JPS61109957A - Speed change ratio control device for stepless change gear for vehicle, which is equipped with fail-safe function - Google Patents

Abstract

PURPOSE:To permit to prevent over-revolution of an engine by a method wherein the speed change ratio of the engine is not set larger than the same upon generating a trouble in case the trouble, related to an input shaft rotation sensor, is detected. CONSTITUTION:An objective revolving speed of the engine upon abnormality is determined so that the engine 10 is not brought into over-revolution condition by the trouble of the input shaft rotation sensor 58. Even in case a trouble, related to the input shaft rotation sensor 58, is generated, the objective revolving speed upon abnormality is determined from a predetermined relation. The objective revolving speed upon abnormality is determined so that the speed change ratio is not set larger than at least the value of speed change ratio immediately before the trouble, therefore, the over-revolution of the engine 10 may be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a speed ratio control device for a continuously variable transmission for a vehicle.
The present invention relates to a speed ratio control device having a fail-safe function that prevents over-speeding of an engine regardless of the occurrence of a failure related to an input shaft rotation sensor of a continuously variable transmission.

Conventional technology: In a continuously variable transmission inserted in the power transmission path from the engine to the drive wheels of a vehicle, the rotation of the input side rotating shaft of the continuously variable transmission is detected in order to control the speed ratio of the continuously variable transmission. A speed ratio control device equipped with an input shaft rotation sensor is known. For example, patent application 1983-. This is the device described in No. 93036.

Problems to be Solved by the Invention However, according to the conventional gear ratio 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 The problem was that the rotation of the rotating shaft was determined to be zero at the signal, causing the engine to overspeed due to the speed ratio control of the continuously variable transmission.

Means for explaining the problem The present invention was made against the background of the above circumstances,
As shown in the complaint correspondence diagram in Figure 1, the gist of this is that: (2) an input shaft rotation sensor failure detection means for detecting a failure related to the input shaft rotation sensor; and (2) a failure related to the rotation sensor. The present invention further includes a gear ratio adjusting means for preventing the gear ratio of the continuously variable transmission from becoming larger than at least the gear ratio at the time of occurrence of the failure.

Operation and Effect of the Invention With this structure, when a failure related to the input shaft rotation sensor is detected by the input shaft rotation sensor failure detection means, the gear ratio adjustment means adjusts the gear ratio of the continuously variable transmission to at least detect the failure. This prevents the gear ratio from becoming larger than the one at the time of occurrence. Therefore, regardless of the occurrence of a failure related to the input shaft rotation sensor, over-speeding of the engine is prevented.

Other means for solving the problem The gist of another aspect of the present invention is as shown in the claim correspondence diagram in FIG. 2: (1) failure related to the input shaft rotation sensor; (2) ignition signal selection means for selecting a signal corresponding to the rotation of the engine, for example, an ignition signal when a failure related to the input shaft rotation sensor occurs; It consists in including.

Operation and other effects of the invention In this way, when a failure related to the input shaft rotation sensor is detected by the input shaft rotation sensor failure detection means,
A signal corresponding to the rotation of the engine is selected by the signal selection means, and the rotation of the input side rotation shaft of the continuously variable transmission is detected based on the signal. Therefore, even if a failure occurs related to the input shaft rotation sensor, the rotation of the input shaft will be detected, and the control of the continuously variable transmission based on the rotation speed of the input shaft will be executed without any problem. , engine overspeed is completely eliminated.

Here, failures related to the input shaft rotation sensor include not only a failure of the input shaft rotation sensor itself, but also a disconnection or short circuit of the wire harness connected to the input shaft rotation sensor, and a failure of the input shaft rotation sensor. This includes failures in the circuit that measures the pulse interval of pulsed signals.

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

In FIG. 3, a vehicle engine 10 is connected to an input rotating shaft 16 of a continuously variable transmission 14 via a lock-up fluid coupling 12.

The input side rotating shaft 164 is
A variable pulley 22 is provided on which the groove width, that is, the hanging diameter of the transmission belt 20 is changed, and the output side rotating shaft 24 is provided with a variable boolean IJ 28 whose V-groove width is changed by a hydraulic cylinder 26. . 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 conduction heald 20 wrapped around the
transmitted to. The sub-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.
By selectively operating the low-speed gear brake 40 and the reverse brake 42 by a hydraulic actuator (not shown), the gear ratio Rf is switched as shown in FIG. 4, or forward rotation and reverse rotation are switched. ing.

