JP2661339B2 - Line pressure control device for continuously variable transmission - Google Patents

Description

Description: (a) Industrial application field The present invention relates to a line pressure control device for a continuously variable transmission.

(B) Conventional technology As a conventional line pressure control device for continuously variable transmissions,
There are those disclosed in JP-A-63-225754 and JP-A-63-225755. The line pressure regulating valve shown in these
Basically, it is of a hydraulic control type that does not use an electromagnetic valve, and is configured to control the line pressure in accordance with the gear ratio, the throttle pressure corresponding to the engine load, and the engagement state of the lock-up clutch.

(C) Problems to be Solved by the Invention However, in the conventional line pressure control device of the continuously variable transmission as described above, the gear ratio is mechanically fed back to the line pressure regulating valve, and Since the throttle pressure is detected by converting the negative pressure of the engine intake pipe to the throttle pressure using a vacuum diaphragm, precise control can be performed so that the hydraulic characteristics correspond to the theoretically required hydraulic pressure. There is a problem that can not be. For this reason, an unnecessarily high line pressure is set, and the efficiency is reduced.

In order to perform more precise control, it is necessary to use an electronic control type using an electromagnetic valve whose duty ratio is controlled. As such a type of line pressure control device, for example, a maintenance manual issued by Nissan Motor Co., Ltd. “Full range electronically controlled automatic transmission” (Showa 62)
Issued in March of the year. In this case,
The pressure modifier pressure is adjusted according to the oil pressure obtained by the line pressure control solenoid valve, and the pressure is applied to the line pressure regulating valve. This line pressure control device is for a stepped automatic transmission, but if a similar configuration is applied to a continuously variable transmission, many variables such as the engine load, the gear ratio, and the operating state of the lock-up clutch are changed. Because it is necessary to control the line pressure based on
These programs and electronic circuits are complicated, and it takes time to create and input control data. Also,
In the case of a continuously variable transmission, a control range from a low oil pressure to a relatively high oil pressure is required, but the range of the control pressure obtained by one solenoid valve is limited, and the pressure obtained correspondingly is limited. Since the control range of the modifier pressure and the line pressure is also limited, it is difficult to control the line pressure with high accuracy. An object of the present invention is to solve such a problem.

(D) Means for Solving the Problems The present invention solves the above problems by using two solenoid valves for line pressure control. That is,
The line pressure control device of the continuously variable transmission according to the present invention includes a line pressure regulating valve 502 that controls a line pressure by displacing according to oil pressure supplied to two control pilot ports 502a and 502b;
Two solenoid valves 526, 528, each of which has a duty ratio controlled
And a pressure adjusting valve (pressure modifier valve, accumulator control valve) 50 which adjusts the hydraulic pressure controlled by these electromagnetic valves 526,528 and supplies it to the two control pipe ports 502a, 502b of the line pressure adjusting valve 502.
4,514, and accumulators 519, 517 connected to oil passages connecting these regulating valves 504, 514 and the control pipe ports 502a, 502b, respectively.

(E) Action For example, one solenoid valve is operated according to a duty ratio determined according to the throttle opening and the gear ratio, and the other solenoid valve is controlled according to a duty ratio controlling the operation state of the lock-up clutch. You. Since the control oil pressure obtained by one solenoid valve and the control oil pressure obtained by the other solenoid valve act on the control pilot port of the line pressure regulating valve, respectively, the line pressure obtained by the line pressure regulating valve is It is determined according to the degree, the gear ratio, and the operating state of the lock-up clutch. Therefore, a program, data, an electronic circuit configuration, and the like for controlling the solenoid valve based on a three-dimensional or more map are not required, and the control is simplified and the price is reduced.

(F) Example An example is shown in FIGS. FIG. 2 shows a frame diagram of the friction wheel type continuously variable transmission. A torque converter 12 to which a rotational force is input from a crankshaft 10 of the engine has a pump impeller 12a, a turbine runner 12b, a stator 12c, and a lock-up clutch 12d. Lock-up clutch 1
2d is capable of mechanically connecting or disconnecting the pump impeller 12a and the turbine runner 12b according to the oil pressure in the apply-side oil chamber 12e and the release-side oil chamber 12f. Torque converter
A turbine shaft 14 that rotates integrally with the 12 turbine runners 12b
Is connected to the forward / reverse switching mechanism 15. The forward / reverse switching mechanism 15 includes a planetary gear mechanism 17, a forward clutch 40, and a reverse brake 50. The planetary gear mechanism 17 is a sun gear
19, a pinion carrier 25 having two pinion gears 21 and 23, and an internal gear 27. Pinion gears 21 and 23 of the same diameter mesh with each other,
Further, the pinion gear 21 meshes with the internal gear 27, and the pinion gear 23 meshes with the sun gear 19.
The sun gear 19 is connected so as to always rotate integrally with the turbine shaft 14. Pinion carrier 25 is a forward clutch
40 allows the turbine shaft 14 to be connected. Also, the internal gear 27 is rotated by the reverse brake 50 to the casing 11.
Can be fixed to The pinion carrier 25 is always connected to the transmission shaft 37 to the continuously variable transmission.

