JPS62110057A - Drive pulley of v-belt stepless speed change gear - Google Patents

Abstract

PURPOSE:To improve fuel cost and to increase the driving force by setting the shape of a cam surface where a fly weight contacts in such a manner that at a point of time transmission torque becomes large, a clutch is turned on. CONSTITUTION:The rear cam surface 15 of a movable pulley half body 3 where a fly weight 34 contacts has a point where the direction of inclination changes. A clutch portion is formed on the rotating axis side of that point, and a speed change portion is formed on the outer peripheral side of the point. The distance (c) between a segment (l) passing a supporting point P of the fly weight 34 and intersecting perpendicularly to the rotating axis increases gradually at the clutch portion in the direction of expanding the fly weight 34, and decreases gradually at the speed change portion, so that when transmission torque is small, the clutch will not be operated, and when the revolving speed for a fixed transmission torque is attained, the clutch is operated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel structure of a drive pulley used in a V-belt continuously variable transmission, and particularly to the structure of a cam surface on which a flyweight operates.

[Prior Art] A V-belt type continuously variable transmission that uses flyweights to change the belt diameter and performs continuously variable transmission is well known.

The drive pulley in this transmission consists of a fixed pulley half and a movable pulley half, and the movable pulley half slides on the shaft by the action of a flyweight that is integrated with the engine output shaft such as a crank, and moves back and forth. The distance between both pulley halves can be freely changed. This changes the rotation radius of the V-belt wrapped between both pulley halves.

Continuously variable speed.

By the way, the W of the movable pulley half by fly weight!
In the J-motion type, a cam surface is formed on the back side of the movable pulley (the back side of the pulley that is in contact with the V-belt, the same applies hereinafter), and the cam surface is expanded by centrifugal force using a support point located away from the rotation axis as a fulcrum. Some slides are made by bringing a flyweight that moves open into contact with this cam surface. In this type of cam surface, the distance between the cam surface and a line passing through the support point of the flyweight and perpendicular to the output shaft gradually decreases as the weight expands, that is, toward the outer circumference of the movable pulley half. It is supposed to be done.

Also, the rising portion of the cam surface near the output shaft usually doubles as a clutch. In other words, when not rotating, a gap is formed between the pulley surface of the movable pulley half and the belt side surface, and when the output shaft reaches a certain rotation speed, the movable pulley half slides in a predetermined position toward the belt side due to the weight. When the belt side surface contacts the pulley surface for the first time, torque is transmitted from the pulley surface to the belt, turning the clutch on.

As an example of such, U.S. Pat.
There is one listed in No. 9.

[Problems to be solved by the invention] In the above conventional example, changes in the expansion angle of the weights,
The sliding stroke amount of the movable pulley half changes approximately proportionally. This is the same before and after the clutch is turned on, that is, at the time of startup. However, if the clutch is turned on at too low a rotation speed, the transmitted torque is not that large, so belt slip occurs between the pulley surface and the belt side, and the required driving force is not generated.
Moreover, fuel efficiency is deteriorated.

In order to avoid such a situation, it is conceivable to ensure that the movable pulley half has a sufficient stroke amount so that the clutch is turned on when the transmitted torque is large. However, in this case, the initial distance between the fixed and movable pulley halves must be increased accordingly, leading to an increase in the size of the device.

In order to solve these problems, the present invention aims to improve the startup characteristics, enable clutch on with a small stroke and large transmission torque, and achieve improved fuel efficiency and compactness of the device.

[Means for Solving the Problems] The drive pulley of the V-belt type continuously variable transmission of the present invention has the following configuration. Namely.

Consisting of a fixed pulley half and a movable pulley half provided on the same rotating shaft, the movable pulley half has a cam surface extending in the radial direction on the back surface opposite to the pulley surface that contacts the V-belt. A flyweight is provided which moves in an expanding manner while contacting the cam surface around a support point which is separated from the cam surface and rotates integrally with the rotating shaft, and the cam surface has a point at which the direction of inclination changes. , a clutch part is provided on the rotation axis direction side from the point where the direction of the inclination changes, and a transmission part is provided on the outer circumferential direction side from the point where the above-mentioned direction changes, passing through the support point, The distance between a line segment orthogonal to the rotating shaft and the cam surface gradually increases in the clutch portion and gradually decreases in the transmission portion in the direction in which the flyweights expand. .

[Operation of the Invention] When the flyweight expands during startup, it presses the cam surface of the clutch portion. At this time, the cam surface tends to gradually escape in the direction of movement of the flyweight. Therefore, even if the rotational speed increases, the amount of forward stroke of the movable pulley half does not increase that much.

When the flyweight moves on the cam surface close to the point where the inclination direction changes, the number of rotations becomes high enough and the transmitted torque becomes large, and the pulley surface and belt side finally come into contact and the clutch is turned on. .

In the transmission part, on the other hand, the cam surfaces tend to have smaller spacings in the direction in which the flyweights expand. Therefore, from this part, the movable pulley half slides with a relatively large stroke amount in response to changes in the rotational speed to change speed.

