JPS62255240A - Stepless speed changer control device - Google Patents

Abstract

PURPOSE:To provide stable running by fixing the speed change ratio through sensing of any failure during regular running, which has caused inaccurate control of the speed change ratio, and thereby preventing the ratio from varying. CONSTITUTION:A control device 101 makes control so that the target number of revolutions corresponds to the engine load on the basis of speed change control characteristic diagram, in which the engine load represented by throttle valve opening Th from sensing means 102, 106 and target number of revolutions TNp of the input shaft of speed changer are used as parameters. In this constitution, a regular running sensing means 201 senses that it is regular running. In case the point specific to the engine load and the number of input shaft revolutions of a stepless speed changer is deviated from the speed change control characteristic diagram for a certain amount when regular running is sensed, the failure sensing means 202 judges that it is failure and emits a signal is fix the speed change ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a control device for a continuously variable transmission that controls a gear ratio of a continuously variable transmission that is interposed in an engine drive system. More specifically, the present invention relates to a control device having a failure compensation function, particularly for continuously variable transmissions and the like.

(Prior Art) As one of the transmissions that are interposed in the drive system of the engine in order to efficiently transmit the output of the engine of an automobile etc. to the wheels, it is described in, for example, Japanese Patent Application Laid-Open No. 1986-9S2SG@. There is known a V-belt type continuously variable transmission that can continuously and steplessly change the gear ratio within a predetermined range.

In such a continuously variable transmission, as described in the above-mentioned publication, generally the speed change control characteristics as shown in FIG.
That is, for example, using the engine load expressed by the throttle valve opening Th and the target rotation speed (target input rotation speed) of the input shaft of the transmission (TNI) as parameters, the target input rotation speed increases as the valve opening Tb decreases. The rotational speed (input rotational speed) of the input shaft of the transmission is determined based on a transmission control characteristic diagram that is set so that the number TNI) decreases (in this case, the decrease in TNp includes TNp unchanged). At each throttle valve opening Th, the gear ratio is controlled so that the target input rotational speed TNp corresponds to the opening Th. For example, if the input rotational speed is N11tt at a certain point in time with the throttle valve opening Th1 in the figure, gear ratio control is performed to downshift the transmission and increase the gear ratio so that the rotational speed becomes TNpt. , rotation speed is N
In the case of p1b, on the other hand, gear ratio control is performed to shift up the transmission and increase the gear ratio so that the rotational speed becomes TND s.

Note that the gear ratio here means the number of revolutions of the input shaft of the transmission divided by the number of revolutions of the output shaft of the transmission. Also,
The characteristic diagram shown in FIG. 8 is a shift control characteristic diagram determined in consideration of fuel efficiency and the like.

(Problems to be Solved by the Invention) In a continuously variable transmission in which the gear ratio control is performed as described above, it is obvious that during steady running, the throttle valve opening Th and the input rotation speed Np of the transmission are The specified point should be located on or near the shift control characteristic diagram.

Therefore, even during steady running, if the point specified by Th and Np is not located on or near the characteristic diagram, the gear ratio control is not being performed reliably, and the transmission There may be some kind of failure in the engine drive system, etc.

Therefore, in such a case, if left as is, the gear ratio control may not be performed reliably and running may become unstable, so it is desirable to take some countermeasures.

In view of the above circumstances, it is an object of the present invention to provide control of a continuously variable transmission that can ensure stable running even if some kind of failure occurs in the transmission etc. and the gear ratio control is no longer performed in accordance with the characteristic diagram. The goal is to provide equipment.

(Means for Solving the Problems) In order to achieve the above object, the control device for a continuously variable transmission according to the present invention detects a steady running state from, for example, the rate of change in throttle valve opening. detection means;
At a certain point in time when a steady running signal indicating a steady running state is input from the detection means, there is a point specified by the engine load expressed through the throttle valve opening and the input rotation speed of the transmission, for example. If it is not located on or near the shift control characteristic diagram, that is, if it is away from the characteristic diagram by a predetermined amount or more, it is determined that there is a failure,
and failure detection means for outputting a signal for fixing the gear ratio.

