JPS61109952A - Control device for stepless speed change gear for vehicle equipped with fail-safe function - Google Patents

Abstract

PURPOSE:To permit to carry out the control of the stepless speed change gear based on the rotating speed of an output side rotary shaft without any trouble by detecting the rotation of the output side rotary shaft based on a vehicle speed signal upon the trouble of a rotation sensor. CONSTITUTION:The rotating speed of the output side rotary shaft 24 is operated based on the vehicle speed signal SV selected by a signal selecting circuit 70 even when a trouble related to the output shaft rotation sensor 60 is generated. According to this constitution, the control of the stepless speed change gear 14, a speed change ratio control based on the setting of an objective rotating speed and the tension control of a transmission belt 20 may be effected without any trouble. Accordingly, the speed change ratio of the stepless speed change gear 30 may be adjusted in the same manner as a normal driving operation in which they are connected.

Description

Detailed Description of the Invention Technical Field The present invention relates to a control device for a continuously variable transmission for a vehicle, and in particular, the present invention relates to a control device for a continuously variable transmission for a vehicle. The present invention relates to a control device equipped with a fail-safe function that allows rotation of a side rotation shaft to be detected.

Conventional technology In a continuously variable transmission inserted in the power transmission path from the engine to the drive wheels of a vehicle, the output side of the continuously variable transmission is used to control the speed ratio or transmission belt tension of the continuously variable transmission. A control device is known that includes an output shaft rotation sensor that detects rotation of a rotating shaft. For example, the patent application
This is the device described in No. 3036.

Problems to be Solved by the Invention However, according to such a conventional control device, when a failure occurs related to the output shaft rotation sensor for detecting the rotation of the output side rotation shaft of the continuously variable transmission, the output side rotation shaft This had the disadvantage that the rotation of the motor was determined to be zero at a signal, making it difficult to control the continuously variable transmission.

Means for Solving the Problems The present invention has been made against the background of the above circumstances.
As shown in the complaint correspondence diagram in Fig. 1, the gist of this is that (1) a rotation sensor failure detection means for detecting a failure related to the output shaft rotation sensor; The fourth step when a related failure occurs is to include signal selection means for selecting a vehicle speed signal output from a vehicle speed sensor provided for detecting the speed of the vehicle.

In this way, when the rotation sensor failure detection means detects a failure related to the output shaft rotation sensor, the signal selection means selects the vehicle speed signal output from the vehicle speed sensor, and the vehicle speed signal is selected by the signal selection means. The rotation of the output-side rotating shaft of the continuously variable transmission is detected based on this. Therefore, even if a failure related to the rotation sensor occurs, the rotation of the output rotating shaft is detected based on the vehicle speed signal, so the control of the continuously variable transmission based on the rotational speed of the output rotating shaft can be performed without any problems. It will be done.

Here, failures related to the output shaft rotation sensor include not only a failure of the output shaft rotation sensor itself, but also disconnections or short circuits in the wire harness connected to the rotation sensor, and pulses output from the output shaft rotation sensor. This includes failures in the circuit that measures the pulse interval of the signal.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIG. 2, a vehicle engine 10 is connected to an input rotating wheel 16 of a continuously variable transmission 14 via a lock-up fluid coupling 12.

The input end rotating shaft 16 is provided with a variable boob IJ 22 in which the V-groove width, that is, the hanging diameter of the transmission belt 20 is changed by the hydraulic cylinder 18.
A variable pulley 28 whose groove width is changed by a hydraulic cylinder 26 is provided. Therefore, the rotational force transmitted to the input side rotating shaft 16 is transmitted to the variable pulleys 22 and 2.
The transmission is transmitted to the output side rotating shaft 24 via the transmission heald 20 wrapped around the
transmitted to. The auxiliary transmission 30 includes a Ravigneau type compound planetary gear device consisting of a first sun gear 32, a second sun gear 34, a ring gear 36, etc., and a high speed clutch 38, a low speed brake 40, and a reverse brake 42 are not shown. By selectively operating the hydraulic actuator, the gear ratio Rf is switched as shown in FIG.
Alternatively, it is possible to switch between forward rotation and reverse rotation.