A first continuously variable transmission mechanism 22 and a second continuously variable transmission mechanism 24 are provided in the casing 11 downstream of the forward / reverse switching mechanism 15. The first continuously variable transmission mechanism 22 has an input disk 26, an output disk 28, and a pair of friction rollers 30 and 31 that transmit a rotational force between the two. The contact surfaces of the input disk 26 and the output disk 28 with the friction rollers 30 and 31 are toroid surfaces. By changing the contact state of the friction rollers 30 and 31 with the input disk 26 and the output disk 28, the rotation speed ratio between the input disk 26 and the output disk 28 can be continuously changed. The second continuously variable transmission mechanism 24 also
It has an input disk 32, an output disk 34, and a pair of friction rollers 36 and 37 similar to the first continuously variable transmission mechanism 22. However, the arrangement of the input disk 32 and the output disk 34 is opposite to that of the first continuously variable transmission mechanism 22. That is,
The output disk 28 and the output disk 34 are arranged adjacent to each other. The input disk 26 is connected to the transmission shaft 37 described above.
It is supported via a ball spline 61 on the outer periphery of the input shaft 38 connected to rotate integrally with the input shaft 38. A column flange 42 is arranged on the back side of the input disk 26. A cam roller 46 is provided on the cam surfaces of the column flange 42 and the input disk 26 facing each other. The cam roller 46 is shaped so as to generate a force for pressing the input disk 26 toward the output disk 28 when the input disk 26 and the cam flange 42 rotate relative to each other. A loading cam 63 is constituted by the cam flange 42, the input disk 26, and the cam roller 46. Input disk 32 of second continuously variable transmission mechanism 24
Is also connected to the input shaft 38 via a ball spline 65. The input disk 32 is always the output disk by the disc spring 51
It has 34 directions of force. An output disk 28 of the first continuously variable transmission mechanism 22 and an output disk 34 of the second continuously variable transmission mechanism 24 are rotatably supported on an input shaft 38, respectively. A drive gear 55 is provided so as to rotate integrally with the output disk 28 and the output disk 34. The drive gear 55 meshes with a driven gear 60 that is integrally and rotatably coupled to one end of an intermediate shaft 59 disposed parallel to the input shaft 38. A gear 67 integrally formed on the other end side of the intermediate shaft 59 meshes with a gear 71 integrated with the output shaft 62 via an idler gear 69.

FIG. 1 shows a hydraulic control circuit. This hydraulic control circuit
Forward shift control valve 150, line pressure regulating valve 502, manual valve
506, lock-up control valve 508, constant pressure regulating valve 51
0, pressure modifier valve 504, relief valve 51
2, accumulator control valve 514, accumulator
519, accumulator 517, forward clutch accumulator 521, reverse brake accumulator 520, reverse speed ratio command valve 522, forward / reverse switching valve 524, lock-up solenoid valve 52
6, a line pressure solenoid valve 528, etc., which are connected as shown in the figure. The oil pump 15, a high (low gear ratio) side oil chamber 516 and a low (Large gear ratio) side oil chamber 518, forward clutch 44, reverse brake 36, apply side oil chamber of torque converter 12
12e, a release-side oil chamber 12f of the torque converter 12, an oil cooler 530, an oil pump displacement control chamber 531, a lubrication circuit 532, and the like are also connected as illustrated.

FIG. 1 schematically shows a hydraulic servo device of the first continuously variable transmission mechanism 22 and the second continuously variable transmission mechanism 24. Roller support members 83 and 85 that rotatably support the friction rollers 30 and 31 of the first continuously variable transmission mechanism 22 are supported rotatably about their axes and movable in the axial direction. Pistons 87 and 89 are connected to the roller support members 83 and 85, respectively. High-side oil chambers 516 and low-side oil chambers 518 are formed on both sides of the pistons 87 and 89, respectively. The gear ratio increases as the hydraulic pressure of the low-side oil chamber 518 relatively increases. The second continuously variable transmission mechanism 24 also has basically the same configuration, and has a high-side oil chamber 516 and a low-side oil chamber 518. As the hydraulic pressure of the low-side oil chamber 518 increases relatively, The gear ratio increases.