[Embodiment] FIGS. 1 to 6 show a drive pulley of a V-belt type continuously variable transmission which is an embodiment of the present invention.

(Overall Structure of Drive Pulley) FIG. 1 shows the overall structure of the drive pulley in this embodiment.

This drive pulley 1 consists of a fixed pulley half 2 and a movable pulley half 3, which face each other to form a groove having a substantially V-shaped cross section, and accommodate a belt 4.

A cover 5 is provided on the back surface of the movable pulley half 3 (the surface opposite to the fixed pulley half), and the fixed pulley half 2, the movable pulley half 3, and the cover 5 are supported on the same rotating shaft 6. has been done.

In the space formed by the movable pulley half 3 and the cover 5,
Spider 7 and flyweight 8 are housed.

The spider 7 is fixed to the rotating shaft 6, and a portion of the spider 7 protrudes in the radial direction and serves as a support portion for the flyweight 8. One end of the flyweight 8 is supported by the spider 7, and the flyweight 8 is capable of expanding movement using the spider 7 as a fulcrum. The head of the rotation shaft 6 of the cover 5 is open, and a cap 9 made of resin or the like is detachably attached thereto.

The fixed pulley half 2 is integrated with the shaft end of the rotating shaft 6, cannot be slid in the axial direction, and is fixed to the rotating lower part LM. The side surface of each pulley half 2.3 on the V-belt 4 side is a pulley surface 10.11 that presses against the side surface of the belt 4, and both pulley surfaces are
It is formed into a slightly curved surface that is convex toward the belt.

The movable pulley half 3 is axially slidably supported on the rotating shaft 6 by bearings 12 and seals 13,14. A radially extending cam surface 15 is provided on the back surface of the pulley surface 11.
are formed at equal intervals in the circumferential direction.

The outer peripheral edge of the movable pulley half 3 forms a thick-walled mounting part 16, and the outer peripheral edge 17 of the bowl-shaped cover 5 is attached here.
are put together via an O-ring O and fastened with a bolt 18. A bearing 1 is provided at the portion where the cover 5 contacts the rotating shaft 6.
9 is press-fitted and is allowed to slide in the axial direction.

The rotating shaft 6 is a hollow shaft, and the outer periphery of the mounting portion of the spider 7 is formed into a tapered portion 20, and is connected to the spider 7 in a tapered manner. Furthermore, there is a stepped portion between the tapered portion 20 and the fixed pulley half 2, and the movable pulley half 3 is supported on the outer peripheral surface by the sliding rotating portion and the rotating rotating portion. . A grease cup 22 is inserted inside the stepped portion 21 to form an oil supply portion 23. An oil chamber 24 that communicates with the rotating shaft 6-H, which corresponds to the oil supply section 23, is opened, and the bearing 12 is supplied with oil from there.

A tapered portion 2'5 is formed on the inner surface of the shaft on the shaft end side from the oil supply portion 23 to which the fixed pulley half 2 is fixed. The tip of a crankshaft 27 having a corresponding taper portion and a screw hole is fitted into this taper portion 25 from the open end on the body 2 side of the fixed pulley. The crankshaft 27 is the output shaft of the engine, and forms part of the rotating shaft of this embodiment.

A long bolt 26 is inserted from the end of the rotary shaft 6 on the cover 5 side, fastened to a threaded hole in the crankshaft 27, and tightened to connect the crankshaft 27 and the rotary shaft 6 in a tapered manner.

After the long port 26 is fastened, the cap 9 is attached to the opening of the cover 5 by screwing or the like to seal the inside.

The spider 7 is fixed to the rotating shaft 6 by a key 28 and a nut 29 so as to be immovable in the axial direction and unrotatable.

A spring 31 is provided between the spider 7 and the cover 5 via a retainer 30, and the cover 5 is always urged to move to the left in the figure with respect to the spider 7. As a result, when the rotating shaft 6 is not rotating, a predetermined stroke S is maintained between the pulley surface 11 and the V-belt 4, and a spring set load is applied so that the clutch is in an OFF state.

Furthermore, flyweights 8 are supported at the tip of the spider 7 and are arranged corresponding to cam surfaces 15 provided at equal intervals in the circumferential direction. The flyweight 8 has a roller 33 rotatably attached to one end of an arm 32 and a weight roller 34, which is a roller-shaped weight, attached to the other end of the arm 32.
The weight roller 34 is held between a pair of arms 32 (only one of which is visible in the figure). roller 33
is accommodated in a support recess 35 formed at the tip of the spider 7, and its outer periphery is held down by a bent part of a support plate 36,
A weight roller 34 is rotatably supported. The pivot point of this roller 34 serves as the support point of the present invention.

The support plate 36 is a plate-shaped member formed concentrically with the spider 7, and is fixed to the side surface of the spider 7. The weight roller 34 is rotatably brought into contact with the cam surface 15.

