JP3404185B2 - Belt transmission - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved technique for a belt transmission device.

[0002]

2. Description of the Related Art Conventionally, in agricultural machinery and the like, a pulley type transmission utilizing belt transmission has been widely used in order to shift the power of an engine and transmit it to a drive wheel or various working devices. As an example of a pulley type transmission utilizing this belt transmission, there is a conventional one such as, for example, Japanese Utility Model Laid-Open No. 57-16.
As shown in Japanese Patent Laid-Open No. 4352, a fixed sheave fixed to each of a pair of rotating shafts arranged in parallel with each other is integrally and non-slidably fixed to each of the rotating shafts. A movable sheave, which is arranged so as to face the fixed sheave so as to form a belt groove having a substantially V-shaped cross section, and is rotatably integrated and slidably supported, and one of the movable sheaves faces the fixed sheave. And a pair of variable pulleys in which the direction of the other movable sheave toward the fixed sheave is set to be opposite to each other, and a transmission belt is wound between the belt grooves of these variable pulleys to move the variable pulleys. The movable sheave is fixed to the fixed sheave by the rotation of the rotation cam with respect to the fixed cam. To approach and separate By arranging a cam mechanism for moving, and connecting the rotating cams of both cam mechanisms with a rod and a speed change shaft, when the movable sheave of one variable pulley approaches the fixed sheave facing it, the other variable pulley moves. The rotating cams of the two cam mechanisms are rotated in cooperation with each other so that the sheave moves away from the fixed sheave facing the sheave, and the effective radius (pulley diameter) of each variable pulley with respect to the transmission belt is changed so that the sheave moves between the two rotating shafts. A variable pulley type is known in which the gear ratio is changed.

By the way, not only the transmission having such a speed change pulley but also a belt transmission device having a plurality of pulleys and a transmission belt wound around the pulleys,
A tension mechanism having a tension pulley that presses the loose side span of the belt between the pulleys and a tension spring that biases this tension pulley in the pressing direction is provided, and the tension pulley of this tension mechanism presses the belt loose side span. It is common practice to apply tension to the belt.

[0004]

However, when the tension pulley is biased in the pressing direction by the belt spring force of the tension spring as described above, the tension spring is in a spring force generation state (a tension spring is in an expanded state and a compression spring is in a contracted state). It is necessary to assemble while keeping the state), there is no case in the belt transmission and the pulley and belt are in the opened state, but there is no problem, but if these pulleys and belts are housed in the case, The work of assembling the tension spring in a state where the spring force is generated in the case is troublesome, and it becomes necessary to use a special dedicated jig.

The present invention has been made in view of the above problems, and its main object is to improve the tension structure for a belt transmission device provided with a case by improving the locking structure of the tension spring on the case side. The purpose is to make it easy to assemble the spring so that the spring can be assembled in a state in which no spring force is generated.

[0006]

In order to achieve the above object, the present invention provides means for switching the tension spring from the outside of the case to a spring force generating state.

That is, according to the first aspect of the invention, at least one pair of rotating shafts supported by the case, pulleys respectively provided on the rotating shafts in the case, and a transmission belt wound between the pulleys. And a tension pulley that presses the loose side span of the belt, and a tension spring that urges the tension pulley to move so that the belt is pressed, and the loose side span of the belt is pressed by the tension pulley. Spring actuating means for causing the tension spring to generate a spring force from outside the case so that the tension pulley presses the belt with respect to the belt transmission device having a tension mechanism for applying tension.

According to the second aspect of the present invention, a pair of rotating shafts are arranged in parallel with each other and supported by the case, and are provided on the rotating shafts in the case. A fixed sheave that is fixedly supported immovably in the axial direction, and is provided facing the fixed sheave so as to form a belt groove having a substantially V-shaped cross section between the fixed sheave and the fixed sheave;
A movable sheave that has a boss portion that extends in the axial direction on the back side and that is externally fitted and supported by the boss portion so as to rotate integrally with the rotating shaft and be movable in the axial direction. Of the driven and driven pulleys, the direction of which is opposite to the direction of the other movable sheave to the fixed sheave,
A belt wound between the belt grooves of the drive and driven pulleys, and a first cam and a second cam that are respectively arranged on the back side of the movable sheaves of the drive and driven pulleys and are in cam contact with each other. One of the first and second cams is supported on the boss of the movable sheave via a bearing so as to be movable integrally and relatively rotatably with the movable sheave in the axial direction, and the other is immovably and rotatable in the axial direction on the rotating shaft. The rotary cam is provided so as to be rotatable relative to the shaft, and one of the cams is a rotary cam rotatable about the rotary shaft, while the other is a non-rotatable fixed cam. A drive pulley side and a driven pulley side cam mechanism for moving the movable sheave in the axial direction so as to move toward and away from the fixed sheave by relative rotation with respect to the drive pulley side and the driven pulley side cam mechanism,
Rotating the rotating cams of the two cam mechanisms interlockingly with each other so that when one movable sheave of the drive and driven pulleys approaches an opposing fixed sheave, the other movable sheave moves away from the opposing stationary sheave. , A gear change mechanism for changing the gear ratio between the two rotating shafts, an operating means for operating the gear change mechanism from outside the case, and a tension for pressing the loose side span of the belt wound between the drive and driven pulleys. The belt has a pulley and a tension spring that urges the tension pulley to move so that the belt is pressed, and the tension pulley pushes the loose side span of the belt so that the belt bites into the belt groove of each pulley. It is premised on a belt transmission having a tensioning mechanism for generating thrust to.

As in the first aspect of the invention, there is provided a spring actuating means for causing the tension spring to generate a spring force from outside the case so that the tension pulley presses the belt.

[0010] In these claims 1 or 2 invention, further
In addition, the spring actuating means penetrates the inside and outside of the case.
The rotating shaft that is rotatably supported in the through state and the rotating shaft
It is fixed to the inner end of the case at the base end so that it can rotate together.
The inner arm with the tension spring locked to
The rotation shaft is fixed to the outer end of the case at the base end so that it can rotate together.
On the outer surface of the case
Provided to fix the engaging portion at the tip of the outer arm.
And an outer arm, and the outer arm is connected to the inner arm.
Rotate around the rotation axis together with the arm to
By fixing the engaging part to the locking part of the case, tension
The spring is configured to generate a spring force. This
Therefore, in the invention of claim 1 or 2, the spring actuation is performed.
The tension spring is applied from outside the case by the means.
The tension pulley is turned on, which causes the tension pulley to
Press. That is, the tension spring is
While it is locked to the end of the
It is installed together with the belt, but in this installed state the tension
The spring has no spring force. After the assembly,
Rotate the outer arm together with the inner arm around the rotation axis.
And this inner arm causes the tension spring to spring.
Change to force generation state (biased state of tension pulley),
Fix the engaging part at the tip of the outer arm to the locking part of the case.
Then, the spring force generation state of the tension spring is fixed.
Holds constant. Since the tension spring can be switched from the outside of the case to the spring force generating state in this way, the tension spring is first made into the spring force non-generating state and installed in the case together with the pulley and the belt, and then the tension spring is spring-loaded from outside the case. It is only necessary to switch to the spring force generation state by the operating means, and the assembling work can be facilitated by assembling the tension spring in the spring force non-generation state.

Further, according to the second aspect of the invention, when the gear ratio between both rotary shafts is switched, one rotating cam (one of the first and second cams) of the drive pulley side or the driven pulley side cam mechanism is fixed. When rotated relative to the cam (the other of the first and second cams), the movable sheave of the pulley on the cam mechanism side moves in the axial direction to approach the fixed sheave, and the pulley closes. On the other hand, since the rotating cams of the drive and driven pulley side cam mechanisms are linked so as to interlock with each other by the shift changeover mechanism, the other rotating cam of the drive pulley side or the driven pulley side cam mechanism is also a fixed cam. Relative to the cam mechanism, the movable sheave of the pulley on the cam mechanism side moves axially away from the fixed sheave, and the pulley opens. In this way, in both pulleys, the contacting / separating operation of each movable sheave with respect to the fixed sheave becomes opposite, and the gear ratio between both rotary shafts is switched and changed by the movement of both movable sheaves in opposite directions.

The slack side span of the belt wound between the driving and driven pulleys is pressed by the tension mechanism, and the belt bites into the belt groove of each pulley, and a belt thrust is generated by the wedge effect at that time. Then, this belt thrust causes power to be transmitted between the rotating shafts.

