JPS62184270A - Belt driven type non-stage transmission - Google Patents

Abstract

PURPOSE:To enable the frictional force between a block and a pulley to be adjusted, by forming plural rectangular grooves on the block or a V-shaped groove. CONSTITUTION:A driving belt comprises hoops which are formed by overlapping a prescribed number of metal sheet bands forming loops and a metal block 3 having both side end surfaces which are brought into contact with the conical surfaces of pulleys, and is provided between a fixed pulley 5 and a movable pulley 6. Plural grooves 8 which are intersected with each other and have almost the same width in the depth direction are provided for at least one of the side end surface 3a of the block or pulley driving surfaces 5a, 6a. The grooves 8 have rectangular sections which are 0.1mm wide and 5-20mum deep at intervals of0.2mm, and the directions of the grooves 8 are respectively inclined 45 deg. in the longitudinal direction of the side end surface of the block. Thus, even in case of long time use, the controlling effect of forming oil film can be maintained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention transmits driving force by winding a block around a pair of pulley hoops whose width dimensions can be changed, and changes the deceleration ratio by changing the groove width. Related to belt-driven transmissions.

[Background technology] In recent years, belt-driven continuously variable transmissions, which have been attracting attention for their adoption in automobiles, are made by attaching multiple metal blocks to a hoop of multi-layered metal thin strips forming a loop.
It forms the drive belt. This drive belt is wound around a pair of V-shaped pulleys arranged in parallel, and torque is transmitted from one pulley to the other pulley.

The pulley consists of a fixed pulley having a conical driving surface and a movable pulley having the same driving surface facing the fixed pulley, and both driving surfaces form a V-groove. The movable pulley is moved by means such as hydraulic pressure, and the distance between the V groove and the fixed pulley is variable.

Both side end surfaces of the blocks that constitute the drive belt have a taper angle that is approximately the same as the taper angle of the V groove formed by the drive surface of the pulley, and the diameter of the drive belt wrapped around the pulley is determined by the interval between the V grooves of the pulley. changes. Since the diameter wrapped around one pulley is different from the diameter wrapped around the other pulley, speed change for speed increase or deceleration is performed steplessly. The diameter of the drive belt wound around the pulley is determined by the balance of means such as hydraulic pressure acting on a pair of parallel pulleys.

Torque is transmitted by a drive belt wrapped around a pair of figure-7 pulleys arranged in parallel. That is, torque is transmitted by friction between the bobbin and the drive belt, and between blocks and hoops in the drive belt.

Torque transmission between the pulley and drive belt is carried out via the block that is in contact with the pulley, so the efficiency of this torque transmission strongly depends on the magnitude and stability of the frictional force between the pulley and block under oil lubrication. sell.

If this frictional force is small, the drive belt slips against the pulley, reducing the transmission efficiency of the drive belt and further causing damage such as scratches to the end surface of the drive belt and the drive surface of the pulley.Such slipping can be suppressed. Therefore, it is conceivable to increase the means such as hydraulic pressure applied to the pulley, but due to the power loss required to increase the hydraulic pressure, this method also results in a decrease in the transmission efficiency of the entire system, and is not a good idea. Through research conducted by the present inventors, it has been found that in order to improve efficiency, means such as hydraulic pressure applied to the pulley and slippage between the pulley and the drive belt should be minimized.

On the other hand, in the belt-driven continuously variable transmission described in JP-A No. 53-1747, infinitely small irregularities are randomly formed on the side end surface of the drive belt and/or on the surface of the conical disk (pulley) that comes into contact with the side end surface of the drive belt. ing. On a surface having countless such micro-asperities, only the convex portions of the micro-asperities come into contact with the other surface. As a result, these minute irregularities can improve the oil film removal and provide a relatively high level of friction coefficient of about 0.2 at the initial stage of use.

However, as wear progresses, as the number of flat parts that come into contact with the mating surface increases, an oil film gradually becomes more likely to form, resulting in a decrease in the coefficient of friction and thus a decrease in transmission efficiency, so this problem poses a problem in terms of durable use. becomes.

