JPH0526366Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is a pulley that changes the diameter of each of a pair of variable pulleys around which a transmission belt is wound, thereby making the speed ratio between the two pulleys variable. This invention relates to improvements in transmissions.

(Prior Art) This type of pulley type transmission has been widely used in relatively low-load power transmission systems, such as transmissions for agricultural machinery and light vehicles. This transmission has, for example, a pair of variable pulleys (driving and driven pulleys) respectively attached to a pair of rotating shafts arranged parallel to each other, and each pulley is rotatably integral with the rotating shaft and slides. a fixed sheave that is fixed irremovably; and a movable sheave that is rotatably and slidably supported on a rotating shaft and that forms a belt groove with a V-shaped cross section around which a transmission belt is wound. The gear ratio between both rotating shafts can be switched from low speed to high speed by moving the movable shaft toward and away from the fixed shaft to change the pulley diameter (effective radius of the belt groove). be.

(Problem to be solved by the invention) By the way, in this transmission device, when the rotating shaft positions of the driving and driven pulleys are fixed, when applying tension to the belt, a tension pulley is generally arranged between both pulleys. At the same time, a method called reverse tensioning is employed in which tension is applied to the belt by urging the pulley with a biasing means such as a spring to press the slack side span of the belt.

When this tension pulley is displaced in the opposite direction to the belt pressing direction against the urging force of the urging means, the pressing force against the belt is removed and the belt tension becomes zero, so that the tension between the driving and driven pulleys is reduced. power transmission can be stopped. That is, the tension mechanism can function as a clutch. Therefore, the transmission has not only a gear shifting function but also a clutch function, and the clutch can be turned off immediately regardless of the gear ratio, eliminating the need for a separate multi-disc clutch or the like as an emergency clutch. It is advantageous.

In this case, in order to improve the effectiveness of the clutch by reliably eliminating power transmission between the pulleys when the clutch is OFF, it is important to prevent the belt from rotating with the pulley when the clutch is OFF. Therefore, by using a belt regulating member to restrict the outward spread of the belt span between the pulleys so that the belt is positioned radially outward from the pitch line of the pulleys when the clutch is OFF, it is possible to eliminate belt rotation. It is possible to do so.

However, since the pitch diameter of each pulley differs due to switching of the speed ratio, there is a problem in that the mounting position of the belt regulating member is restricted. That is,
When the belt regulating member is placed at a position where the clutch is activated in a low speed state, the belt contacts the regulating member in a high speed state. On the other hand, if the belt regulating member is positioned in accordance with the high speed state, the belt will not be regulated by the regulating member in the low speed state, causing the belt to rotate and reducing the effectiveness of the clutch.

This invention was made in view of these points,
The purpose of this is to change the mounting structure of the belt regulating member mentioned above, so that when the clutch is OFF, the movement of the belt tension side span is regulated regardless of changes in the gear ratio, and the rotation of the belt with the pulley can be reliably stopped. The object of the present invention is to improve the clutch function of a pulley type transmission.

(Means for Solving the Problem) In order to achieve the above object, the invention according to claim (1) utilizes a tension mechanism that presses the slack side span of the belt to generate belt tension. The belt regulating member is moved in accordance with the displacement of the pulley in .

Specifically, in this invention, a pair of rotating shafts are arranged parallel to each other, a fixed shaft is fixed to each of the rotating shafts so as to be rotatable and immovable in the axial direction;
and a driving and driven pulley constituted by a variable pulley consisting of a movable sheave that is rotatably supported on each rotating shaft so as to be movable in the axial direction and that forms a belt groove with a V-shaped cross section between it and the fixed sheave. , a transmission belt wound between the belt grooves of both pulleys, a pair of transmission mechanisms that change the diameter of the pulleys by moving the movable sheave of each pulley toward and away from the fixed sheave, and A speed change mechanism is provided between the two pulleys, and a speed change mechanism is arranged between the two pulleys to change the speed ratio between the two rotary shafts by interlocking the two speed change mechanisms so that the diameters of the pulleys change in opposite directions. A tension mechanism is provided that applies tension to the belt by pressing the slack side span of the belt when it is transmitted to the pulley.