Further, in this way, the thrust on the belt is generated by the pressing of the slack side span, and at the time of gear shifting between the two rotary shafts, the gear shifting mechanism drives and the rotating cam in the driven pulley side cam mechanism interlocks, Since both pulleys open and close in synchronization with each other, the opening and closing behaviors of the drive and driven pulleys are reversed, the opening and closing thrusts between the two pulleys partially cancel each other, and the rest becomes the shift operation force. That is, in general,
The initial tension acting on the belt is divided into tension on the tension side and tension on the slack side by the rotational torque input to the drive pulley, and the difference between these tensions transmits power from the drive pulley to the driven pulley. The thrust force (the force that the pulley pushes on the belt) is substantially the same in the static state where the pulley does not rotate, or in the light load state where the transmission load is small even if the pulley rotates. On the other hand, when the transmission load increases, the thrust on the drive pulley side always becomes larger than the thrust on the driven pulley side due to the change in the tension distribution in the belt, and a difference occurs between the two thrusts. Further, in the present invention, the cam mechanism is arranged on the back side of the movable sheave of each pulley, and all of them move the movable sheave in the axial direction by the relative rotation of the first cam and the second cam. The thrusts generated in the two pulleys cancel each other out, and by applying an external force larger than the difference between the two thrusts, the gear shift operation can be performed. Therefore, since the gear shift operation force may be an operation force that exceeds the difference between the thrusts generated in the two pulleys, the gear shift operation force can be significantly reduced not only when the load is light but also when the load is high. it can.

In addition, at that time, since the thrust generated in one pulley is transmitted to the other pulley as a thrust by the cam mechanism arranged on the back side of the movable sheave of each pulley, the thrust of each pulley is It is possible to efficiently convert into torque for relatively rotating both cams of the pulley side cam mechanism, and the power transmission path between them can be shortened so that the sliding resistance becomes extremely small, and the gear shift operation force can be further reduced. .

At this time, a cam rotation reaction force is generated on both cams by the torque for relatively rotating the first and second cams, which is converted from the thrust of the pulley. Then, the cam rotation reaction force generated on one of the cams supported on the boss portion of the movable sheave via the bearing acts so as to press the boss portion of the movable sheave supporting the cam. That is, the cam rotation reaction force on the boss portion is the moment acting in the direction of tilting the movable sheave with respect to the rotation shaft when the movable sheave receives thrust from the belt due to the clearance in the sliding portion between the boss portion and the rotation shaft. The boss portion maintains a substantially parallel degree to the rotation axis by the moment in the opposite direction, and the pressing force by the cam rotation reaction force has a predetermined width. Since it acts on the boss portion via the bearing, the surface pressure distribution of the inner periphery of the boss portion of the movable sheave with respect to the outer periphery of the rotation shaft is dispersed in the axial direction to eliminate a large peak, and as a result, the sliding resistance of the boss portion decreases. . As the sliding resistance becomes smaller, the belt-generated thrust is transmitted to the cam mechanism as a take-out thrust that is larger than the conventional thrust.

Further, in the transmission, the rotating cams of both cam mechanisms are connected by a gear change mechanism so that the opening and closing forces between both pulleys are reversed and the opening and closing forces between both pulleys partially cancel each other out. Since the extraction thrust of one cam mechanism is used for the belt thrust of the other cam mechanism, if this relationship is compared to a seesaw, when the gear ratio is constant and gear shifting is not performed, Although the thrust itself is larger in the case of the present invention than in the conventional case, the extraction thrust is the same on the drive side and the driven side, and these are balanced with each other, and the thrust extraction efficiency is the same as in the conventional case.

However, when changing the gear ratio,
Since the difference between the belt-generated thrust and the take-out thrust is the load (operating force) necessary for the gear shifting operation, in the conventional case, the remaining operation force increases as the take-out thrust becomes smaller, whereas in the present invention, Since the take-out thrust is large, the operating force is correspondingly small. As a result, the speed change between the rotary shafts can be quickly performed with a small operating force.

[0018]

[0019]

According to the third aspect of the invention, the tension spring is a tension spring.

According to a fourth aspect of the present invention, in the belt transmission device according to the second aspect of the present invention, the operating means transmits the movement of the operating portion operably arranged on the outer surface of the case to the gear shift mechanism. And a coupling mechanism for

Further, on the outer surface of the case, there is provided a gear ratio range adjusting means for regulating the operating range of the operating portion and adjusting the range of the gear ratio between the both rotary shafts.

With this configuration, even if the range of the gear ratio between the two rotary shafts of the belt transmission is deviated, after the assembly, the gear ratio range adjusting means on the outer surface of the case regulates the operating range of the operating portion to change the speed. The ratio range can be finely adjusted to a target range, and an accurate gear ratio range can be easily obtained.

In the invention of claim 5, the operating portion is an operating shaft rotatably supported in the case in a penetrating state. Further, the gear ratio range adjusting means is a pair of adjusting levers which are integrally attached to the operation shaft so as to rotate, and an adjusting unit which is attached to an outer surface of the case and which is capable of position adjustment for restricting a rotation range of the adjusting levers. And stopper.

According to this structure, the gear ratio can be changed by rotating the operating shaft. In addition, the adjustment lever integrally rotates with the rotation of the operation shaft, and the rotation range of the adjustment lever is restricted by the adjustment portions of the pair of stoppers on the outer surface of the case. Since the adjusting portion of each stopper is positionally adjustable, the rotation range of the adjusting lever can be changed by changing the position of the adjusting portion, and thus the range of the gear ratio can be adjusted. Therefore, the gear ratio range adjusting means can be embodied.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 4 and 5 show the entire structure of a pulley type continuously variable transmission T as a belt transmission device according to the present invention. This transmission T is not shown in the drawings but it is located between an engine and drive wheels in a traveling agricultural machine. Is arranged in the power transmission path of.

In FIGS. 4 and 5, reference numeral 1 is a case of the transmission T, which is divided into a front case 2 on the left side of FIG. 5 and a rear case 3 on the right side. The front case 2 is a dish-shaped one opened to the right side in FIG. 5, and a boss-shaped (cylindrical) input bearing hole 2a is formed in the upper part of the front case 2 in FIG. The bearing hole 2b is recessed. Further, the rear case 3 is a dish-shaped member opened to the left side in FIG. 5, and a boss-shaped input bearing hole 3a in the upper part of FIG. 5 corresponds to the input bearing hole 2a of the front case 2 described above. Similar output bearing holes 3b are formed in the lower portion so as to correspond to the output bearing holes 3b of the front case 2. A flange 2c is provided on the opening edge of the front case 2.
Is formed, and a plurality of screw holes 4, 4 are formed in the flange 2c.
4, ... are opened. On the other hand, a flange 3c joined to the flange 2c of the front case 2 is formed at the opening edge of the rear case 3, and a plurality of flanges 3c corresponding to the screw holes 4, 4, ... Bolt insertion hole 5,
5 are provided, and when assembling the front and rear cases 2 and 3, the flanges 2c and 3c are brought into contact with each other, and the assembly bolts 6 are inserted into the bolt insertion holes 5 of the rear case 3, respectively. The front end of the bolt 6 is screwed into the corresponding screw hole 4 of the front case 2 so that the cases 2 and 3 can be integrally assembled.

A plurality of screw holes 4 in the front case 2
, A predetermined pair of screw holes 4, ... In the illustrated example, a screw hole 4 (FIG.
Collars 7, 7 are fitted and inserted as knock pins into a pair of a screw hole 4 (on the left side at the upper end) and a screw hole 4 (on the right side at the lower end in FIG. 4) located substantially opposite to the tension pulley 41 with respect to the screw hole 4. The collars 7, 7 are used to perform centering when the front and rear cases 2, 3 are assembled.

As shown in FIG. 4, the lower left and right middle portions of the transmission case 1 are partially recessed so that the lower side of the transmission T does not interfere with the propeller shaft 113 extending in the longitudinal direction of the agricultural machine. There is.

The transmission case 1 includes an input shaft 9 (rotating shaft) and an output shaft 13 which are arranged in parallel with each other.
It is rotatably supported over 3. The input shaft 9 and the output shaft 13 rotate counterclockwise in FIG. The front end portion (the left end portion in FIG. 5) of the input shaft 9 rotates in the input bearing hole 2a of the front case 2 via the bearing 10, and the rear end portion rotates in the input bearing hole 3a of the rear case 3 via the bearing 11. Supported as possible. The front end of the input shaft 9 (the left end in FIG. 5) projects from the case 1 to the outside, and the output shaft of the engine (not shown) is drive-connected to this end.

On the other hand, a small diameter portion 13a is formed at the front end portion (the left end portion in FIG. 5) of the output shaft 13, and the small diameter portion 13a allows the output shaft 13 to pass through the bearing 14 in the output bearing hole 2b of the front case 2. It is rotatably supported. On the other hand, the rear end of the output shaft 13 is rotatably supported in the output bearing hole 3b of the rear case 3 via a bearing 15.
The rear end projects outside the case 1 and is drivingly connected to driving wheels (not shown). A sleeve 16 (in this embodiment, the sleeve 16 and the output shaft 13 constitute a rotating shaft in the present invention) is fitted to the intermediate portion of the output shaft 13 so as to be relatively rotatable. The inner diameter of the front end portion of the sleeve 16 is made larger than that of the other portion to form a large diameter portion 16a. The large diameter portion 16a and the small diameter portion 13 at the front end of the output shaft 13 are formed.
A bearing 17 is provided between the bearing 14 and the rear portion of the bearing 14 by engaging the inner ring 17a with the small diameter portion 13a of the output shaft 13 and the outer ring 17b with the sleeve 16.

