JPH066982B2 - Control device for continuously variable transmission for vehicle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device for a continuously variable transmission for a vehicle.

2. Description of the Related Art A continuously variable transmission that continuously changes the rotation of an engine and transmits the rotation to a driving wheel, and a first solenoid, and a change of a gear ratio of the continuously variable transmission in response to the operation of the first solenoid. A shift direction switching valve for switching the direction and a second solenoid are provided, and in response to the operation of the second solenoid, the speed ratio change speed of the continuously variable transmission is at least in two states of a rapid shift state and a slow shift state. There has been proposed a vehicle having a shift speed control valve for adjusting, and adjusting a gear ratio of the continuously variable transmission by a combination of operations of the shift direction switching valve and the shift speed control valve. According to such a vehicle, the gear ratio can be continuously changed according to the driving state (driving parameter), so that a preferable fuel consumption rate can be obtained. Further, since the gear ratio change speed is changed according to the deviation between the gear ratio or the engine rotation speed and its target value, there is a characteristic that a suitable control response (stability) is obtained. For example, it is the one described in Japanese Patent Application No. 58-203130 previously filed by the present applicant.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention By the way, in such a vehicle, when the solenoid of the shift direction switching valve or the shift speed control valve is disconnected or short-circuited during use, or the output of the control circuit power supply fails, It may stop, and in such a case, automatic control of the gear ratio of the continuously variable transmission may fail.

The present invention has been made in the background of the above circumstances,
An object of the invention is to provide a control device for a continuously variable transmission for a vehicle, which is expected to continue safer running even if a solenoid or a power source fails during running.

Means for Solving the Problems The gist of the present invention for achieving such an object is to provide a continuously variable transmission that continuously changes the rotation of an engine and transmits the rotation to a drive wheel, and a first solenoid. And a shift direction switching valve for switching the gear ratio change direction of the continuously variable transmission in response to the operation of the first solenoid, and a second solenoid, and responding to the operation of the second solenoid. And a shift speed control valve for adjusting the speed ratio change speed of the continuously variable transmission to at least two states of a sudden speed change state and a slow speed change state, the combination of the operation of the shift direction switching valve and the shift speed control valve In a control device for a vehicle continuously variable transmission of a type that adjusts a gear ratio of a continuously variable transmission, (a) the shift direction switching valve and the shift speed control valve are both the first solenoid and the second solenoid. Non And a solenoid abnormality detecting device configured to detect a disconnection or a short circuit of the first solenoid and the second solenoid, and which is configured so that the continuously variable transmission is in a slow speed shift state when energized. ) When a disconnection or a short circuit of at least one of the first solenoid and the second solenoid is detected by the solenoid abnormality detection device,
There is provided fail-safe control means for controlling the other continuously variable transmission so that the continuously variable transmission is in a slow shift state.

With this configuration, the continuously variable transmission is configured to enter the slow shift state when both the first solenoid and the second solenoid are in the non-energized state. When a disconnection or a short circuit of at least one of the first solenoid and the second solenoid is detected by the, the fail-safe control means deactivates the other solenoid to shift the continuously variable transmission. The ratio can be changed slowly. Further, because of the above-mentioned configuration, when the output is stopped due to a failure of the solenoid abnormality detection device or the power supply of the control circuit, that is, the first
Even when both the solenoid and the second solenoid are de-energized, the gear ratio of the continuously variable transmission is gradually changed. Therefore, even if the solenoid malfunctions or the output is stopped during traveling, safer continuation of traveling can be expected.

Embodiment Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory diagram showing a control device according to an embodiment of the present invention together with a belt type continuously variable transmission for an automobile. In the figure, 10 is an engine, which is a fluid coupling,
The belt type continuously variable transmission 14 is connected via a clutch 12 such as a torque converter, a magnetic powder type electromagnetic clutch, a centrifugal clutch or the like. The belt type continuously variable transmission 14 continuously changes the speed of the engine 10 and transmits it to drive wheels (not shown). The input side rotating shaft 16 connected to the clutch 12 and the input side rotating shaft 16 are connected to the input side rotating shaft 16. An input side variable pulley 18 having a variable effective diameter attached to the shaft 16, an output side rotary shaft 20 for transmitting a rotational force to the drive wheel via a rotation direction changing device or a differential gear device (not shown), and the like. An output variable pulley 22 having a variable effective diameter attached to the output rotary shaft 20, an input variable pulley 18 and a transmission belt 24 wound around the output variable pulley 22, an input variable pulley 18, and an output side Hydraulic cylinders 26 and 2 for changing the effective diameter by changing the V groove width of the variable pulley 22.
8 and is configured such that the effective diameters of the variable pulleys 18 and 22 change as the hydraulic oil is supplied to and discharged from the hydraulic cylinders 26 and 28, thereby changing the gear ratio. . And those hydraulic cylinders 2
The hydraulic device 30 supplies and discharges the hydraulic oil to and from 6 and 28.