The above-mentioned tension mechanism includes a tension arm that is swingably supported by a fixed body, and a tension arm that is pivotally supported at the tip of the tension arm, and the slack side of the belt when the power of the drive pulley is transmitted to the driven pulley. a tension pulley capable of pressing the span; and a biasing means disposed between the tension arm and the fixed body to bias the tension arm so that the tension pulley presses the belt; The belt tension is applied by pressing the slack side span.

Furthermore, a belt regulating support member is attached and fixed to the tip of the tension arm, and the tip extends toward the belt tension side span, and a belt regulating support member is attached to the tip of the belt regulating support member, and the tension pulley is arranged in the opposite direction to the belt pressing direction. A belt regulating member is provided that regulates the belt tension side span from moving outward when the belt pressing force becomes zero due to displacement in the direction of a predetermined amount or more.

(Operation) With the above configuration, the device according to claim (1):
When the clutch is ON, the tension arm rotates due to the biasing force of the biasing means of the tension mechanism, and the tension pulley at its tip presses the slack side span of the belt between the drive and driven pulleys, and this pressure causes the belt to tighten. The tension increases, belt thrust is generated, and power is transmitted between both pulleys.

On the other hand, when turning the clutch OFF, if the tension arm is rotated in the opposite direction to the belt pressing direction against the urging force of the urging means, the pressing force of the tension pulley against the belt span is removed and the belt The tension becomes zero, and no power is transmitted between both pulleys, and the clutch becomes OFF. Since the belt regulating member is attached to the tip of the tension arm via the belt regulating support member, even if the belt tension side span between both pulleys tries to move outward when the clutch is in the OFF state, it will not move. is regulated by the belt regulating member, and due to this regulation, the belt at the pulley is positioned outside the pitch line, eliminating the rotation of the belt, thereby making it possible for the clutch to work reliably.

In this case, the belt regulating member is provided at the tip of a belt regulating support member that is attached and fixed to the tip of the tension arm of the tension mechanism, and since the belt regulating member is displaced in accordance with the displacement of the tension pulley, when the clutch is OFF, The belt regulating member is always located at the optimal position to regulate movement to the outside of the belt tension side span even when the gear ratio is low or high speed, and the belt regulating member does not come into contact with the belt or do not regulate the belt. No slackening occurs, and therefore clutch effectiveness can be reliably obtained regardless of the gear ratio.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

1 and 2 show the overall structure of an embodiment in which the present invention is applied to a transmission of an agricultural machine. In both figures, 1 is a vehicle body of an agricultural machine, and in this vehicle body 1, an engine 3 as a power source having a crankshaft 2 is elastically supported by a plurality of vibration isolating rubbers 4, 4, . . . as elastic members. This anti-vibration rubber 4, 4...
Thus, transmission of engine vibration to the vehicle body 1 is suppressed. Reference numeral 5 denotes an intermediate shaft rotatably supported by the vehicle body 1 via a bearing (not shown), and this intermediate shaft 5 is an axle (not shown) of an agricultural machine.
is connected to. These crankshaft 2 and intermediate shaft 5 are arranged parallel to each other.

A cylindrical drive shaft 6 serving as a first rotation shaft is attached to the crankshaft 2 so as to rotate integrally therewith.
That is, a center hole 6a is formed through the drive shaft 6, and the crankshaft 2 is inserted into the center hole 6a from one end side (upper side in FIG. 2) of the drive shaft 6.
The drive shaft 6 is rotatably attached to the crankshaft 2 by screwing a fastening bolt 8 from the other end of the drive shaft 6 to the end of the crankshaft 2 via a stopper 7.

Further, a cylindrical driven shaft 9 serving as a second rotating shaft is rotatably attached to the intermediate shaft 5 with the same mounting structure as the drive shaft 6 described above. That is, the intermediate shaft 5 is inserted into the center hole 9a of the driven shaft 9 from one end side (lower side in FIG. 2), and the fastening bolt 11 is inserted into the intermediate shaft 5 from the other end of the driven shaft 9 via the stopper 10. A driven shaft 9 is attached to the intermediate shaft 5 by screwing and fastening the end portion thereof.

