JP2004270708A - Belt type transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid lowering of transmission ability even if the size of a transmission is reduced accompanying reduction in a minimal pulley pitch diameter, by preventing a belt 3 from being bottomed on a driving pulley 1, when the belt 3 is elastically deformed in a direction widening a belt bottom face side on the pulley 1 whose pulley pitch diameter is reduced, in the belt-type continuously variable transmission which transmits torque of the driving pulley 1 though the belt 3 to a driven pulley 2 by frictional contact of both side faces of each of V-shaped grooves 1a, 2a of the driving pulley 1 and the driven pulley 2 with both side faces 3c, 3c forming a V-shaped section of the double cogged V-type belt 3, and which changes a speed ratio between the pulleys 1, 2 by changing the pulley pitch diameters of the pulleys 1, 2 in opposite directions. <P>SOLUTION: A cut angle ρ as a belt angle γ between the belt both side faces 3c, 3c when no tension is applied is set larger than a V groove angle β of the driving pulley 1, (ρ/β). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００４０】
比較例１，比較例２および発明例１から判るように、カット角度ρが大きくなるほど、伝動能力が高くなっている。特に、従来の場合を示す比較例２と、発明例１とを対比すると、発明例１では、比較例２の１０６％を超える伝動能力を示している。
【００４１】
ところが、発明例１と発明例２とでは、伝動能力は互いに同じ（６５０Ｎ／ｍ）である。これは、カット角度ρには上限があり、カット角度ρが上限に達してベルト側面がＶ溝側面に十分にフィットするようになれば、そのときに、駆動プーリおよびダブルコグドＶベルト間の所与の伝動能力が十分に発揮されるからであると考えられ、したがって、カット角度ρが上限以上に大きくなっても、それ以上の伝動能力は発生しないと推察される。むしろ、カット角度ρがＶ溝角度βよりも大き過ぎる場合には、プーリピッチ径が大径化したときに、ベルト底面側のベルト幅寸法が大きくなる方向の弾性変形が不十分になり、このために、ベルト側面の面圧分布のピークがベルトピッチラインの半径方向外方側に偏位するという「上当り」（図４参照）を招く虞れがある。
【００４２】
−実験例２−
次に、カット角度ρが異なる場合に、プーリピッチ径Ｄの変化によるベルト角度γの変化を調べるために行った実験について説明する。
【００４３】
先ず、カット角度ρの異なる４種類のダブルコグドＶベルト（サンプル１〜サンプル４）を作製した。カット角度ρは、サンプル１ではρ＝３０°，サンプル２ではρ＝２８°，サンプル３ではρ＝２６°，サンプル４ではρ＝２４°とした。
【００４４】
実験の要領は、各サンプルを、プーリピッチ径Ｄが、Ｄ＝６０〜１２０ｍｍの範囲で変化したときと同じ状態になるように曲げつつ、その曲がった部分のベルト角度γをそれぞれ測定するようにした。以上の結果を、図６に併せて示す。
【００４５】
