JPH0735209A - Gear ratio control device for continuously variable transmission - Google Patents

Abstract

(57) [Summary] [Object] The present invention facilitates traveling in an abnormal state by switching the gear shift limiting valve only when the gear ratio control pressure supplied to the gear ratio control valve falls into an abnormal level. There is something to do. [Structure] Primary pulley 30 and secondary pulley 31
The drive belt 32 is wound between the two, and the continuously variable transmission unit 16 that changes the winding diameter ratio of both pulleys to continuously change speed is provided.
A forward / reverse switching unit 15 for switching the forward / backward speed by a manual valve 43 for speed change is provided, and in particular, a gear ratio control valve 49 supplies a hydraulic pressure when the spool 53 is switched to a position where the primary pulley control hydraulic pressure is eliminated. A low speed stage port 494 for receiving the low speed stage switching oil passage 45 is connected to the port 494 for supplying pressure oil when the valve is switched from the manual valve 43 to the low range L or the reverse range R. The oil passage is equipped with a normally closed shift limiting valve 54 that allows the oil passage to communicate with the oil passage only when the gear ratio control pressure Pc is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling a gear ratio of a transmission which changes a winding diameter ratio of a belt wound around a pair of pulleys to continuously change gears, and more particularly, a gear ratio control valve for an engine. The gear ratio of a continuously variable transmission that switches the spool based on the gear ratio according to the operating information, supplies the pulley control hydraulic pressure to both hydraulic actuators of both pulleys, and changes the winding diameter ratio of both pulleys to perform continuous gear shifting. Regarding the control device.

[0002]

2. Description of the Related Art Conventionally, a belt drive type continuously variable transmission in which a drive belt is wound between a primary pulley and a secondary pulley, and the winding diameter ratio of the belt wound around both pulleys is changed to perform continuously variable transmission. It has been known. This continuously variable transmission supplies the shift control oil pressure based on the gear ratio determined according to the operating information of the engine to the spool of the gear ratio control valve, and the pulley control hydraulic pressures adjusted based on the hydraulic pressure switching operation of the spool. Is supplied to both hydraulic actuators for operating the relative distance between the fixed pulley material and the movable pulley material of both the primary and secondary pulleys. As a result, the winding diameter ratio of the belt wound around the pair of pulleys is changed to continuously change the speed. Further, the power transmission system including the continuously variable transmission section is provided with a forward / reverse switching section for switching the forward / backward step, and the hydraulic actuator for switching the forward / backward step of the switching section is provided with each switching control from the manual valve for changing the shift step. Pressure oil is supplied, and both hydraulic actuators are configured to switch between forward and backward stages.

By the way, as shown in FIG. 7, the primary cylinder 1 and the secondary cylinder 2, which are hydraulic actuators for both the primary pulley (driving side) and the secondary pulley (driven side), increase in the level of pressure oil supplied to each. Accordingly, the winding diameter ratio of the belt wound around each pulley can be greatly adjusted. Here, the secondary cylinder 2 is constantly supplied with line pressure from the regulator valve 3 side, and the primary cylinder 1 is supplied with pulley control hydraulic pressure from the gear ratio control valve 4. Moreover, the pressure receiving area of the primary cylinder 1 side is set to be larger than that of the secondary cylinder 2 side. Therefore, when the same hydraulic pressure is supplied to both cylinders, the winding diameter ratio of the primary pulley becomes larger than that of the secondary pulley, and the low gear ratio. (High gear stage) is achieved, and conversely, a high gear ratio (low gear stage) is achieved as the hydraulic pressure on the primary cylinder 1 side is reduced.

The gear ratio control valve 4 is a primary port 4
01, secondary port 402, drain port 403
And a control pressure port 404. The internal spool 5 is constantly pressed by the spring 6 in the direction of equalizing the primary port 401 and the secondary port 402, and conversely, depending on the target gear ratio from the solenoid valve 7 via the low gear ratio control pressure port 404. The spool 5 is configured to be pressed in the direction of communicating the primary port 401 with the drain port 403 by receiving the gear ratio control pressure.

The solenoid valve 7 has a control means 8
A gear ratio control pressure signal corresponding to the target gear ratio is input, and the solenoid valve 7 regulates the solenoid supply pressure P1 to the gear ratio control pressure P2 based on the signal. Here, the control means 8 is configured to calculate a target gear ratio according to engine operating information such as the engine speed and engine load, and output a gear shift control hydraulic signal according to the target gear ratio.