The line pressure regulating valve 502 regulates the oil pressure (line pressure) of the oil passage 534 to which the discharge pressure from the oil pump 15 is supplied. Pressure Modifier Valve 504 is Lock-up Solenoid Valve 5
The oil pressure in the oil passage 538 is adjusted according to the operation state of the valve 26, and this oil pressure is supplied to the line pressure regulating valve 502. Forward shift control valve 1
The reference numeral 50 adjusts the distribution of the hydraulic pressure to the high-side oil chamber 516 and the low-side oil chamber 518 in accordance with the operation of the step motor 152, as described later, to realize a predetermined gear ratio. Manifold valve 506 is oil line 534
Is supplied to the forward clutch 44 or the reverse brake 36 in accordance with the position of the select lever to switch between forward and reverse. Lock-up control valve 508
Adjusts the supply direction and the hydraulic pressure value of the hydraulic pressure to the apply-side oil chamber 12e and the release-side oil chamber 12f in accordance with the hydraulic pressure obtained by the duty-ratio controlled lock-up solenoid valve 526, and engages the lock-up clutch 12d. Control release. The constant pressure regulating valve 510 regulates the constant pressure used by the lock-up solenoid valve 526, the line pressure solenoid valve 528, etc.
Output to oil passage 540. Relief valve 512 is a torque converter
This is a valve that prevents the oil pressure supplied to 12 from exceeding a certain value. The accumulator control valve 514 is a valve that adjusts the oil pressure of the oil passage 542 according to the operation of the line pressure solenoid valve 528. Since the oil pressure in the oil passage 542 is acting on the line pressure regulating valve 502, the line pressure can be controlled by the line pressure solenoid valve 528. The oil pressure in the oil passage 542 acts as a back pressure for the forward clutch accumulator 518 and the reverse brake accumulator 520. Accumulator 516 mitigates oil pressure changes in oil passage 538, and accumulator 517 mitigates oil pressure changes in oil passage 542, thereby
The line pressure does not vibrate. The forward clutch accumulator 521 alleviates the rise of the hydraulic pressure of the forward clutch 44. The reverse brake accumulator 520 reduces the rise of the hydraulic pressure of the reverse brake 36. The reverse gear ratio command valve 522 is a valve that sets the continuously variable transmission mechanism to a constant gear ratio state when the vehicle moves backward. The forward / reverse switching valve 524 is a valve for reversing the operation state of the hydraulic servo device at the time of forward movement and at the time of reverse movement. Can be switched.

Next, operations of the line pressure regulating valve 502, the line pressure solenoid valve 528, the lock-up solenoid valve 526, and the like will be described. The line pressure solenoid valve 528 adjusts the oil pressure of the oil passage 601 so as to be in inverse proportion to the applied duty ratio. The oil pressure in the oil passage 601 acts on the accumulator control valve 514, and the oil pressure in the oil passage 542 corresponds to the oil pressure in the oil passage 601. The oil pressure in the oil passage 542 acts on the control pilot port 502b of the line pressure regulating valve 502. Therefore, as the duty ratio of the line pressure solenoid valve 528 increases, the oil pressure in the oil passage 601 and the oil passage 542 decreases, and accordingly the line pressure regulated by the line pressure regulating valve 502 also decreases. On the other hand, lock-up solenoid valve 526 adjusts the oil pressure of oil passage 553 so as to be in inverse proportion to the applied duty ratio. The oil pressure in the oil passage 553 is supplied to the oil passage 551 via the speed change control valve 150 except for the state of the maximum speed ratio, and the oil pressure in the oil passage 551 acts on the pressure modifier valve 504. The pressure modifier valve 504 adjusts the oil pressure of the oil passage 538 according to the oil pressure of the oil passage 551. The oil pressure in the oil passage 538 acts on the control pilot pressure port 502a of the line pressure regulating valve 502. Therefore, oil passage 55
The hydraulic pressure of the oil passage 1 and the oil passage 538 is inversely proportional to the duty ratio of the lock-up solenoid valve 526, and the line pressure regulated by the line pressure regulating valve 502 is also inversely proportional to the duty ratio.