図６から判るように、何れのサンプルの場合でも、ベルト角度γは、カット角度ρよりも小さい（γ＜ρ）。また、プーリピッチ径Ｄが小さくなるのに応じて小さくなっているが、プーリピッチ径が１２０ｍｍから略８０ｍｍに変化する範囲では、ベルト角度γは１°程度しか小さくなっていないが、プーリピッチ径Ｄが略８０ｍｍから６０ｍｍに変化する範囲では、ベルト角度γは２°以上小さくなっている。このことから、カット角度に拘わらず、プーリピッチ径Ｄが小径である程、ベルト角度γが小さくなって「底当り」が発生することに起因する伝動能力の低下が顕著になることが判る。
【００４６】
サンプル２では、実験例２における発明例１の場合と同じカット角度ρ（＝２８°）であり、プーリピッチ径ＤがＤ≒７０ｍｍであるときのベルト角度γが、実験例２のＶ溝角度β（＝２６°）と同じ（γ＝２６°）になることが判る。また、サンプル１では、実験例２における発明例２の場合と同じカット角度ρ（＝３０°）であり、プーリピッチ径ＤがＤ≒７０ｍｍであるときのベルト角度γが、γ＝２８°になっている。これらのことから、Ｖ溝角度βを基準にした場合に、少なくとも、ベルト角度γがβ＜γ≦β＋２°の範囲に収まるようにカット角度ρを定めておけば、伝動能力を十分に発揮できるということが判る。
【００４７】
一方、サンプル３およびサンプル４では、それぞれ、実験例２における比較例２および比較例１の場合と同じカット角度ρ（＝２６°，２４°）であり、プーリピッチ径ＤがＤ＝７０ｍｍであるときのベルト角度γが、それぞれ、γ＝２４°およびγ＝２２°になっている。これらのことから、ベルト角度γが、γ＝β−２°およびγ＝β−４°になるようにカット角度ρが定められている場合には、伝動能力は、それぞれ、サンプル１およびサンプル２の場合の略９４％および略９０％に低下することが判る。
【００４８】
【発明の効果】
以上説明したように、請求項１の発明によれば、駆動プーリおよび従動プーリの各Ｖ溝両側面と、ダブルコグドＶベルトのベルト両側面との摩擦接触により駆動プーリのトルクをダブルコグドＶベルトを介して従動プーリに伝達するとともに、両プーリの各プーリピッチ径の互いに逆の方向への変化により該両プーリ間の速比を変更するようにしたベルト式変速装置において、ダブルコグドＶベルトの無張力時のベルト両側面間のベルト角度をＶ溝角度よりも大きくすることで、各プーリのプーリピッチ径が小径化するのに伴って該プーリ上でベルト角度がＶ溝角度よりも小さくなることによる底当りを抑えることができるので、伝動能力の低下を抑えつつ、最小プーリピッチ径の小径化を伴う変速装置の小形化を図ることができ、よって、二輪スクータ，バギー車，スノーモビルなどのような小型自動車における高出力化に貢献することができる。
【００４９】
請求項２の発明によれば、上記ダブルコグドＶベルトの無張力時のベルト両側面間のベルト角度を、速比Ｌｏｗ時の駆動プーリ上でのベルト角度がＶ溝角度に一致するように定めることで、最も高い伝動能力が必要とされるＬｏｗ時の駆動プーリに対するダブルコグドＶベルトの底当りを回避することができ、これにより、変速装置の伝動能力を十分に発揮させることができるので、請求項１の発明による効果を適正に得ることができる。
【図面の簡単な説明】
【図１】本発明の実施形態に係るベルト式無段変速装置でのダブルコグドＶベルトのカット角度と駆動プーリのＶ溝角度との関係を模式的に示す断面図である。
【図２】ベルト式無段変速装置の全体構成を模式的に示す側面図である。
【図３】ダブルコグドＶベルトの構成を模式的に示す斜視図である。
【図４】駆動プーリ上におけるダブルコグベルトの速比トップ時および速比ロー時の各ベルト角度を、各速比時のＶ溝側面に対するベルト推力の面圧分布と併せて模式的に示す断面図である。
【図５】実験例１におけるカット角度とトルク伝達能力との関係を示す特性図である。
【図６】実験例２におけるプーリピッチ径の変化に伴うベルト角度の変化を示す特性図である。
【図７】従来のダブルコグドＶベルトの構成を示す図１相当図である。
【符号の説明】
１ 駆動プーリ
２ 従動プーリ
３ ダブルコグドＶベルト
３ａ 上コグ
３ｂ 下コグ
ρ カット角度（無張力時のベルト角度）
β Ｖ溝角度
ｒ ベルト角度[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a belt-type transmission in which a double cogged V-belt is wound between a driving pulley and a driven pulley with a variable pulley pitch diameter, and more particularly to a measure for suppressing a reduction in transmission capacity due to downsizing of the transmission.