[0006]

However, as described above, the control means 8 outputs the target gear ratio signal to the solenoid valve 7 as described above.
If the solenoid valve 7 fails or the drive cable of the valve is broken even if the valve 7 tries to supply the gear ratio control pressure to the gear ratio control valve 4, the gear ratio control valve 4 Is not supplied with the gear ratio control pressure, the spool 5 of the gear ratio control valve 4 causes the primary port 401 and the secondary port 402 to communicate with each other by the spring 6, and as a result, the continuously variable transmission has a low gear ratio (high gear stage).
Is switched to.

When such an abnormal situation occurs, the vehicle is moved to a predetermined safety zone or a repair shop.
It is a problem that it is presumed that only high gears can be used when traveling, which makes it impossible to start and drive on slopes. On the contrary, when the gear ratio control pressure is not supplied to the gear ratio control valve 4 due to the non-energization of the solenoid, if the gear ratio control valve having a structure in which the spool communicates the primary port with the drain port is adopted, in this case, When a failure occurs during traveling, the gear ratio is switched to a high gear ratio (low gear), and the primary pulleys of the engine and the continuously variable transmission over rotate, which causes abnormal wear of rotating members such as bearings. Will end up.

[0008] In this case, a structure is adopted in which the clutch disposed between the engine and the continuously variable transmission side is disengaged to prevent abnormal wear of the rotating member.
It is disclosed in Japanese Patent No. 6022. However, even in this case, the problem that the primary pulley side excessively rotates and abnormal wear of the rotating member such as the bearing occurs is not solved. An object of the present invention is to provide a gear ratio control device for a continuously variable transmission, which is capable of facilitating traveling during an abnormality by switching the gear limit valve only when the gear ratio control pressure supplied to the gear ratio control valve falls to an abnormal level. To provide.

[0009]

In order to achieve the above-mentioned object, the present invention has a drive belt wound between a primary pulley and a secondary pulley to control a gear ratio control pressure according to a target gear ratio. A pressure supply means is generated, and a gear ratio control valve regulates the pulley control oil pressure adjusted based on the gear ratio control pressure by operating the relative distance between the fixed pulley material and the movable pulley material of the two pulleys. It is provided with a continuously variable transmission for supplying to a hydraulic actuator and changing the winding diameter ratio of both pulleys to perform continuously variable transmission, and is provided in a power transmission system including the continuously variable transmission and a manual for gear shift. It is equipped with a forward / reverse switching part that receives the switching control pressure oil from the valve with both hydraulic actuators and switches the forward / backward speed. A low speed stage port is formed which receives a hydraulic pressure when switching to a position where the primary pulley control hydraulic pressure is removed, and when the low speed stage port is switched to a low range or a reverse range from the manual valve, the low speed stage port is formed. A low speed stage switching oil passage for supplying pressure oil was connected, and a normally closed shift limiting valve was attached to the low speed stage switching oil passage to communicate the oil passage only when the speed ratio control pressure becomes low. It is characterized by

[0010]

[Function] The manual valve communicates with the low speed stage port of the gear ratio control valve through the low speed gear switching oil passage and the speed limit valve, and this manual valve is switched to the low range or the reverse range and the gear ratio control pressure Only when the pressure is lowered, the shift limiting valve releases the low speed gear switching oil passage and supplies the pressure oil to the low speed port, so if the manual valve is switched to the low range or the reverse range only when the gear ratio control pressure is lowered. Therefore, the pressure oil of the hydraulic actuator of the primary pulley can be removed without fail, and the continuously variable transmission can be switched to a high gear ratio (low gear).

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The gear ratio control system for a continuously variable transmission shown in FIG. 1 is installed in a power transmission system of a vehicle. As shown in FIG. 2, this power transmission system includes an engine 1, a fluid coupling 2, a continuously variable transmission 3, a speed reducer 4, a differential 5, left and right axle shafts 6 and drive wheels (not shown). It is configured to be done. The fluid coupling 2 is the engine output shaft 7
A compressor 8 that rotates integrally with the turbine 8, a turbine 9 that receives rotational energy of the compressor 8 via oil, and a direct coupling clutch 10. The tip of the compressor 8 is coaxially supported by the base of the casing 14 via a bearing 12 concentrically with the turbine shaft 11. Here this compressor 8
Of the oil pump doubles as the drive shaft of the oil pump 13, which allows oil to be supplied to the continuously variable transmission 3 and the fluid coupling 2.