The transmission case 1 accommodates a speed change pulley mechanism 20 for drivingly connecting the input shaft 9 and the output shaft 13 with a V belt 30 so that the speed can be changed. The speed change pulley mechanism 20 has a drive pulley 21 that is a speed change pulley arranged on the input shaft 9. This drive pulley 21
Is a flange-shaped fixed sheave 22 that is rotationally integrated and non-slidably keyed on the input shaft 9, and is slidable on the input shaft 9 by a boss portion 23a so as to face the fixed sheave 22. A flange-shaped movable sheave 23 supported so as to be relatively rotatable, and a belt groove 24 having a substantially V-shaped cross section is formed between the sheaves 22 and 23. On the back surface of the fixed sheave 22, there are a plurality of fins 22a, 22 for radially cooling the air which are radially arranged at equal intervals in the circumferential direction.
a, ... Are integrally formed.

On the other hand, a driven pulley 26, which is a speed change pulley having the same diameter as the drive pulley 21, is provided on the sleeve 16 which is fitted over the output shaft 13. The driven pulley 26 has a structure similar to that of the drive pulley 21, and includes a flange-shaped fixed sheave 27 key-joined to the sleeve 16 of the output shaft 13 so as to rotate integrally with the sleeve 16 and the sleeve 16 (output shaft). 13) is slidably and relatively rotatably coupled to the fixed sheave 27 by the boss portion 28a so as to face the fixed sheave 22 of the drive pulley 21 in the opposite direction to the facing direction of the movable sheave 23. It is composed of a flange-shaped movable sheave 28, and a belt groove 29 having a substantially V-shaped cross section is formed between these sheaves 27, 28. Fixed sheave 27 in this driven pulley 26
A plurality of fins 27a, 27a, ... Radially arranged radially at equal intervals in the circumferential direction are also integrally formed on the back surface of the fins, and the fins 22a of the respective fixed sheaves 22, 27 are formed. An air flow is generated in the case 1 by 27a to cool the heat generating portion.

The sliding structure of the movable sheave 23 of the drive pulley 21 with respect to the input shaft 9 and the sliding structure of the driven sheave 28 of the movable sheave 28 with respect to the sleeve 16 (output shaft 13) are the same. The driven pulley 26 will be described, and the same reference numerals are given to the drive pulley 21 side and detailed description thereof will be omitted. That is, as also shown in FIG. 6, on the inner peripheral surface of the boss portion 28a of the movable sheave 28 in the driven pulley 26, the fixed sheave 27 from the end on the fixed sheave 27 side of the boss portion 28a is located at a position opposed to the diametrical direction. A pair of engagement grooves 31, 31 having a substantially rectangular cross-section extending in the axial direction over the entire end to the opposite side is formed by broaching.

On the other hand, on the outer peripheral surface of the sleeve 16 (the input shaft 9 on the drive pulley 21 side), at a position facing in the diametrical direction,
Notches 32, 32 formed by partially cutting a part of the outer peripheral surface of the sleeve 16 in the axial direction in parallel with the tangential direction by a predetermined depth.
Are formed. In addition, the sleeve 16 and the output shaft 13
A pin 33 penetrating both of them in the diametrical direction is fixedly supported on the (rotation shaft) by press-fitting to the sleeve 16 (press-fittingly fixed to the input shaft 9 on the drive pulley 21 side). It projects from the notch 32 by a predetermined dimension. As shown in FIG. 6, the pin 33 has a long hole 36 having a longer diameter than the outer diameter of the pin 33 in the output shaft 13.
And is rotatable relative to the output shaft 13 by a predetermined angle. A pair of bearings 34, 34 are respectively supported by the inner rings 34b on the protruding portions at both ends of the pin 33, and the bearings 34 are engaged with each other on the inner periphery of the boss portion 28a of the movable sheave 28. The outer ring 34 a is engaged with the groove 31 and comes into contact with the side surface of the engaging groove 31 to roll. The outer diameter of each bearing 34 (outer diameter of the outer ring 34a) is equal to that of the sleeve 16
The outer diameter of the (input shaft 9) is 1 / 2.5 or more.

Then, the belt groove 2 of the drive pulley 21.
4 and the belt groove 29 of the driven pulley 26 are wound around the V belt 30 such as a block belt, and the movable sheaves 23 and 2 of the pulleys 21 and 26 are wound around each other.
8 is brought into contact with and separated from the fixed sheaves 22 and 27, respectively, to change the belt winding diameter of the pulleys 21 and 26. For example, when the movable sheave 23 of the drive pulley 21 is brought close to the fixed sheave 22 and the movable sheave 28 of the driven pulley 26 is separated from the fixed sheave 27, the belt winding diameter of the drive pulley 21 is made larger than that of the driven pulley 26. As a result, a high speed state in which the rotation of the input shaft 9 is increased and transmitted to the output shaft 13 is established. On the other hand, conversely, when the movable sheave 23 of the drive pulley 21 is separated from the fixed sheave 22 and the movable sheave 28 of the driven pulley 26 is brought close to the fixed sheave 27, the belt winding diameter of the drive pulley 21 is reduced, By increasing the belt winding diameter of the driven pulley 26, the rotation of the input shaft 9 is decelerated and transmitted to the output shaft 13 in a low speed state.

In the transmission case 1, the loose side span 30a of the pair of spans of the V belt 30 stretched between the driving and driven pulleys 21 and 26 is pressed outward from the inner surface thereof. A tension mechanism 38 that generates a belt thrust by applying tension to the belt 30 is provided. As shown in FIG. 2, the tension mechanism 38 has a tension arm 39 rotatably fitted to and supported by a boss portion 39a on the base end side of a boss-shaped portion around the output bearing hole 2b in the front case 2. The boss portion 39a of the tension arm 39 is integrally welded to the main body of the tension arm 39. A tension shaft 40 extending rearward in parallel with the output shaft 13 (input shaft 9) is integrally welded to the tip end of the tension arm 39, and the tip end of the tension shaft 40 is a belt groove 24, 29 in each pulley 21, 26. A tension pulley 41, which is located at a portion and is capable of pressing the loose side span 30 a of the V belt 30 from the inner surface, is rotatably supported via a bearing 42. The position of the tension pulley 41 is always constant regardless of the axial movement of the V-belt 30 due to the gear shift.
1 is set at a position where it can contact a part of the inner surface of the belt 30 and press it. Both side surfaces of the tension pulley 41 in cross section have belt grooves 24 of the pulleys 21 and 26,
The angle is parallel to the side surface of the tension pulley 41, so that the inclination angle of the side surface of the tension pulley 41 matches the sectional angle of the belt grooves 24 and 29, and the axial length of the outer peripheral surface of the tension pulley 41 is smaller than the width on the outer surface side of the belt 30. Has also been made smaller.

The tension arm 39 is integrally formed with a spring mounting arm portion 39b extending in the direction from the tip end toward the base end side (substantially opposite to the tension shaft 40). The spring mounting arm portion 39b is formed. A ring-shaped tension collar 43 is provided at the tip of the connecting collar 43a.
Bolt 43b parallel to the output shaft 13 (input shaft 9) via the
One end of a tension spring 44, which is a tension spring, is locked to the tension collar 43 in an externally fitted state.

On the other hand, as shown in FIGS. 1 and 4, in the front case 2, a tension spring 44 is provided from outside the case 1 so that the tension pulley 41 presses the loose side span 30a of the V belt 30. (Tensioned state)
A spring operating mechanism 45 is provided. The spring actuation mechanism 45 includes a rotation shaft 46 rotatably supported by the front case 2 in a penetrating state inside and outside the front case 2. An inner arm 47 is fixed to the inner end of the rotating shaft 46 inside the case 1 so as to rotate integrally with the base end, and a ring-shaped tension collar 48 is attached to the end of the inner arm 47.
Mounting bolt 4 extending in parallel with the output shaft 13 (input shaft 9)
This tension collar 48 is attached and fixed by 8a.
The other end of the tension spring 44 is locked in the state of being externally fitted.

Further, an outer arm 49 is fixed to the outer end of the rotary shaft 46 on the outer side of the case 1 so as to rotate integrally with the base end, and a fixing bolt 78 can be inserted into the tip of the outer arm 49. A bolt insertion hole 49a as an engaging portion is formed. The outer arm 4 is provided on the outer surface of the front case 2.
A bolt screwing hole 2d as a locking portion that can be fixed to the bolt insertion hole 49a by the fixing bolt 78 is formed at a predetermined position on the rotation path of the bolt insertion hole 49a at the front end of the outer arm 49. Is rotated around the rotation shaft 46 together with the inner arm 47, the bolt insertion hole 49a at the tip of the outer arm 49 is aligned with the bolt screw hole 2d on the outer surface of the front case 2, and the fixing bolt 78 is passed through the bolt insertion hole 49a. The inner arm 4 can be fixed by fastening and fixing it in the bolt screw hole 2d.
7, the tension spring 44 is pulled into a state in which a predetermined spring force is generated, and the spring force of the tension spring 44 urges the tension arm 39 to rotate counterclockwise in FIG.
The inner surface of the loose side span 30a of the belt 30 is pressed.
The tension spring 41 applies a rotational biasing force to the tension arm 39 so that the tension pulley 41 moves the loose side span 30a of the belt 30 to the loose side span 30a.
It is set so as to press with a tension larger than the maximum tension generated in the belt, and the belt thrust is generated by this tension.

