JPS6037446A - Safety device of automatic speed change gear - Google Patents

Abstract

PURPOSE:To improve safety by closing an oil path between a reversing friction element and an oil pressure source when a car velocity exceeds a fixed value. CONSTITUTION:An oil path 3 between a low reverse brake 5 and an operating condition switch valve 1 is provided with an oil path switch valve 22 for closing the oil path 3 when a car velocity exceeds a fixed value. In this arrangement, when the car velocity exceeds a fixed value, a reverse step can not be accomplished, so that even if the operating condition switch valve 1 is switched to a reverse position by mistake during forward running, the reverse step is not accomplished so as to improve safety.

Description

DETAILED DESCRIPTION OF THE INVENTION 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 erroneously selected during forward running.

Generally, automatic transmissions installed in passenger cars include a torque converter, a planetary gear type transmission mechanism configured to combine multiple frictional elements to achieve forward and backward gears, and hydraulic pressure that supplies and discharges hydraulic pressure to the frictional elements. It consists of a control device, etc. The above hydraulic control device normally operates the operating state switching valve by operating the shift lever.
The vehicle is configured to supply and discharge hydraulic pressure to and from the plurality of friction elements by switching to the parking position of the T, Fi, or P ranges.

In an automatic transmission with such a configuration, when the operating state switching valve 1 is switched to the R range as shown in Fig. 1, pressure oil flows from the hydraulic source through the box 1 as indicated by the arrow, and the oil It is supplied through paths 2 and 3 to the front clutch 4 and low reverse brake 5, which are engaged by the reverse friction element, and the reverse gear is immediately achieved. Therefore, in commercial vehicles equipped with such automatic transmissions, it is possible to accidentally shift the shift lever while driving forward.
If the operating state switching valve 1 was changed to the 17I range by operating ft, there was an inconvenience that sudden braking or engine stalling could occur, which could be dangerous.

In view of the prior art, it is an object of the present invention to provide a safety device a for an automatic transmission that prevents the reverse gear from being achieved even if the operating state switching valve is accidentally switched to the reverse position during forward travel. purpose. The structure of the present invention that achieves such a goal is to supply pressurized oil to +M number of friction elements by switching the operating state switching valve to the forward position or the reverse position to achieve the forward/reverse gear change. In automatic transmissions, when the vehicle speed exceeds a certain value, an oil passage switching mechanism is provided that closes the oil passage between the reverse friction element and the hydraulic pressure source or discharges pressure oil from the oil passage, so that the vehicle speed remains constant. The present invention is characterized in that the reverse gear cannot be achieved even if the operating state switching valve is switched to the reverse position when the value exceeds the value.

EMBODIMENT OF THE INVENTION Hereinafter, the present invention will be described in detail based on an embodiment in which the present invention is applied to a vehicle.

FIG. 2 shows a first embodiment of the present invention. Note that the features of the present invention are not related 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 is connected to the oil passage 6't- to the hydraulic power source (not shown).
A hydraulic pressure P1 is applied to the oil passage 6 in the direction of the arrow in the figure. The operating state switching valve is in the forward position M
(D range, L range).

It is equipped with a spool valve 7 which can be made of metal such as the reverse position (1'L range) and the parking position (P range), and lands 8 and 9 are formed on this spool valve 7. Therefore, by operating the operating state switching valve 1 and positioning the oil passages 6 and 2t between the lands 8 and 90 as shown in the figure, the R range will be obtained. The operating state switching valve l is generally operated using a shift lever, but the spool valve 7
A servo motor may be provided to drive the vehicle left and right in the figure, and the servo motor may be operated by a forward/reverse selection switch.

On the other hand, an oil passage switching mechanism is provided which 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 IO is interposed in the oil wr3, and the core oil passage switching valve 10 is equipped with a spool valve 11 that slides in a cylindrical hole, and the spool valve 11 has a pot and a land 12, 13. It is formed. A coil spring 1 is placed between the land 2 and the cylindrical hole on the H side in the figure.
4 are provided in the cylindrical hole, and in order from the left in the figure, oil passages 27. The oil passages 3, 3 and the oil drainage passage 15 are open.

