JPH01120467A - Automatic transmission safety device - Google Patents

Abstract

PURPOSE:To disable achievement of reverse stage even if an operating state switching valve is switched to reverse position during drive operation by providing an oil path switching mechanism for discharging hydraulic pressure to be fed to a reverse friction element when the engine rotation is higher than a predetermined level and the operating state switching valve is switched to first position. CONSTITUTION:Upon erroneous switching of an operating state switching valve 1 to reverse position when the vehicle speed exceeds over a predetermined level, hydraulic pressure P1 flows between the lands 8, 9 in the switching valve 1 into oil paths 2, 3. A vehicle speed sensor 20 detects vehicle speed exceeding over a predetermined level, then a controller 18 controls a solenoid valve 17 based on an output from the sensor 20 to release pressure oil from an oil path 16 so as to slide a spool valve 11 to the left and bring to a hydraulic pressure discharging position. Consequently, pressure oil fed through the oil path 3 between lands 12, 13 of an oil path switching valve 10 is discharged through an oil discharge path 16 and not fed to a low reverse brake 5. Since reverse stage is not achieved even upon switching of the switching valve 1 to reverse position, abrupt braking or engine stall does not occur.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Utilization Public Funds> The present invention relates to a safety device for an automatic transmission that makes it impossible to achieve the reverse gear even if the reverse gear is accidentally selected during forward travel.

<Prior Art> Automatic transmissions generally installed in passenger cars include a torque converter, a planetary gear type transmission mechanism configured to combine a plurality of friction elements to achieve forward and backward gears, and the above-mentioned g.
It consists of a hydraulic control device etc. that supply and discharge hydraulic pressure to the i-rubbing element. The above hydraulic control device normally switches the operating state fp1 by operating the shift lever, leading to a forward position in the L range, a reverse position a in the R range, a neutral position in the N range, or 1! The vehicle is configured to supply and discharge hydraulic pressure to the plurality of friction elements when the vehicle is switched to the parking position of the P range.

<Problems to be Solved by the Invention> In an automatic transmission having such a configuration, when the operating state switching valve 1 is switched to the R range as shown in FIG. The oil passes through the valve 1 and is supplied to the front clutch 4 and low reverse brake 5, which are friction elements for reversing, through oil passages 2 and 3, and the reverse gear is immediately achieved. Therefore, in a vehicle equipped with such an automatic transmission, if you accidentally operate the shift lever and switch the driving state selector valve 1 to the R range while driving forward, sudden braking or engine stall may occur, which can be dangerous. There was some inconvenience.

Means for Solving the Problems> In view of the above-mentioned prior art, the present invention provides a safety feature for an automatic transmission that prevents the reverse gear from being achieved even if the operating state selector valve is accidentally switched to the reverse position during forward travel. The purpose is to provide equipment. The configuration of the present invention that achieves such an object includes a first position for supplying pressure oil from a hydraulic source to a friction element for reverse driving that puts the transmission in a reverse driving state, and a first position that puts the transmission in a state other than reverse driving. an operating state switching valve that can be switched to a second position for controlling the hydraulic pressure, and is disposed in an oil passage that communicates the hydraulic pressure source with the backward movement gI friction element, so that hydraulic pressure is supplied to the gI friction element; A hydraulic switching valve that can be switched between a supply position and a hydraulic discharge position that discharges hydraulic pressure to the same gJ friction element, and a solenoid valve that switches the position of the hydraulic switching valve, a rotation speed sensor that detects the engine rotation speed, and the above operation. It consists of a position sensor that detects that the state switching valve has been switched to the first position, a rotation speed sensor, and a controller that operates the solenoid valve according to the output of the position sensor. and an oil passage switching mechanism for discharging the hydraulic pressure supplied to the reversing friction element when the operating state switching valve is switched to the first position.

Embodiments Hereinafter, the present invention will be described in detail based on embodiments in which it is applied to a vehicle.

FIG. 2 shows a first embodiment of the present invention. Note that the special effects of the present invention have no relation to the forward friction elements and their hydraulic circuits, so they are omitted in the drawings and their explanations will be omitted. That is, in the embodiment shown in the figure, the operating state switching valve 1 and the front clutch and low reverse brake 5, which are reversing friction elements, are connected through oil passages 2 and 3, respectively. The operating state switching valve 1 is connected to a hydraulic power source (not shown) via an oil passage 6, and a hydraulic pressure P in the direction of the arrow in the figure is applied to the oil passage 6. The operating state switching valve 1 includes a spool valve 7 that can take a forward position (D range, L range), a reverse position (R range), a parking position U (PL, NJ), etc. ap 9 is formed. Therefore, the R range can be obtained by operating the operating state switching valve 1 and positioning the oil passages 6 and 2 at the gates of the lands 8 and 9 as shown in the figure. The operating state switching valve 1 is generally operated by a shift lever, but a servo motor is provided to drive the spool valve 7 from side to side in the figure.
The servo motor may be operated by a forward/reverse selection switch.