The case where the distance is greater than the predetermined amount refers to, for example, the case where the difference between the input rotation speed at a certain point in time and the target input rotation speed corresponding to the engine load at that certain point in time is a predetermined value M or more.

In addition to fixing the gear ratio as described above, in addition to fixing and maintaining the gear ratio at the time when a failure is determined, for example, a failure response map is prepared in advance and the engine load at the time when a failure is determined is input from the map. This also includes the case where the running ratio is fixed to a safer running ratio determined based on the rotational speed.

(Effects of the Invention) Since the control device for a continuously variable transmission according to the present invention is configured as described above, if the gear ratio control is not performed accurately due to some kind of failure during steady running, that is, when the engine load If the point specified by the transmission input rotation speed is away from the shift control characteristic diagram by a predetermined amount or more, this will be detected and the gear ratio will be fixed as it is, or the gear ratio will be changed to a safer one. Therefore, the gear ratio may change even though the gear ratio change signal is not output, making driving unstable, or the gear ratio may change even though there is some kind of failure. Therefore, there is no risk of unexpectedly unstable running due to an unexpected movement, and stable running can be ensured.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an example of an engine drive system for an automobile, which includes a υ112a device according to the present invention, a continuously variable transmission, etc. controlled by the control device.

In FIG. 1, 1 is an engine, and the output (rotation) of the engine 1 is transmitted through a clutch 2, a gearbox 3, a continuously variable transmission 4. The power is transmitted to the drive wheels 6 via the differential gear 5, and the power transmission mechanism from the engine 1 to the drive wheels 6 constitutes an engine drive system.

An intake pipe 8 is connected to the engine 1 via an intake manifold 7, and the output of the engine 1 is adjusted by adjusting the opening degree of a throttle valve 9 disposed in the intake pipe 8 to mm. Further, as will be described later, the gearbox 3 can be manually operated to operate between R (reverse), N (neutral), D (drive), and L (low) ranges. Further, the engagement and disengagement of the clutch 2 and the gear ratio control of the continuously variable transmission 4 are automatically performed as will be described later by controlling an actuator using hydraulic pressure.

Next, the clutch 2. Gearbox 3. The continuously variable transmission 4 will be sequentially explained based on FIG. 2.

The clutch 2 has a clutch input shaft 21 which also serves as the crankshaft of the engine 1, and a latch output shaft 22 which is rotatable with respect to the input shaft 21.

A clutch disc 23 is spline-fitted to the clutch output shaft 22, and by press-contacting the clutch disc 23 to a flywheel 24 that is integrated with the clutch input shaft 21, a connected state is established in which both wheels 21 and 22 are connected. Conversely, clutch disc 23 and flywheel 24
When the two shafts 21 and 22 are separated from each other, the shafts 21 and 22 are disconnected from each other, resulting in a disconnected state. In order to press the latch disk 23 against the flywheel 24 in this manner, a sleeve 25 is fitted to the output shaft 22 so as to be slidable and rotatable. One end of a spring member 27 such as a disc spring that can swing freely is connected, while the other end of the spring member 27 is connected to a clutch pressure plate 28 facing the back side of the clutch disc 23. There is. As a result, when the sleeve 25 moves to the left in FIG. 2, the clutch pressure plate 28, that is, the clutch disc 23 is displaced to the left in the figure via the spring member 27, resulting in a connected state, and conversely, from this connected state, the sleeve 25 is moved to the left in the figure. If it moves to the left in Figure 2, it will be in a cutting state.

The displacement position of the sleeve 25 in the leftward direction in FIG. 2 is adjusted by a cylinder device 29. That is, the piston rod 30 of the cylinder device 29 is connected to one end of a swinging arm 32 that is swingable about a fulcrum 31, while the other end of the cough swinging arm 32 is connected to the back surface of the sleeve 25. It is coming. Further, the oil chamber 34 defined by the piston 33 of the cylinder device 29 is
It is connected to a clutch solenoid valve 36 consisting of a three-way electromagnetic switching valve via a pipe 35, and the clutch solenoid valve 3G is connected to a pipe 3 extending from the discharge side of a hydraulic pump 37.
8, and piping 40 extending from the reservoir tank 39,
each connected. A filter 41 is connected to the suction side of the hydraulic pump 37 and a reservoir tank 39 is connected thereto.
A pipe 42 that extends further is connected.