Here, in FIG. 4, ρ1 is Z-+/Z+i, and ρ2 is Z sz/Z R. However, Z1) is the number of teeth of the first sun gear 32, Z3□ is the number of teeth of the second sun gear 34,
Z8 is the number of teeth of the ring gear 36. The output-side rotating shaft 24 of the belt-type continuously variable transmission 14 constitutes the input shaft of the sub-transmission 30, and the carrier 44 that supports the planetary gear in the sub-transmission 830 constitutes the output shaft, so the sub-transmission The gear ratio of the machine 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].

In the vicinity of the variable pulleys 22 and 28, there is an input 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 couch 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 sensor 64 is provided on a throttle valve (not shown) provided in the intake pipe of the vehicle, and a throttle signal Sθ representing the throttle valve opening degree θ is supplied from the throttle sensor 64 to the human cover sofa 56. Also,
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. 4, and when it is operated to the neutral range, a high speed clutch 38, a low speed brake 40, and a reverse brake 42 are activated in a hydraulic circuit (not shown). prevent hydraulic pressure from being supplied to any of the hydraulic actuators that operate the respective
When the reverse range is operated, hydraulic oil is supplied only to the hydraulic actuator that operates the reverse brake 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 68 is provided within the controller 54. The microcomputer 68 is a CPU, R
It includes OM, RAM, etc., processes the input signal supplied via the input 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, shift direction switching valve 74,
A drive signal SHL is output to a shift speed switching valve 76 and a line oil pressure adjustment valve 77 via an output cover sofa 78 .

Output SDI, SD2 and SPL respectively.

The signal selection circuit 70 receives the selection signal SEL from the inverter 82.
The first AND gate 80 is supplied via the second AND gate 84 and the selection signal SEL is directly supplied to the microcomputer 68. input capture data) and an OR gate 86 that supplies the input capture data to the IC. In the normal case where the content of the selection signal SEL is rOJ, the output shaft rotation sensor 6 passes through the first AND gate 80.
The signal SP2 output from 0 is supplied to the input capture boat IC, but when a failure related to the output shaft rotation sensor 60 occurs or when the auxiliary transmission 30 is switched to neutral, the selection signal SEL becomes "1". Therefore, the vehicle speed signal S output from the vehicle speed sensor 62
(2) is supplied to the input capture board IC via the second AND gate 84.

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 switched between a state in which hydraulic oil is supplied to the hydraulic cylinder 1 and a state in which hydraulic oil is discharged from the hydraulic cylinder 18, and the shift direction switching valve 74 is configured to switch between a state in which hydraulic oil is supplied to the hydraulic cylinder 18 and a state in which hydraulic oil is discharged from the hydraulic cylinder 18. Switch the shift direction (speed ratio change direction). For example, when hydraulic oil is supplied into the hydraulic cylinder 18, the gear ratio (input side rotational shaft rotational speed Nin/output side rotational shaft rotational speed Nout) is changed in the direction of decreasing, and conversely, When discharge of the hydraulic oil is allowed, the gear ratio is changed in the direction of increasing it.

Further, the shift speed switching valve 76 is connected to the shift direction switching valve 74.
It is provided in series with the hydraulic cylinder 18 and can be selectively switched between a state of permitting and a state of suppressing the flow of hydraulic oil supplied into the hydraulic cylinder 18 or hydraulic oil discharged from the hydraulic cylinder 18. As a result, the continuously variable transmission 14
The change speed of the gear ratio is increased or maintained at a desired gear ratio. In addition, the shift speed switching valve 76
can continuously control the gear ratio change speed according to duty control. The control device for such duty control, the shift direction switching valve 74 and the shift speed switching valve 76 are constructed in the same manner as described in, for example, Japanese Patent Application No. 58-251677.