On the other hand, an oil passage switching mechanism is provided that discharges pressure oil from the oil passage 3 between the low reverse brake 5 and the operating state switching valve 1 when the vehicle speed exceeds a certain value. That is, an oil passage switching valve 19 is interposed in the oil passage 3, and the oil passage switching valve 10 includes a spool valve 11 that slides in a cylindrical hole.
1 has lands 12 and 13 formed thereon. A coil spring 14 is provided between the cylindrical hole and the land 12 on the left side of the cylindrical hole in the drawing, and oil drain passages 27 are provided in the cylindrical hole in order from the left in the drawing.
° The oil passages 3, 3 and the oil drain passage 15 are open. The right end of the cylindrical hole is connected to a hydraulic power source (not shown) via an oil passage 16, and a hydraulic pressure P2 in the direction of the arrow in the figure is applied to the oil passage 16. This oil passage 16 is provided with a solenoid valve 17, which allows pressure oil to be discharged from the oil passage 16 to appropriately regulate the oil pressure P2.

Therefore, the hydraulic pressure P2 is appropriately regulated by the solenoid valve 17,
By sliding the spool valve 11 and positioning only the oil passages 3 and 3 between the lands 12 and 13, pressure oil can be supplied to the low reverse brake 5 through the oil passage 3 (this position is referred to as the oil pressure supply position). ), and land 12. If the oil M83 and the oil drain path 15 are located between 13 and 13, pressure oil will be discharged from the oil drain path 15 (this position will be considered as the oil pressure discharge position), and no pressure oil will be supplied to the low reverse brake 5. Become.

Further, a controller 18 for duty-controlling the electromagnetic valve 17, an R-range detection sensor 19 for detecting the R-range of the operating state switching valve 1, a vehicle speed sensor 20 for detecting vehicle speed, and a rotational speed sensor 21 for detecting engine rotation and number. is provided. The above controller 18 has each sensor 19.20
, 21, when the vehicle speed exceeds a certain value or the number of revolutions exceeds a certain value, the solenoid valve 17 is duty controlled to release pressure oil from the oil passage 16, and the hydraulic pressure P
It is designed to lower the value of 2. When the oil pressure becomes low, the spool valve 11 of the oil passage switching valve 10 slides to the left in the figure, switching from the oil pressure supply position to the oil pressure discharge position.

In the automatic transmission safety device of the present invention having the above configuration, when the vehicle speed exceeds a certain value, the driving state switching valve 1
When the vehicle is switched to the R range, that is, the reverse position, the oil pressure P1 flows into the oil passages 2 and 3 through between the lands 8 and 9 of the operating state switching valve 1.On the other hand, when the vehicle speed exceeds a certain value, The controller 18 controls the electromagnetic valve 17 based on the output of the vehicle speed sensor 20 to release pressure oil from the oil @is, and slides the spool valve 11 to the left in the figure to the oil pressure discharge position. Therefore, the pressure oil that has flowed between the lands 12 and 13 of the oil path switching valve 10 through the oil path 3 is discharged from the oil drain path 16, and the pressure oil is not supplied to the low reverse brake 5. In this way, even if the driving state switching valve 1 is mistakenly switched to the reverse position when the vehicle speed exceeds a certain value, the reverse gear will not be achieved, so sudden braking or stalling will not occur, the missile will not be damaged, and safety will be improved. Excellent. Also, here,
As the constant value of the vehicle speed, a speed that does not cause dangerous situations such as sudden braking is selected, and usually a very low value is selected.

Furthermore, in this embodiment, the rear gear is not advanced even when the rotational speed exceeds a certain value, as well as when the vehicle speed exceeds a certain value. This is because if the reverse gear is suddenly achieved when the rotational speed is high, a sudden start will occur and an excessive shock will occur, which is dangerous. In this embodiment, the front clutch 4. is used as the reverse friction element. A low reverse brake 5 is used, and the configuration is such that the reverse gear cannot be achieved unless pressure oil is supplied to both the front clutch 4 and the low reverse brake 5. However, the present invention is not limited to such a system. Alternatively, the retraction friction element may be a single element instead of a plurality.

<Effects of the Invention> As specifically explained above based on the embodiments, in the present invention, even if reverse gear is selected by mistake during forward driving, the reverse gear is not achieved, resulting in sudden braking or engine stalling. Safety is improved as there is no danger of damage to the transmission.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the hydraulic circuit of a conventional automatic transmission ff1la, and FIG.
FIG. 2 is a schematic configuration diagram of an embodiment of the present invention. In the drawing, 1 is an operating state switching valve, 2.3 is an oil passage, 4 is a front clutch (reverse friction element), 5 is a low reverse brake (reverse AM element > 10 is an oil passage switching valve, 17 is a solenoid valve) , 18 is a controller, and 20 is a vehicle speed sensor. Patent applicant: 1 engineer, Mitsubishi Motors Corporation.

Claims (1)

[Claims] Switching between a first position for supplying pressure oil from a hydraulic source to a reverse friction element that puts the transmission in a reverse drive state, and a second position for putting the transmission in a state other than reverse. A possible operating state switching valve, a hydraulic pressure supply position that is disposed in an oil passage that communicates the hydraulic power source and the reverse friction element, and that supplies hydraulic pressure to the friction element, and a hydraulic discharge that discharges hydraulic pressure to the friction element. a hydraulic switching valve that can be switched to the first position, a solenoid valve that switches the position of the hydraulic switching valve, a rotational speed sensor that detects the engine rotational speed, and a detection that the operating state switching valve has been switched to the first position. a position sensor, a rotation speed sensor, and a controller that operates the solenoid valve according to the output of the position sensor, and when the engine rotation speed is above a predetermined value, the operating state switching valve is switched to the first position. A safety device for an automatic transmission, comprising: an oil passage switching mechanism for discharging the hydraulic pressure sometimes supplied to the reverse friction element.