JPH0539848A - Control device for toroidal continuously variable transmission - Google Patents

Abstract

(57) [Summary] [Purpose] When a loading cam mechanism is used to generate the pressing force in a toroidal CVT, increase the hysteresis of the loading cam, etc. to eliminate the pressing force during negative loading. [Composition] A hydraulic cylinder 41 is provided in parallel with the loading cam to increase the hydraulic pressure when a negative torque is applied. When the hydraulic valve 78 is used to obtain the hydraulic pressure as the _loading cam control pressure P _CONT , the control pressure P _{HI of} the toroidal CVT,
By utilizing P _LO , it can be guided to the hydraulic valve 78 to generate a hydraulic pressure that rises when the load is negative. The pressure is introduced into the cylinder oil chamber in the loading cam, and the thrust by the hydraulic pressure is added to the loading cam force to increase the pressing force in the negative load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a toroidal continuously variable transmission, and more particularly to a control device capable of controlling a pressing force when a loading cam mechanism is used as a pressing force urging mechanism in a toroidal transmission mechanism. ..

[0002]

2. Description of the Related Art A toroidal continuously variable transmission can be constructed by using a speed change mechanism having an input / output disk and a power roller arranged between them. The gear ratio can be continuously changed, and the power ratio can be continuously changed by offsetting the power roller with respect to the input / output disk and changing the contact position. Japanese Unexamined Patent Publication No. 1-255758 proposes a technology of a cam device (loading cam device) applicable as a pressing force urging mechanism in a toroidal CVT of this type of continuously variable transmission. , When the positive direction torque is applied (when positive torque is applied) and when the reverse direction torque is applied (when negative torque is applied), the cam surface is released.
The lead angle of the cam surface corresponding to the reverse direction torque is set to be smaller than that corresponding to the forward direction torque, and the cam device having such a cam surface shape is used for the transmission. It is used to prevent slippage during reverse torque.

[0003]

In the loading cam device, generally, when the cam lead is made small, the wedge effect is enhanced because the inclination becomes gentle. However, by making the cam lead smaller in the case of reverse torque. Attempting to meet the required pressing force at the time of negative torque, on the other hand, causes the following points.

That is, the accuracy of the cam lead with respect to the manufacturing error becomes severer, and the friction due to the increase of the pressing force in the cam increases, so that the hysteresis of the cam increases. When the pressing force in the cam is increased, the increase in friction is greatly affected, and when the generated force of the cam has a large hysteresis and the friction element becomes large, it becomes difficult to exert a sufficient effect.

An object of the present invention is to provide a toroidal continuously variable transmission that uses a loading cam mechanism as a pressing force generating mechanism of a toroidal transmission mechanism, while avoiding the increase of the hysteresis of the cam as described above while avoiding a negative load. It is an object of the present invention to provide a control device which can increase the pressing force and can secure the pressing force under a negative load.

[0006]

According to the present invention, the following controller for a toroidal continuously variable transmission is provided. A toroidal continuously variable transmission having a toroidal speed change mechanism including an input / output disk and a power roller between the disks and using a loading cam mechanism as a mechanism for generating a pressing force between the disk and the power roller of the speed change mechanism. Toroidal stepless, characterized in that a hydraulic pressure generating means for generating a hydraulic pressure that rises at a negative torque is provided, a hydraulic cylinder is provided in parallel with the loading cam, and the hydraulic pressure from the hydraulic pressure generating means is introduced into the hydraulic cylinder. It is a control device for a transmission.

[0007]

In the above toroidal continuously variable transmission, the loading cam mechanism generates the pressing force of the toroidal transmission mechanism to transmit the torque, but when the load is negative, the hydraulic pressure generating means generates the hydraulic pressure that rises when the engine has a negative torque. The hydraulic pressure from the above acts on a hydraulic cylinder provided in parallel with the loading cam, and the thrust by the hydraulic pressure thus obtained is added to the loading cam force. As a result, the pressing force at the time of negative load can be increased, and in comparison with the case where the cam lead is made small to increase the pressing force, the disadvantage in that case can be avoided and the hysteresis of the loading cam can be avoided. It is possible to secure the pressing force during the negative load without increasing the load.

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows mainly the configuration of a hydraulic control system of an embodiment apparatus according to the present invention, and FIG. 2 is a skeleton diagram showing an example of a toroidal continuously variable transmission having a toroidal transmission mechanism that can be applied. FIG. 3 is a vertical cross-sectional view showing an example of the structure of the loading cam device and the toroidal speed change mechanism including the internal hydraulic cylinder mechanism of the cam device by the hydraulic pistons arranged in parallel with the loading cam.