A drive pulley side cam mechanism 50 is provided on the input shaft 9 on the rear side of the movable sheave 23 of the drive pulley 21 as a drive mechanism for bringing the movable sheave 23 into and out of contact with the fixed sheave 22. ing. The cam mechanism 50 includes a rotating cam 51 having a cylindrical cam body 52 made of, for example, an aluminum alloy, and the rotating cam 51 is
On the boss portion 23a of the movable sheave 23, an outer fitting support is provided via a bearing 57 so as to be relatively rotatable around the input shaft 9 and axially movable integrally. On the end surface of the cam body 52 on the side opposite to the drive pulley 21, radially outward of the bearing 57 and circumferentially equiangularly spaced (180 ° apart).
As shown in FIGS. 7 to 9, arc plate-shaped cam tips 53, 53 made of a sintered metal are inserted into the bolt insertion holes 53 a formed in each cam tip 53 at the upper and lower positions. The cam tips 53 are screwed and fixed to the cam body 52 to be attached and fixed, and each cam tip 53 has an inclined cam surface 55 which is inclined at a predetermined angle. Further, on the outer periphery of the cam body 52, a rotating lever 5 extending downward along a line passing through both the cam tips 53, 53.
Reference numeral 6 (see FIG. 4; in FIG. 5 is shown to extend to the side opposite to the output shaft 13 for the sake of explanation) is provided so as to integrally rotate.

On the back side of the rotating cam 51, the cam tips 53 are provided at positions corresponding to the cam tips 53.
A pair of cam receiving bearings 59, 59 serving as fixed cams, which come into cam contact with the cam surface 55 of the above, are arranged and fixed on the inner surface of the front case 2 along the radial direction of the input shaft 9. It is supported by the supporting shaft 60. That is, as shown in the enlarged view of FIG.
1 on the inner surface of the shaft 1 arranged in the radial direction of the input shaft 9
A pair of bearings 61 and 63 are provided so as to project, and one of the bearings 6
1 is formed with a bottomed screw hole 62 extending in a direction parallel to the input shaft 9, that is, in a direction from the inner surface of the front case 2 toward the opening. Further, a concave portion 64 having a substantially semicircular cross section is formed at the tip of the other bearing portion 63. And the support shaft 6
One end of 0 has a flat plate shape and a through-hole bolt hole 60a is formed therein, and the other end of the support shaft 60 is tightly fitted in the recess 64 of the other bearing 63, and the mounting bolt 65 is
Is inserted into the bolt hole 60a at one end of the support shaft 60 and screwed into the screw hole 62 of the one bearing portion 61, so that the cam bearing 59 is fixedly supported on the inner surface of the front case 2 by the support shaft 60. Has become.

On the other hand, on the output shaft 13, the driven pulley 26
On the back side of the movable sheave 28 in
A driven-pulley-side cam mechanism 67 for bringing the stationary sheave 27 into and out of contact with the stationary sheave 27 is provided. The driven pulley-side cam mechanism 67 has the same structure as the drive pulley-side cam mechanism 50, and is mounted around the output shaft 13 via the bearing 74 on the bearing collar 68 fitted outside the boss portion 28a of the movable sheave 28. It has a rotating cam 69 which is relatively rotatable and axially movable and integrally fitted and supported. This rotating cam 6
Reference numeral 9 denotes a cam main body 70, and an end face opposite to the driven pulley 26, which is fixedly mounted at a vertical position outside the bearing 74 in the radial direction of the output shaft 13 and at equal angular intervals in the circumferential direction. Cam tips 71, 71 made of a sintered metal having a pair 72, and each of the cam tips 71 is a rotating cam 51 of the drive pulley side cam mechanism 50.
The tapping screw 54 is attached to the cam tip 7 in the same manner as described above (which will be described with reference to FIGS. 7 to 9 which is the same as the rotating cam 51).
It is fixed by being inserted into the first bolt insertion hole 71a and screwed and fastened to the cam body 70. Also, this cam body 7
On the outer periphery of 0, a rotating lever 73 (FIG. 5) extending downward along a line passing through the cam tips 71, 71, that is, in the same direction as the rotating lever 56 of the drive pulley side cam mechanism 50.
For the sake of explanation, it is described so as to extend on the side opposite to the input shaft 9) and is provided so as to integrally rotate.

On the back side of the rotating cam 69, a pair of cam receiving bearings 76, 76 as fixed cams that come into cam contact with the cam tips 71 are provided.
Are arranged in correspondence with the respective cam receiving bearings 76
Are supported on a support shaft 77 arranged and fixed on the inner surface of the rear case 3 along the radial direction of the output shaft 13. Since the support structure of the cam receiving bearing 76 is the same as that of the drive pulley side cam mechanism 50 (see FIG. 10), FIG.
The same parts as 0 are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIGS. 11 and 12,
In the drive pulley side cam mechanism 50, the tip end of the turning lever 56 on the outer circumference of the cam 51 and the tip end of the turning lever 73 on the outer circumference of the cam 69 of the driven pulley side cam mechanism 67 are linked to each other so that they rotate. They are connected by 79. The link bar 79 is made of a substantially slender triangular plate material, and an intermediate portion thereof is a concave portion in the lower portion of the transmission case 1 (see FIG. 4).
The upper end is bent upward so as not to interfere with the front end, and a rib-shaped flange 79a is integrally formed on the front edge thereof.
A pin hole 80 is provided at one end of the link bar 79 (a portion forming one of the three apexes of the triangle), and the drive pulley side cam mechanism 5 is provided.
A pin hole 81 having a diameter smaller than that of the pin hole 80 is penetratingly formed in parallel with the input shaft 9 at the front end portion of the turning lever 56 of 0.
When the bush 82 made of sintered metal is fitted into the pin hole 80 of the link pin 83, the link pin 83 is inserted into both the pin holes 80 and 81 to prevent the link pin 83 from being pulled out.
The six tip portions are swingably connected by a link pin 83.

On the other hand, at the other end of the link bar 79, a pin hole 85 is formed also at the rear end (a portion forming one of the remaining two apexes of the triangle), and the tip end of the rotary lever 73 of the driven pulley side cam mechanism 67. The pin hole 8 having a smaller diameter than the pin hole 85
6 are formed so as to penetrate in parallel to the output shaft 13, respectively, so that both pin holes 85 and 86 are aligned with each other and the pin hole 8 of the link bar 79 is formed.
By inserting the link pin 88 into both pin holes 85 and 86 in a state where the sintered metal bush 87 is inserted into the pin 5, and preventing the link pin from coming off, the link bar 79 and the tip end portion of the rotating lever 73 are linked. Are connected so that they can swing. Then, the rotating levers 56, 73 and the link pins 83, 88
A gear shift switching mechanism 89 is configured by the link bar 79 and the link bar 79, and each cam mechanism 5 is configured by the gear shift switching mechanism 89.
The rotating cams 51, 69 of 0, 67 are rotated around the boss portions 23a, 28a of the movable sheaves 23, 28 in association with each other, and the cam surfaces 55, 7 of the respective cam tips 53, 71 are moved.
By rolling the cam receiving bearings 59 and 76 on the moving shaft 2, the movable sheaves 23 and 28 of the pulleys 21 and 26 are moved in the axial direction to be brought into contact with and separated from the fixed sheaves 22 and 27, respectively. The effective radii of the belt grooves 24 and 29, that is, the belt winding diameters of the pulleys 21 and 26 are made variable, and the pulley ratio between the pulleys 21 and 26, that is, the gear ratio of the transmission T is changed.

On the driven pulley 26 side, a torque cam mechanism 91 for moving the movable sheave 28 in the axial direction to generate a belt thrust when a transmission torque acts to relatively rotate the movable sheave 28 and the output shaft 13. Is provided. This torque cam mechanism 91, as shown in FIG.
The boss portion 28a of the movable sheave 28 is inclined at a diametrically opposed position (a position offset by 90 ° from the engaging grooves 31, 31) toward the circumferential direction toward the axial direction of the output shaft 13. Moreover, a pair of cam holes 92, 92 penetrating the inner and outer surfaces of the boss portion 28a are provided. Further, the output shaft 1 is provided at a position diametrically opposed to the outer peripheral surface of the portion of the output shaft 13 not covered by the sleeve 16.
3. Notches 93, 93 are formed by cutting out a part of the outer peripheral surface in the axial direction partially in parallel to the tangential direction by a predetermined depth. A pin 94 penetrating in the diametrical direction is fixedly supported on the output shaft 13 by press fitting, and both ends of the pin 94 project from the notches 93, 93 by a predetermined dimension, and the projecting parts at both ends of the pin 94 respectively. , The movable sheave 2
8 is engaged with the cam hole 92 in the boss portion 28a of the outer ring 9
A bearing 95 for rolling the 5a in contact with the side surface of the cam hole 92 is supported. When a transmission torque acts on the driven pulley 26, the cam effect of the cam hole 92 and the bearing 95 causes the movable sheave 28 to move in the axial direction. It is moved to generate belt thrust.