The hydraulic device 30 includes, for example, a pump 34 that pumps hydraulic oil from a tank 32 to a line oil passage 36 connected to an output hydraulic cylinder 28, and a return amount of the hydraulic oil from the line oil passage 36 to a drain conduit 44. Line oil pressure control valve 38 for adjusting the line oil pressure of the line oil passage 36 by adjusting
Then, the working hydraulic pressure from the line oil passage 36 is supplied to the input side hydraulic cylinder 26 and the pressure is increased to increase the effective diameter of the input side variable pulley 18, or the working hydraulic pressure in the input side hydraulic cylinder 26 is increased. Supply to the shift direction switching valve 40 for switching to the shift direction (change ratio of the gear ratio) and the hydraulic cylinder 26 on the input side by discharging to the drain line 44 and reducing the pressure to reduce the effective diameter of the variable pulley 18. By adjusting the flow rate of the working oil or the flow rate of the working oil discharged from the input-side hydraulic cylinder 26 to control the changing speed of the effective diameter of the input-side variable pulley 18, thereby changing the shift speed (gear ratio changing speed). ) Of the shift speed control valve 42 and the like.

The line hydraulic control valve 38 is provided with, for example, a linear solenoid that continuously changes the amount of oil returned to the drain conduit 44, and this linear solenoid serves as the drive circuit 11 described later.
By being operated on the basis of the line oil pressure command signal SP supplied from 6, the line oil pressure of the line oil passage 36 is adjusted according to the operating state of the vehicle such as the rotation speed of the engine 10 and the throttle opening. It has become.

The shift direction switching valve 40 and the shift speed control valve 42
Are solenoid valves of a single-solenoid two-position type, each of which responds to solenoid valves 46 and 48 as pilot valves and the operation of the solenoid valves 46 and 48 as shown in FIG. The spool valves 50 and 52 are respectively provided. However, a solenoid valve device of a direct acting type in which a solenoid directly drives the spool valves 50 and 52 may be used.

The line hydraulic pressure is supplied to the solenoid valve 46 through the line oil passage 36, and an orifice 54 is provided on a passage connecting the solenoid valve 46 and the oil passage 36. When the solenoid valve 46 is closed (non-excited), the line oil pressure passing through the orifice 54 is changed to the spool valve 50.
When applied to the end surface 58 of the spool valve element 56, the spool valve element 56 is moved against the spring 60. Further, the downstream side is discharged from the orifice 54 by the opening operation (at the time of excitation) of the electromagnetic valve 46, and the spool valve element 56 is moved according to the urging force of the spring 60. That is, the spool valve element 56 is positioned at the two positions in response to the operation of the solenoid valve 46. Then, at the position moved against the spring 60, the line oil passage 36 and the supply pipeline 62 are connected, while the discharge pipeline 64 and the drain pipeline 44 are cut off, and the input side is closed. Hydraulic cylinder 26
The supply of line hydraulic pressure to the engine is allowed. FIG. 2 shows this state. At the other position, the communication between the line oil passage 36 and the supply pipeline 62 is blocked, while the discharge pipeline 64 is opened to the drain pipeline 44, so that the hydraulic oil from the hydraulic cylinder 26 on the input side is opened. Is allowed to be discharged. That is, in the shift direction switching valve 40, the supply / discharge of the hydraulic oil to / from the input side hydraulic cylinder 26 is controlled by controlling the excitation state of the electromagnetic valve 46, and thus the effective diameter of the input side variable pulley 18 is increased / decreased. That is, the change direction of the gear ratio (shift direction) can be controlled.