First, in order to explain the transmission train in the frame diagram of FIG. 2, reference numeral 10 in the figure denotes a toroidal continuously variable transmission, in which torque from an engine (not shown) is transmitted to the continuously variable transmission 10 via a torque converter 12. Is entered. The torque converter 12 includes a pump impeller 12a, a turbine runner 12b, a stator 12c,
The lockup clutch 12d, the apply-side oil chamber 12e, the release-side oil chamber 12f, and the like are provided, and the input shaft 14 penetrates through the central portion thereof.

In the illustrated example, the input shaft 14 is connected to a forward / reverse switching mechanism 36, which is a planetary gear mechanism.
42, a forward clutch 44, a reverse brake 46 and the like. The planetary gear mechanism 42 includes a ring gear 42b and a sun gear 42c that mesh with each of the double planetary gears.
The carrier of the planetary gear mechanism 42, which can be connected to the input shaft 14 by the forward clutch 44, is always connected to the transmission shaft to the continuously variable transmission mechanism. A torque transmission shaft 16 is arranged coaxially with the transmission shaft.

In this example, on the torque transmission shaft 16, a first continuously variable transmission mechanism (toroidal transmission mechanism) 18 and a second continuously variable transmission mechanism (toroidal transmission mechanism) 20 are provided in a transmission case 22 at a downstream side. Arranged in tandem (dual-cavity type). The body of the control valve system (Fig. 1) is placed in the space indicated by reference numeral 64.

The first continuously variable transmission mechanism 18 has a pair of input disks 18a and output disks 18b whose opposing surfaces are toroidal curved surfaces and frictional contact between the opposing surfaces of these input / output disks and the torque transmission shaft 16 thereof. A pair of power rollers 18c, 18d symmetrically arranged with respect to each other, a support mechanism for supporting the power rollers in a tiltable manner, and a servo piston (see FIG. 1) as a hydraulic actuator are provided. Similarly, the second continuously variable transmission mechanism 20 also includes input / output disks 20a and 20b having opposing toroidal curved surfaces, a pair of power rollers 20c and 20d, a support mechanism therefor, and a servo piston.

Continuously variable transmission mechanism 1 on the torque transmission shaft 16
8 and 20 are arranged in opposite directions so that the output discs 18b and 20b face each other, and are the input discs of the first continuously variable transmission mechanism 18.
18a is pressed rightward in the axial direction in the drawing by a loading cam device 34 that generates a pressing force (pressing force) according to the input torque that has passed through the torque converter 12. The loading cam device 34 includes an input disc 18a, a cam flange arranged on the back side of the disc, and a roller provided between them.
It can be configured by having a ding cam (cam roller) 34a, and the cam roller is arranged on the cam surfaces of the cam flange and the input / output disc which face each other, and the input is performed when the input disc and the cam flange rotate relative to each other. Output disc
It is assumed that a force (thrust) to be pressed to the 18b side is generated (an example of such a loading cam mechanism will be shown later together with the structure of the hydraulic piston cylinder in the cam device added to the device according to the present invention. ). The loading cam device 34 may be configured to be supported by the shaft 16 via a thrust bearing 38. 2nd continuously variable transmission 20
The input disk 20a is pressed and biased by the disc spring 40 toward the left side in the axial direction in the drawing. Each input disc 18a, 2
0a is rotatably and axially movably supported by the transmission shaft 16 via ball splines 24 and 26. In the above mechanism, each power roller is tilted by a servo piston that operates by receiving a control pressure from the shift control valve so as to obtain a tilt angle according to the gear ratio, and the input rotation (input torque) of the input disk. Is continuously variable and transmitted to the output disc.

The output disks 18b, 20b are the torque transmission shaft 16
The transmission torque is spline-coupled to the output gear 28 which is relatively rotatably fitted to the upper side, and the transmission torque is transmitted to the gear 30a coupled to the output shaft (counter shaft) 30 through the output gear 28. A torque transmission mechanism 32 is configured. Further, a gear 52 provided on the output shaft 30, a gear 56 provided on the output shaft 50, and an idler gear 54 that meshes with these gears, respectively.
It is assumed that the transmission mechanism 48 consisting of is provided and the output shaft 50 is connected to the propeller shaft 60.

In the transmission train, when the engine torque is input, the torque is transferred to the continuously variable transmission mechanism portion by the loading cam device 34, the input disks 18a and 20a, the power roller 18 and the like.
c, 18d, 20c, 20d and output discs 18b, 20b are transmitted in this order (at positive torque). On the other hand, when torque is applied to the continuously variable transmission in the opposite direction to the above from the load side (when the torque is negative) like braking, the pressing force between the loading / unloading disk and the power roller during such a negative load is large. In order to raise the load, the loading cam device 34 is provided with a hydraulic cylinder previously touched in parallel with the loading cam (torque cam) so as to generate thrust by hydraulic operation and add this to the loading cam force. In addition, the hydraulic pressure that rises when the engine has a negative torque is introduced as the loading cam control pressure. For this reason, in this control device, as shown in FIG. 1, the shift control hydraulic system is also provided with a hydraulic valve 78 as a means for generating a hydraulic pressure that rises under a negative load, and the hydraulic pressure is controlled by the loading cam control pressure P. _CONT The loading cam control pressure P _CONT can be obtained by utilizing the control pressure in the hydraulic control circuit that operates the shifting hydraulic servo device. In this embodiment, such a method is adopted.