Further, in the front wall portion of the front case 2, there is a boss-shaped shaft insertion hole 97 at a position on the plane substantially between the input shaft 9 and the output shaft 13 and passing through the shaft centers of both shafts 9 and 13. An operating shaft 98 (operating portion) is formed through the shaft inserting hole 97 and extends in a direction parallel to the input shaft 9 (output shaft 13).
Is rotatably supported by the operation shaft 98. One end of the operation shaft 98 extends out of the transmission case 1 and has a quadrangular cross section.

Further, as shown in FIGS. 4, 11 and 12, a coupling mechanism 96 for transmitting the rotational movement of the operating shaft 98 to the speed change mechanism 89 is provided inside the transmission case 1. The connecting mechanism 96 and the operating shaft 98 constitute an operating means for operating the shift switching mechanism 89 from outside the case 1. The coupling mechanism 96 is used in the transmission case 1
At the other end of the operating shaft 98 located inside, a crank arm 100 having a base end welded and fixed integrally with the rotation is provided. The crank arm 100 is made of a plate material curved in a substantially V shape, and one end of a connecting rod 102 is connected to the tip end of the crank arm 100. The connecting rod 102 is formed by connecting a pair of link balls 101 and 101, each of which has a shaft 101a rotatably supported at its tip end, in such a manner that the shafts 101a and 101a are arranged in opposite directions. One link ball 101 of the connecting rod 102 is connected to the tip of the crank arm 100 by its shaft portion 101a.
The other end of the connecting rod 102, that is, the shaft portion 101a of the other link ball 101 is connected to the link bar 79 in the vicinity of the rotation lever 56 of the drive pulley side cam mechanism 50. Then, the operation shaft 98 is rotationally switched between the Lo position and the Hi position by the operation lever,
By operating the speed change mechanism 89, the rotary cams 51, 69
The rotation arms 56 and 73 protruding from the
By rotating between the i positions and changing the pulley ratio of the speed change pulley mechanism 20, the output shaft 13 is switched to the decelerating state or the accelerating state with respect to the input shaft 9 to shift gears.

Further, as shown in FIG. 3, on the front surface of the front case 2 which is the outer surface of the transmission case 1, the rotary operation range of the operation shaft 98 as an operation portion is restricted so that the input / output shafts 9,
A gear ratio range adjusting mechanism 1 for adjusting a gear ratio range between 13
03 is provided. This gear ratio range adjusting mechanism 103
Is an adjustment lever 106 that is attached to the operation shaft 98 so as to rotate together and is different from the above-mentioned operation lever, and a predetermined angle is formed on the front surface (outer surface) of the front case 2 on a circular arc centered on the position of the operation shaft 98. Pair of stoppers 10 attached and fixed by
Each of the stoppers 104 is provided with a stopper bolt 105 (adjustment portion) that comes into contact with the adjustment lever 106 on the operation shaft 98 at the head 105a so as to be adjustable in position by screwing. The stopper bolts 105 regulate the turning range of the adjusting lever 106 and the operating shaft 98 to set the range of the gear ratio in the Lo state and the Hi state of the transmission T to a predetermined value. still,
A dust seal 107 is arranged around the input shaft 9, the output shaft 13, and the operation shaft 98.

Next, the operation of the transmission according to the above embodiment will be described. Since the engine mounted on the agricultural machine is drivingly connected to the input shaft 9 of the transmission T and the output shaft 13 thereof is drivingly connected to the drive wheels, the rotational power of the engine is changed by the transmission T and then the drive wheels are changed. Be transmitted to. Since the rotating levers 56 and 73 of the drive and driven pulley side cam mechanisms 50 and 67 are linked by the link bar 79, the gear ratio switching mechanism 89 is switched by the switching operation of the operating shaft 98 via the coupling mechanism 96. As a result, the transmission ratio of the transmission T is switched by changing the pulley ratio of the transmission pulley mechanism 20.

(Low-speed state) Specifically, when the transmission gear ratio of the transmission T is lowered to the low-speed state (Lo state), the operating shaft 9
8 is rotated and switched by the operation lever and is positioned at the Lo position. That is, the base end of the crank arm 100 of the connecting mechanism 96 is integrally fixed to the inner end of the operating shaft 98, and the tip end of the crank arm 100 is connected to the connecting rod 1.
02 is connected to the link bar 79 of the gear ratio switching mechanism 89. The link bar 79 is connected to the rotation lever 56 on the outer circumference of the rotation cam 51 of the drive pulley side cam mechanism 50 and the rotation lever 56 of the driven pulley side cam mechanism 67. Since the rotation lever 73 on the outer circumference of the moving cam 69 is connected, the crank arm 100 rotates in accordance with the rotation of the operation shaft 98, and both rotation levers 56 and 73 rotate. Then, Lo of the operation shaft 98
In the state of switching to the position, the driven pulley side cam mechanism 67 is
Of the rotating cam 69 is the cam surface 71 of the cam tip 71, 71.
The movable sheave 28 in the driven pulley 26 while rolling the cam receiving bearings 76, 76 on 2, 2, 72, respectively.
It rotates in one direction around the boss portion 28a. By this rotation, the cam surfaces 72 are pushed by the cam receiving bearings 76, and the rotating cams 69 move on the sleeve 16 around the output shaft 13, and the movable sheaves integrally moved to the cams 69 via the bearings 74. 28 moves in the same direction and approaches the fixed sheave 27. As a result, the driven pulley 26 is closed to increase the belt winding diameter, and the V belt 30 is pulled toward the driven pulley 26 side due to the increase in the belt winding diameter.

At the same time, L of the operating shaft 98 is
With the switching to the o position, the drive pulley side cam mechanism 50 is synchronized with the movement of the movable sheave 28 of the driven pulley 26.
The rotating cam 51 rotates on the input shaft 9 in the same one direction as the cam 69 of the driven pulley side cam mechanism 67. This cam 5
The rotation of 1 eliminates the pressing of the cam surface 55 of each cam tip 53 against the cam receiving bearing 59. Therefore, the tension of the belt 30 moving to the driven pulley 26 side causes the movable sheave 23 connected to the cam 51 and the bearing 57 to move on the input shaft 9 in a direction away from the fixed sheave 22. Both sheaves 22, 23
The drive pulley 21 is opened due to the separation of the above, and the belt winding diameter is reduced. As a result, the belt winding diameter of the driven pulley 26 becomes larger than that of the drive pulley 21, and the rotation of the input shaft 9 is decelerated and transmitted to the output shaft 13. As a result, the transmission T is brought into the Lo state, and the rotation of the engine is decelerated and transmitted to the drive wheels.

The tension arm 39 is moved by the urging force of the tension spring 44 of the tension mechanism 38 as shown in FIG.
Is urged to rotate in a clockwise direction by the tension pulley 41 at its tip end to press the inner surface of the loose side span 30a of the belt 30, and the pressing force imparts tension to the belt 30.
At this time, this tension is larger than the maximum tension generated in the slack side span 30a, so that the belt tension causes a wedge effect on the pulleys 21 and 26 of the belt 30 to generate thrust, and this thrust causes both pulleys 21 and 26 to be generated. Power is transmitted via the belt 30 between them.

(High speed state) On the other hand, the operating shaft 98 is set to Hi.
When it is set to the position, in the switching state to this Hi position,
While the cam 51 of the drive pulley side cam mechanism 50 rolls the cam receiving bearing 59 on the cam surface 55 of each cam tip 53, the movable sheave 23 in the drive pulley 21.
It rotates in the other direction around the boss portion 23a. As a result, the cam surface 55 is pushed by the cam receiving bearing 59, the cam 51 moves on the input shaft 9, and the movable sheave 23, which is integral with the cam 51, moves in the same direction to move the fixed sheave 22.
Approach. As a result, the drive pulley 21 is closed to increase the belt winding diameter, and the V belt 30 is pulled toward the drive pulley 21 side due to the increase in the belt winding diameter.

At the same time, the cam 69 of the driven pulley side cam mechanism 67 rotates on the sleeve 16 in the same other direction as the cam 51 of the drive pulley side cam mechanism 50.
The rotation of the cam 69 eliminates the pressure on the cam receiving bearing 76. Therefore, due to the tension of the belt 30 moving to the drive pulley 21 side, the movable sheave 2 connected to the cam 69 and the bearing 74 via the cam 69.
8 moves on the sleeve 16 in a direction away from the fixed sheave 27, and the separation of the sheaves 27, 28 opens the driven pulley 26, and the belt winding diameter is reduced. As a result, the belt winding diameter of the drive pulley 21 becomes smaller than that of the driven pulley 26.
The rotation of the input shaft 9 is accelerated and transmitted to the output shaft 13. As a result, the transmission T is in the Hi state, and the rotation of the engine is accelerated and transmitted to the drive wheels.