The line oil pressure regulating valve 77 adjusts line oil pressure exclusively to control the tension of the transmission bell (20) and supplies it to the hydraulic cylinder 26. This line oil pressure is the detected input side rotating shaft 1
Continuously variable transmission calculated based on the respective rotational speeds of 6 and output side rotating shaft 24 [transmission calculated based on the actual gear ratio of 14, detected throttle valve opening θ and engine rotational speed] Controlled according to torque. As a result, the pressure value is set as low as possible within a range where the transmission belt 20 does not slip, and the power loss of the engine 10 is reduced. The frictional force between the variable pulleys 22, 28 and the transmission belt 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. 5, when step S1 is executed, output signals Sθ from the throttle sensor 64, input shaft rotation sensor 58, output shaft rotation sensor 60, and vehicle speed sensor 62, SPI
, 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 of the output side rotation shaft 24, the degree Nout, the vehicle speed V, etc. are read. Next, a target rotational speed determination routine in step S2 is executed. That is, as shown in FIG. 6, 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 rLJ, so step SM2 is executed and the target rotation speed No. of the input side rotation shaft 16 is set to the throttle valve opening θ and the output side rotation. It is determined based on the rotational speed Nout of the shaft 24. This target rotational speed N is set using Nout as a parameter so that the engine 10 is operated approximately along the minimum fuel consumption rate curve. is determined from a predetermined relationship between and θ. Note that the target rotation speed N. may be determined based on only the throttle valve opening θ or based on it and the vehicle speed V, or the amount of load required for the engine 10, such as the operating amount of the accelerator pedal or the intake piping of the engine 10, may be determined instead of the throttle valve opening θ. Negative pressure may also be used.

Returning to FIG. 5, in step S3, the target rotational speed N is determined. The deviation E between this 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 pulley 22 is expanded. On the other hand, if it is determined in step S4 that the deviation E is positive, it means that the actual rotational speed Nin of the input side rotating shaft 16 is too low, and it is necessary to downshift, so step S6 is executed. Been,
The shift direction switching valve 74 is brought into a downshift state. Therefore, the hydraulic oil in the hydraulic cylinder 18 is allowed to be discharged, and the effective diameter of the variable pulley 18 is reduced.

After the shift-up state is achieved 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 AI or smaller than A4. If the deviation IEI is larger than A or smaller than A4, step S8 or 510 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) ・1/10
0. . . (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 315, the shift speed switching valve 76 is reciprocated according to the duty ratio in step S17, 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 of the deviation is larger than a predetermined constant value A2 or smaller than A3, and if it is larger than A2, If it is smaller than A3, steps S12 and S14 are executed to set the shift speed to the maximum state and minimum state. However, if the deviation IE1 is between A2 and A3, the duty ratio is determined in step S16. The duty ratio D (%) in this case is determined by equation (2). Here, special D= (1-((1/B) l E l l +C)・
1/100... (2) Similar to the control device described in Intercondylar No. 59-14010, the constant values are A+>A4, A2>A3.

Az>A4, and the state where the shift speed switching valve 76 allows the flow and the state where the flow is suppressed are the shift direction switching valve 7.
4, the shift amplifier state and the shift down state are inverted.

As described above, after the gear ratio of the continuously variable transmission 14 is adjusted, the diagnosis in step 318 is executed.

The steps shown in FIG. 7 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 the pulse train is not present, steps SD2 to SD5 are skipped, but if it is present, step 5D24 is skipped. Then, it is determined whether a pulse train exists in the signal SP2 outputted from the output 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 content of the output shaft rotation sensor failure flag Fso is set to zero. Ru. However, if it is determined in step SD2 that the pulse train does not exist, it is related to the output shaft rotation sensor 60.