On the other hand, the line oil pressure is also supplied to the solenoid valve 48 via the line oil passage 36, and an orifice 66 is provided on the passage connecting the solenoid valve 48 and the line oil passage 36. In the case of this solenoid valve 48 as well as in the case of the solenoid valve 46, at the time of closing, the line hydraulic pressure that has passed through the orifice 66 is applied to the end surface 70 of the spool valve 68 of the spool valve 52, and the spool valve 68 is opened. The spring valve 72 is moved against the biasing force of the spring 72, and when opened, the action of the line hydraulic pressure on the spool valve 68 is released, and the spool valve 68 is moved according to the biasing force of the spring 72. The spool valve 52 is provided with a first port 74 and a second port 76 communicating with the hydraulic cylinder 26 on the input side, and the supply line 62 is provided.
And the supply port 7 connected to the discharge line 64, respectively
8 and the exhaust port 80, and the deceleration port 84 connected to the exhaust pipe 64 through the orifice 82, and as described above, the closing operation of the solenoid valve 48 (when not excited).
When the spool valve element 68 is positioned on the spring 72 side by the above, the connection between the second port 76 and the reduction port 84 is blocked, while the second port 76 and the discharge port 80 are blocked.
The first port 74 and the supply port 78 are communicated with each other through an orifice 86 formed in the spool valve 68.
Further, when the spool valve element 68 is moved according to the urging force of the spring 72 in accordance with the opening operation (during excitation) of the electromagnetic valve 48, between the first port 74 and the supply port 78,
The second port 76 and the deceleration port 84 are communicated with each other, and the second port 76 and the discharge port 80 are blocked from each other.

That is, the spool valve element 68 of the spool valve 52 has two positions, that is, an upshift speed suppressing side position that suppresses the flow of the hydraulic oil from the supply pipeline 62 to the first port 74 and an upshift speed non-suppressing side position that does not suppress the circulation of the hydraulic oil. And a downshift speed suppression side position that does not suppress the flow of the hydraulic oil flowing from the second port 76 toward the discharge pipeline 64 and a downshift speed suppression side position that suppresses the flow of the working oil corresponding to the two positions. It can be positioned at two positions, the side position and the side position, respectively. This shift speed control valve 4
2 controls the excitation state of the solenoid valve 48 to selectively control the moving position of the spool valve element 68 between the above two positions, regardless of the supply / discharge state of the shift direction switching valve 40, that is, the gear ratio. In both changing directions, the flow rate of the hydraulic oil to the input side hydraulic cylinder 26 is changed so that the changing speed (shift speed) of the gear ratio can be changed between two states of a rapid shift state and a slow shift state. is there. That is, the shift direction and the shift speed of the gear ratio can be controlled by selecting the energized state (opening / closing operation) of the solenoid valves 46 and 48, and those controls are performed by the shift direction command signal SD and the shift described later. By being performed based on the speed command signal SV, the gear ratio is set to the optimum value according to the operating condition. It should be noted that the orifice 86 provided for suppressing the upshift speed and the orifice 82 provided for suppressing the downshift speed are selected within a range in which the respective circulating diameters include zero as necessary. . Orifices 86 or 82 may be eliminated if the flow diameter is zero.

On the other hand, as shown in FIG. 1, a throttle valve 90 operated by an accelerator pedal 88 is attached to the intake pipe of the engine 10, and the throttle valve 90 detects the throttle opening θ. A throttle sensor 92 is attached. The voltage corresponding to the throttle opening θ detected by the throttle sensor 92 is supplied as a throttle signal TH to the A / D converter 94, where it is converted into a code signal and supplied to the I / O port 96.

Further, the belt type continuously variable transmission 14 is provided with rotation sensors 98 and 100 for detecting the rotation speeds of the input-side rotary shaft 16 and the output-side rotary shaft 20, respectively. The pulse-shaped rotation signal SE corresponding to the rotation speed of the shaft 16, in other words, the rotation speed of the crankshaft of the engine 10, is also transmitted to the rotation sensor 1
From 00, the pulse-shaped rotation signal SC corresponding to the rotation speed of the output side rotation shaft 20, in other words, the vehicle speed is I / O.
It is supplied to the F circuit 102. And
The I / F circuit 102 I / F outputs a code signal corresponding to the number of pulses of the rotation signals SE and SC per unit time.
It is supplied to the O port 96.