As a result, the line pressure characteristics obtained by the line pressure regulating valve 502 are as shown in FIG. That is,
Basically, the line pressure decreases as the duty ratio of the line pressure solenoid valve 528 increases, and the line pressure decreases as the duty ratio of the lock-up solenoid valve 526 increases. The duty ratio given to the line pressure solenoid valve 528 is determined according to the throttle opening and the gear ratio, and the duty ratio of the lock-up solenoid valve 526 is determined according to the throttle opening and the vehicle speed. The control program is simplified without the need for a four-dimensional map. The oil pressure in the oil passage 551 obtained by the lock-up solenoid valve 526 also acts on the lock-up control valve 508, whereby the lock-up clutch 12d is released when the duty ratio is small, and is engaged when the duty ratio becomes large. Will be.

The reason why the hydraulic characteristic shown in FIG. 3 does not change on the small duty ratio side of the line pressure solenoid valve 528 is as follows. That is, although the theoretical value of the oil pressure in the oil passage 542 obtained by the accumulator control valve 514 is shown by a broken line in FIG. 3, the oil pressure in the oil passage 542 cannot be higher than the line pressure. In a region where the theoretical value of the hydraulic pressure of the passage 542 is higher than the line pressure, the duty does not change depending on the duty ratio of the line pressure solenoid valve 528. In the lock-up state, there is not much need to change the line pressure, and thus such a line pressure characteristic is provided.

Note that an accumulator 517 is connected to the oil passage 542, and an accumulator 519 is connected to the oil passage 538, so that the oil pressure in both oil passages is prevented from generating hydraulic vibration. The occurrence of hydraulic vibration in the line pressure is prevented.

FIG. 4 shows another embodiment. This embodiment controls the pressure modifier valve 504 by the hydraulic pressure obtained by the line pressure solenoid valve 528, and also controls the hydraulic pressure obtained by the lock-up solenoid valve 526 through the forward shift control valve 150 to the line pressure regulating valve. 502. In this embodiment, basically, the same operation as in the above-described embodiment can be obtained.

(G) Effects of the Invention As described above, according to the present invention, the hydraulic pressure obtained by the two solenoid valves is caused to act on the control pilot ports of the line pressure regulating valve, respectively.
When each of the two solenoid valves is controlled based on a predetermined variable, the obtained line pressure changes according to all of the variables for controlling the two solenoid valves, and control of the solenoid valves can be simplified. In this case, the hydraulic pressure controlled by the duty ratio from the solenoid valve is regulated by the pressure regulating valve, respectively.
Since the generation of hydraulic vibrations including the self-excited vibration of the adjusted hydraulic pressure is absorbed by the accumulator when acting on the two control pipe ports of the line pressure regulating valve, it acts on the control port of the line pressure regulating valve. The applied hydraulic pressure is stabilized, and the control accuracy of the line pressure is significantly improved.

Also, the hydraulic pressure from one of the solenoid valves can be used as the hydraulic pressure for controlling the lock-up mechanism, and the control system can be simplified accordingly.

Further, since the two accumulators are housed in the same bore, the structure becomes compact.

[Brief description of the drawings]

1 is a diagram showing a hydraulic circuit, FIG. 2 is a diagram showing a continuously variable transmission, FIG. 3 is a diagram showing line pressure characteristics, and FIG. 4 is a diagram showing another embodiment. 12: Torque converter, 12d: Lock-up clutch, 22, 24: Friction wheel type continuously variable transmission mechanism, 502: Line pressure regulating valve, 502a, 502b: Pilot port for control, 52
6… Lock-up solenoid valve, 528… Line pressure solenoid valve.

Claims (3)

(57) [Claims] 1. Two control pilot ports 502a and 502b
Line pressure regulating valve 502 for controlling the line pressure by being displaced in accordance with the hydraulic pressure supplied to the solenoid valve, and two solenoid valves 526 and 528 each of which has a duty ratio controlled.
Pressure regulating valves 504, 514 for adjusting the hydraulic pressure controlled by the solenoid valves 526, 528 and supplying the control valves 502a, 502b of the line pressure regulating valve 502 with the pressure regulating valves 504, 514; It port 502a,
A line pressure control device for a continuously variable transmission, comprising accumulators 519 and 517 respectively connected to oil paths connecting 502b. 2. The continuously variable transmission includes a torque converter 12 having a lock-up mechanism and a friction wheel type continuously variable transmission mechanism through which a rotational force is input. 2. The line pressure control device for a continuously variable transmission according to claim 1, wherein one of the two is also used for adjusting a hydraulic pressure for controlling a lock-up mechanism. 3. The line pressure control device for a continuously variable transmission according to claim 1, wherein the accumulators 517 and 519 are arranged in the same bore.