In the case of this embodiment, the speed change pulley mechanism 20
The rotary cams 51, 69 of the cam mechanisms 50, 67 are supported on the bosses 23a, 28a of the movable sheaves 23, 28 of the pulleys 21, 26 of the above through the bearings 57, 74, respectively. , 69 Outer rotation lever 5
Since 6 and 73 are connected to each other by one link bar 79, when the speed change of the speed change pulley mechanism 20 is performed, the cam receiving bearings 59 and 76 respectively supported by the front case 2 and the rear case 3 move from the rotating cam 51. , 69, the force is applied to the cam surfaces 55 and 72 of the cam tips 53 and 71.
5, 72 acting in a direction perpendicular to the input shaft 9 and the output shaft 13, and a perpendicular component force of this force in the direction orthogonal to the input shaft 9 and the output shaft 13.
When operated at a right angle to the line connecting the shaft center of 3 and the connection point to the link bar 79, the pulley ratio of the line connecting the shaft center of the input shaft 9 and the output shaft 13 to the connection point to the link bar 79 Regardless of the change, a cam rotation reaction force that is a right angle and is opposite to the right angle component force is generated, and this cam rotation reaction force is applied to the boss portions 23a and 28a of the movable sheaves 23 and 28 on which the rotating cam is supported. , The pulleys 21 and 26 act so as to press the boss portions 23a and 28a at the center position of the area around which the belt 30 is wound. That is, the boss portions 23a, 28
The cam rotation reaction force with respect to a is a clearance in the sliding portion between the boss portions 23a and 28a and the input shaft 9 and the output shaft 13, and when the movable sheaves 23 and 28 receive thrust from the belt 30, the movable sheaves 23 and 28 are moved. Acts on the input shaft 9 and the output shaft 13 so as to generate a moment in the direction opposite to the moment acting in the tilting direction, and this moment cancels the original moment to make it smaller, and the boss portions of the movable sheaves 23, 28 become smaller. The surface pressure distributions of the inner circumferences of 23a and 28a with respect to the outer circumferences of the input shaft 9 and the output shaft 13 are dispersed in the axial direction, and the sliding resistance of the boss portions 23a and 28a is reduced. As the sliding resistance becomes smaller, the load of the belt-generated thrust applied to the fixed point by the rotating cams 51, 69 (that is, the take-out thrust) becomes larger. In other words, the belt-generated thrust does not have a large resistance and the rotating cam does not have a large resistance. It is transmitted to 51 and 69 as extraction thrust. When the pulley ratio is changed, the difference between the belt-generated thrust and the take-out thrust is the load (operating force) required for the gear shifting operation. Therefore, the amount of take-out thrust is large and conversely the operating force can be small. become. As a result, both of the speed change pulleys 2 in the speed change pulley mechanism 20.
The gear shift operation force can be reduced by the thrust balance of the belt 30 between the Nos. 1 and 26.

Further, in this embodiment, the movable sheave 23 of the drive pulley 21 moves on the input shaft 9 at the time of shifting as described above.
Further, when the movable sheave 28 of the driven pulley 26 receives the transmission load torque on the sleeve 16 and moves in the axial direction, the bearings 34 on the pins 33 projecting from the outer periphery of the input shaft 9 or the sleeve 16 are changed. Movable sheaves 23, 2
The bosses 23a and 28a of FIG. 8 roll in the engaging groove 31 on the inner peripheral surfaces thereof with the outer peripheral surface of the outer ring 34a of the bearing 34 abutting the side surface of the engaging groove 31. The sliding resistance at this time is the rolling resistance between the outer peripheral surface of the outer ring 34a of the bearing 34 and the side surface of the engagement groove 31 and the rolling resistance of the inner and outer rings of the bearing 34, and no sliding resistance occurs. Therefore, the shift operation force can be further reduced by the sliding resistance composed of the rolling resistance.

Further, since the outer diameter of the bearing 34 is 1 / 2.5 or more of the outer diameter of the input shaft 9 or the sleeve 16, which is a relatively large diameter, the Hertz stress generated in the engagement groove 31 and the bearing 34 is small. The outer ring 34 of the bearing 34 becomes smaller
a It is not necessary to quench the outer peripheral surface and the side surface of the engaging groove 31,
The cost can be reduced.

Further, one pin 33 is pierced through the input shaft 9 or the sleeve 16 in the diametrical direction so that both ends are projected to the surface of the input shaft 9 or the sleeve 16, and the projected pin 33 is formed.
Since the bearings 34, 34 are respectively supported on both ends of the bearing, the pins 33 for supporting the bearings 34, 34 can be commonly used to reduce the number of parts and facilitate assembly.

Further, the engaging groove 31 on the inner circumference of the boss portions 23a, 28a of each of the movable sheaves 23, 28 is formed by the boss portion 23.
Since the a and 28a are broached in the lengthwise direction, the sheave portions of the movable sheaves 23 and 28 are obstructed as compared with the case where the engaging groove 31 is punched from the outer peripheral side of the boss portions 23a and 28a. Without engaging the engaging groove 31 with the bosses 23a, 2
8a can be machined over the entire length, and the bearing 3
4 is effectively moved, and the boss 2
The total length of 3a and 28a can be shortened, and movable sheaves 23 and 28
As a result, the pulleys 21 and 26 can be made compact.

Further, the rotating cams 51, 69 in the cam mechanisms 50, 67 are composed of the cam bodies 52, 70 and the cam tips 53, 71 made of sintered metal attached to the cam bodies 52, 70. That is, only the portions of the rotating cams 51, 69 that come into contact with the cam receiving bearings 59, 76 are separated from the other portions, and the hard sintered metal cam tips 53, 71 are different from them. The cam surfaces 55 and 72 of the rotating cams 51 and 69 are hardly worn by repeated rolling of the cam receiving bearings 59 and 76, and the transmission operability of the transmission T is kept stable for a long period of time. be able to.

By forming the cam surfaces 55 and 72 of the cams 51 and 69 on the cam tips 53 and 71 which are separate from the cam bodies 52 and 70, the cam tips 53 and 71 are formed.
Can be easily replaced with another, and the cam surface 55,
It becomes easy to change the specification of the inclination of 72.

Moreover, the cam tips 53, 71 of the rotary cams 51, 69 have a radius larger than the positions of the bearings 57, 74 for supporting the cam bodies 52, 70 on the boss portions 23a, 28a of the movable sheaves 23, 28. Since it is arranged on the outside in the direction, the cam surfaces 55 of the cam tips 53 and 71,
72 can be arranged closer to the center side of the pulleys 21 and 26 (to the fixed sheaves 22 and 27 side) than the bearings 57 and 74. Accordingly, the lengths of the cam mechanisms 50 and 67 in the axial direction can be shortened to make the pulleys 21 and 26 compact.

Further, since the torque cam mechanism 91 is provided on the driven pulley 26 side, when a transmission torque acts on the driven pulley 26 and the movable sheave 28 and the output shaft 13 relatively rotate, the boss of the movable sheave 28 is rotated. The side surface of each inclined cam hole 92 of the portion 28 a is the bearing 9 on the outer circumference of the sleeve 16.
5, the movable sheave 28 is axially moved by the cam effect, and a belt thrust is generated.

At this time, the pair of bearings 95, 95 of the torque cam mechanism 91 are supported by both ends of the pin 94 press-fitted and fixed to the output shaft 13 at a portion not covered by the sleeve 16, while the movable sheave is being moved. The pin 33 for supporting the bearing 34, which slidably engages the sleeve 28 with the sleeve 16, is inserted into an elongated hole 36 having a longer diameter larger than the outer diameter of the pin 33 in the output shaft 13 so as to form a predetermined angle with the output shaft 13. Since it is capable of relative rotation, the output shaft 13
The engagement of the torque cam mechanism 91 with the movable sheave 28 and the engagement of the sleeve 16 with the movable sheave 28 are separated. Therefore, the pulley 26 including the torque cam mechanism 91
Even in this case, the sliding structure of the movable sheave 28 can utilize the bearing 34.

The small diameter portion 13a at the front end of the output shaft 13
The sleeve 16 on the outer ring 17b of the bearing 17 arranged in
Of the small diameter portion 13 of the output shaft 13 to the inner ring 17a.
Since the step portion between a and the other portion is locked, the inner ring 17a of the bearing 17 shares the thrust load by the torque cam mechanism 91, and the outer ring 17b shares the thrust load acting on the fixed sheave 27 from the belt 30. Thus, the resistance of the relative rotation of the sleeve 16 and the output shaft 13 can be made a small rolling resistance between the inner and outer races 17a and 17b of the bearing 17. The sleeve 16
A needle bearing (not shown) may be interposed between the inner peripheral surface and the outer peripheral surface of the output shaft 13, or the needle bearing and the bearing 17 may be provided in combination.