[0002]
[Prior art]
For example, as a belt-type continuously variable transmission mounted on a small vehicle such as a two-wheeled scooter, a buggy vehicle, a snowmobile, or the like, an upper cog and a belt inner surface are provided between a drive pulley and a driven pulley having a variable pulley pitch. It is known that a double cogged V belt provided with a lower cog is wound around the belt. With the increase in the output of small vehicles as described above, the belt-type continuously variable transmission is required to have a small size and a high transmission capability.
[0003]
In this example, as schematically shown in FIG. 7, both side surfaces b of a double cogged V-belt a having a V-shaped cross section formed on both side portions of the belt are pressed against both side surfaces of a V groove d of each pulley c. The pulleys c, c change the pulley pitch diameter in directions opposite to each other to change the speed ratio between the pulleys c, c.
[0004]
In the conventional case, in the process of manufacturing the double cogged V-belt a, when the both sides of the belt are cut into a V-shaped cross section to form both sides b, b, the cut angle ρ is set to each pulley c. (Ρ = β) so that both side surfaces b, b of the belt can be properly fitted to both side surfaces of the V groove d of each pulley c. .
[0005]
[Problems to be solved by the invention]
By the way, in the above-described belt-type continuously variable transmission, the double cogged V-belt a, when wound around each pulley c, elastically deforms in a direction in which the belt width dimension on the belt bottom surface side (the lower surface side in FIG. 7) increases. Therefore, the actual belt angle γ between the belt side surfaces b, b is smaller than the cut angle ρ (γ <ρ).
[0006]
At this time, in the conventional case, if the minimum pulley pitch diameter is reduced in order to reduce the size of the apparatus, the belt side surfaces b and b do not sufficiently fit on both side surfaces of the V groove d, and the belt side surfaces A so-called "bottom contact" occurs in which the portions b and b on the bottom surface side of the belt (the lower surface side in FIG. 7) strongly press against both side surfaces of the V-groove d. However, there is a problem that it is not possible to cope with the increase in output.
[0007]
The present invention has been made in view of such a point, and a main object of the present invention is to provide a belt-type transmission in which a double cogged V-belt is wound around a driving and driven pulley having a variable pulley pitch diameter. In reducing the diameter, by reviewing the relationship between the cut angle between both sides of the belt and the V-groove angle of the pulley, both sides of the belt can be properly fitted to both sides of the V-groove. An object of the present invention is to reduce the size while avoiding a decrease in performance.
[0008]
[Means for Solving the Problems]
To achieve the above object, the present invention focuses on the fact that the maximum transmission capacity is required when the pulley pitch diameter of the drive pulley is at a minimum speed ratio, and at that time, the double cog-doped V belt on the drive pulley is required. The belt angle ρ at no tension is determined so that the belt angle γ of coincides with the V-groove angle β (γ = β).
[0009]
More specifically, according to the first aspect of the present invention, each of the driving pulleys and the driven pulleys having a V-shaped cross section and having a variable pulley pitch diameter, and an upper cog on a belt rear side and a belt bottom side. And a lower cog, and a double cogged V-belt having both side surfaces of a V-shaped cross section on both side portions of the belt and wound between the driving pulley and the driven pulley. The frictional contact between both sides of each V-groove of the driven pulley and both sides of the belt of the double cogged V-belt transmits the torque of the driving pulley to the driven pulley via the double cogged V-belt, while the pulley pitch diameters of the driving and driven pulleys are mutually different. It is premised on a belt type transmission in which the speed ratio between the driving and driven pulleys is changed by changing in the opposite direction.
[0010]
The belt angle ρ between both side surfaces of the double cogged V belt when there is no tension is set to be larger than the V groove angle β between both side surfaces of each V groove of the driving and driven pulleys (ρ> β). Shall be.
[0011]
In the above configuration, the double cogged V-belt is bent on the driving and driven pulleys so that the belt pitch line coincides with the pulley pitch line, and is elastically deformed in a direction to increase the belt width dimension on the bottom surface of the belt. The belt angle γ between both side surfaces is smaller than the belt angle ρ when there is no tension (γ <ρ).