Furthermore, regarding the belt block described in Japanese Utility Model Application Publication No. 58-97337, in which an appropriate number of grooves are provided, the grooves are oriented in only one direction, and that direction is zero in the counterclockwise direction with respect to the traveling direction of the drive belt. The angle ranges from 45° to 45°. The existence of a certain relationship between the direction of the groove and the direction of friction has been clarified through experiments by the present inventor, but the results were
-97337 is the opposite.

Additionally, according to the inventor's experiments, the direction of speed change or drive in the drive belt does not necessarily coincide with the radial direction or circumferential direction of the pulley drive surface, which maintains the performance of the continuously variable transmission and maximizes the transmission efficiency. It is known that in order to achieve this, it is necessary that the friction coefficient of the contact surface remains stable and does not change, regardless of the direction of friction. Therefore, if the groove is unidirectional, there is a problem that not only the performance cannot be maintained and the transmission efficiency is lowered, but also that the control circuit for hydraulic pressure etc. becomes complicated.

[Objective of the Invention 1] This invention relates to a means for adjusting the frictional force between the block end face and the pulley drive face, and improves the problems of the prior art by changing the shapes of the block end face and the pulley drive face, and improves the friction between the two contact faces. The frictional force of each does not decrease as the wear progresses,
Another object of the present invention is to provide a belt-driven continuously variable transmission having an end face shape that is constant regardless of the sliding direction or sliding speed of the block and pulley and is relatively easy to manufacture.

[Description of the Invention] The torque transmission system of the belt-driven continuously variable transmission according to the present invention is as shown in FIGS. 1 and 2.

The driving belt consists of a hoop 4 made by stacking a predetermined number of metal thin strips forming a loop, and a metal block 3 having both end surfaces that come into contact with the conical surface of the pulley, and is wound around a pair of pulleys 1 and 2 that are arranged substantially parallel to each other. It is designed to transmit torque. Here, the pulley 1.2 consists of a fixed pulley 5 fixed to its shaft and a movable pulley 6 which faces the fixed pulley 5 and is movable in the axial direction, each having a conical drive surface 5a and a conical drive surface 6.
A V groove is formed by a. Further, the block 3 constituting the drive belt has both side end surfaces 3a that come into contact with the drive surfaces 5a and 6a of the boob, and further has a hoop contact surface 3b that comes into contact with the hoop 4.

Next, FIG. 3 shows a cross section of the contact surface between the pulley drive surface 6a and the block side end surface 3a taken along the line m-■ in FIG. 2. In the case of rigid bodies, the contact is a line contact, and In the case of elastic bodies, there is a surface contact with a trapezoidal contact surface. A wedge-shaped plow in which the contact surface can be seen on the entire block side end face 3a under extremely high surface pressure. II7 is present on both sides of the contact surface. Pulley drive surface 5a and block side end surface 3
A similar relationship exists in contact with a.

In a system having such a structure, this IJll crosses the block side end surface 3a and at least one of the pulley drive surfaces 5a, 6a, and has a plurality of substantially the same width dimensions when viewed in the depth direction. It is located at the point where groove 8 was made.

Since the belt-driven continuously variable transmission is lubricated with oil, if there is a wedge-shaped gap 7 between the contact surfaces between the block side end surface 3a and the pulley drive surfaces 5a and 6a, relative slip between the block and the pulley will occur. As a result, pressure is generated by the oil film in the wedge-shaped gap, making it easier for an oil film to form between the contact surfaces. As shown in Figure 4, when the relative speed increases, the coefficient of friction decreases to 0.1 in contact between flat surfaces, where oil films are most likely to form, and an oil film is formed between the contact surfaces. I understand.

On the other hand, when the contact surface has a groove of a predetermined width and depth as in the present invention, the oil that forms the oil film flows into the groove, and as a result, pressure is less likely to occur in the wedge-shaped gap. , the formation of an oil film on the contact surface is suppressed.