The hydraulic control circuit adjusts and controls the hydraulic cylinder of the hydraulic servo system for shifting functioning as a power roller actuator of the toroidal transmission mechanism, and the cylinder supply hydraulic pressure so that the cylinder operates to shift at a predetermined gear ratio. The shift control valve and other various valves are components. The gear shift is performed by changing the hydraulic pressure difference between the cylinder chambers (the high (small gear ratio) side oil chamber and the low (high gear ratio) side oil chamber) in the cylinder of the speed change hydraulic servo device.

A part of the hydraulic servo device of the continuously variable transmission mechanism is also shown in a simplified manner in FIG. 1. For example, the power rollers 18c and 18d of the first continuously variable transmission mechanism 18 will be described below. It seems A roller supporting member 105 that rotatably supports the power roller 18d of the first continuously variable transmission mechanism 18 is supported so as to be rotatable about its axis and movable in the axial direction. The roller support member 105 includes the piston of the cylinder 100.
107 are connected to define a high side oil chamber 101 and a low side oil chamber 102 above and below the piston 107. The same applies to the power roller 18c side, but the relationship between the high-side oil chamber and the low-side oil chamber is opposite between the power roller 18c side and the illustrated power roller 18d side, and the power roller not shown For the cylinder 100 on the roller 18c side, the high side oil chamber 101,
A low oil chamber 102 is formed on the lower side. Power roller
When changing the gear ratio by changing the contact position radius of 18c, 18d with the input / output disk, the pistons on each side can move up and down in opposite directions by the hydraulic pressure acting on the oil chamber of each cylinder. The ratio becomes larger as the oil pressure in the low side oil chamber 102 is relatively increased. The second continuously variable transmission mechanism 20 has basically the same configuration, and for each power roller 20c, 20d, the high side oil chamber 101 of each cylinder 100 is provided on both sides of the control piston connected to the roller support member.
The low-side oil chamber 102 and the low-side oil chamber 102 are arranged in the opposite relationship.

The hydraulic pressure of each cylinder 100 is controlled by a control valve 70 including a shift control valve through oil passages 176 and 177. The control valve 70 is supplied with the line pressure of the oil passage 150 obtained by adjusting the discharge pressure from the oil pump 95 driven by the engine. To realize a gear ratio corresponding to the gear shift command. Here, regarding the oil chambers 101 and 102 of the cylinder 100, the relationship between the hydraulic pressures thereof at the time of plus torque and at the time of minus torque can be shown as follows. (1) In case of high side oil chamber 101 At plus torque At high pressure At minus torque At low pressure (2) In case of low side oil chamber 102 At plus torque At low pressure At minus torque At high pressure

In this embodiment, with respect to the oil passages 176 and 177 for supplying the control pressure to each cylinder 100, a branch oil passage 17 is further provided.
6 _1, 177 ₁ are installed, and these are set to the loading cam control pressure P
_The ports 78g and 78h of the hydraulic valve 78 for _CONT generation are reached. The valve 78 has a control pressure P _HI, P for shifting control.
It is assumed that an oil pressure having a pressure adjusting characteristic as shown in FIG. 4 is generated in the oil passage 181 according to _LO . Therefore, the valve 78 is a spring 78a.
In addition to the ports 78g and 78h, a port 78c connected to the line pressure oil passage 150 and a port connected to the oil passage 181 are provided. 78d, oil passage 181
The pressure inside is passed through the orifice and the chamber 7 at the left end of the spool in the figure
A port 78e for exerting a force on the spool to the right in the figure and a drain port 78f are provided as shown in the drawing. The control pressures P _{HI and} P _LO are used because the control pressure of the toroidal CVT is the differential pressure ΔP (= P _HI −P
_(LO ) is generated, and this is introduced into the control piston of the hydraulic servo device and exhibits a pressure proportional to the transmission force at that time.
These are led to the ports 78g and 78h of the valve 78, and the spool is stroke-controlled in accordance with the pressure difference ΔP. The valve structure is basically a pressure reducing valve,
When _PHI is high and control pressure _PHI is low, it is on the right side of the spool, and conversely, when control pressure _PHI is low and control pressure _PHI is high, it is on the left side of the spool. The pressure obtained by adjusting the pressure control characteristics as shown in Fig. 4 is the loading cam control pressure P
_It occurs as _CONT .