A drive pulley 12 is provided at one end of the drive shaft 6. The drive pulley 12 includes a flange-shaped fixed sheave 14 that is rotatably and non-slidably fixed to the drive shaft 6 by a key 13, and a boss portion 1 that is attached to the drive shaft 6 so as to face the fixed sheave 14.
It consists of a flange-shaped movable sheave 15 which is slidably and rotatably connected to each other by a key 16 at 5a, and a belt groove 17 is formed between these two sheaves 14 and 15.

On the other hand, a driven pulley 18 is provided on the driven shaft 9. This driven pulley 18 has the same configuration as the drive pulley 12 described above, and includes a flange-shaped fixed sheave 20 that is rotatably and non-slidably fixed to the driven shaft 9 by a key 19, and a flange-shaped fixed sheave 20 that is fixed to the driven shaft 9 by a key 19 to drive the drive pulley 12. A flange is slidably and rotatably connected to the boss portion 21a of the driven shaft 9 by a key 22 so as to face the movable sheave 15 in the drive pulley 12 on the shaft 6 in a direction opposite to the direction in which the movable sheave 15 faces the fixed sheave 14. It consists of a movable sheave 21 with a shape of
A belt groove 23 is formed between them. and,
A V-belt B is wound between the belt groove 17 of the drive pulley 12 and the belt groove 23 of the driven pulley 18.
Each movable sheave 15, 21 is brought into contact with and separated from the fixed sheave 14, 20, respectively, and each pulley 1
Change the diameter of pulleys 2 and 18 (effective radius for V-belt B). For example, when the movable sheave 15 of the drive pulley 12 is brought close to the fixed sheave 14 and the movable sheave 21 of the driven pulley 18 is separated from the fixed sheave 20, the drive pulley 12
By making the pulley diameter larger than that of the driven pulley 18, the rotation of the drive shaft 6 is transmitted to the driven shaft 9 at an increased speed. On the other hand, when the movable sheave 15 of the drive pulley 12 is separated from the fixed sheave 14 and the movable sheave 21 of the driven pulley 18 is brought closer to the fixed sheave 20, the drive pulley 12
The rotation of the drive shaft 6 is decelerated and transmitted to the driven shaft 9 by reducing the pulley diameter of the driven pulley 18 and increasing the pulley diameter of the driven pulley 18.

A first cam mechanism 24 is provided on the drive shaft 6 for moving the movable sheave 15 of the drive pulley 12 toward and away from the fixed sheave 14. The cam mechanism 24 has a cylindrical cam 26 externally fitted and supported on the boss portion 15a of the movable shaft 15 via a bearing 25 so as to be relatively rotatable and movable in the axial direction. This cam 26 has a pair of inclined cam surfaces 26 on its end surface opposite to the drive pulley 12.
a, 26a are at equal angular intervals in the circumferential direction (180° intervals)
A rotary lever 27 is integrally rotatably protruded from the outer periphery.

Further, a roller mount 29 serving as a cam follower is supported on the outer periphery of the other end of the drive shaft 6 via a bearing 28 so as to be relatively rotatable. Two pins 30, 30 extending in the radial direction are integrally attached to the outer periphery of the roller mounting base 29 so as to face each other in the diametrical direction. The head side of each pin 30 protrudes from the roller mounting base 29, and a cam roller 31 that rolls in contact with each cam surface 26a of the cam 26 is rotatably supported on the protruding portion.

Furthermore, a mounting flange 32 is integrally provided on the outer periphery of the roller mounting base 29, and the flange 32
The tip of the roller mounting base 29 is connected to the vehicle body 1 via pins 33, 34 and a fixing rod 35.
is fixed so that it cannot rotate.