In addition, the right end of the cylindrical hole is connected to an oil passage 16t- to a hydraulic power source (not shown).
The hydraulic pressure P1 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 so that pressure oil can be discharged from the oil passage 16 and the oil pressure P can be appropriately regulated.

Therefore, the hydraulic pressure P is appropriately regulated by the solenoid valve 17,
By sliding the spool valve 11 and positioning only the oil passage 3.3 between the lands 12.13, pressure oil can be supplied to the low reverse brake 5 through the oil passage 3't. If the oil passage 3 and the oil drainage passage 15 are located between the lands 12 and 13, pressure oil will be discharged from the oil drainage passage 15 (this position will be referred to as the hydraulic discharge position). )t
2-This indicates that pressure oil cannot be supplied to the reverse brake 5.

Furthermore, a controller 718 for duty-controlling the electromagnetic valve 17, and a controller R for detecting the R range of the operating state switching valve l.
Range detection sensor 19. Vehicle speed sensor 20 that detects vehicle speed
, a rotation speed sensor 21 for detecting the rotation speed of the engine is provided.

The upper 1i-1 coy trollers 18 are each 19,20゜2
Based on the output from 1, when the vehicle speed exceeds a certain value or when the rotational speed exceeds a certain value, the solenoid valve 17 is duty-controlled to release pressure oil from the oil passage 16 and lower the oil pressure P2. It has become. When the oil pressure P2 becomes low, the spool valve 1 of the oil passage switching mechanism 0 slides to the left in the figure, and the oil pressure (II supply) also switches from the 7 position to the n11 pressure discharge position. There is.

-1-! li: In the automatic transmission safety device of the present invention, when the vehicle speed exceeds a certain value, the operating state switching valve 1 is closed and switched to the R range, that is, the reverse position.
Hydraulic pressure P through the lands 8 and 9 of the operating state switching valve 1
1 flows into the oil passage 2.3. On the other hand, the vehicle speed sensor 20 detects that the vehicle speed exceeds a certain value, and based on the output, the controller:j]8 controls the solenoid valve 17, and the oil passage 16 The pressure oil is released from the spool valve 12, and the spool valve 11 is slid to the left in the figure to the oil pressure 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. It is. In this way, when the vehicle speed exceeds a certain value, the operating state switching valve l
Since the 41st gear is not achieved by switching to the reverse position,
No sudden braking or engine stalling, no damage to the tensioner, and excellent safety. In addition, here, a constant value of vehicle speed and a speed that does not cause dangerous situations such as sudden braking are selected.
Usually a very low value is chosen.

Furthermore, in this embodiment, the reverse gear is not achieved even when the rotational speed exceeds a certain value, similar to when V', one vehicle train, 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. The low reverse brake 5 is used to supply pressure oil to both the front clutch 4 and the low reverse brake 5 so that the reverse gear is not achieved if the brakes are exhausted, but the present invention is limited to such a system. Instead, a single retraction friction element may be used instead of a plurality of friction elements.

Further, in the first embodiment, the oil passage switching valve i.