Here, in Fig. 3, ρ1 is ZS+/Z*, ρ2
is zsz/zR. However, Z S l is the number of teeth of the first sun gear 32, Z5□ is the number of teeth of the second sun gear 34, and Z
R is the number of teeth of the ring gear 36. The output rotating shaft 24 of the belt-type continuously variable transmission] 4 constitutes the input shaft of the sub-transmission 30, and the carrier 44 that supports the planetary gears in the sub-transmission 30 constitutes the output shaft. The gear ratio of the transmission 30 is a value obtained by dividing the rotation speed of the carrier 44 by the rotation speed of the output side rotating shaft 24. The rotational force transmitted to the carrier 44 is transmitted to the drive wheels 52 of the pair of vehicles via the intermediate gears 46, 48 and the final reduction gear 50, respectively.

In the vicinity of the variable pulleys 22 and 28, there is a human-powered shaft rotation sensor 58 and an output shaft rotation sensor that outputs pulse signals SPI and SP2 of frequencies corresponding to the rotational speeds of the variable pulleys 22 and 28 to the input cover sofa 56 in the controller 54. A sensor 60 is provided. Also, intermediate gear 4
A vehicle speed sensor 62 is provided near 8 to output a pulsed vehicle speed signal SV having a frequency corresponding to the rotational speed of the intermediate gear to the input cover sofa 56 . This vehicle speed sensor 62 is provided exclusively to display the vehicle speed on a speedometer provided in front of the driver's seat. Also, engine 10
A throttle valve (not shown) provided in the intake pipe is provided with a throttle/nottle sensor 64, and the throttle sensor 64 sends a slow signal Sθ representing the throttle valve opening degree θ to the large cover sofa 56. Supplied.

Further, a neutral signal SN indicating that the shift lever has been operated to the neutral position is supplied to the input buffer 56 from a neutral sensor 66 provided on a shift lever (not shown). This shift lever is configured to be operated to each range shown in FIG. 3, and when it is operated to the neutral range, the high speed clutch 38 and the low speed brake 4 are connected to a hydraulic circuit (not shown).
0. Hydraulic pressure is prevented from being supplied to any of the hydraulic actuators that operate the reverse brakes 42, but when the reverse range is operated, hydraulic oil is supplied only to the hydraulic actuators that operate the reverse brakes 42. . Furthermore, when the forward range is operated, hydraulic oil is allowed to be supplied to either of the hydraulic actuators that actuate the high speed clutch 38 and the low speed brake 40.

A microcomputer 8 is provided within the controller 54 . The microcomputer 68 is a CPU, R
It includes OM, RAM, etc., and processes input signals supplied via the large cover sofa 56 while utilizing the temporary storage function of the RAM according to a program stored in advance in the ROM, and outputs a selection signal SEL to the signal selection circuit 70. On the other hand, the high/low speed switching valve 72 of the sub-transmission 30, the shift direction switching valve 74,
Drive signal S HL to shift speed switching valve 76 and line oil pressure regulating valve 77 via output buffer 78 .

Output SDI, SD2 and SPL respectively.

The signal selection circuit 70 receives the selection signal SEL from the inverter 82.
a first AND gate 80 to which the selection signal SEL is directly supplied; a second AND gate 84 to which the selection signal SEL is directly supplied;
It consists of an AND gate 80 and an OR gate 86 that supplies the signal output from the second AND gate 84 to the input capture port 1C of the microcomputer 68. In the normal case where the content of the selection signal SEL is rOJ, the signal SP2 output from the output shaft rotation sensor 60 via the first AND gate 80 is supplied to the input capture port [c, but the output shaft rotation When a failure related to the sensor 60 occurs or when the auxiliary transmission 30 is switched to neutral, the selection signal SEL becomes "1".
Therefore, the vehicle speed signal SV output from the vehicle speed sensor 62 is supplied to the input capture port IC via the second AND gate 84. That is, in this embodiment, the signal selection circuit 70 selects the output shaft rotation sensor 6.
This constitutes signal selection means that selects the vehicle speed signal SV in response to the failure of the vehicle speed signal SV.

The high/low speed switching valve 72 is a hydraulic actuator that operates the high speed clutch 38 or the low speed brake 40 when the shift lever is operated in the drive range or the low range of the forward range. This is for selectively supplying hydraulic oil to the pump, and is switched according to the drive signal SHL. When the shift lever is in the drive range, the microcomputer 68 follows a predetermined shift pattern, and when the vehicle speed ■ reaches a predetermined value, switches the auxiliary transmission 30 from a low gear to a high gear, and vice versa. It may be configured to switch from high speed gear to low speed gear when the value falls below this value.