On the other hand, a second cam mechanism 36 is provided on the driven shaft 9 as a speed change mechanism for moving the movable sheave 21 of the driven pulley 18 toward and away from the fixed sheave 20. The second cam mechanism 36 has the same configuration as the first cam mechanism 24, and is a cylindrical cam that is externally fitted and supported on the boss portion 21a of the movable shaft 21 via a bearing 37 so as to be rotatable and non-slidable. 38, and the driven pulley 18 of this cam 38
A pair of inclined cam surfaces 38a, 38 are provided on the opposite end surface.
a is formed, and a rotary lever 39 is rotatably attached to the outer periphery of the rotary lever 39. The rotating lever 39
An operating lever mounting member 40 is attached to the bolt 4 at the tip of the
1, 41, and its mounting member 40
The tip is connected to an operating lever (not shown). Further, a bearing 42 is provided on the outer periphery of the other end of the driven shaft 9.
A roller mounting base 43 (cam follower) is supported through the roller mounting base 43, and a mounting flange 44 is integrally provided on the outer periphery of the roller mounting base 43, and the tip of the flange 44 is connected to the vehicle body 1 via a pin 45. Ori,
The roller mounting base 43 is fixed to the vehicle body 1 and cannot rotate. A pair of pins 46, 46 extending in the radial direction are attached to the outer periphery of the roller mount 43 at equal intervals in the circumferential direction, and the protruding portion of each pin 46 from the roller mount 43 has the above-mentioned A cam roller 47 that comes into contact with each cam surface 38a of the cam 38 is rotatably supported.

The rotary lever 2 of the first cam mechanism 24 is
A link ball 48 is rotatably supported at the tip of 7. One end of a straight bar-shaped link 49 is screwed to the link ball 48 . This link 49 extends toward the driven shaft 9, and its other end is rotatably connected to the operating lever mounting member 40 via a link ball 55 with a rotation center parallel to the driven shaft 9. Therefore, the above link ball 4
8, 50 and the link 49, the cams 26, 38 in each cam mechanism 24, 36 are linked to each other according to the switching device of the operating lever, and the movable shake 1
By rotating the cam rollers 31, 47 on the cam surfaces 26a, 38a of the movable shaves 15, 21, the movable shaves 15, 21 are moved in the axial direction to form the fixed shaves. 14 and 20 in opposition to each other, and the effective radius of the belt grooves 17 and 23, that is, the pulley 1
A speed change switching mechanism 51 is configured in which the diameters of pulleys 2 and 18 are made variable and the speed ratio between the crankshaft 2 and the intermediate shaft 5 is changed.

As shown in FIG. 1, between the driving and driven pulleys 12 and 18, one of the pair of pans B ₁ and B ₂ of the belt B stretched between both the pulleys 12 and 18 is connected to the driving pulley 12. A tension mechanism 52 is provided that applies tension to the belt B by pressing the slack side span _B2 , which becomes the slack side, from the back side when the driving force is transmitted to the driven pulley 18. The tension mechanism 52 includes a tension arm 54 that is swingably supported on the vehicle body 1 (fixed body) by a shaft 53;
A tension pulley 56 is rotatably supported by a shaft 55 at the tip of the arm 54, and a tension pulley 56 is extended between the middle part of the tension arm 54 and the vehicle body 1, and the tension arm 54 is connected to the tension pulley 5.
6 consists of a spring 57 as a biasing means that rotates and biases the belt in the clockwise direction in FIG. 1 so as to press the back side of the belt slack side span _B2 . When the tension arm 54 is rotated by a predetermined angle or more in the counterclockwise direction in FIG. By setting the value to zero, power transmission between the driving and driven pulleys 12 and 18 is stopped and the clutch is turned off.

Further, the base end of a support plate 58 made of a thin plate serving as a belt regulating support member is integrally bonded and fixed to the distal end of the tension arm 54. The tip of the support plate 58 extends toward the tension side span B ₁ of the belt B, and a first regulating pin 59 as a belt regulating member extending parallel to the axis 55 of the tension pulley 56 projects from the tip. The support plate 58 and regulation pin 59 allow
As the tension arm 54 rotates counterclockwise in FIG. 1, the tension pulley 56 is displaced by a predetermined amount or more in the direction opposite to the belt pressing direction, and the clutch is turned OFF.
A belt regulating mechanism 60 is configured in which a regulating pin 59 regulates the movement of the belt tension side span B ₁ to the outside when this occurs. Position of the above regulating pin 59 (length of support plate 58)
is appropriately set according to the hardness of the belt B and the diameter of the pulley 12 so that the belt B is positioned radially outward from the pitch line of the drive pulley 12 when the clutch is OFF. Further, a second regulating pin 61 is fixedly attached to a predetermined position of the vehicle body 1 corresponding to the slack side span _B2 of the belt B.

The feature of the present invention is that, as described above, the first regulating pin 59 is connected to the tension arm 54 via the support plate 58, so that the regulating pin 59 is attached to the tension pulley 56. It is connected to the tension mechanism 52 so that it can be displaced in the same direction in conjunction with the displacement.