Although it is operated electrically, it may also be operated mechanically as in the second embodiment shown in FIG. That is, as shown in the figure, the operating state switching valve 1 is connected to the front clutch 4# and the low reverse brake 5, which are friction elements for reversing, through oil passages 2 and 3, respectively (about the operating state switching valve 1). is the same as that of the first embodiment described above, so its explanation will be omitted here.) An oil passage switching valve 22 is provided in the oil passage 3 between the low reverse brake 5 and the operating state switching valve 1 as an oil passage switching mechanism that closes the oil passage 3111 when the vehicle speed exceeds a certain value. The core oil passage switching valve 22 includes a spool valve 23 that slides in a cylindrical hole, and lands 24 and 25 are formed in the spool valve 23. A coil spring 26 is interposed between the cylindrical hole and the land 24 on the left side of the cylindrical hole in the figure, and oil drain passages 28, 29° oil passages 3, 3 are opened in the cylindrical hole in order from the left in the figure. . In addition, the governor pressure Pg is connected to the right end of the cylindrical hole through an oil passage 30.
K is set so that . Therefore, when the width of the vehicle is at a standstill, the syspool valve 23 is pressed by the coil spring 26, and only the oil passages 3, 3 are located between the lands 24 and 15, and the low reverse brake 5 is applied through the oil passage 3. When the governor pressure Pg increases in proportion to the vehicle speed, the spool valve 23 slides to the left, the land 25 is positioned between the oil passages 3, and the oil passage 3 is closed. Therefore, pressure oil cannot be supplied to the low reverse brake 5.

In other words, when the vehicle speed exceeds a certain value, the oil passage switching valve 22 closes the oil passage 3'ft, making it impossible to achieve the reverse gear. Therefore, even if the operating state switching valve 1t is switched to the reverse position by mistake during forward travel, the reverse gear will not be achieved, improving safety.

Furthermore, in this embodiment, a three-way check valve 31 is interposed in the oil passage 3 between the low reverse brake 5 and the oil passage switching valve 22, and the pressure oil flows through the three-way check valve 31 to achieve the L range. An oil passage 32 is connected thereto. Therefore, when the operating state switching valve 1 t-i is switched to the range and pressure oil is diverted to the oil passage 32, the three-way check valve 31 prevents the pressure oil from flowing back to the oil passage switching valve 22, so that the low reverse brake 5 receives no pressure. Oil can be supplied.

Hereinafter, as specifically explained based on the embodiment, in the present invention, even if the reverse gear is selected by mistake while the vehicle is traveling forward, the reverse gear will not be achieved, so sudden braking or engine stalling will not occur. This improves safety, as there is no damage to the transmission or damage to the transmission.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a hydraulic circuit of a conventional automatic transmission, FIGS. 2 and 3 are related to a safety device for an automatic transmission of the present invention, and FIG. 2 is a schematic configuration diagram of a first embodiment. , FIG. 3 is a schematic diagram of the second embodiment. ■ is the operating state switching valve, 2.3 is the oil passage, 4 is the front clutch (reverse friction element), 5 is the low reverse brake (reverse friction element), 10.22 is the oil passage switching valve, 17 is the solenoid valve , 18 is a controller, and 20 is a vehicle speed sensor. Patent Applicant Mitsubishi Motors Corporation Representative Patent Attorney Mitsuishi Shibu (and 1 other person) Figure 1 ↑ Figure 2 Figure 3

Claims (1)

[Claims] ■ In an automatic transmission that achieves forward/reverse gears by switching an operating state switching valve to a forward position or a reverse position, pressurized oil is supplied to a plurality of friction elements to change the vehicle speed. An oil passage switching mechanism is provided that closes the oil passage between the reverse friction element and the hydraulic pressure source or discharges pressure oil from the core oil passage when the vehicle speed exceeds a certain value. A safety device for an automatic transmission characterized in that a reverse gear cannot be achieved even if an operating state switching valve is switched to a reverse position. (1) In claim 1, the oil passage switching mechanism includes a hydraulic switching valve having a hydraulic pressure supply position and a hydraulic pressure discharge position interposed in the oil passage between the reversing friction element and the hydraulic pressure source, and A solenoid valve is provided to switch between a hydraulic pressure supply position and a hydraulic pressure discharge position of the hydraulic pressure switching valve, and a vehicle speed sensor is provided, and the solenoid valve is controlled based on the output from the vehicle speed sensor to control the hydraulic pressure when the vehicle speed exceeds a certain value. A safety device for an automatic transmission, comprising a controller that switches a switching valve to a hydraulic discharge position.