Further, the shift direction switching valve 74 is connected to the hydraulic cylinder 18.
The shift direction (speed ratio changing direction) of the continuously variable transmission [14] can be switched between a state in which hydraulic oil is supplied to the hydraulic cylinder 18 and a state in which the hydraulic oil is discharged from the hydraulic cylinder 18. For example, when hydraulic oil is supplied into the hydraulic cylinder 18, the gear ratio (input side rotating shaft rotational speed Nin/output side rotating shaft rotational speed Nout) is changed in the direction of decreasing, and conversely, the hydraulic cylinder 1
When discharge of the hydraulic oil in 8 is allowed, the gear ratio is changed in the direction of increasing it. Further, the shift speed switching valve 76 is provided in series with the shift direction switching valve 74, and is configured to control the hydraulic oil supplied into the hydraulic cylinder 18 or the hydraulic cylinder 1.
8 can be selectively switched between a state of permitting and a state of suppressing the flow of hydraulic oil discharged from inside. As a result, the speed ratio change speed of the continuously variable transmission 14 is increased or maintained at a desired speed ratio. Further, the shift speed switching valve 76 can continuously control the speed ratio change speed according to duty control. A control device that performs such duty control, the shift direction switching valve 74 and the shift speed switching valve 76 are disclosed in, for example, Japanese Patent Application No.
8-251677.

The line oil pressure regulating valve 77 exclusively adjusts the line oil pressure to control the tension of the conduction bell 1-20 and the hydraulic cylinder 26.
supply to. This line oil pressure is based on the actual gear ratio of the continuously variable transmission I4, which is calculated based on the detected rotational speeds of the input side rotating shaft 16 and the output side rotating shaft 24, and the detected throttle valve opening θ. and the transmission torque calculated based on the engine rotation speed. As a result, the pressure value is set to be as small as possible within a range where the transmission belt 20 does not slip, and the power loss of the engine 1o is reduced. The frictional force between the variable pulleys 22, 28 and the transmission heald 20 is reduced, and the load on the hydraulic pump driven by the engine 10 is reduced. The line oil pressure regulating valve 77 is constructed in the same manner as described in Japanese Patent Application No. 58-93036, for example.

The operation of the control device configured as above will be explained.

In FIG. 4, when step s1 is executed, output signals Sθ, 'SP from the throttle valve opening 64, input shaft rotation sensor 58, output shaft rotation sensor 60, and vehicle speed sensor 62
l, SP2. According to the SV, the throttle valve opening θ, the rotation speed Nin of the input side rotation shaft 16 (engine 10), the rotation speed Nout of the output side rotation shaft 24, the vehicle speed ■, etc. are read. Next, a target rotational speed determination routine in step S2 is executed. That is, as shown in FIG. 5, for example, it is determined in step SMI whether the content of the input shaft rotation sensor failure flag Fsi is "1".

Normally, the input shaft rotation sensor 58 is not in failure and the input shaft rotation sensor failure flag Fsi is not "1", so step SM2 is executed and the target rotation speed N of the input side rotation shaft 16 is changed to the throttle valve opening θ and It is determined based on the rotational speed Nout of the output side rotating shaft 24. This target rotational speed N is determined from a predetermined relationship between NI and θ, with Nout as a parameter, so that the engine 10 is operated substantially along the minimum fuel consumption rate curve. Note that the target rotational speed N may be determined based on only the throttle valve opening θ or it and the vehicle speed V, or may be determined based on the amount of load required for the engine 10, such as the amount of operation of the accelerator pedal, instead of the throttle valve opening θ. Alternatively, the negative pressure of the intake pipe of the engine 10 may be used.

Returning to FIG. 4, in step S3, the deviation E between the target rotational speed ND and the actual rotational speed Nin is determined, and in the subsequent step S4, it is determined whether the deviation E is positive or negative. If the deviation E is determined to be negative, it means that the actual rotational speed Nin of the input side rotating shaft 16 is too high, and it is necessary to shift up, so step S5 is executed to change the shift direction. The switching valve 74 is switched to the shift amplifier state. That is, hydraulic oil is supplied into the hydraulic cylinder 18, and the effective diameter of the variable boob 18 is expanded. On the other hand, if it is determined in step s4 that the deviation E is positive, the input side rotating shaft 16
This means that the actual rotational speed Nin is too low and it is necessary to downshift, so step S6 is executed and the shift direction switching valve 74 is brought into the downshift state. Therefore, the hydraulic oil in the hydraulic cylinder 18 is allowed to be discharged, and the effective diameter of the variable boob 1J22 is reduced.