In addition, the grooves provided to suppress the formation of oil film due to relative slipping cause differences in the way oil flows from the wedge-shaped gap to the groove depending on the sliding direction and the direction of the groove.
The effect of suppressing oil film formation differs depending on the direction of relative slip and the direction of the groove. Figures 5 and 6 show the measurement results of the friction coefficient when grooves are provided in one direction. FIG. 5 shows the case where the sliding direction and the groove direction are the same direction, and FIG. 6 shows the case where the sliding direction and the groove direction are perpendicular.

When the contact surface has grooves, compared to when the contact surface is flat, it suppresses the formation of an oil film and exhibits a somewhat higher coefficient of friction, but as the relative sliding speed increases, the coefficient of friction decreases slightly. , the decrease is greatest when the slip direction and the groove direction are in the same direction. Therefore, when the direction of the groove is unidirectional, the coefficient of friction in the contact changes depending on the sliding direction, and it can be seen that the effect of the groove on suppressing oil film formation differs. On the other hand, in the grooves of the present invention having different arrangement angles, at least one groove is not in the same direction as the sliding direction, and the formation of an oil film on the contact surface is effectively suppressed.
Therefore, the formation of an oil film on the contact surface is suppressed regardless of the sliding direction, and the coefficient of friction does not change.

Furthermore, the grooves according to the present invention have good safety against wear. In other words, on a surface with minute irregularities, most gates are approximately triangular with the valley as the apex;
As wear progresses, the ratio of concavities and convexities changes, and the ratio of flat surfaces on the contact surface increases. Furthermore, the depth of the micro-asperities is shallow, approximately several tens of gm, and it is thought that the effect of the micro-asperities weakens as wear progresses, and the friction coefficient of the contact surface decreases relatively quickly.

On the other hand, since the grooves according to the present invention can have a substantially rectangular cross section, the ratio of concavity and convexity on the contact surface to the wear of the contact surface does not change, and the shape of the concave portion, which is important for oil leakage, does not change. Also,
Since the depth of the grooves can be relatively deep compared to minute irregularities, etc., the effect of suppressing oil film formation is maintained even during long-term use.

Furthermore, if the friction between the drive belt and the pulley in the drive belt of a belt-driven continuously variable transmission is stable against slipping or abrasion, not only will the drop in transmission efficiency due to slippage or abrasion be eliminated, but the belt Since there is no need to take special consideration to slippage, the control system for hydraulics and the like that controls the device is simplified.

[Description of implementation] Embodiments of the present invention will be described below.

If a plurality of grooves (for example, intersecting grooves) formed at predetermined widths, depths, and intervals with different arrangement angles are present on the block side end face, the formation of an oil film at the contact between the block side end face and the pulley contact surface may be avoided. A suppressive effect can definitely be expected from individual contact. The contact between the block and the pulley occurs at approximately the same location when viewed from the end face of the block, and the effect of suppressing the formation of an oil film in the groove on the contact surface can be ensured with a small number of grooves.

In addition, a plurality of grooves (for example, intersecting t
J) can also be expected to suppress the formation of an oil film during contact between the drive belt and the pulley. In the contact between the drive belt and the pulley, the contact occurs on a portion of the pulley drive surface,
Also, since its position changes, the pulley drive surface is more blocked! It is difficult to wear compared to the end face, so when the groove is provided on the pulley drive surface, the change in the groove shape due to the progress of wear is smaller, and therefore the effect of suppressing the formation of an oil film on the groove is less likely to change. Also from a production perspective.

Since the pulley drive surface has fewer parts and is easier to machine than the block of the drive belt, it is advantageous to provide the groove in the boob.

There are a plurality of grooves formed on the pulley drive surface and the block side end surface, each with a predetermined width, depth, and spacing, and even when these grooves intersect with each other when the pulley and block are in contact, there is a problem in the contact between the drive belt and the pulley. The effect of suppressing the formation of oil film can be expected. Since the grooves provided on the boot drive surface and the grooves provided on the block side end surface are arranged so as to intersect with each other when they come into contact, the intersection of those grooves crosses the block when the booth and block come into contact. It can be expected to have the effect of suppressing the formation of an oil film in all cases of contact. Further, when the block and pulley are relatively interlocked, the intersection of the grooves formed on the contact surfaces moves, and the oil can be efficiently discharged into the grooves, which is effective in suppressing the formation of an oil film.