In addition, the movable sheave 15 in the fixed sheave 14, 20 of the driving and driven pulleys 12, 18,
Belt grooves 17 and 2 are provided on the surface opposite to belt groove 21, respectively.
3. A cylindrical ring portion 14a extending concentrically with the drive and driven shafts 3 and 6 toward the movable shafts 15 and 21 at a predetermined position on the inner peripheral edge corresponding to the bottom portion.
20a is integrally provided in a protruding manner. On the other hand, annular grooves 15b and 21b as annular recesses are formed on the surfaces of the movable sheaves 15 and 21 facing the fixed sheaves 14 and 20.
are formed corresponding to the ring portions 14a, 20a, and when the movable sheave 15, 21 approaches the fixed sheave 14, 20, the ring portions 14a,
20a is accommodated in the annular grooves 15b and 21b.

Next, the operation of the above embodiment will be explained.

First, the normal driving state (clutch
ON state), the tension arm 5 is
4 is biased clockwise in _FIG . A thrust is generated, and power is transmitted from the driving pulley 12 to the driven pulley 18 via the belt B.

For example, when the rotation of the engine 3 is to be reduced to a low speed state that is transmitted to the axle, the operating lever of the speed change switching mechanism 51 is positioned at the low speed position (Lo). This operating lever is connected to a rotating lever 39 on the outer periphery of the cam 38 in the second cam mechanism 36 via a mounting member 40, so that when the switching operation to the low speed position (Lo) is performed, the cam 38 is rotated. The driven pulley 18 rotates in one direction around the boss portion 21a of the movable sheave 21 while rolling each cam roller 47 on the surface 38a. This results in
The cam surface 38a is pushed by the roller 47 and the cam 3
8 moves downward on the driven shaft 9 in FIG.
approaches 0. As a result, the driven pulley 18 closes and its pulley diameter increases, and this increase in pulley diameter draws the V-belt B toward the driven pulley 18.

Furthermore, since the rotary lever 27 is drivingly connected to the mounting member 40 via a link 49 and link balls 48 and 50, when the operating lever is switched to the low speed position (Lo), the driven pulley 18 is rotated. In synchronization with the movement of the movable shake 21, the cam 26 of the first cam mechanism 24 rotates on the drive shaft 6 in the same direction as the cam 38 of the second cam mechanism 36. This rotation of the cam 26 eliminates the pressure on the cam roller 31. Therefore, the driven pulley 18
Due to the tension of the belt B moving to the side, the cam 26 and the movable sheave 15 connected to it via the bearing 25 move on the drive shaft 6 in a direction away from the fixed sheave 14 (downward in the figure), and both Drive pulley 1 due to the separation between sheaves 14 and 15
2 opens and the pulley diameter decreases. These results
The pulley diameter of the drive pulley 12 becomes smaller than that of the driven pulley 18, and the rotation of the drive shaft 6 is decelerated and transmitted to the driven shaft 9.

Conversely, in a high-speed state where the rotation of the engine 3 is increased and transmitted to the axle, the operating lever is positioned at the high-speed position (Hi). With this switching operation of the operating lever, the cam 26 of the first cam mechanism 24 rotates in the other direction around the boss portion 15a of the movable sheave 15 on the drive pulley 12 while rolling the cam roller 31 on its cam surface 26a. Rotate. This rotation of the cam 26 causes the cam surface 26a to rotate against the cam roller 3.
1 and moves upward on the drive shaft 6 as shown in FIG. do. This increase in pulley diameter draws the V-belt B toward the drive pulley 12.

Further, in synchronization with the movement of the movable shake 15, the cam 38 of the second cam mechanism 36 rotates on the driven shaft 9 in the same direction as the cam 26, and the rotation of the cam 38 causes the cam roller to rotate. 47 is no longer pressed, and the tension of the belt B causes the driven pulley 1 to
The movable sheave 21 of No. 8 moves on the driven shaft 9 in the direction away from the fixed sheave 20 (upward in the figure) together with the cam 38. Due to the separation between the two sheaves 20 and 21, the driven pulley 18 opens and its pulley diameter decreases. As a result, the pulley diameter of the drive pulley 12 becomes larger than that of the driven pulley 18, and the rotation of the drive shaft 6 is accelerated and transmitted to the driven shaft 9.