Further, in the tension mechanism 38,
Since the tension arm 39, its boss portion 39a, the tension shaft 40, and the spring mounting arm portion 39b are all joined and integrated by welding, the structure of the tension mechanism 38 is simplified, the number of parts is reduced, and the assemblability is improved. Can be improved.

Further, since one end of the tension spring 44 is locked by the tension collar 48 at the tip of the inner arm 47 in the transmission case 1 in the spring operating mechanism 45, the spring 44 changes its speed. Since it does not go out of the machine case 1, the degree of sealing of the transmission case 1 can be enhanced.

The operation of putting the tension spring 44 in tension after the transmission T has been assembled by assembling the front and rear cases 2 and 3 will now be described. The outer arm 49 and the inner arm 47 of the spring operating mechanism 45 will be described.
Is set to be rotatable about a rotation shaft 46, and one end of the tension spring 44 (the spring 44 is attached to the tension collar 48 at the tip of the inner arm 47).
The other end of the spring mounting arm portion 39b is locked to the tension collar 43 at the end of the spring mounting arm portion 39b), the transmission pulley mechanism 20 and the cam mechanisms 50, 6 are provided in the front case 2.
7 and the like are accommodated, and then the flange 2c of the front case 2 is fitted to the flange 3c of the rear case 3, and both cases 2 and 3 are assembled by inserting and fastening the assembly bolts 6, 6 ,. assemble.

At this time, since the collars 7, 7 as knock pins are fitted in the pair of screw holes 4, 4 of the front case 2 in advance, when the rear case 3 is positioned and assembled to the front case 2, Both the above collars 7 and 7 are attached to the rear case 3
It is possible to perform accurate positioning simply by fitting and inserting into the corresponding bolt insertion holes 5 and 5, and the positioning can be performed easily.

Further, in the state immediately after the assembling, the inner arm 47 is rotatable about the rotary shaft 46, so that the inner arm 47 and the outer arm 49 are pulled by the tension springs 44, and the time is shown in FIG. The tension spring 44 is located at the rotational end position in the rotating direction.
Is in a contracted state and the spring force is not generated.

After the transmission T is assembled, the outer arm 49 and the inner arm 47 are rotated around the rotary shaft 46 as shown in FIG.
When rotated in the counterclockwise direction with, the inner arm 47
By the rotation of the tension spring 44, the tension spring 44 is pulled to change to a spring force generating state (a biasing state of the tension pulley 41), which causes the tension arm 39 to rotate counterclockwise in FIG. Tension pulley 41
Presses the inner surface of the V-belt 30, and tension is started to be applied to the belt 30. Then, the bolt insertion hole 49a at the tip of the outer arm 49 is aligned with the bolt screwing hole 2d on the outer surface of the front case 2, the fixing bolt 78 is inserted into the bolt inserting hole 49a, and the bolt is screwed into the bolt screwing hole 2d. , The arms 47, 49 are non-rotatably fixed, whereby the spring force generation state of the tension spring 44 is fixed and held, and a predetermined tension is applied to the belt 30. Therefore, since the tension spring 44 is switched from the outside of the case 1 to the spring force generating state after assembling the transmission T in this way, the tension spring 44 is first made into the spring force non-generating state and the pulleys 21 and 26 and the belt are provided in the case 1. It can be incorporated together with 30, and the work of assembling the tension spring 44 can be facilitated.

Further, after the transmission T is assembled as described above, the gear ratio is finely adjusted. That is, the adjusting lever 106 is attached to the operation shaft 98 for changing the gear ratio by the rotating operation as described above. Then, a pair of stoppers 104, 104 are attached to the outer surface of the front case 2 around the operation shaft 98 in advance, and each stopper 10
4, the stopper bolts 105 of both stoppers 104 restrict the turning range of the adjusting lever 106 and set the range of the gear ratio. Since the stopper bolts 105 of the stoppers 104 can be screwed to adjust their positions, the rotation range of the adjusting lever 106 can be changed by changing the position of the stopper bolts 105. As a result, even if the range of the transmission ratio of the transmission T is slightly deviated, after the assembly, the range of the transmission ratio can be easily fine-tuned to the target range from outside the transmission case 1, and thus the accurate transmission ratio can be obtained. The range is easily obtained.

The link bar 79 is made of a substantially triangular plate material, and one end of one of the three vertices of the link bar 79 has a turning lever 5 of the turning cam 51 of the driving pulley side cam mechanism 50.
6 is connected, the rotation lever 73 on the outer periphery of the rotation cam 69 of the driven pulley-side cam mechanism 67 is connected, and the connecting rod 1 on the operation shaft 98 side is connected to the rear peak of the remaining two vertices.
Since the end of 02 is connected to the drive pulley side cam mechanism 50 near the turning lever 56, compared to the case where the end of the connecting rod 102 is connected to the front apex of the remaining two apexes. Since there is no concentration of bending stress on the link bar 79, it is possible to reliably prevent breakage and the like.

Further, the bushes 8 made of sintered metal are respectively provided in the pin holes 80 and 85 at both ends of the link bar 79.
2, 87 are fitted and inserted, and with the bushes 82, 87 fitted, the link pins 83, 88 are inserted into the pin holes 80, 85 and the pin holes 81, 86 at the tips of the rotating levers 56, 73. Since the rotating levers 56, 73 and the link bar 79 are swingably connected, wear of these connecting portions is reduced by the bushes 82, 87, and stable shift operability is ensured over a long period of time. Obtainable.

The cam bearings 59 and 76 of the cam mechanisms 50 and 67 are supported on support shafts 60 and 77 mounted on the inner surface of the transmission case 1, and one end of each of the support shafts 60 and 77 is used for shifting. Bearing part 6 on the inner surface of machine case 1
3 is fitted in the concave portion 64, and the other end is screwed and fastened to the other bearing portion 61 by the mounting bolt 65. Therefore, the mounting bolt 65 is fixedly attached to the case 1 only by bolting the other end portion. The cam bearings 59 and 76 can be supported on the inner surface of the transmission case 1 in a cantilevered manner.
It can be easily attached and supported by.

The screw holes 62 into which the mounting bolts 65 for fastening the ends of the support shafts 60 and 77 are screwed are formed in the transmission case 1 in a direction parallel to the input / output shafts 9 and 13. Since it extends in the direction from the inner surface toward the opening, if the hole portion for the screw hole 62 is formed when casting the transmission case 1, it can be easily formed only by processing the screw portion thereafter. The screw hole 62, the input / output shaft 9,
A hole for inserting a tool and a lid portion after the machining are not required when forming in a direction orthogonal to 13.

[0079]

As described above, in the invention of claim 1, at least one pair of pulley and belt are provided in the case, and the loose side span of the belt is pressed by the tension pulley urged by the tension spring. In the belt transmission device for applying the belt tension, the spring actuating means for bringing the tension spring into the state where the spring force is generated from the outside of the case is provided. Further, in the invention of claim 2, the drive and driven pulleys respectively provided on the pair of rotating shafts arranged and supported in parallel with each other in the case, the belt wound between the both pulleys, and the pulleys. A cam mechanism that is arranged on the rear side of the movable sheave and that moves the movable sheave in the axial direction by relative rotation of the rotating cam with the fixed cam, and when one of the variable sheaves of the variable pulleys approaches the fixed sheave, the other pulley The gear shift mechanism that changes the gear ratio between both rotary shafts by rotating and interlocking the rotary cams of both cam mechanisms so that the movable sheave of the vehicle moves away from the fixed sheave, and the gear shift mechanism from outside the case. The operating means for actuating and the loose side span of the belt wound between both variable pulleys are tensioned so that the belt bites into the belt groove of each pulley to generate thrust on the belt. The belt transmission device that includes a tension mechanism for pressing by the energized tension pulley in pulling, similarly, provided with the spring actuating means for the tension spring from outside the case to the spring force generation. Further claims
In each of the inventions 1 and 2, the spring actuating means is provided.
As a rotating shaft that penetrates the inside and outside of the case,
The inner arm is fixed to the inner end of the case of the drive shaft so that
The tension spring at its tip.
On the other hand, the outer arm is fixed to the outer end of the case of the rotating shaft by rotating.
The outer edge of the case on the outer surface of the case.
The outer arm is provided with a locking part that can fix the engaging part at the end of the arm.
The arm around the rotation axis together with the inner arm, and
By fixing the end engaging part to the locking part of the case,
The tension spring to generate spring force.
It was Therefore, according to the first or second aspect of the invention, the tension spring can be switched from the outside of the case to the operating state, so that the tension spring can be assembled in a state in which the spring force is not generated, and the assembling work can be facilitated. Can be planned.