[0012]
At this time, since the belt angle ρ under no tension is larger than the V-groove angle β of each pulley (ρ> β), the belt angle γ is the same as the conventional belt angle ρ under no tension as the V-groove angle. Compared with the case where (ρ = β), the degree that the angle is smaller than the V-groove angle β is less.
[0013]
Therefore, when the minimum diameter of the pulley pitch diameter is reduced, the "bottom contact" of the double cogged V-belt with respect to each pulley caused by the belt angle γ being smaller than the V-groove angle β is suppressed, and V Since it fits appropriately on both sides of the groove, the reduction of the transmission capacity is suppressed by that much.
[0014]
According to a second aspect of the present invention, in the first aspect of the invention, the belt angle ρ between both side surfaces of the double cogged V belt when there is no tension is determined by the speed ratio between the driving and driven pulleys (the driven side rotating speed / the driven side rotating speed). ) Is the lowest (Low), the belt angle γ on the drive pulley is determined to be equal to the V-groove angle β (γ = β).
[0015]
In the above configuration, when the torque of the driving pulley is transmitted to the driven pulley via the double cogged V-belt, the highest transmission capability is required because the pulley pitch diameter of the driving pulley is minimized and the driven pulley This is the time when the speed ratio between the two pulleys at which the pulley pitch diameter is maximized is the lowest, that is, Low. That is, when the belt angle γ of the double cogged V-belt on the driving pulley becomes minimum.
[0016]
At this time, since the belt angle γ on the drive pulley matches the V-groove angle β of the drive pulley, both side surfaces of the belt properly fit to both V-groove sides, and the “bottom contact” of the double cogged V-belt with respect to the drive pulley is Does not occur. Therefore, the transmission capacity of the transmission is sufficiently exhibited.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
FIG. 2 schematically shows the entire configuration of a belt-type continuously variable transmission according to an embodiment of the present invention. This transmission is mounted on a small vehicle such as a two-wheeled scooter, a buggy or a snowmobile. used.
[0019]
This belt-type continuously variable transmission is composed of a variable speed pulley having a variable pulley pitch diameter (diameter of pulley pitch lines L1 and L2), and a driven pulley 1 and a driven pulley arranged such that their rotation axes are parallel to each other. A pulley 2 and a double cogged V-belt 3 wound around the driving pulley 1 and the driven pulley 2 are provided.
[0020]
The driving and driven pulleys 1 and 2 each include a fixed sheave that cannot move in the axial direction and a movable sheave that can move in the axial direction, and a V-shaped cross section is provided between the fixed sheave and the movable sheave. V-grooves 1a and 2a having a predetermined V-groove angle β (for example, β = 26 °) are formed. When the movable sheave moves in the direction approaching the fixed sheave, the pulley pitch diameter increases. On the other hand, when the movable sheave moves away from the fixed sheave, the pulley pitch diameter decreases. In the drive pulley 1 and the driven pulley 2, the arrangement of the fixed sheave and the movable sheave in the axial direction is reversed.
[0021]
Further, the movable sheave of the drive pulley 1 is provided with a centrifugal clutch (not shown) that presses the movable sheave toward the fixed sheave in accordance with the centrifugal force caused by the rotation of the drive pulley 1. Although not shown, the movable sheave of the driven pulley 2 is provided with an urging means such as a spring that constantly urges the movable sheave toward the fixed sheave, and a cam that uses a cam to apply torque applied to the movable sheave. A torque cam mechanism for converting the sheave into an axial thrust (belt thrust) for the double cogged V-belt 3 is connected to the sheave. That is, as the rotation speed of the drive pulley 1 increases, the pulley pitch diameter of the drive pulley 1 increases, and accordingly, the pulley pitch diameter of the driven pulley 2 decreases, while the rotation speed of the drive pulley 1 decreases. Accordingly, the pulley pitch diameter of the driving pulley 1 becomes smaller, and the pulley pitch diameter of the driven pulley 2 becomes larger accordingly.