Since a failure has occurred, step SD4 is executed, the content of the output shaft rotation sensor failure flag Fso is set to "1," and then the output shaft rotation sensor abnormality process of 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, the range of the gear ratio of the continuously variable transmission 14 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 16 and the output side rotation shaft 24, the same number of pulse trains are output for one rotation of the output rotation shaft 24,
When at least one pulse of the signal SP2 is not detected within the pulse period, it is determined that a failure related to the output shaft rotation sensor 60 has occurred, and at least one pulse of the signal sp1 is detected within the 4-pulse period of the signal SP2. If not, it is determined that a failure related to the input shaft rotation sensor 58 has occurred. FIG. 8 shows an example of detecting the occurrence of a failure related to the output shaft rotation sensor 60, in which the signal SP
Assume a counter (not shown) (or counter means consisting of an equivalent program) that counts 2 and is reset at every four pulses of the signal SP1. 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 correspond to output shaft rotation sensor failure detection means, and steps SD6 and SD7 correspond to input rotation sensor failure detection means. It is preferable that the step shown in FIG. 7 is executed when the vehicle speed (2) is greater than a predetermined small 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 output from the stencils SD7 to SD5.
DIO is skipped, but if it exists, step SD7 is executed and the output signal S of the input shaft rotation sensor 58 is
It is determined whether a pulse train exists in the PI. If the pulse train exists, the input shaft rotation sensor 58 is in a normal state, so step SD8 is executed and the content of the input shaft rotation sensor failure flag Fsi is set to zero. However, if the pulse train does not exist, the input shaft rotation sensor 58 is in a normal state. Since a failure related to the 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 processing of step 5DIO is executed. be done. 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). Note that during the execution of the above steps, each time a pulse signal is supplied to the input capture board IC of the microcomputer 68, the ninth
The interrupt routine shown in the figure is executed. In the normal case, steps SWI to SW3 are performed for each pulse of signal SP2.
is executed to determine the rotational speed of the output side rotating shaft 16. Further, by executing steps not shown, the content of the neutral flag Fn is set to "1" while the vehicle is running and the neutral signal SN is being input.
When the neutral signal SN is not input, it is set to "0". 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 IC of the microcomputer 68 via the second AND gate 84. As a result, in the interrupt routine shown in FIG. 9 that is executed every time a pulse is supplied to the input carburetor 1-1c, SW2 and SW3 are executed to calculate the rotational speed of the output side rotating shaft 24. Instead of the normal flow, the rotational 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 calculation formula (3) in which tq is written in advance.
・(3) It will happen. In formula (3), K is a constant,
(2) is the vehicle speed, and G is a composite gear ratio that is predetermined according to each gear ratio of the intermediate gear 48 and the auxiliary transmission 30.

On the other hand, if the content of the input shaft rotation sensor failure flag Fsi is set to "1" by executing step SD9 in FIG. 7, step SD9 as the gear ratio adjustment means in FIG. SM3 is executed. In this step SM3, in order to prevent the engine 10 from being over-speeded due to a 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. The relationship shown in FIG. 10 is the target rotational speed N at the time of abnormality so that the gear ratio is minimized. ° is determined according to vehicle speed. However, even if the gear ratio is not minimized, a certain effect can be obtained even if the gear ratio is suppressed to a value that is not larger than the gear ratio at the time of occurrence of the abnormality. In addition, the 10th
The relationship shown in the figure is such that when the microcomputer 68 automatically switches between the high and low gears of the auxiliary transmission 30 in accordance with a predetermined shift pattern in the drive range, the relationship between the low and high gears of the auxiliary transmission 30 is Due to the switching, it may be defined in a sawtooth shape. Furthermore, when the sub-shift m30 is not used, a linearly increasing target rotational speed N,1 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 heald 20 based on the setting of the target rotational speed No. are performed without any problem. Furthermore, even if the auxiliary transmission 30 is set to neutral and the output side rotating shaft 24 and the drive shaft 52 are disconnected, the gear ratio of the continuously variable transmission 30 is adjusted in the same way as during normal driving when they are connected. Therefore, even if the shift lever is switched from neutral to forward range while driving, the shift shock or temporary locking of the wheels is largely eliminated.

Further, according to this embodiment, even if a failure related to the input shaft rotation sensor 58 occurs, the target rotation speed ND' at the time of abnormality is determined from a predetermined relationship. Since the target rotational speed No. ``at the time of abnormality'' is determined so that at least the gear ratio does not become larger than the value immediately before the failure, overspeeding of the engine 10 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-mentioned embodiment, the gear ratio of the continuously variable transmission 41) 4 is controlled so that the target rotation speed and the actual rotation speed are the same, but the control target is the throttle valve opening θ,
It may be a target speed ratio determined from the vehicle speed V or a target driving force. Even in such a case, the same control as in normal times can be performed regardless of the failure of the output shaft rotation sensor 60.

Furthermore, in the above-described embodiment, if a failure related to the input shaft rotation sensor 58 occurs, even if the gear ratio of the continuously variable transmission 14 is configured to be small (or configured so that it does not increase any further), a temporary effect may not be obtained. It will be done.

