the vehicle is detected. Running state detecting means, target speed ratio setting means for setting a target speed ratio of the continuously variable transmission based on the detection result of the detecting means, and selecting the path according to the speed ratio of the continuously variable transmission. Transmission path switching means for selectively switching, as long as the switching means can achieve the target gear ratio set by the setting means on the current path, even if the target gear ratio is in the overlapping range. Do not switch the power transmission path. Only when the gear ratio deviates from the overlapping range and is not achievable on the current path, the power transmission path is switched to the achievable target gear ratio, and the switching is not achievable on the current path. A control device for a power train, wherein the control is performed after a predetermined standby time has elapsed after a target gear ratio is set. 2. The speed ratio of the continuously variable transmission is maintained at the speed ratio closest to the target speed ratio among the speed ratios achievable on the current route until the standby time elapses. Item 2. The power train control device according to item 1. 3. After the standby time has elapsed, the speed ratio of the continuously variable transmission is changed to the same achievable speed ratio between the paths that are switched by the transmission path switching means. The power transmission path is switched when the speed ratio of the continuously variable transmission becomes the same speed ratio, and a change in vehicle speed due to the speed ratio being changed to the same speed ratio is reduced. The power train control device according to claim 1, wherein the engine speed is controlled so as to be suppressed. 4. An acceleration request judging means for judging the presence or absence of a driver's acceleration request based on the detection result of the traveling state detecting means is provided, and when the judgment means judges that there is a driver's acceleration request, The power train control device according to claim 1, wherein the standby time is shorter than when the determination is not made. 5. The power train control device according to claim 1, wherein the standby time is set longer in a cold state than in a warm state.