[0022]
As shown in FIG. 3, the double cogged V-belt 3 has an adhesive rubber layer 5 in which a core wire 4 is buried, and an upper rubber layer 6 laminated on the back side of the adhesive rubber layer 5 (upper side in FIG. 3). And a lower rubber layer 7 laminated on the bottom surface side of the adhesive rubber layer 5 (the lower surface side in the figure), and a canvas layer 8 laminated on the lower rubber layer 7 on the bottom surface side of the belt. On the back side of the belt, a plurality of upper cogs 3a, 3a, ... provided so as to extend in the belt width direction are arranged at a predetermined pitch in the belt length direction. These upper cogs 3a, 3a,... Are formed on the upper rubber layer 6. On the other hand, a plurality of lower cogs 3b, 3b,... Provided to extend in the belt width direction are arranged at a predetermined pitch in the belt length direction on the belt bottom surface side. These lower cogs 3b are formed on the lower rubber layer 7.
[0023]
On both side portions of the double cogged V-belt 3, belt side surfaces 3c, 3c having a V-shaped cross section are formed so as to be in pressure contact with both side surfaces of the V grooves 1a, 2a of the driving and driven pulleys 1, 2. The belt side surfaces 3c, 3c are formed by cutting both side portions of the belt at a predetermined angle ρ in the manufacturing process of the double cogged V-belt 3, and the cut angle ρ is equal to the belt side surfaces 3c, 3c when no tension is applied. 3c is the belt angle γ.
[0024]
In this embodiment, as schematically shown in FIG. 1, the cut angle ρ of the double cogged V-belt 3 is determined by the speed ratio between the driving and driven pulleys 1 and 2 (the driven rotation speed / the driving rotation speed). When the belt angle γ (<ρ) on the drive pulley 1 is the lowest, that is, when the speed ratio is Low (the pulley pitch diameter of the drive pulley 1 is the minimum and the pulley pitch diameter of the driven pulley 2 is the maximum), the V groove (Eg, ρ = 28 °> 26 °), so that the cut angle ρ is determined by the V-grooves 1a, 2a is larger than the V groove angle β between both side surfaces (ρ> β).
[0025]
Here, the operation of the belt-type continuously variable transmission configured as described above will be described with reference to FIG.
[0026]
In the belt-type continuously variable transmission described above, the double cogged V-belt 3 is tensioned, so that the drive and driven pulleys 1 and 2 are adjusted so that the belt pitch line L3 coincides with each of the pulley pitch lines L1 and L2. Wrap around. As a result, the double cogged V-belt 3 is elastically deformed on the driving and driven pulleys 1 and 2 so that the belt width becomes larger on the belt bottom side, and as a result, the belt angle γ is smaller than the cut angle ρ (γ <Ρ).
[0027]
At this time, since the cut angle ρ is larger than the V groove angle β of each of the pulleys 1 and 2 (ρ> β), the belt angle γ has the same cut angle ρ as the V groove angle β (ρ = β ), The degree to which the angle becomes smaller than the V-groove angle β may be smaller.
[0028]
Therefore, the "bottom contact" of the double cogged V-belt 3 with respect to each of the pulleys 1 and 2 caused by the belt angle γ being smaller than the V-groove angle β (γ <β) is suppressed, and the surface pressure of the belt side surface against the V-groove side surface is reduced. The center (peak of the surface pressure) is located on the belt pitch line L3, and the belt side surfaces 3c, 3c fit properly on both side surfaces of the respective V-grooves 1a, 2a. It will be suppressed.
[0029]
When the torque of the driving pulley 1 is transmitted to the driven pulley 2 via the double cogged V-belt 3, the highest transmission capacity is required because the speed ratio between the driving and driven pulleys 1 and 2 is most important. It is when it is low. That is, when the pulley pitch diameter D1 of the driving pulley 1 is the minimum and the belt angle γ of the double cogged V-belt 3 is the minimum on the driving pulley 1.