The continuously variable transmission 3 comprises a forward / reverse switching unit 15 and a continuously variable transmission unit 16. Here, the forward / reverse switching unit 15
Is a turbine shaft 11 pivotally supported between a pair of bearings 12 and 17.
A forward clutch 18 and a reverse clutch 19 are provided in front of and behind. The forward clutch 18 includes a peripheral portion of a front rotating body 20 which is integral with the turbine shaft 11 and a carrier 22 of a planetary gear train 21 described later.
The hydraulic piston 23 for the forward clutch is used to switch between the peripheral portions of the vehicle. Here the planetary gear train 2
1 is a sun gear 24 that is integral with the turbine shaft 11, a plurality of planet gears 25 that are meshed around the sun gear 24 and are pivotally supported by a carrier 22,
Ring gear 26 having inner peripheral teeth with which the planetary gear 25 meshes
Composed of and. The reverse clutch 19 has a braking function to bring the outer peripheral portion of the ring gear 26 into contact with and separate from the casing 14, and is switched by a hydraulic piston 27 for the reverse clutch 19.

In this case, when only the forward clutch 18 is engaged, the turbine shaft 11 and the carrier 22 side are integrated, the engine rotation is transmitted to the main shaft 28 of the continuously variable transmission portion 16 as it is, and when only the reverse clutch 19 is engaged, the turbine shaft 1 is connected.
1 is reversed and the continuously variable transmission unit 1 on the carrier 22 side
6 is transmitted to the main shaft 28.

The continuously variable transmission portion 16 is provided with a main shaft 28 which is integral with the carrier 22 and a sub shaft 2 which is arranged parallel to the main shaft 28 at a predetermined distance.
9, the main shaft has a main pulley 30 and the sub shaft 29 has a sub pulley 3
1 is provided, and an endless belt 32 is stretched between both pulleys. The pulleys 30 and 31 are both divided into two parts, and the movable-side pulley members 301 and 311 are fitted onto the fixed-side pulley members 302 and 312 so that they can rotate relative to each other and can be spaced apart from each other. This movable pulley material 30
Reference numerals 1 and 311 denote primary cylinders 3 as hydraulic actuators for operating a relative distance from a fixed pulley material.
3 and the secondary cylinder 34 are mounted. In this case, the movable-side pulley member 301 is brought closer to the fixed-side pulley member 302 of the main pulley 30 to increase the winding diameter of the main pulley, and the movable-side pulley 311 is separated from the fixed-side pulley member 312 of the sub-pulley 31 and the winding diameter is increased. To reduce the winding diameter ratio (sub-pulley winding diameter / main pulley winding diameter), that is, to set a low gear ratio (high gear stage), and operate in reverse to increase the high gear ratio (low gear stage). Configured to achieve.

The speed reducer 4 has a structure in which a final gear 37 is connected to a gear 35 integral with the auxiliary shaft 29 via a gear train 36. The differential 5 accommodates an operating mechanism in a differential casing (not shown) integral with the final gear 37. However, a well-known configuration is adopted in which the rotational force is divided into two and output after allowing the left-right rotation difference. The hydraulic circuit of the continuously variable transmission 3 of FIG. 2 will be described with reference to FIG. This hydraulic circuit is provided with an oil pump 13, and the oil discharged from the hydraulic coupling 2 and the forward clutch 18 and the reverse clutch 19 of the forward / reverse switching portion 15 are used.
Is supplied to the primary cylinder 33 and the secondary cylinder 34 of the continuously variable transmission unit 16.

Here, the oil pump 13 is driven according to the rotation of the engine to change its oil pressure, and therefore the maximum allowable pressure of the discharge pressure is regulated by the line pressure regulator valve 38, and the line pressure which is a set value is set. The regulator valve 39 operates to regulate the pressure so as to hold the pressure. A part of the line pressure passage 40 is adjusted to a set value by the clutch pressure control valve 41, and the clutch oil passage 42
And is supplied to the manual valve 43. This manual valve 43 is interlocked with a manual switching lever for shifting gears, and is provided with each range of forward D, 2, L and reverse R.
A range and neutral N and parking P ranges are provided.

This manual valve 43 is particularly equipped with an oil supply port 431 communicating with the clutch oil passage 42 and a forward clutch 1.
8, a reverse port 432 communicating with the reverse clutch 19, a reverse port 433 communicating with the reverse clutch 19, and a refueling port 431 in the L range.
L ports 434 communicating with the respective L port 434 are formed. Here, in particular, the reverse drive port 433 and the L port 434 are connected to the low speed stage switching oil passage 45 via the check valve 44. This low speed stage switching oil passage 45 communicates with the shift limiting valve 54 and the low shift stage port 494 described later. In this case, the forward clutch 18 is engaged in each of the forward drive ranges D, 2 and L, and the engine rotation is transmitted to the continuously variable transmission section 16 as it is, while the engine rotation is reversed in the reverse drive R range and the continuously variable transmission section 16 is transmitted. Be transmitted to.