The I / O port 96 has a microcomputer (EC
U) constituting CPU 104, RAM 106, ROM 1
08 is connected via a data bus line. CP
The U 104 processes a signal supplied through the I / O port 96 according to a program stored in the ROM 108 in advance while utilizing the storage function of the RAM 106 to change the gear ratio (shift direction) and speed. The shift direction command signal SD and the shift speed command signal SV corresponding to (shift speed) are detected by the solenoid abnormality detecting / driving circuit 11
0 and 112, and a line hydraulic pressure command signal SP (voltage signal) that commands the line hydraulic pressure of the line oil passage 36 via the D / A converter 114.
Supply to. The signals amplified by these drive circuits are, as described above, the linear shift solenoid of the line hydraulic pressure control valve 38 and the solenoid valve 4 of the shift direction switching valve 40.
6 and the solenoid valve 48 of the shift speed control valve 42, respectively, whereby the line hydraulic pressure is transmitted to the transmission belt 24.
Power loss is reduced as much as possible within the range where slippage does not occur, and the gear ratio of the belt-type continuously variable transmission 14 is set to an optimum value so that fuel consumption is appropriately maintained. There is. That is, in this embodiment, the CPU 104, R
The control device is constituted by the AM 106, the ROM 108 as a storage means, and the like.

The solenoid valve 46 and the solenoid valve 4 are used to detect disconnection and short circuit of the first solenoid 120 of the shift direction switching valve 40 and the second solenoid 122 of the shift speed control valve 42.
Solenoid abnormality detection / drive circuit 11 for driving 8
0 and 112 respectively supplied to the shift direction command signal SD and the shift speed command signal SV, and the solenoid abnormality detection / drive circuits 110 and 112 from these I / O
This is performed based on the determination signal SJ output to the port 96. Since the solenoid abnormality detection / drive circuits 110 and 112 have exactly the same configuration, the second solenoid 12 of the solenoid valve 48 of the shift speed control valve 42 will be described below.
A solenoid abnormality detection / drive circuit (solenoid abnormality detection device) 112 for driving the second solenoid 122 and detecting the disconnection and short circuit of the second solenoid 122 will be described.

In FIG. 3, when the second solenoid 122 is neither disconnected nor short-circuited, when the solenoid abnormality detection / drive circuit 112 is supplied with the H-level shift speed command signal SV, the solenoid abnormality detection / drive circuit 112 is detected. Is activated to supply an exciting current to the solenoid valve 48. That is, first the first transistor 124 is turned on, then the second transistor 126 is turned off, and the third transistor 128 is turned on.
Is turned on, and the amplified shift speed command signal SV is supplied to the second solenoid 122. Further, in the L level state in which the shift speed command signal SV is not supplied, the third transistor 128 is turned OFF contrary to the above case, and the supply of the drive current to the second solenoid 122 is stopped. When the shift speed command signal SV is output to the solenoid abnormality detection / drive circuit 112 via the I / O port 96, the second solenoid 122 is excited according to the shift speed command signal SV. That is, the solenoid valve 48 is turned on.
It becomes the (operation) state. The fourth transistor 130 operates in accordance with an increase in the voltage across the resistor 132 having a very low resistance value for detecting the drive current, and limits the collector current in the third transistor 128. It is provided to protect the circuit when 122 is short-circuited.

On the other hand, the drive current passes from the B power source through the resistor 132, the third transistor 128, and the second solenoid 122.
Is supplied to the second solenoid 12
The disconnection or short circuit of the second solenoid 122 can be detected by operating the solenoid disconnection / short circuit detection circuit based on the voltage at the end of the B power source side of 2 (voltage at point J in FIG. 3). ing. That is, the second solenoid 1
In the state where the drive current is supplied to 22, the voltage at the point J is B due to the voltage drop of the second solenoid 122.
It is maintained at a predetermined high voltage level (H level) close to the power supply voltage, and when the drive current is not supplied, the resistor 134 having a high resistance value is connected to the B power supply, so that the ground potential is maintained. The voltage is changed to a near predetermined low voltage level (L level). Then, the fifth transistor 136 is ON / OFF controlled by the level at the point J, so that the determination signal SJ having the inverted level at the point J is supplied to the I / O port 96. There is. That is, when the second solenoid 122 is normally driven, the determination signal SJ having a level inversion relationship with the shift speed command signal SV is output from the drive circuit 112 to the I / O port 9.
6 is supplied.