A plurality of grooves formed at predetermined widths, depths, and intervals with different arrangement angles may be provided together with minute irregularities formed on a flat surface on which no grooves are formed. All of the unevenness may be formed on the drive surface of the pulley or on the block, or only the intersecting grooves may be formed on one side and the minute unevenness may be formed on the other. Furthermore, one groove may be formed on the drive surface of the pulley and the block. Grooves intersecting this groove and minute irregularities may be formed on the drive surface of the pulley and on the other side of the block.

The drive belt is composed of a plurality of blocks and a plurality of hoops, and it has been revealed through experiments by the inventor that the force is better when each block has the same dimensions. If the dimensions of the blocks are not the same, it is necessary to equalize the dimensions to allow the drive belt to break in. However, with only grooves formed on the end face of the block, wear progresses slowly on the flat surface, and it takes a long time to break in. Become. #1 The surface with only small irregularities progresses relatively quickly, but as mentioned above, there is a problem with stability as a friction surface. Therefore, by providing the above-mentioned grooves on the contact surface and also providing minute irregularities on the flat surface to facilitate the progress of the break-in, it becomes possible to obtain a friction surface that allows the break-in to progress quickly and is stable.

In addition, when the block dimensions of the drive belt are uniform, when the drive belt contacts the pulley, the positional relationship between the parts that make contact with the hoop is good, the force acting on the hoop becomes uniform, and the life of the hoop can be extended. This has become clear through experiments conducted by the inventor.

[Example 1] An example in which a plurality of grooves having predetermined widths, depths, and intervals with different arrangement angles are provided on the end face of the block will be described.

The cross-sectional shape of the formed groove 8 is @Q,1 as shown in FIG.
It has a rectangular cross section with a depth of 5 to 20 mm and an interval of 0.2 mm, and was machined on the end face of the block using a milling machine. Therefore, the groove width is the same when viewed in the depth direction.

As shown in Figure 8, the direction of the grooves is inclined at 45 degrees in the longitudinal direction of the end face of the block, and when the block moves in the radial direction or circumferential direction of the pulley, the sliding direction and the groove are inclined by the same angle. are doing.

Y! To measure the friction coefficient, a measuring device made to imitate a belt-driven continuously variable transmission was used, and a block test piece was brought into contact with a pulley test piece with a conical surface on the right side. The coefficient of friction with the pulley test piece was kept constant at A1. The results are shown in Figure 9, where the horizontal axis is the relative rotational speed between the block test piece and the boolean test piece, the vertical axis is the measured friction coefficient, and the load applied to the block test piece is 20 to 50K.
g. The direction of friction is the circumferential direction of the pulley, and this direction is the direction in which oil is most likely to form on the contact surface due to the relative movement between the block and the pulley. If there is no groove on the end face of the block, as shown in FIG. 4, an oil film is formed on the contact surface due to the relative motion between the block and the pulley, reducing the coefficient of friction.

It can be seen that the block shown in Example 1 has a good effect of suppressing the formation of an oil film on the contact surface due to relative motion over a wide range of slipping speeds.

[Embodiment 2] As shown in FIG. 10, one groove direction is the longitudinal direction of the end face of the block 3.

As described above, the coefficient of friction of a surface having a plurality of grooves in only one direction changes depending on the sliding direction and the direction of the grooves. In a belt-driven continuously variable transmission, a relatively large sliding speed occurs, and the direction in which an oil film is likely to form on the contact surface is the circumferential direction of the pulley, so grooves with different angles are provided on the friction surface.

One direction is the direction perpendicular to the circumferential direction of the pulley, ie.

It is considered a good idea to use the pulley radial direction on the pulley surface and the longitudinal direction of the end surface on the block side end surface.