[0030]
At this time, since the belt angle γ on the driving pulley 1 matches the V groove angle β of the driving pulley 1 (γ = β), the both side surfaces 3c of the belt properly fit to both side surfaces of the V groove 1a, No “bottom contact” of the double cogged V-belt 3 with respect to the driving pulley 1 occurs. Therefore, the transmission capacity of the transmission is sufficiently exhibited.
[0031]
Therefore, according to the present embodiment, the torque of the driving pulley 1 is reduced by the frictional contact between the both side surfaces of the V-grooves 1a, 2a of the driving pulley 1 and the driven pulley 2 and the both side surfaces 3c, 3c of the double cogged V-belt 3. In the belt-type continuously variable transmission, the power is transmitted to the driven pulley 2 via the double cogged V-belt 3 and the speed ratio between the pulleys 1 and 2 is changed by changing the pulley pitch diameter in opposite directions. By increasing the cut angle ρ, which is the belt angle γ between the belt side surfaces 3c and 3c when the double cog V belt 3 is not tensioned, larger than the V groove angle β (ρ> β), the pulley pitch diameter is reduced. Thus, the "bottom contact" caused by the belt angle γ being smaller than the V groove angle β on the pulleys 1 and 2 is suppressed, and the belt side surfaces 3c and 3c are properly fitted to both side surfaces of the V grooves 1a and 2a. It is possible to bet. Therefore, the transmission can be downsized with a reduction in the minimum pulley pitch diameter of the driving and driven pulleys 1 and 2 while suppressing a reduction in the transmission capacity, so that it is possible to reduce the size of a transmission such as a two-wheeled scooter, a buggy or a snowmobile. This can contribute to higher output in automobiles.
[0032]
Further, by setting the above-mentioned cut angle ρ such that the belt angle γ on the drive pulley 1 at the time of the low speed ratio matches the V-groove angle β (γ = β), the highest transmission capacity is required. In this case, the bottom contact of the double cogged V-belt 3 against the drive pulley 1 at the time of a low load can be avoided, whereby the transmission capacity of the transmission can be sufficiently exhibited, so that the above effects can be appropriately obtained. .
[0033]
In the above-described embodiment, a case of a belt-type continuously variable transmission in which a centrifugal clutch is connected to a driving pulley 1 and an urging means and a torque cam mechanism are connected to a driven pulley 2 will be described. However, the means for changing the pulley pitch diameters of the pulleys 1 and 2 in directions opposite to each other is not limited to the above, and a known technique can be appropriately employed.
[0034]
-Experimental example 1-
Here, a description will be given of an experiment conducted for examining the transmission capacity of the above-described belt-type continuously variable transmission.
[0035]
Specifically, in the drive and driven pulleys, the pulley pitch diameters D1 and D2 are variable within a range of D1 and D2 = 68.8 to 112.0 mm, respectively, and the V-groove angle β is β = 26 °. Was used.
[0036]
As a double cogged V belt, the elastic modulus in the belt width direction is 500 MPa, and three strands each of which the core wire is twisted with two aramid fiber yarns (1666.5 dtex @ 1500 de) are twisted. The canvas used was nylon 6 warp and wooly-treated nylon 6 weft.
[0037]
The double cogged V-belt described above has a cut angle ρ of ρ = 28 ° (> β) (Invention Example 1) and a cut angle ρ of ρ = 30 ° (> β) (Invention Example 2). While applying tension to the double cogged V belt such that each of the double cogged V belts presses the sheave of the driven pulley with a force of 1250 N in the axial direction, the speed ratio is adjusted to the pulley pitch diameter D1 of the drive pulley by D1 = The drive pulley is driven to rotate at a rotation speed of 2000 rpm while the pulley pitch diameter D2 of the driven pulley is 68.8 mm and the pulley pitch diameter D2 of the driven pulley is 112.0 mm. 1 and Invention Example 2 were measured.