Therefore, as shown in FIG. 4, the second solenoid 1
If 22 is disconnected, the voltage at the point J becomes H level regardless of whether or not the drive current is supplied to the second solenoid 122, that is, whether or not the shift speed command signal SV is supplied. SJ is maintained at the L level even when the drive current is not supplied to the second solenoid 122. On the other hand, when the second solenoid 122 is short-circuited, the second solenoid 1
Even when the drive current is supplied to 22, the point J is maintained at the L level and the determination signal SJ is set at the H level.
That is, by comparing the contents of the shift speed command signal SV and the determination signal SJ, the second solenoid 122
Is normally driven, or is disconnected or short-circuited. Here, the short circuit of the solenoid means that any part from the collector of the third transistor 128 to the ground side terminal of the second solenoid 122 is in contact with or grounded, and the current is bypassed at that part. While a current larger than the rated value flows through the resistor 132, the second solenoid 122
A state in which a sufficient drive current is not supplied to the whole.
Further, the disconnection of the solenoid means that the resistance value becomes excessively large at any part from the point J to the ground side lead wire of the second solenoid 122 due to the disconnection or the like.

FIG. 5 is a flowchart showing the control executed by the microcomputer. After the initialization routine and the routine for reading the input signal from the sensor, etc. are executed, the routine is executed thereafter based on the read signal, etc. A control mode to be selected is selected. The control modes are fail-safe control, cranking control, target engine speed control,
There are five types of overrun control and neutral control, and when it is determined that the vehicle is stopped and the starter for starting the engine 10 is operated, the cranking control is executed and, for example, the engine is performed. 1
When it is determined that the clutch 12 is disengaged during the operation of 0, the neutral control is executed, and when it is determined that the vehicle is running and the accelerator pedal is operated, the target engine is executed. The rotation speed control is executed, and when it is determined that the engine 10 has exceeded the allowable rotation speed, the belt type continuously variable transmission 14
The overrun control for reducing the rotation speed of the engine 10 is executed by changing the gear ratio so that the rotary shaft 20 on the output side shifts to the speed increasing side. Then, after the target engine rotation speed control and the overrun control are executed, the line pressure control is executed. In addition, the first solenoid 12 in the shift direction switching valve 40 and the shift speed control valve 42.
If it is determined that either 0 or the second solenoid 122 is broken or short-circuited, the fail-safe control is executed. After the above control is executed, the control value output control is executed, and the shift speed command signal SV and the shift direction command signal SD for changing the gear ratio of the continuously variable transmission 14 to a desired value are output. To be done. The target engine rotation speed control is a control for matching the actual engine rotation speed with the target engine rotation speed determined from the relationship obtained in advance based on the operating parameters of the vehicle. The fuel efficiency of the vehicle is improved while ensuring the above. The main parts of the target engine speed control and the line pressure control are disclosed, for example, in the specifications and flow charts of Japanese Patent Application No. 58-203130 and Japanese Patent Application No. 59-14010 previously filed by the present applicant. .

In the fail-safe control, step SS which constitutes fail-safe control means as shown in the flowchart of FIG.
1 to SS4 are included. These steps SS1 to SS4 are performed so that the belt-type continuously variable transmission 14 enters the slow shift state when the disconnection or the short circuit of one of the first solenoid 120 or the second solenoid 122 is detected. It constitutes a fail-safe control means for controlling the signals SV and SD supplied to the first solenoid 120 or the second solenoid 122.

That is, regardless of the shift direction command signal SD, if the determination signal SJ is at H level or L level, step SS
In step 1, it is determined that the first solenoid 120 is open or short-circuited, and step SS2 is executed. Step SS2
In the above, the drive signal supplied to the second solenoid 122, that is, the shift speed command signal SV is blocked from being supplied to the second solenoid 122, the second solenoid 122 is de-energized, and the solenoid valve 46 and Both 48 are deactivated. When it is not determined that the first solenoid 120 is open or short-circuited in step SS1, step SS3 is executed to determine whether the second solenoid 122 is open or short-circuited.
That is, regardless of the shift speed command signal SV, the determination signal S
If J is at the H level or the L level, it is determined that the second solenoid 122 is open or short-circuited, and step SS4 is executed. In step SS4, the first
The drive signal, that is, the shift direction command signal SD supplied to the solenoid 120 of the solenoid valve is blocked, and the solenoid valves 46 and 48 are blocked.
Are both deactivated.