In this way, the differential pressure ΔP is introduced to the hydraulic valve 78 which generates the _loading cam control pressure P _CONT ,
It is possible to generate a hydraulic pressure that rises when the load is negative. Further, the pressure causes a thrust to be generated by a hydraulic pressure at the time of a negative torque, and is supplied to the hydraulic cylinder 41 in the cam device through the oil passage 181 so as to be added to the loading cam force and introduced into the oil chamber in the cam. The hydraulic cylinder 41 is arranged in parallel with the loading cam, and can be constructed as shown in FIG. 3, for example. In the figure, the cam flange 34b of the loading cam device 34 is restricted at the left end position in the figure by a stopper, a nut, etc., and the cam flange 34b and the input disc are
The cam roller 34a is arranged on the cam surface between the cam cylinder 18a and 18a, and in addition, the oil chamber 41a of the hydraulic cylinder 41 is provided between the cam flange 34b and the input disk 18a. The oil chamber 41a is connected to the oil passage 181 through the oil passage 181a, and functions as a hydraulic piston that operates according to the _loading cam control pressure P _CONT that rises according to the characteristics of FIG. 4 when the torque is negative. Let In the illustrated example, the oil passage 181a and the oil passage 181 are formed by utilizing the transmission shaft to the continuously variable transmission mechanism 18 together with the lubricating pressure oil passage, and the torque transmission shaft is rotatably fitted to the outer periphery thereof. The input disk 18a, on the other hand, is supported via ball splines. The lead angle of the cam surface of the loading cam device 34 may be the same when loaded and when loaded negatively.

In the above construction, the hydraulic pressure in the hydraulic cylinder 41 corresponding to the loading cam control pressure P _CONT is added to the loading cam force in accordance with the negative torque when the load is negative. That is, in this case, the hydraulic valve 78 that generates a hydraulic pressure that rises when the engine has a negative torque is obtained according to the characteristics shown in FIG.
Since the loading cam control pressure P _CONT increases from the above and acts on the hydraulic cylinder 34, a force is generated in the direction in which the cam flange 34b and the input disc 18a are spread by the operation of the hydraulic piston in the loading cam. Since such a piston is in parallel with the loading cam, the pressing force is added by that amount, and thus the pressing force during a negative load can be appropriately increased. Therefore, as in the case of preventing slippage under negative load by changing the shape of the cam surface, the accuracy with respect to the manufacturing error of the cam lead becomes high, and the friction due to the increased pressing force in the cam increases. By doing so, it is possible to avoid a situation in which the hysteresis of the cam is increased and it is difficult to obtain sufficient merit, and it is possible to secure the pressing force which is insufficient when the load is negative. It should be noted that the present invention is not limited to the configuration of FIG. 1 as means for generating hydraulic pressure that rises when the engine has a negative torque, and the toroidal transmission mechanism is also shown in FIG.
The configuration is not limited to that shown in FIG.

[0022]

According to the present invention, in a toroidal continuously variable transmission using a loading cam mechanism as a pressing force generating mechanism of a toroidal transmission mechanism, a hydraulic pressure that rises when the engine has a negative torque is generated and the loading cam mechanism is used. Since the hydraulic pressure can be introduced to the hydraulic cylinders installed in parallel with each other to increase during negative torque, the pressing force during negative load can be increased while increasing the pressing force during negative load while avoiding increase in cam hysteresis. You can secure power.

[Brief description of drawings]

FIG. 1 is a diagram mainly showing a configuration of a hydraulic control system of an embodiment apparatus according to the present invention.

FIG. 2 is a skeleton diagram showing an example of a basic configuration of a toroidal continuously variable transmission.

FIG. 3 is a vertical cross-sectional view showing an example of a structure of a loading cam device and a toroidal transmission mechanism part including a hydraulic cylinder mechanism in a cam device by a hydraulic piston.

FIG. 4 is a diagram showing an example of pressure regulation characteristics for obtaining a loading cam control pressure.

[Explanation of symbols]

 10 Toroidal continuously variable transmission 18, 20 Continuously variable transmission mechanism (toroidal transmission mechanism) 18a, 20a Input disc 18b, 20b Output disc 18c, 18d, 20c, 20d Power roller 34 Loading cam device 34a Cam roller 40 Hydraulic cylinder 41a Oil Chamber 78 hydraulic valve

Claims (1)

[Claims] 1. A toroidal stepless mechanism having a toroidal speed change mechanism comprising an input / output disk and a power roller between both disks, and a loading cam mechanism being used as a mechanism for generating a pressing force between the disk and the power roller of the speed change mechanism. In the transmission, a hydraulic pressure generating means for generating a hydraulic pressure that rises when the engine has a negative torque is provided, a hydraulic cylinder is provided in parallel with the loading cam, and the hydraulic pressure from the hydraulic pressure generating means is introduced into the hydraulic cylinder. Control device for toroidal continuously variable transmission.