The clutch solenoid valve 36 has two solenoids 36a and 36b for connection and disconnection, and the connection solenoid 36a is energized (l, 7J disconnection solenoid 36b).
11) When the hydraulic pump 37 and cylinder device 2
9 is communicated with the oil chamber 34, the piston rod 30 is extended, and the clutch 2 is connected. The transmission torque of the clutch 2 during this connection increases as the amount of oil supplied to the oil chamber 34 increases (the pressing force of the clutch disc 23 against the flywheel 24 increases). Furthermore, when the disconnection solenoid 36b is energized (the connection solenoid 36a is demagnetized), the oil chamber 34 is opened to the reservoir tank 39, the piston rod 30 is retracted by the return spring 43, and the clutch 2 is disconnected. Ru.

Further, when both the solenoids 36a and 36b are demagnetized, the oil chamber 34 is sealed and the piston rod 30 is maintained as it is.

The input shaft of the gearbox 3 is the clutch output shaft 2.
2, and a first gear 51 and a second gear 52 having a smaller diameter than the first gear 51 are integrally formed on the clutch output shaft 22. A gearbox output shaft 53 is disposed parallel to the output shaft 22, and a back gear 54 that constantly meshes with the second gear 52 is disposed between the two shafts 22 and 53. has been done. A large-diameter intermediate gear 55 that constantly meshes with the first gear 51 is rotatably fitted to the gearbox output shaft 53, while the sleeve 5
6 are integrated. A clutch gear 57 is always spline-fitted to this sleeve 5G.
As shown in FIG. 2, the clutch gear 57 can also be spline-fitted to the intermediate gear 55 as it is displaced in the axial direction.

In such a gearbox 3, when the clutch gear 57 is at the rightmost position as shown in FIG. 2, the rotation of the clutch output shaft 22 is caused by the rotation of the first gear 51. Intermediate gear 55. Clutch gear 57. It is transmitted to the gearbox output shaft 53 via the sleeve 56, and the rotational direction of the output shaft 53 at this time corresponds to the forward direction of the automobile.

Furthermore, when the clutch gear 57 is displaced to the leftmost position in FIG.
．． Back gear 54. Clutch gear 57. It is transmitted to the gearbox output shaft 53 via the sleeve 56, and the rotational direction of the output shaft 53 at this time corresponds to the backward direction of the automobile. Further, when the clutch gear 57 is at the intermediate stroke position in the left-right direction in FIG. 2 (when the clutch gear 57 is not spline-fitted with the intermediate gear 55 and is not engaged with the back gear 54), the clutch output II! 122 and the gearbox output shaft 53 are disconnected from each other, resulting in a neutral state.

The displacement position of the clutch gear 57 is adjusted by a cylinder device 58.

That is, the piston rod 59 of the cylinder device 58 is
It is linked to the clutch gear 57 via the interlocking arm 60, so that when the piston rod 59 is extended, the clutch gear 57 is displaced to the left in FIG. This cylinder device 58 has two oil chambers 62 and 63 defined by its piston 61, and a manual valve consisting of a three-way switching valve is connected to the oil chamber 62 through a pipe 64 and the oil chamber 63 through a pipe 65. 66, respectively.

The manual valve 66 is connected to the hydraulic pump 37 via a pipe 67 and to the reservoir tank 39 via a pipe 68.

Such a manual valve 66 is switched by manually operating an operating lever 70 that is swingable about a fulcrum 69, and the operating lever 10 is pivoted clockwise in FIG. As the temperature increases, the R range, N range, and D range are sequentially changed.