As a result, when it is determined that either the first solenoid 120 or the second solenoid 122 is disconnected or short-circuited, the other second solenoid 122 or the first solenoid 122 is disconnected.
The drive signal SD or SV is blocked so that the solenoid 120 is in a non-excited state, that is, the belt type continuously variable transmission 14 is in a gentle shift state.
Both solenoid valves 46 and 48 are deactivated. Therefore, as shown in FIG. 2, the spool valves 50 and 52 are positioned at the shift-up side position and the shift-up speed suppression side position, and the gear ratio of the continuously variable transmission 14 is gradually changed in the shift-up direction. Or, if the orifice 86 is not provided, the upshift speed is maintained at substantially zero. Therefore, even if one of the first solenoid 120 and the second solenoid 122 is broken or short-circuited, it is possible to avoid a rapid change in the gear ratio of the continuously variable transmission 14.

In the target engine rotational speed control, when one of the first solenoid 120 and the second solenoid 122 becomes abnormal due to disconnection or short circuit, as shown in the failure results of Table 1 and Table 2, However, there are cases where the gear ratio of the continuously variable transmission 14 changes rapidly and the control of the continuously variable transmission 14 becomes impossible.

However, according to this embodiment, the first solenoid 1
When one of the 20 and the second solenoid 122 is broken or short-circuited, the above steps SS1 to SS4 are performed.
So that the other solenoid is not energized,
That is, since the signal SD or SV supplied to the second solenoid 122 or the first solenoid 120 is controlled so that the belt type continuously variable transmission 14 is in the slow speed change state, the belt type continuously variable transmission 14 is controlled. It is expected that sudden shifts will be avoided and safer driving will continue. The first
When the solenoid 120 and the second solenoid 122 are both disconnected or short-circuited, and when the output is stopped due to a failure of the solenoid abnormality detection / drive circuits 110 and 112 or the power supply of the microcomputer, the first solenoid 120 and Since the second solenoid 122 is in the non-energized state, that is, the solenoid valves 46 and 48 are both in the non-actuated state, the same result as in the case of executing the steps SS1 to SS4 is obtained.

Incidentally, in the above-mentioned embodiment, the spool valves 50 and 52
Is configured to be positioned at the shift-up side position and the shift-up speed suppression side position when the solenoid valves 46 and 48 are not operated, but is conversely located at the shift-down side position and the shift-down speed suppression side position. It does not matter even if it is configured like this.

Further, in the above-described embodiment, the solenoid drive circuit and the solenoid abnormality detection circuit are integrated into the solenoid abnormality detection / drive circuits 110 and 112, but they may be separately configured.

Although the embodiment of the present invention has been described above with reference to the drawings, the present invention can be variously modified without departing from the spirit thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing an embodiment of the present invention together with a belt type continuously variable transmission. FIG. 2 is an explanatory diagram showing a main part of the hydraulic control device of FIG. FIG. 3 is a circuit diagram showing an example of the solenoid abnormality detection / drive circuit shown in FIG.
FIG. 4 is a time chart explaining the operation of the circuit of FIG. FIG. 5 is a flow chart for explaining the operation of the embodiment of FIG. 1, and FIG. 6 is a flow chart for explaining the operation of the fail safe control in FIG. 10: engine, 14: belt type continuously variable transmission, 40: shift direction switching valve, 42: shift speed control valve, 110, 1
12: Solenoid abnormality detection / drive circuit (solenoid abnormality detection device), 120: first solenoid, 122: second
Solenoid, steps SS1 to SS4: fail-safe control means

Front Page Continuation (72) Inventor Mitsuru Takada 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation (56) References JP-A-58-81258 (JP, A)

Claims (1)

[Claims] 1. A continuously variable transmission that continuously changes the rotation of an engine and transmits it to drive wheels, and a first solenoid. The continuously variable transmission is responsive to the operation of the first solenoid. A shift direction switching valve for switching the gear ratio changing direction of the control unit and a second solenoid, and in response to the operation of the second solenoid, the gear ratio changing speed of the continuously variable transmission is at least a rapid speed change state and a slow speed change speed. And a shift speed control valve for adjusting the gear ratio of the continuously variable transmission by a combination of operations of the shift direction switching valve and the shift speed control valve. In the control device, the shift direction switching valve and the shift speed control valve are configured such that the continuously variable transmission is in a slow shift state when both the first solenoid and the second solenoid are in a non-energized state, And said Abnormality detecting device for detecting disconnection or short circuit of the solenoid and the second solenoid, and when the disconnection or short circuit of at least one of the first solenoid and the second solenoid is detected by the solenoid abnormality detecting device. Is provided with fail safe control means for controlling the other solenoid to be in a non-energized state so that the continuously variable transmission is in a slow speed change state.