Further, as shown in FIG. 1), a signal selection circuit similar to the signal selection circuit 70 that selects a pulse signal corresponding to the rotation of the engine 10, for example, an ignition (pulse) signal, instead of the output signal SPI of the input shaft rotation sensor 58, may be used. A signal selection circuit 88 is provided,
and the contents of the input shaft rotation sensor failure flag Fsi are rlJ
, the microcomputer 68 selects an ignition signal generator (for example, an igniter) 89 from the signal selection circuit 88.
The configuration may be such that the ignition signal from the ignition signal is selected. In such a case, the interrupt routine shown in FIG. 12, which is executed every time a pulse is input to another input capture port IC, is executed, and its step SW'
1. SW' 4. When a failure related to the input shaft rotation sensor 58 occurs by executing SW' 5, the rotation speed of the engine 10 is determined based on the ignition pulse signal. Therefore, in this embodiment, the signal selection circuit 88 constitutes a signal selection means for selecting an ignition signal in response to a failure of the input shaft rotation sensor 58. If the fluid coupling 12 is in a direct connection state, the same control as when the input shaft rotation sensor 58 fails is possible, and even if the fluid coupling 12 is not in a direct connection state, the rotation speed difference between the engine 10 and the input side rotation shaft 16 can be controlled. is not that large, so a certain bank-up 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 the drawing]

FIG. 1 and FIG. 2 are diagrams corresponding to claims of the present invention. FIG. 3 is an explanatory diagram showing the configuration of an embodiment of the present invention. FIG. 4 is a diagram showing switching states in the sub-transmission of FIG. 3. 5, 6, 7, and 9 are flowcharts illustrating the operation of the embodiment of FIG. 2. FIG. 8 is a time chart showing an example of detecting the presence or absence of a pulse train in the flow chart of FIG. FIG. 10 is a diagram showing the relationship used to determine the target rotational speed in the event of an abnormality in the embodiment of FIG. 3. FIG. 1) is a diagram showing a main part of another embodiment of the present invention, and FIG. 12 is a flowchart showing an interrupt routine in this embodiment. 10 Engine 14: Continuously variable transmission 58: Input shaft rotation sensor 60: Output shaft rotation sensor 88: 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 Step SM3: Gear ratio adjustment means Applicant: Toyota Motor Corporation Figure 1 Figure 4 Vehicle speed ■

Claims (4)

[Claims] (1) In a continuously variable transmission inserted in the power transmission path from the engine to the drive wheels of a vehicle, rotation of the input side rotating shaft of the continuously variable transmission is performed to control the gear ratio by the gear ratio control means. A transmission ratio control device comprising an input shaft rotation sensor that detects the input shaft rotation, and a fail-safe function that prevents the engine from overspeeding in the event of a failure related to the input shaft rotation sensor, the gear ratio control device comprising: An input shaft rotation sensor failure detection means for detecting a failure related to the sensor; and when a failure related to the input shaft rotation sensor occurs, the gear ratio of the continuously variable transmission is set to be at least larger than the gear ratio at the time of occurrence of the failure. What is claimed is: 1. A gear ratio control device for a continuously variable transmission for a vehicle, comprising: a gear ratio adjusting means for preventing such occurrence; (2) The gear ratio adjusting means has a fail-safe function as set forth in claim 1, wherein the gear ratio adjusting means minimizes the gear ratio of the continuously variable transmission when a failure related to the rotation sensor occurs. Gear ratio control device for continuously variable transmissions for vehicles. (3) In a continuously variable transmission inserted in the power transmission path from the engine to the driving wheels of a vehicle, rotation of the input side rotating shaft of the continuously variable transmission is performed in order to control the gear ratio by the gear ratio control means. The control device is equipped with an input shaft rotation sensor that detects the input shaft rotation sensor, and has a fail-safe function that prevents the engine from over-speeding in the event of a failure related to the input shaft rotation sensor, the control device comprising: input shaft rotation sensor failure detection means for detecting a related failure; and signal selection means for selecting a signal corresponding to the rotation of the engine when a failure related to the input shaft rotation sensor occurs; A continuously variable vehicle equipped with a fail-safe function, characterized in that when a failure related to the rotation sensor occurs, the rotation of the input-side rotating shaft is detected based on a signal corresponding to the rotation of the engine. Transmission control device. (4) The control device for a continuously variable transmission for a vehicle having a fail-safe function according to claim 3, wherein the signal selection means selects an ignition signal as the signal corresponding to the rotation of the engine.