It is designed to be able to take the L range. In this R Reno 2 position, the oil chamber 62 is communicated with the hydraulic pump 37, and the oil chamber 63 is opened to the reservoir tank 39, so that the piston rod 59 is extended and the gearbox 3 is in the backward state. . Also, in the N range position,
Both parts! 62 and 63 are both opened to the reservoir tank 39, and due to the balancing action of the return spring 71, the piston rod 59, that is, the clutch gear 57 is at the intermediate stroke position, and the gear box 3 is at the neutral position described above.

Further, in the D-shin 2 position, the oil chamber 62 is opened to the reservoir tank 39, the oil chamber 63 is communicated with the hydraulic pump 37, the piston rod 59 is retracted, and the gear box 3 is moved as described above. It is in a forward state.

Note that in the L range position, the manual valve 66 is at the same position as in the D range.

The continuously variable transmission 4 has an input shaft 81 and an output shaft 82 that are parallel to each other.The input shaft 81 is provided with a primary pulley 83, and the output shaft 82 is provided with a secondary pulley 84. Between 83 and 84, a belt 85 is wound. The primary pulley 83 is connected to the input shaft 81
The movable flange 81 is composed of a fixed flange 86 integral with the input shaft 81 and a movable flange 81 that can be slidably displaced with respect to the input shaft 81. Accordingly, the belt 85 approaches the fixed flange 86, and the winding radius of the belt 85 around the primary pulley 83 becomes larger. Similarly to the primary pulley 83, the secondary pulley 84 also includes a fixed 7 flange 89 that is integral with the output shaft 82, and a movable flange 90 that can be slidably displaced with respect to the output shaft 82. As the amount of oil supplied to the hydraulic actuator 91 increases, the fixed flange 8
9, the winding radius of the V-belt 85 around the secondary pulley 84 becomes larger.

The hydraulic actuator 88 is connected to the three-way N via a pipe 92, and the hydraulic actuator 91 is connected to the three-way N via a pipe 93.
Each is connected to a speed change solenoid valve 94 consisting of a magnetic switching valve, and the speed change solenoid valve 94 is arranged! F9
5 to the hydraulic pump 37, and to the reservoir tank 39 via piping 96.

The speed change solenoid valve 94 has two valves, one for speed increase and one for deceleration.
It has two solenoids 94a and 94b to energize the speed increase solenoid 94a (the M speed solenoid 94b is demagnetized).
When the hydraulic actuator 88 is turned off, the hydraulic pump 37
Since the hydraulic actuator 91 is opened to the reservoir tank 39, the winding radius of the V-belt 85 around the primary pulley 83 becomes large, while the winding radius around the secondary pulley 84 becomes small, and the output shaft 82 The engine enters a speed increasing state where the rotational speed increases (speed ratio is small). Furthermore, when the deceleration solenoid 94b is energized (the speed increase solenoid 94a is demagnetized), the hydraulic actuator 91 is connected to the hydraulic pump 37, and the hydraulic actuator 88 is opened to the reservoir tank 39, so that the V The winding radius of the belt 85 around the primary pulley 83 becomes smaller, while the winding radius around the secondary pulley 84 becomes larger, and the output shaft 82 enters a deceleration state in which its rotational speed decreases (speed ratio is large). Further, when both solenoids 94a and 94b are turned off, the winding radius of the V-belt 85 around both pulleys 83 and 84 remains unchanged (speed ratio fixed). Of course, the gear ratio is determined by the input shaft 810.
The rotation speed is divided by the rotation speed of the output shaft 82 (the winding radius of the V-belt 85 around the secondary ribs 84 is divided by the winding radius around the primary pulley 83).

Reference numeral 97 in FIG. 2 is an electromagnetic relief valve, which continues to maintain the illustrated position during clutch control and gear ratio control, which will be described later.

1 and 2, reference numeral 101 denotes a control unit, to which the outputs of the respective sensors 102 to 109 are input, and from the control unit 101, the outputs of the clutch solenoid valve 36. Speed change solenoid valve 94. It is output to the relief valve 91. Each of the sensors 102~
109, the sensor 102 is a throttle sensor that detects the opening degree of the throttle valve 9.