The shift limiting valve 54 is a normally closed valve that normally closes the low speed stage switching oil passage 45, and as shown in FIG. 6, the upstream port 541, the downstream port 542, and the limiting port 543 that receives the gear ratio control pressure Pc. And drain port 5
44 are provided. The spool 55 of this gear shift limiting valve 54
Indicates that the portion opposed to the restriction port 543 normally receives the gear ratio control pressure Pc of a predetermined level or higher (Pc1 or higher).
At that time, the spring 56 is moved rightward against the elastic force of the spring 56 and is held at the closed position A shown by the solid line to be connected to the upstream and downstream ports 541.
When the gear ratio control pressure Pc is reduced due to a failure of the solenoid valve 47 or the like by shutting off the valve 542, the upstream and downstream ports 54 are switched to the open position B indicated by the two-dot chain line.
1, 542 are connected.

A part of the line pressure passage 40 following the oil pump 13 is adjusted to a set value by a pressure control valve 46, and the hydraulic pressure is changed by a solenoid valve 47 as a gear ratio control pressure supply means according to a target gear ratio. The pressure is adjusted to the specific control pressure Pc. The solenoid valve 47 is connected to the gear shift control unit 48, and the gear ratio control pressure P corresponding to the output signal of the gear shift control unit 48 is used.
c is output to a gear ratio control valve 49 described later. The gear shift control unit 48 takes in engine operating information such as the engine speed N, throttle opening θ, and intake air amount Q from each of the sensors 50, 51, 52, calculates an optimum gear ratio, and presents it as a target gear ratio. It is configured to drive the solenoid valve 47 with an output signal capable of correcting the gear ratio.
The primary cylinder 33 and the secondary cylinder 34 of the continuously variable transmission unit 16 are respectively connected to the main port 491 and the sub port 492 of the gear ratio control valve 49, and in particular, the secondary cylinder 34 is also directly connected to the line pressure passage 40.

The gear ratio control valve 49 has a main port 491,
In addition to the sub port 492, the low gear stage port 494 described above,
A pilot port 493 that receives the gear ratio control pressure Pc of the solenoid valve 47 and a drain port 495 that communicates with the oil tank 60 are provided, and the spool 53 controls switching of the oil passage. Here, as shown in FIG. 5, the portion of the spool 53 facing the pilot port 493 has a large diameter portion 531 and a small diameter portion 532, and a spring 57 is attached to one end thereof. The spool 53 has a pressing force Fs of the spring 57.
To the right, and the gear ratio control pressure Pc acts on the area difference S (= A−B) between the large diameter portion 531 and the small diameter portion 532 to receive the oil pressure Fp to the left. Moreover, the small diameter portion 5 of the spool 53
The end surface of 32 opposes the low speed stage port 494 and is also configured to receive the low speed stage switching oil pressure in a timely manner.

For this reason, the spool 53 is basically switched and moved to the balance position of the pressing force Fs and the hydraulic pressure Fp,
As shown in FIG. 3, when the gear ratio control pressure is Pc1, the dead zone a1 is released and the movement amount is increased. At this time, the drain port 495 is closed according to the right movement of the spool 53 (the gear ratio control pressure Pc is increased), is completely closed after a certain movement, and is further closed by the large diameter portion 531 by the large diameter portion 531 after the certain movement.
2 increases release amount in sequence. Main port 49 at this point
It is possible to increase / decrease the pulley control hydraulic pressure of the primary cylinder 33 and increase / decrease the gear ratio by increasing the amount of increase in the communication state of 1 and the sub port 492. In this case, when the gear ratio control pressure Pc is large, the sub port 492 is closed and the main port 491 is closed.
Is communicated with the drain port 495 to have a high gear ratio (low gear), and when the gear ratio control pressure is small, the sub port 492 opens greatly and the hydraulic pressures of the main and sub ports 491, 492 become equal, and the low gear ratio (high gear ratio Dan).

The gear ratio control device for such a continuously variable transmission receives the engine rotation through the fluid coupling 2 when the vehicle is running, and designates the engine rotation through the designated gear range, engine speed, throttle opening θ, intake air amount. It operates so that the gear is shifted at the target shift speed based on Q etc. and is output to the speed reducer 4 side. At this time, when the manual valve 43 is switched to the L range or the reverse R range, the refueling port 431 is connected to the upstream port 541 of the shift limiting valve via the L port 434 and the check valve 44 or the reverse port 433 and the check valve 44. Join. In this normal state, the gear ratio control pressure Pc is a normal pressure equal to or higher than Pc1, the shift limiting valve 54 maintains the closed state, the low speed shift oil passage 45 is closed, and the continuously variable transmission 3 normally operates.