[Embodiment 3] Fig. 11 shows an example in which grooves 8 intersecting the pulley drive surface are provided.The groove intervals etc. are determined based on the contact conditions with the block, that is, blood pressure, transmitted torque, etc. change depending on the radial direction. It can be established by considering such things. In this embodiment, since the number of blocks is small in the small radius part, the interval between grooves is narrowed in the small diameter part.

[Example 4] Grooves were provided on the pulley drive surface and the block side end surface,
When grooves are provided on both sides of the contact surface, as shown in FIG. 12, an example in which the grooves are provided so as to intersect in a state of contact, there is an advantage that the intersection point of the grooves moves due to relative movement of the surfaces.

In this embodiment, when the block 3 moves in the circumferential direction of the pulley 1 (2), the intersection of the grooves moves, which is considered to be highly effective in suppressing the formation of an oil film on the contact surface.

[Example 5] Fig. 13 shows an example in which intersecting grooves 8 are provided on the side end face of the block 3, and minute irregularities 9 are also provided on the side end face. Since there are many center portions of the side end surfaces, when providing minute irregularities, it is preferable to provide them centering on the center portion of the block side end surfaces.

In addition to the milling process used in the embodiments as a method for forming the grooves in the above description, there are other methods such as planing and grinding, and also forging by plastic working, rolling, etc. can be considered. Further, although the shape of the groove has been basically a straight line or a helical line, curves such as circular arcs may also be considered. Even in that case, it is thought that the effect of suppressing the formation of an oil film is enhanced by intersecting the grooves in different directions.

[Effects of the Invention] As explained above, the present invention brings the both side end surfaces of a plurality of blocks into contact with the V grooves of a pair of pulleys whose width dimensions can be changed,
It is a belt-driven continuously variable transmission in which these blocks are connected by a band-shaped endless hoop, which intersects with both end surfaces of the blocks or the grooves of the pulley, and whose width dimensions are approximately the same when viewed in the depth direction. Since it is characterized by the formation of a plurality of grooves, it has an excellent effect of being able to adjust the frictional force between the block and the pulley.

[Brief explanation of drawings]

FIG. 1 is a front view of a belt-driven continuously variable transmission according to the present invention, FIG.
Figure (B) is a side view of the block, and Figure 3 is m-■ in Figure 2.
An enlarged view of the line cross section. Figure 4 is a diagram showing the change in the friction coefficient with respect to the relative rotation speed of a contact surface without grooves. Figure 5 is a graph showing the friction with respect to the relative rotation speed when the direction of the groove and the direction of the groove are the same. A diagram showing changes in the coefficient. Figure 6 is a diagram showing changes in the friction coefficient with respect to the relative rotation speed when the edge direction and the groove direction are perpendicular. Figure 7 is an enlarged cross-sectional view of the groove of Example 1. Figure, 8th
The figure is a front view of the block side end face of Example 1, Figure 9 is a diagram showing the change in friction coefficient with respect to the relative rotation speed when using the block of Example 1, and Figure 1O is the block side end face of Example 2. 11 is a front view of the pulley drive surface of Embodiment 3, FIG. 12 (A) is a front view of the pulley drive surface of Embodiment 4, FIG. 12 (B) is a front view of the end face of the block, and FIG. 13 FIG. 3 is a front end view of the block side of Example 5. FIG. 1.2...Pulley, 3...Block, 4...Hoop, 8...Groove.

Claims (2)

[Claims] (1) A belt-driven continuously variable transmission in which both end surfaces of a plurality of blocks are brought into contact with the V-grooves of a pair of pulleys whose width dimensions can be changed, and these blocks are connected by a band-shaped endless hoop, A belt-driven continuously variable transmission characterized in that a plurality of grooves are formed which intersect with both end surfaces of the block or V-grooves of the pulley and have substantially the same width dimension when viewed in the depth direction. (2) The belt-driven continuously variable transmission according to claim (1), wherein the grooves are formed in the block and the V-groove, respectively, and these grooves are arranged to intersect with each other in abutting state.