The sensor 103 is a rotation speed sensor that detects the rotation speed NE of the engine 1 (in the embodiment, the same as the rotation speed E of the clutch input shaft 21). The sensor 104 is connected to the clutch output shaft 22
This is a rotation speed sensor that detects the rotation speed C of the engine. sensor 10
5 is a position sensor that detects the R, N, D, and L positions of the operating lever 70. The sensor 10G is a rotation speed sensor that detects the rotation speed Np of the input shaft 81 of the continuously variable transmission 4. The sensor 107 is a vehicle speed sensor that detects the rotational speed of the output shaft 82 of the continuously variable transmission 4, that is, the vehicle speed. Sensor 108 is an accelerator sensor for detecting the opening degree of accelerator pedal 110. Sensor 109 is a brake sensor for detecting whether brake pedal 111 is being operated.

Next, the contents of control by the control unit 101 will be explained based on FIGS. 3 to 7.

FIG. 3 is a flowchart showing the entire processing system. First, after the system is initialized in step $1, various data necessary for control are input in step s2, and then clutch control is performed in step S3, and step s4 is performed. The gear ratio control will be performed in step s4 (some of them are read during the control in step s4 in consideration of responsiveness). In addition, in the following explanation, the routine for clutch & lJ DO and the gear ratio tll
It is divided into routines for all.

Clutch Control Routine (Fig. 4) First, in step 121, it is determined whether the operating lever 7o, that is, the gearbox 3 is in the N range or not. If it is not in the N range, the process moves to step 122. In this step 122, it is determined whether the vehicle speed is high (for example, 10 KM/h or more), and if the vehicle speed is high, a vehicle speed flag is set in step 123, and then step 124
Move to.

In step 124, the differential value IE' of the rotational speed E of the clutch input shaft 21 is determined, and it is determined whether or not the differential value E' is positive indicating an increase in the rotational speed. If the differential 1inE' is positive, , the process moves to step 125. In this step 125, it is determined whether the rotation speed E of the clutch input shaft 21 is larger than the rotation speed C of the clutch output shaft 22, and if Etc, the process moves to step 126. In step 126, the connecting solenoid 36a of the clutch solenoid valve 36 is energized, while the disconnecting solenoid 36b is deenergized to connect the clutch 2, that is, increase its transmission torque. Also, step 125
If it is determined that E>C is not the case, step 12
8, connect the clutch solenoid valve 36,
Both the disconnection solenoids 36a and 36b are demagnetized to maintain the transmission torque of the clutch 2 as it is.

If it is determined in step 124 that E'>0 is not the case, the process moves to step 127, where it is determined whether E<C. When E<C, the process moves to step 126, clutch 2 is connected, and E<C.
If not C, the process moves to step 128 and the connected state of the clutch 2 is maintained as it is.

The flow from step 124 to 125 described above is based on the assumption that the rotation of the clutch input shaft 21 is increasing, and the flow from step 125 to 126 is performed when the rotation speed E of the clutch input shaft 21 is increased. Since this is the case when the rotational speed is higher than C, it is necessary to increase the transmission torque of the clutch 2, and therefore the clutch 2 is connected in order to increase the transmission torque of the clutch 2. This case corresponds to, for example, a so-called half-clutch state when starting an automobile. Further, since the flow from step 125 to step 128 is when the transmission torque of the clutch 2 is exactly balanced, the clutch 2 is held in that state, and in this case, for example, it corresponds to a steady running state. .

Conversely, the flow from step 124 to step 127 is based on the assumption that the rotational speed of the clutch input shaft 21 is decreasing, and the transfer of torque between the clutch input and output shafts 21 and 22 is performed from step 124 to step 125. Since the flow is opposite to that of step 125, the determination in step 127 is
In contrast to the determination in , it is checked whether it is Etc or not. Note that the flow from step 121 to step 126 corresponds to, for example, a case where the operation lever 70 is changed to D range while driving with the control lever 70 set to N range, and in this case as well, the so-called half-clutch state form.

Further, the flow from step 121 to step 128 corresponds to a deceleration traveling state using engine braking, for example.