After the shift amplifier state is entered by executing step S5, steps s7 and s9 are executed, and the deviation I
It is determined whether EI is larger than a predetermined constant value A1 or smaller than A. If the deviation IEI is larger than A1 or smaller than A4, step S8 or SIO is executed and the shift speed switching valve 76 is set to the maximum shift speed state or the minimum shift speed state. That is, the flow rate supplied to the hydraulic cylinder 18 is set to the maximum or minimum state. However, if the deviation IEI is between A and A4, step S15 is executed and the duty ratio D (%) is calculated by the following formula (
1).

D= ((1/B)l E l +C)・1/100
...(1) However, B and C are constants, for example, B=100, C=
It is set to about -0.3.

After the duty ratio is determined in step S15, the shift speed switching valve 76 is reciprocated according to the duty ratio in step 317, and the speed ratio change speed (shift speed) is continuously adjusted according to the magnitude of the deviation. .

Even after the downshift state is set in step S6, it is similarly determined whether the absolute value IEI of the deviation is larger than a predetermined constant value A2 or smaller than A3. If the shift speed is also small, steps S12 and 314 are executed to set the shift speed to the maximum state and the minimum state. However, if the deviation IEI is between A2 and A3, the duty ratio is determined in step 816. The duty ratio D (%) in this case is determined by equation (2). Here, in Japanese Patent Application No. 59-14010, D= (1-
+(1/B) l E l l +C)・1/100・
...(2) Similar to the mounted control device, the constant value is A,>As
, Az > A3. A3 > Aa, and the state where the shift speed switching valve 76 allows the flow and the state where the flow is suppressed are reversed as the shift direction switching valve 74 is switched to the upshift state or downshift state. ing.

As described above, after the gear ratio of the continuously variable transmission 14 is adjusted, the diagnosis in step S18 is executed.

The steps shown in FIG. 6 are a part of it. First, in step SDI, it is determined whether or not there is a pulse train of the signal SPI output from the input shaft rotation sensor 58. If it is not present, steps SD2 to SD5 are skipped, but if it is present, it is output in step SD2. It is determined whether a pulse train exists in the signal SP2 output from the shaft rotation sensor 60.

If it is determined in step SD2 that a pulse train exists, the output shaft rotation sensor 60 is operating normally, so step SD3 is executed and the contents of the output shaft rotation sensor failure flag FSO are set to zero. Ru. However, if it is determined in step SD2 that the pulse train does not exist, a failure related to the output shaft rotation sensor 60 has occurred, so step SD4 is executed and the output shaft rotation sensor failure flag Fso is set. The content is “
1'', and then the output shaft rotation sensor abnormality processing in step SD5 is executed. In step SD5, for example, an abnormality of the output shaft rotation sensor 60 is displayed on an optical display or an audio display (not shown) to notify the abnormality of the output shaft rotation sensor 60, and the content of the selection signal SEL is "1". It is said that The presence or absence of the pulse train is detected as follows. For example, continuously variable transmission 1
4, the range of the gear ratio is 2.0 to 0.5, and the signal SPI output from the input shaft rotation sensor 58 and the signal SP2 output from the output shaft rotation sensor 60 are connected to the input side rotation shaft 16 and the output side rotation. Assuming that the same number of pulse trains are output for each rotation of the shaft 24, 4 of the signal SPI
If at least one pulse of the signal SP2 is not detected within the pulse period, and if at least one pulse of the signal SPI is not detected within the period, it is determined that a failure related to the output shaft rotation sensor 60 has occurred, and the signal If at least one pulse of the signal SPI is not detected within the four-pulse period of SP2, it is determined that a failure related to the input shaft rotation sensor 58 has occurred. FIG. 7 shows an example of detecting the occurrence of a failure related to the output shaft rotation sensor 60, in which a counter (not shown) that counts the signal SP2 and is reset at the rise of every four pulses of the signal SPI is used. or a counter means consisting of an equivalent program)
Assume that As shown in the figure, when the count of this counter is zero at the time of reset, it can be determined that the pulse train of signal SP2 does not exist.

Therefore, in this embodiment, steps SDI and SD2
corresponds to the output shaft rotation sensor failure detection means, and step S
D6 and SD7 correspond to input shaft rotation sensor failure detection means. Note that the steps shown in FIG. 6 are desirably executed when the vehicle speed (2) is greater than a predetermined small constant value Vα.