In that case, since the engine 3 is elastically supported by the vehicle body 1 via the vibration isolating rubbers 4, 4..., the vibration isolating rubbers 4, 4... are compressed due to changes in the tension side tension of the transmission belt B when the load changes. When the amount of deformation changes and the distance between the crankshaft 2 and the intermediate shaft 5 changes, for example, when the transmission load increases and the distance between the shafts decreases accordingly, this decrease in the distance between the shafts causes the first
The cam 26 in the cam mechanism 24 rotates clockwise in FIG. 1, and the gear ratio is about to change. However, the roller mounting base 29 of the first cam mechanism 24
are connected and fixed to the vehicle body 1 via pins 33, 34 and a fixing rod 35, so the roller mounting base 2
9 rotates in the same direction (clockwise) in response to the rotation of the cam 26, and as a result, the opening/closing amount of the drive pulley 12 does not change. Therefore, even if load fluctuations occur, the gear ratio can be kept constant, and the agricultural machine can be stably run at a constant speed.

Furthermore, since the gear ratio does not change when the load changes, no undue force is applied to the link 49 that connects both cam mechanisms 24 and 36, and deformation thereof can be effectively prevented.

Furthermore, since the speed changeover mechanism 51 has a straight rod-shaped link 49, the cam mechanisms 24, 36 of both pulleys 12, 18 are connected to each other with high rigidity by the link 49, and the operating force of the operating lever is transmitted efficiently, thereby reducing loss.

Further, since the link 49 is a straight bar, the space for arranging the speed change switching mechanism 51 is small, and its layout can be simplified. Therefore, it is possible to both facilitate the arrangement and layout of the speed change switching mechanism 51 and to suppress vibration transmission by employing the straight rod-shaped link 49.

In this embodiment, the pulley 56 of the tension mechanism 52 applies tension to the V-belt B by pressing the back surface of the slack side span _B2 of the V-belt B, and this tension increases the belt thrust. occurs, and the driving and driven pulley 1
Movable shields 15, 21 in both 2 and 18
is moved in the axial direction by mechanical drive by the speed change switching mechanism 51, so that the drive and driven pulley 1
The opening and closing forces between 2 and 18 are reversed, and both pulleys 1
The opening and closing forces between 2 and 18 partially cancel each other out, and the remainder becomes the operating force. In this way, both pulleys 1
When the gear ratio between the drive and driven shafts 6 and 9 is changed by moving the movable shafts 15 and 21 of 2 and 18 in the opposite direction, each cam mechanism changes as shown in FIGS. 5 and 6. 24, 36 cylindrical cams 26, 38
The roller mounting base 2 is attached to the cam surfaces 26a and 38a in
Component force A1 in the direction parallel to the driving or driven shafts 6, 9 due to the force A acting from the rollers 31, 47 of 9, 43
and a component force A2 in the orthogonal direction is generated, and the latter component force A2 is generated between the axes of the driving or driven shafts 6 and 9 and the speed change switching mechanism 51.
This action acts perpendicularly to the line connecting the connecting point to the link 49, and as shown in FIG. A cam rotational reaction force W is generated which is always perpendicular to the line and in the opposite direction to the component force A2, and as shown in FIG. , 21 so as to press the boss portions 15a, 21a at the center position of the range where the belt B of the pulleys 12, 18 is wound. In other words, the cam rotation reaction force W against the boss portions 15a, 21a is due to the clearance at the sliding portion between the boss portions 15a, 21a and the drive or driven shafts 6, 9, which causes the movable shafts 15, 21 to move toward the belt B.
Movable shields 15, 21 when receiving thrust from
A moment M2 is generated in the opposite direction to the moment M1 acting in the direction of tilting the drive or driven shafts 6, 9. This moment M2 cancels out the moment M1 and reduces it, as shown in Figure 7a.
As shown in FIG.
The surface pressure distribution on the inner periphery of the driving or driven shafts 6, 9 is distributed in the axial direction, and the cylindrical cam 2
6 and 38 are the boss parts 15 of the movable shakes 15 and 21
a, when not supported on 21a (Fig. 7b)
There is no large peak in the surface pressure distribution as in (see), and the sliding resistance of the boss portions 15a, 21a is reduced. As this sliding resistance becomes smaller, the load that the belt-generated thrust F gives to the fixed points of the cylindrical cams 26 and 38, that is, the take-out thrust F' increases. 26 and 38 as the extraction thrust F'.