On the other hand, if f11 is determined to be the N range in step 121, the vehicle speed flag is reset in step 129, and then the process moves to step 130. In step 130, the connection solenoid 36a of the clutch solenoid valve 36 is deenergized, while the disconnection solenoid 36b is energized to disconnect the clutch 2.

In other words, in this case, it is clear that the driver himself is requesting a neutral state, so clutch 2 is unconditionally applied.
cut.

Further, when it is determined in step 122 that the vehicle speed is low, the process moves to step 131, where the accelerator pedal is pressed down.
It is determined whether or not 10 is turned ON by being stepped on. When this accelerator is not ON, that is, when it is OFF,
Since this is the time when the output of the engine 1 is not being requested, the process moves to step 132 and it is determined whether the vehicle speed flag is set. When the vehicle speed flag is set, it means that the vehicle speed has not yet decreased sufficiently, and in this case, the process moves to step 133, where it is determined whether or not the brake pedal 111 is depressed. be done. Then, when the brake is ON, step 1
34, here the engine speed NE is 1500
If it is determined that the rpm is below, the process moves to step 130 via step 129 (clutch 2 is disengaged). Further, if it is determined in step 133 that the brake is not turned on, the process moves to step 135, and if it is determined here that the engine rotation speed NE is 11,000 rpm or less, the process proceeds to step 130 via step 129. is performed (clutch 2 is disengaged). If it is determined in step 134 that the engine speed NE is not less than 1500 rpm, and in step 135 the engine speed NE is 1100 rpm or less,
If it is determined that the rpm is not below 0rp, step 12
4, the above-described processing is performed.

In this way, the engine rotation speed N is used as a criterion for determining whether or not to disengage the clutch 2 when the brake is turned on or off.
The reason why the magnitude of E is made different is to provide enough margin to avoid the danger of engine stalling, considering that the vehicle speed decreases faster when the brake is ON than when the brake is not applied. Note that when it is determined in step 132 that the vehicle speed flag is not set, the process of step 130 is performed via step 129 to prevent the engine from stalling (clutch 2 is disengaged).

■, Gear ratio control routine (Fig. 7) This gear ratio tIIllI! The control unit 701, which is a t/J control device of the transmission, controls the engine load as shown in FIG. 5 (in this embodiment, the throttle valve opening Th is used to indicate this engine load). ) and the target input rotation speed TNp as parameters. Of course, the control method is such that, as mentioned above, the transmission input rotation speed (Nl) is always set to TNp corresponding to that T for each Th.
Upshifts and downshifts are performed so that

The control device constituted by the control unit 101 performs upshifts and downshifts based on the shift control characteristic diagram.
Steady running detection means 201 and failure detection means 2 as shown in the figure
02, and when the steady running signal indicating the steady running state is output from the steady running detecting means 201 to the failure detecting means 202, the failure detecting means 202 detects the input from the sensors 102 and 106. When it is determined that the point A (see Fig. 5), which is specified based on the throttle valve opening Thα indicating the engine load and the input rotation speed N of the transmission, is away from the characteristic diagram by a predetermined amount or more, for example, The target input rotational speed TNpa- corresponding to the above Thα and the above N
When it is determined that the difference B from pL is greater than a predetermined number of revolutions, the transmission 4, especially the transmission solenoid valve 9
4, a signal is output to fix the gear ratio.

The steady running state can be detected by the steady running detecting means 201 using any method, but in this embodiment, the above sensor 10 input to the control unit 101 is used.
When the rate of change of the throttle valve rRIaTh from 2 to 2 is less than a predetermined value, it is determined that steady running is occurring.

The above-mentioned fixing of the gear ratio may be fixed to the gear ratio at the time when the failure was determined as described above, or may be fixed to the gear ratio based on the failure response map.

Note that the throttle valve opening corresponds to the accelerator opening, and therefore each throttle valve fFIU described above can be replaced with the accelerator rWJ IQ.

Next, an example of gear ratio control by a control device equipped with the steady running detection means and failure detection means as described above will be explained with reference to the flowchart shown in FIG.