[0038]
For comparison, a double cogged V belt having a cut angle ρ of ρ = 24 ° (<β) (Comparative Example 1) and a cut angle ρ of ρ = 26 ° (= β) (Comparative Example) 2) were prepared, and the transmission capacity [unit: N / m] was measured for Comparative Examples 1 and 2 in the same manner as in Invention Examples 1 and 2, respectively. The above results are shown together in Table 1 and FIG.
[0039]
[Table 1]

[0040]
As can be seen from Comparative Example 1, Comparative Example 2 and Invention Example 1, the larger the cut angle ρ, the higher the transmission capacity. In particular, when the comparative example 2 showing the conventional case is compared with the inventive example 1, the inventive example 1 shows a transmission capacity exceeding 106% of the comparative example 2.
[0041]
However, in the invention example 1 and the invention example 2, the transmission capacity is the same (650 N / m). This is because the cut angle ρ has an upper limit, and if the cut angle ρ reaches the upper limit and the side of the belt fits the side of the V-groove sufficiently, then the given distance between the drive pulley and the double cog V-belt It is presumed that this is because the transmission capability is sufficiently exhibited, and therefore, even if the cut angle ρ becomes larger than the upper limit, no further transmission capability is generated. Rather, when the cut angle ρ is too large than the V-groove angle β, when the pulley pitch diameter increases, the elastic deformation in the direction in which the belt width dimension on the belt bottom surface side becomes large becomes insufficient, and In addition, there is a possibility that a "top hit" (see FIG. 4) in which the peak of the surface pressure distribution on the side surface of the belt is shifted outward in the radial direction of the belt pitch line.
[0042]
-Experimental example 2-
Next, an experiment performed for examining a change in the belt angle γ due to a change in the pulley pitch diameter D when the cut angle ρ is different will be described.
[0043]
First, four types of double cogged V belts (Sample 1 to Sample 4) having different cut angles ρ were produced. The cut angle ρ was set to ρ = 30 ° for sample 1, ρ = 28 ° for sample 2, ρ = 26 ° for sample 3, and ρ = 24 ° for sample 4.
[0044]
The point of the experiment was to measure each belt angle γ of the bent portion while bending each sample so that the pulley pitch diameter D was in the same state as when it changed in the range of D = 60 to 120 mm. . The above results are also shown in FIG.
[0045]
As can be seen from FIG. 6, in each case, the belt angle γ is smaller than the cut angle ρ (γ <ρ). In addition, the pulley pitch diameter D decreases as the pulley pitch diameter D decreases, but in a range where the pulley pitch diameter changes from 120 mm to approximately 80 mm, the belt angle γ is reduced only by about 1 °, but the pulley pitch diameter D is substantially reduced. In the range from 80 mm to 60 mm, the belt angle γ is smaller than 2 °. From this, it can be seen that the smaller the pulley pitch diameter D is, the smaller the belt angle γ is, and the lower the transmission performance is due to the occurrence of “bottom hit”, regardless of the cut angle.
[0046]
In Sample 2, the cut angle ρ (= 28 °) is the same as that of Invention Example 1 in Experimental Example 2, and the belt angle γ when the pulley pitch diameter D is D ≒ 70 mm is the V-groove angle β in Experimental Example 2. It can be seen that (γ = 26 °) is the same as (γ = 26 °). In the sample 1, the cut angle ρ (= 30 °) is the same as that of the invention example 2 in the experimental example 2, and the belt angle γ when the pulley pitch diameter D is D ≒ 70 mm is γ = 28 °. ing. From these facts, when the cut angle ρ is determined so that at least the belt angle γ falls within the range of β <γ ≦ β + 2 ° with respect to the V-groove angle β, the transmission performance can be sufficiently exhibited. It turns out that.
[0047]
On the other hand, in Samples 3 and 4, the cut angles ρ (= 26 ° and 24 °) are the same as those in Comparative Examples 2 and 1 in Experimental Example 2, and the pulley pitch diameter D is D = 70 mm. Are γ = 24 ° and γ = 22 °, respectively. From these facts, when the cut angle ρ is determined so that the belt angle γ becomes γ = β−2 ° and γ = β−4 °, the transmission capacity becomes the sample 1 and the sample 2 respectively. It can be seen that it is reduced to about 94% and about 90% in the case of.