On the other hand, when the solenoid valve 47 becomes inoperative due to its own failure or cable breakage, the gear ratio control pressure Pc falls to a low level, and the spool 53 of the gear ratio control valve 49 moves right by the spring 57. Then, the main and sub ports 491 and 492 are made to communicate with each other, and the continuously variable transmission unit 16 is switched to a low speed ratio (high speed stage). At the same time, the spool 55 of the shift limiting valve 54 also moves to the right,
The upstream and downstream ports 541 and 542 are connected. Therefore, even if the vehicle is in a failure state during traveling, the continuously variable transmission 3 is switched to a low speed ratio (high speed stage), so that the engine 1 and the primary pulley 30 side can be prevented from excessive rotation. In addition, when the driver makes an emergency run to move the vehicle to a shelter or a repair shop, the L range or the R range is selected, and the continuously variable transmission unit 16 is always switched to a high gear ratio (low gear stage). Even if it is a slope, you can easily drive.

[0024]

As described above, according to the present invention, only when the gear ratio control pressure is lowered, the shift limiting valve releases the low speed stage switching oil passage and the manual valve is switched to the low range or the reverse stage range. It is possible to switch the continuously variable transmission to a high gear ratio (low gear) by removing the pressure oil from the hydraulic actuator of the primary pulley. (High gear) to prevent over-rotation of the engine and primary pulley side. Moreover, if the manual valve is switched to the low range or the reverse gear range, the continuously variable transmission will always have a high gear ratio (low gear). Therefore, it is possible to easily perform an emergency run, particularly a slope run with a large running resistance.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a gear ratio control device for a continuously variable transmission according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a power transmission system of a vehicle in which the gear ratio control device for the continuously variable transmission of FIG. 1 is mounted.

FIG. 3 is a characteristic diagram of movement of a spool of a gear ratio control valve used by the gear ratio control device of FIG.

4 is a change characteristic diagram of the opening ratios of the drain port 495 and the auxiliary port 492 of the gear ratio control valve used by the gear ratio control device of FIG. 1 and the gear ratio control pressure.

5 is an enlarged side view of the spool of the gear ratio control valve used by the gear ratio control device of FIG. 1. FIG.

6 is an enlarged side view of a shift limiting valve used by the gear ratio control device of FIG.

FIG. 7 is a hydraulic circuit diagram of a conventional device.

[Explanation of symbols]

 1 engine 3 continuously variable transmission 13 oil pump 15 forward / reverse switching unit 16 continuously variable transmission unit 18 forward clutch 19 reverse clutch 30 main pulley 31 auxiliary pulley 32 drive belt 33 primary cylinder 34 secondary cylinder 43 manual valve 45 low speed switching oil passage 47 Solenoid valve 48 Shift control unit 49 Gear ratio control valve 53 Spool 54 Shift limiting valve 301 Main pulley movable side pulley material 311 Sub pulley movable side pulley material 302 Main pulley fixed side pulley material 312 Sub pulley fixed side pulley material 494 Low gear speed port Pc Gear ratio control

Claims (1)

[Claims] 1. A drive belt is wound between a primary pulley and a secondary pulley, a gear ratio control pressure supply means generates a gear ratio control pressure according to a target gear ratio, and the gear ratio control valve controls the gear ratio. The pulley control oil pressure adjusted based on the pressure is supplied to both hydraulic actuators that operate the relative distance between the fixed pulley material and the movable pulley material of both pulleys to change the winding diameter ratio of both pulleys. It is equipped with a continuously variable transmission section for continuously changing gears, and is provided in a power transmission system including the continuously variable transmission section, and both hydraulic actuators receive each switching control pressure oil from a manual valve for shifting gears. In a gear ratio control device for a continuously variable transmission equipped with a forward / reverse switching unit for switching a gear, a spool of the gear ratio control valve is provided with a spool of the primary pulley control hydraulic pressure. A low speed stage port is formed that receives hydraulic pressure when switching to the excluded position, and the low speed stage port supplies pressure oil when the valve is switched from the manual valve to the low range or the reverse range. A step-change oil passage is connected, and the low-speed step change oil passage is provided with a normally-closed shift limiting valve for communicating the oil passage only when the speed ratio control pressure becomes low. Gear ratio control device for transmission.