Subsequently, in step SD6, the output shaft rotation sensor 60
It is determined whether or not a pulse train exists in the signal SP2 outputted from the step SD7 to SD5.
DIO is skipped, but if it exists, Ste-Knob SD7 is executed to determine whether a pulse train exists in the output signal SPI of the input shaft rotation sensor 58. If it exists, the manual shaft rotation sensor 58 is in a normal state, so Step 7 SD8 is executed and the contents of the input shaft rotation sensor failure flag Fsi are set to zero, but if the pulse train does not exist, then the input shaft rotation sensor failure flag Fsi is set to zero. Since a failure related to the input shaft rotation sensor 58 has occurred, step SD9 is executed and the content of the input shaft rotation sensor failure flag Fsi is set to "1", and the input shaft rotation sensor abnormality in step 5010 is executed. Processing is executed. For example, a display indicating an abnormality in the input shaft rotation sensor 58 is displayed on an optical display or an audio display (not shown). During the execution of the above steps, the interrupt routine shown in FIG. 8 is executed every time a pulse signal is supplied to the input capture board 1-IC of the microcomputer 68. In the normal case, the step SWI is executed every pulse of the signal SP2.
SW3 is executed to determine the rotational speed of the output rotating shaft 16. Also, by executing steps not shown in the figure, the neutral signal SN can be set while the vehicle is running.
The content of the neutral flag Fn is set to ``1'' when the neutral signal SN is manually operated, and is set to ``0'' when the neutral signal SN is not operated manually.
”. This neutral state may be detected by the fact that none of the hydraulic actuators of the sub-transmission 30 are operating.

For example, when the content of the output shaft rotation sensor abnormality flag Fso is set to "1" by executing the above steps, or when the auxiliary transmission 30 is set to the neutral range while the vehicle is running according to the operation of the shift lever (not shown), the neutral flag is set. When the content of Fn is set to "1", the microcomputer 68 switches the content of the selection signal SEL from "0" to "1" according to steps not shown. Therefore, the output signal from the vehicle speed sensor 62 is supplied to the input capture port 1C of the microcomputer 68 via the second AND gate 84. As a result, in the interrupt routine shown in FIG. 8, which is executed every time a pulse is supplied to the input capture port C, SW2 and SW3 are executed to calculate the rotational speed of the output side rotating shaft 240. Instead of the flow, the rotation speed of the output side rotating shaft 24 is calculated according to the execution of steps SW4 and SW5.

That is, in step SWI, the content of the output side rotating shaft failure flag Fso or the neutral flag Fn is "
1'', step SW4 is executed to measure the pulse interval of the vehicle speed signal S■ output from the vehicle speed sensor 62, and in step SW5 as a calculating means, the pulse interval is measured based on the pulse interval. The rotational speed of the output side rotating shaft 24 is calculated according to the pre-stored calculation formula (3) NouL=KG-■ ・ ・ ・ ・ ・ ・
・This is (3). In equation (3), K is a constant, ■
is the vehicle speed, and G is a composite gear ratio that is predetermined according to the intermediate gear 4 and each gear ratio of the auxiliary transmission 30.

On the other hand, if the content of the input shaft rotation sensor failure flag Fsi is set to rlJ by executing step SD9 in FIG. 6, step SM3 in FIG. 5 is executed when determining the target rotation speed. In this step SM3, in order to prevent the engine 10 from being over-speeded due to the circuit determining that the actual rotational speed NA is zero due to a failure of the input shaft rotational sensor 58, the target rotational speed N. It is determined from the predetermined relationship shown in the figure. In the relationship shown in FIG. 9, the target rotational speed N,' in the abnormal state is determined according to the vehicle speed so that the gear ratio is minimized. In addition,
The relationship shown in FIG. 9 is such that when the microcomputer 68 automatically switches between the high speed and low speed of the sub-transmission according to a predetermined shift pattern in the drive range, the low and high speeds of the sub-transmission 30 are Due to the switching, it may be defined in a sawtooth shape. Furthermore, when the sub-transmission 30 is not used, a linearly increasing target rotational speed N0° may be used.