[0048]
【The invention's effect】
As described above, according to the first aspect of the present invention, the torque of the driving pulley is transmitted through the double cogged V-belt through the frictional contact between the V-groove both sides of the driving pulley and the driven pulley and the belt both-sides of the double cogged V-belt. In the belt-type transmission, the speed ratio between the two pulleys is changed by changing the pulley pitch diameters of the two pulleys in opposite directions while the pulley pitch is being changed. By making the belt angle between both side surfaces of the belt larger than the V-groove angle, the bottom contact due to the belt angle being smaller than the V-groove angle on each pulley as the pulley pitch diameter of each pulley becomes smaller as the pulley pitch diameter becomes smaller is reduced. As a result, it is possible to reduce the size of the transmission with a smaller diameter of the minimum pulley pitch while suppressing a decrease in the transmission capacity. Wheel scooter, buggy, can contribute to higher output in small car such as snowmobiles.
[0049]
According to the invention of claim 2, the belt angle between both side surfaces of the double cogged V-belt when there is no tension is determined such that the belt angle on the drive pulley at the time of the low speed ratio matches the V-groove angle. Therefore, it is possible to prevent the double cogged V-belt from hitting the bottom of the drive pulley at the time of the Low, which requires the highest transmission capacity, and to thereby sufficiently exhibit the transmission capacity of the transmission. The effect according to the first aspect can be properly obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a relationship between a cut angle of a double cogged V-belt and a V-groove angle of a driving pulley in a belt-type continuously variable transmission according to an embodiment of the present invention.
FIG. 2 is a side view schematically showing the entire configuration of the belt-type continuously variable transmission.
FIG. 3 is a perspective view schematically showing a configuration of a double cog V belt.
FIG. 4 is a cross-sectional view schematically showing each belt angle of a double cog belt on a drive pulley when the speed ratio is top and when the speed ratio is low, together with a surface pressure distribution of a belt thrust on a V groove side surface at each speed ratio. It is.
FIG. 5 is a characteristic diagram illustrating a relationship between a cut angle and a torque transmission capability in Experimental Example 1.
FIG. 6 is a characteristic diagram showing a change in belt angle with a change in pulley pitch diameter in Experimental Example 2.
FIG. 7 is a view corresponding to FIG. 1 showing a configuration of a conventional double cogged V belt.
[Explanation of symbols]
1 Drive pulley 2 Follower pulley 3 Double cogged V belt 3a Upper cog 3b Lower cog ρ Cut angle (belt angle at no tension)
β V groove angle r Belt angle

Claims (2)

A drive pulley and a driven pulley each having a V-shaped cross-section and a variable pulley pitch diameter;
A double cogged belt having an upper cog and a lower cog on the belt rear side and the belt bottom side, and having V-shaped cross sections on both sides of the belt, and being wound between the driving pulley and the driven pulley. With a V-belt,
While transmitting the torque of the driving pulley to the driven pulley via the double cogged V-belt by frictional contact between both side surfaces of each V-groove of the driving and driven pulley and both side surfaces of the double cogged V-belt,
A belt-type transmission configured to change a speed ratio between the driving and driven pulleys by changing the pulley pitch diameters of the driving and driven pulleys in opposite directions.
The belt type transmission device wherein the belt angle between both side surfaces of the double cogged V-belt when there is no tension is set to be larger than the V-groove angle between both side surfaces of the V-grooves of the driving and driven pulleys. . The belt-type transmission according to claim 1,
The belt angle between both side surfaces of the double cogged V-belt when there is no tension is determined such that the belt angle on the driving pulley when the speed ratio between the driving and driven pulleys is the lowest matches the V-groove angle. A belt type transmission device characterized by the above-mentioned.

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