[0080]

According to the invention of claim 4 , in the belt transmission device of the invention of claim 2, an operating portion operably arranged on the outer surface of the case, and a connecting mechanism for transmitting the movement of the operating portion to the gear shift mechanism. By providing the gear ratio adjusting means on the outer surface of the case to regulate the operating range of the operating portion to adjust the range of the gear ratio between the two rotary shafts, the operating portion is operated from the outside of the case after the belt transmission is assembled. It is possible to finely adjust the range of the gear ratio to a target range by restricting the operation range of, and to make the range of the gear ratio accurate and easy.

According to the fifth aspect of the present invention, the operating portion is an operating shaft rotatably supported in the case in a penetrating state, the adjusting lever is attached to the operating shaft so as to rotate integrally, and the adjusting lever is rotated on the outer surface of the case. By attaching a pair of stoppers having position-adjustable adjusting portions that regulate the movement range, the rotation range of the adjusting lever that rotates integrally with the operation shaft is regulated by the pair of stopper adjusting portions on the outer surface of the case. Then, the range of the gear ratio can be adjusted by changing the rotation range of the adjusting lever by changing the position of the adjusting portion of the stopper, and thus the gear ratio range adjusting means can be embodied.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view showing a structure of a spring operating mechanism in a case.

FIG. 2 is an enlarged front view of a tension arm.

FIG. 3 is a front view showing a gear ratio range adjusting mechanism on the outer surface of the case.

FIG. 4 is a front view showing a pulley type transmission with a case opened.

FIG. 5 is a horizontal sectional view of a pulley type transmission according to an embodiment of the present invention.

6 is an enlarged sectional view taken along line VI-VI of FIG.

FIG. 7 is an enlarged development view showing the mounting structure of the cam tip on the cam body.

FIG. 8 is an enlarged front view showing the mounting structure of the cam tip on the cam body.

FIG. 9 is an enlarged cross-sectional view showing the mounting structure of the cam tip on the cam body.

FIG. 10 is an enlarged cross-sectional view showing a structure of a cam receiving bearing mounting portion in the case.

FIG. 11 is an enlarged front view showing the connecting structure of the link bar, the connecting rod, the crank arm, and the operating shaft of the speed change mechanism.

FIG. 12 is an enlarged plan view showing a connecting structure of a link bar, a connecting rod, a crank arm, and an operating shaft of a gear change mechanism.

[Explanation of symbols]

T gearbox 1 Transmission case 2 front case 2d bolt screw hole 3 rear case 4 screw holes 7 colors 9 Input axis 13 Output shaft 16 sleeves 17 Bearing 20 Speed change pulley mechanism 21 Drive pulley 26 Driven pulley 22,27 fixed sheave 23, 28 movable sheaves 23a, 28a Boss part 24,29 Belt groove 30 V belt 31 engagement groove 33 pin 34 Bearing 38 Tension mechanism 39 Tension arm 41 Tension pulley 44 Tension spring 45 Spring actuation mechanism 46 rotation axis 47 inner arm 49 Outer arm 49a Bolt insertion hole 50 Drive pulley side cam mechanism 67 Driven pulley side cam mechanism 51,69 Rotating cam 52,70 Cam body 53,71 cam tip 55,72 Inclined cam surface 56, 73 Rotating lever 57,74 bearings 59,76 Cam bearing 60,77 Support shaft 61, 63 Bearing part 62 screw holes 64 recess 65 mounting bolt 70 cam body 78 fixing bolt 79 Link bar 80,85 pin holes 82,87 bush 83,88 link pin 89 Gear change mechanism 91 Torque cam mechanism 96 connection mechanism 98 Operation axis 102 connecting rod 103 Gear ratio adjustment mechanism 104 stopper 105 Stopper bolt

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Nakao 1-32, Chayamachi, Kita-ku, Osaka City, Osaka Prefecture Yanmar Agricultural Machinery Co., Ltd. (56) Reference JP-A-7-103301 (JP, A) JP Flat 7-89363 (JP, A) Actual open 63-162156 (JP, U) Actual open 5-8102 (JP, U) Actual open 61-119827 (JP, U) (58) Fields investigated (Int .Cl. ⁷ , DB name) F16H 9/00-9/26 F16H ^7/ 00-7/24

Claims (5)

(57) [Claims] 1. A pair of rotating shafts supported by a case, pulleys respectively provided on the rotating shafts in the case, a transmission belt wound between the pulleys, and a looseness of the belt. A tension mechanism that has a tension pulley that presses the side span and a tension spring that moves and biases the tension pulley so that the belt is pressed, and a tension mechanism that applies the belt tension by pressing the loose side span of the belt with the tension pulley. in a belt transmission device including bets, the spring actuating means the tension pulley is a spring force generating state the tension spring from the outside of the case so as to press the belt provided, said spring actuating means, through the inner and outer case Condition
And a rotating shaft that is rotatably supported in a stationary state, and is integrally fixed to the inside end of the case of the rotating shaft at the base end.
And inside with the tension spring locked at the tip
The arm and the rotation shaft are fixed to the outer end of the case at the base end so that they can rotate together.
And an outer arm having an engaging portion at the tip and an outer arm having an engaging portion at the outer surface of the case.
A lockable portion that can be fixed is provided, and the outer arm can be rotated together with the inner arm about a rotation axis.
Fix the engaging part at the tip of the outer arm to the locking part of the case.
The tension spring to generate the spring force.
A belt transmission device characterized by being configured to . 2. A pair of rotating shafts arranged in parallel with each other and supported by the case, and a pair of rotating shafts respectively provided on the rotating shafts in the case.
A fixed sheave, which is fixed to the rotary shaft so as to rotate integrally and immovably in the axial direction, is provided to face the fixed sheave so as to form a belt groove having a substantially V-shaped cross section between the fixed sheave. , And has a boss portion that extends in the axial direction on the back side,
A movable sheave that is externally fitted and supported by the boss portion so as to rotate integrally with the rotating shaft and to be movable in the axial direction, and one of the movable sheaves faces toward the fixed sheave and the other movable sheave faces toward the fixed sheave. Drive and driven pulleys that are set in opposite directions to each other, a belt wound between the belt grooves of the drive and driven pulleys, and arranged on the back side of each movable sheave of the drive and driven pulleys. A first cam and a second cam that are in cam contact with each other
A cam, one of the first and second cams is supported on the boss portion of the movable sheave via a bearing so as to be movable integrally and relatively rotatably together with the movable sheave in the axial direction, and the other is axially supported by the rotary shaft. Is provided so as to be immovable and rotatable relative to the rotary shaft, one of the cams being a rotary cam rotatable about the rotary shaft, and the other being a non-rotatable fixed cam. A drive pulley side and a driven pulley side cam mechanism for changing the effective radius of each pulley by moving the movable sheave in the axial direction so as to move toward and away from the fixed sheave by relative rotation between the rotating cam and the fixed cam, When the movable sheaves of one of the drive and driven pulleys approach the fixed sheaves facing each other, the rotary cams of the two cam mechanisms are interlocked with each other to rotate so that the other movable sheave moves away from the fixed sheaves facing each other. To change the gear ratio between the two rotary shafts, operating means for operating the gear change mechanism from outside the case, and pressing the loose side span of the belt wound between the drive and driven pulleys. And a tension spring that urges the tension pulley to move so that the belt is pressed.The tension pulley pushes the loose side span of the belt so that the belt bites into the belt groove of each pulley. Te, the belt transmission device that includes a tensioning mechanism for generating the thrust of the belt is provided with a spring actuating means the tension pulley is a spring force generating state the tension spring from the outside of the case so as to press the belt, the The spring actuating means penetrates the case inside and outside.
And a rotating shaft that is rotatably supported in a stationary state, and is integrally fixed to the inside end of the case of the rotating shaft at the base end.
And inside with the tension spring locked at the tip
The arm and the rotation shaft are fixed to the outer end of the case at the base end so that they can rotate together.
And an outer arm having an engaging portion at the tip and an outer arm having an engaging portion at the outer surface of the case.
A lockable portion that can be fixed is provided, and the outer arm can be rotated together with the inner arm about a rotation axis.
Fix the engaging part at the tip of the outer arm to the locking part of the case.
The tension spring to generate the spring force.
A belt transmission device characterized by being configured to . 3. The belt transmission device according to claim 1 or 2, wherein the tension spring is a tension spring. 4. The belt transmission according to claim 2, wherein the operating means includes an operating portion operably arranged on the outer surface of the case, and a connecting mechanism for transmitting the movement of the operating portion to the gear shift mechanism. A belt transmission device, characterized in that a gear ratio range adjusting means for adjusting the range of the gear ratio between the two rotary shafts is provided on the outer surface of the case to regulate the operating range of the operating portion. 5. The belt transmission device according to claim 4, wherein the operation portion is an operation shaft rotatably supported in the case in a penetrating state, and the gear ratio range adjusting means is rotationally integrated with the operation shaft. A belt transmission, comprising: an adjusting lever attached to the case; and a pair of stoppers attached to the outer surface of the case, the stopper having a position-adjustable adjusting portion that restricts the rotation range of the adjusting lever.