In this way, according to this embodiment, the output shaft rotation sensor 60
Even if a related failure occurs, the rotational speed of the output side rotating shaft 24 is calculated based on the vehicle speed signal SV selected by the signal selection circuit 70, so that the control of the continuously variable transmission 14, that is, in this embodiment, The gear ratio control and the tension control of the transmission belt 20 based on the setting of the target rotational speed N[l are carried out without any trouble.In addition, the sub-transmission 30 is set to neutral and the output-side rotating shaft 24 and drive wheel 52 are Even if the continuously variable transmission 30 is disconnected, the gear ratio of the continuously variable transmission 30 will be adjusted in the same way as during normal driving when they are connected.
Even when the vehicle is switched from neutral to forward range, shift shock or temporary locking of the wheels is largely eliminated.

Further, according to the present embodiment, even if a failure related to the human power shaft rotation sensor 58 occurs, the target rotation speed N at the time of abnormality is determined based on a predetermined relationship. The target rotational speed No' at this time of abnormality is set to a minimum value so that at least the gear ratio does not become larger than the value immediately before the failure, so overspeeding of the engine 1o is prevented.

Although the embodiment of the present invention has been described above based on the drawings, the present invention can also be applied to other embodiments.

For example, in the above-described embodiment, the gear ratio of the continuously variable transmission 14 is controlled so that the target rotational speed matches the actual rotational speed, but the control target is determined by the throttle valve opening θ and the vehicle speed ■. It may be a target speed ratio or a target driving force. Even in such a case, the same control as in the normal state can be performed regardless of the failure of the output shaft rotation sensor 58.

Further, in the above-described embodiment, if a failure related to the input shaft rotation sensor 58 occurs, a certain effect can be obtained even if the gear ratio of the continuously variable transmission 14 is configured to at least not increase any further.

In addition, a selection circuit similar to the signal selection circuit 70 for selecting a pulse signal corresponding to the rotation of the engine 10, such as an ignition pulse signal, in place of the output signal SPI of the human power shaft rotation sensor 58 is provided, and an input shaft rotation sensor failure flag is provided. It may be configured such that when the content of Fsi is "1", the microcomputer 68 causes its signal selection circuit to select the ignition pulse signal. In such a case, the rotational speed of engine 1.0 can be determined based on the ignition pulse signal. If the fluid force/knob ring 12 is directly connected, the same control as when the manual shaft rotation sensor 58 fails is possible, and even if it is not directly connected, the rotational speed of the engine 10 and the input side rotating shaft 16 can be controlled. Since the rotational speed difference between the two is not so large, a certain amount of backup effect can be obtained.

The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of drawings]

FIG. 1 is a diagram corresponding to claims of the present invention. FIG. 2 is an explanatory diagram showing the configuration of an embodiment of the present invention. FIG. 3 is a diagram showing switching states in the sub-transmission of FIG. 2. 4, 5, 6, and 8 are flowcharts illustrating the operation of the embodiment of FIG. 2. FIG. 7 is a time chart showing an example of detecting the presence or absence of a pulse train in the flow chart of FIG. FIG. 9 is a diagram showing the relationship used to determine the target rotational speed in the event of an abnormality in the embodiment of FIG. 2. 10 Engine 14: Continuously variable transmission 58: Input shaft rotation sensor 60: Output shaft rotation sensor 70: Signal selection circuit (signal selection means) Step SDI, SD2: Output shaft rotation sensor failure detection means Step SD6. SD7: Input shaft rotation sensor failure detection means Applicant Toyota Motor Corporation Figure 1 Figure 3, Prisoner 9

Claims (2)

[Claims] (1) A continuously variable transmission for a vehicle inserted in a power transmission path from the engine to the drive wheels of a vehicle, including an output shaft rotation sensor that detects rotation of an output side rotating shaft of the continuously variable transmission, and A control device equipped with a fail-safe function capable of detecting the rotation of the output-side rotation shaft of the continuously variable transmission even if a state occurs in which the rotation of the output-side rotation shaft cannot be detected by the rotation sensor, rotation sensor failure detection means for detecting a failure related to the output shaft rotation sensor; and a vehicle speed output from a vehicle speed sensor provided to detect the speed of the vehicle when a failure related to the output shaft rotation sensor occurs. a signal selection means for selecting a signal, and the rotation of the output side rotating shaft of the continuously variable transmission is detected based on the selected vehicle speed signal. Control device for gear transmission. (2) The signal selection means selects the vehicle speed signal even when the vehicle is running and the switching position of the auxiliary transmission provided on the output side of the continuously variable transmission is neutral. A control device for a continuously variable transmission for a vehicle having a fail-safe function according to claim 1.