First, in step 301, the input rotation speed N+) of the transmission is read, in step 302, the accelerator riAmα is read, in step 303, the target input rotation speed TNI) for α is calculated from the characteristic diagram, and in step 304, the accelerator opening degree α The rate of change α' is calculated, and in step 305 it is determined whether the absolute value of this rate of change α' is smaller than a predetermined value εl.
If so, it is determined that the vehicle is not in a steady running state and normal control is executed. That is, the process moves to step 306, in which the steady running flag is reset, and in step 30
In step 7, it is determined whether Np is less than or equal to TNO. If YES, in step 308, a shift down signal, that is, a signal that demagnetizes the speed increase solenoid 94a of the speed change solenoid pulp and energizes the deceleration solenoid 94b is output. Also, N
o, in step 309 a shift up signal is generated, energizing the speed increasing solenoid 94a and decelerating solenoid '14b.
Outputs a signal to demagnetize.

Furthermore, in step 305 above, 1α/l<81
When it is determined that the vehicle is in a steady running state, it is determined in step 310 whether the steady running flag has been reset, and if YES, the time T is set to zero in step 311. In step 312, a steady running flag is set, and in step 313, it is determined whether the time T has elapsed by a predetermined value ε2. If No, it is determined that the steady running state has not yet entered, and step 31
4, set the time T to T-T+DT, and then perform the above step 3.
Execute steps 07-309. When the steady running flag is set in step 310, the process moves to step 313.

When it is determined in step 313 that the time T has elapsed ε2, it is determined that the steady running state has completely entered and the process moves to step 315.
It is determined whether the absolute value of the difference between
Execute. If NO, it is determined that there is a failure state, and in step 316, a gear ratio holding signal, that is, a signal that demagnetizes both the speed increase and deceleration solenoids 94a and 94b, is output to fix and maintain the current gear ratio. With,
In step 317, the steady running flag is reset.

The control VR device according to the present invention is configured to detect the control state of the gear ratio during steady running as described above, and when the gear ratio is not controlled according to the characteristic curve, it is determined that there is a failure and the gear ratio is fixed. This ensures stable driving even in the event of a breakdown.

The present invention is also applicable to continuously variable transmissions other than the above-mentioned belt type. Further, the present invention can be modified in various ways without departing from the gist thereof, and is not limited to the embodiments described above.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an engine drive system including an embodiment of the control device 111 according to the present invention, and FIG. 2 shows details of the control device, clutch, and continuously variable transmission shown in FIG. 1. A schematic configuration diagram, FIG. 3 is a flowchart showing an example of control contents by the control device shown in FIG. 1, FIG. 4 is a flowchart showing details of the clutch control part in FIG. 3, and FIG. Shift Il used in ratio control rJII
Figure 6 is a block diagram showing an outline of the control device shown in Figure 1, Figure 7 is a flowchart showing details of the gear ratio control part in Figure 3, and Figure 8 is a diagram showing an example of the II characteristic. FIG. 3 is a diagram for explaining an example of the contents of the speed change control. 1... Engine 4... Continuously variable transmission 9...
・Throttle valve 81...Transmission input shaft 101・
...Control device 201... Steady running detection means 20
2... Failure detection means 5th VgJ? tliaUIillaNp (x lo3rpm) Figure 6

Claims (1)

[Claims] The gear ratio of the continuously variable transmission interposed in the engine drive system is determined based on a shift control characteristic diagram in which the engine load and the target input rotation speed of the input shaft of the continuously variable transmission are used as parameters. A control device for a continuously variable transmission that controls the rotation speed of the input shaft of the continuously variable transmission to a target input rotation speed corresponding to the load at each engine load, and a steady state control device that detects steady running. When a steady running signal is input from the steady running detecting means, the point specified by the engine load and the rotation speed of the input shaft of the continuously variable transmission is determined by a predetermined amount from the shift control characteristic diagram. 1. A control device for a continuously variable transmission, comprising: failure detection means for determining a failure if the deviation is greater than or equal to the above value, and outputting a signal for fixing the gear ratio.