The transmission device includes a driving pulley and a driven pulley 1.
The opening and closing forces between 2 and 18 are reversed, and both pulleys 12,
The cylindrical cams 26 and 38 of both cam mechanisms 24 and 36 are connected so that the opening and closing forces between them partially cancel each other out, and the extraction thrust F1' or F2' of one cam mechanism 24 or 36 is transferred to the other cam mechanism 24 or 36. Cam mechanism 36 or 24
Therefore, when the gear ratio of the transmission is constant and no gear change is performed, as shown in Figs. 8 and 9,
The above extraction thrust F1', F2' is in the case of this embodiment (9th
(see Figure a) is larger than when the cylindrical cams 26, 38 are not supported on the boss portions 15a, 21a of the movable shakes 15, 21 (see Figure 9b); The thrust forces F1' and F2' are the same and cancel each other out, so that the thrust extraction efficiency is the same as in the conventional case. However,
When changing the gear ratio, as shown in FIG. 10, the difference between the belt-generated thrust F and the output thrust F1', F2' is the load (operating force) required for the gear shifting operation, so the cylindrical cams 26, 38 The movable sieve 15,2
In the case of not being supported on the boss portions 15a and 21a of No. 1 (see Fig. 10b), the remaining operating force increases as the take-out thrust forces F1' and F2' are small; In FIG. 10a), since the extraction thrust forces F1' and F2' are large, the operating force can be reduced accordingly.

However, the contact between the cams 26, 38 and the roller mounting bases 29, 43, which are cam followers, is
Since the rolling contact is made by the rollers 31 and 47 rolling on the cam surfaces 26a and 38a, respectively, the sliding resistance is significantly smaller than when the cam follower is brought into direct sliding contact with the cam surface. As a result, the switching operation force required during gear shifting can be reduced, and the gear ratio can be quickly switched in an emergency.

In addition, since the degree of wear on the cam surfaces 26a and 38a is low, the positioning accuracy of the pulleys 12 and 18 is improved, and the switching operation force can be reduced and maintained for a long period of time, furthermore, there is no need for lubricating oil maintenance. It can be done.

On the other hand, when the transmission of power from the engine 3 to the axle is cut off and the clutch is turned OFF in order to emergency stop the running of the agricultural machine, the tension arm 54 resists the biasing force of the spring 57 of the tension mechanism 52. Then rotate counterclockwise in Fig. 1, and tighten the slack side span of the belt B of the tension pulley
The pressure on B ₂ is stopped, and with this stop of the pressure, the tension on the belt B disappears, and power transmission from the drive pulley 12 to the driven pulley 18 is stopped.

In this clutch OFF state, the tension side span B ₁ of the belt B moves outward by the first regulating pin 59, and the slack side span B ₂ moves outward by the second regulating pin 61. Due to this regulation, the belt B at the drive pulley 12 is positioned outside the pitch line, and the belt B is no longer rotated with the pulley 12, so that the clutch can be operated reliably.

In that case, since the first regulating pin 59 is integrally connected to the tension arm 54 of the tension mechanism 52 via the support plate 58, the regulating pin 59 is moved in accordance with the displacement of the tension pulley 56. The position changes accordingly. Therefore, when the clutch is OFF, the regulation pin 59 is always in the position shown by the imaginary line in the figure, even if the gear ratio of the transmission is in the low speed state shown in FIG. 4a or in the high speed state shown in FIG. It will be positioned at the optimum position to restrict outward movement of the belt tension side span _B1 . As a result, the regulating pin 59 does not come into contact with the belt B when the clutch is ON, or cease to regulate the belt B when the clutch is OFF, so that clutch effectiveness can be reliably obtained regardless of the gear ratio. can.

It goes without saying that the present invention can be applied to transmission devices in vehicles and other machines other than agricultural machines.

(Effect of the invention) As explained above, according to the invention recited in claim (1), in a pulley type transmission equipped with a driving pulley and a driven pulley consisting of a pair of variable pulleys, the slack side span of the belt is A tension mechanism that applies pressure to the belt by a tension pulley at the tip of the tension arm, and a tension mechanism attached to the tip of the belt regulating support member provided at the tip of the tension arm so as to extend toward the belt tension side span side. A belt regulating member is provided for regulating outward movement of the belt tension side span when the pulley is displaced by a predetermined amount or more in a direction opposite to the belt pushing direction and the belt pushing force becomes zero. By making it possible to displace the tension pulley in the same direction in conjunction with the displacement of the tension pulley, the belt regulating member always maintains the belt tension when the clutch is turned off, displacing the tension pulley in the opposite direction to the pressing direction and reducing the belt tension to zero. It can be positioned at the optimal position to restrict outward movement of the side span, and the clutch can be reliably effective regardless of the gear ratio of the transmission, thereby improving the clutch function.

[Brief explanation of the drawing]

Fig. 1 is a front view of a transmission according to an embodiment of the present invention, Fig. 2 is a sectional view thereof, Fig. 3 is a partially cutaway plan view of a tension arm, and Figs. 4a and 4b are respectively FIG. 6 is an explanatory diagram schematically showing the displacement of a regulation pin when the gear ratio is switched. Fig. 5 is a schematic plan view showing the state of action of the cam rotation reaction force based on the relationship between the belt generated thrust and the force applied to the link, Fig. 6 is a schematic front view of the same, and Fig. 7 is a movable shaft due to the cam rotation reaction force. Fig. 8 is an explanatory diagram showing the relationship between belt-generated thrust and extraction thrust in both pulleys, and Fig. 9 is an explanatory diagram showing the relationship between the extraction thrust in both pulleys during non-shift operation. Fig. 10 is an explanatory diagram showing the relationship between
This is a corresponding diagram. 1... Vehicle body (fixed body), 6... Drive shaft (rotating shaft), 9... Driven shaft (rotating shaft), 12... Drive pulley, 14... Fixed shake, 15... Movable shake, 17... Belt groove, 18... Driven pulley, 2
0...Fixed sieve, 21...Movable sieve, 2
3... Belt groove, 24... First cam mechanism (speed change mechanism), 36... Second cam mechanism (speed change mechanism), 51...
...speed change mechanism, 52...tension mechanism, 54
... Tension arm, 56 ... Tension pulley, 57 ... Spring (biasing means), 58 ... Support plate (belt regulation support member), 59 ... Regulation pin (belt regulation member), 60 ... Belt regulatory mechanisms;
B...V-belt, _B1 ...Tight side span, _B2 ...Loose side span.

Claims (1)

[Claims for Utility Model Registration] A pair of rotating shafts arranged parallel to each other, a fixed shaft fixed to each of the rotating shafts in a rotationally integral manner and immovable in the axial direction, and a fixed shaft fixed to each of the rotating shafts in a rotationally integral manner. and a movable sheave that is supported movably in the axial direction and forms a belt groove with a V-shaped cross section between it and the fixed sheave, and a driving and driven pulley constituted by a variable pulley; The transmission belt wound between the belt and the movable sheave of each pulley mentioned above are moved toward and away from the fixed sheave to change the pulley diameter of the pulley.
a pair of transmission mechanisms; a transmission switching mechanism that interlocks the transmission mechanisms so that the pulley diameters of the pulleys change in opposite directions to vary the transmission ratio between the rotating shafts; and a fixed body that swings. a tension arm supported by the tension arm; a tension pulley pivotally supported at the tip of the tension arm and capable of pressing the slack side span of the belt when the power of the drive pulley is transmitted to the driven pulley; It has a biasing means disposed between the tension arm and the fixed body, which biases the tension arm so that the tension pulley presses the belt, and presses the slack side span of the belt to apply tension to the belt. It is attached and fixed to the tension mechanism and the tip of the tension arm mentioned above,
a belt regulating support member whose tip extends toward the belt tension side span; and a tension pulley attached to the tip of the belt regulating support member, which displaces the belt pushing force by a predetermined amount or more in a direction opposite to the belt pushing direction, so that the belt pushing force becomes zero. 1. A pulley-type transmission comprising: a belt regulating member that regulates outward movement of a belt tension side span when the belt is stretched.