Further, through holes are formed at equal intervals in the circumferential direction at the tip of the spider 7, and guide pins 38 are fitted through resin sleeves 37 fixed by a support plate 36. A through hole 39 into which a guide pin 38 is loosely fitted is formed in the support plate 36, and the guide pin 38 is inserted into the resin sleeve 3.
7 and a through hole 39, and both ends thereof are supported between the movable pulley half 3 and each inner side surface of the force/heel 5.

FIG. 1 shows a state in which the rotational force of the pulley is not transmitted to the belt, that is, a state in which the clutch is off.

When the crankshaft 27 rotates, the rotating shaft 6 which is tapered connected thereto rotates, and the fixed pulley half 2 and spider 7 also rotate together.

When the spider 7 rotates, centrifugal force acts on the weight roller 34, causing it to expand and move upward in the direction of arrow A on a circular arc centered on the roller 33. At this time, the weight roller 34 presses and slides on the cam surface 15 and urges the movable pulley half 3 in the direction of the outward arrow B. When the weight roller 34 comes into pressure contact with the cam surface, the movable pulley half 3 is pushed, and the cover 5 also tries to slide forward to the right in the figure (in the direction of arrow B) against the force of the spring 31. As a result, the cover 5 is attached to the rotating shaft 6.
The movable pulley half 3 integrally slides forward on the small diameter portion and on the stepped portion 21 to the right in the figure. Eventually, when the pulley surface 11 comes into sliding contact with the V-belt 4 and applies a predetermined side pressure to the V-belt 4, the clutch is turned on and the V-belt 4 is rotated. The V-belt 4 transmits this rotation to a driven pulley (not shown) to rotate it, thereby driving the rear wheels.

Furthermore, as the rotation of the crankshaft 27 increases, the amount of expansion of the weight roller 34 increases accordingly, pushing the movable pulley half 3 to the right and increasing the rotation radius of the V-belt 4. As a result, the rotation radius on the driven pulley side becomes smaller, and the speed is shifted to the high speed side.

Conversely, if the engine speed drops, the engine will act in reverse and slow down. As a result, continuously variable speed is achieved.

(Cam Surface) Next, the cam surface will be explained. A part of the movable pulley half 3 and its cam surface are shown enlarged in FIG.

The cam surfaces 15 are protrudingly formed on the back surface of the movable pulley half 3 in rib-like portions that are arranged at equal intervals in the circumferential direction and protrude 5 in the radial direction. The cam surface 15 has a point Tp where the direction of inclination changes, and a transmission section is provided above the point Tp,
A clutch section is provided below. However, it is not necessary to make the boundary between the transmission section and the clutch section dependent on 12 points.

The cam surfaces in the transmission section and the clutch section have different curvatures or inclinations. That is, a line segment passing through the support point P of the weight roller 34 and perpendicular to the axial center line of the pulley shaft 6
The distance between and the cam surface is in the expansion direction of the weight roller 34 (
The trend is opposite to the direction of the arrow). First, while the distance a at the clutch section tends to gradually increase, the distance at point Tp reaches a maximum, and the distance C at the transmission section tends to gradually decrease. Further, while the cam surface of the clutch section changes linearly, the cam surface of the transmission section changes curved. However, the cam surface of the clutch portion may be curved.

Since the cam surface has such a shape, in the clutch portion, as the weight roller 34 expands, the distance #a of the cam surface increases.
tends to expand and pass through, and even if it expands to near the point Tp, the stroke state of the movable pulley half 3 does not become that large. When the movable pulley half 3 moves forward by an amount corresponding to the stroke S shown in FIG. 1 after expanding close to the point Tp, the pulley surface l1 comes into contact with the side surface of the belt 4 and the clutch is turned on.

When the weight roller 34 passes point Tp and expands to the transmission section, the direction of inclination of the cam surface changes, so a relatively large stroke occurs depending on the amount of expansion of the weight roller 34, and thereafter, the rotation speed changes. In contrast, smooth gear changes with good responsiveness are performed. In this embodiment, since the cam surface is formed on the rib, it serves to reinforce the movable pulley half.

FIG. 3 shows a method for calculating thrust. Weight roller 34
A line 10 connects the center O and the support point P, a tangent at C is the intersection of O and the outer circumference of the weight roller 34, 11 is the tangent at C, 12 is the tangent at D, which is the point of contact between the weight roller 34 and the cam surface 15. Let α and β be the angles that lines -l/ and -2 make with lines perpendicular to the axis of the pulley shaft, respectively, and F be the centrifugal force of the weight roller 34.

In this weight roller 34, the surface pressure F2 is the line OD
and the reaction force F1 is on the line OC. Further, the thrust force Q that causes the movable pulley half body 3 to slide is given by the following equation.

Q=F2・cosβ...■ By the way, if these gravity forces are considered in the x-y orthogonal coordinate system, it will be as follows.

X direction: Flecosα=F2*cosβ...■Y direction: F=F1*5tna+F2esinβ...■Therefore, from ■, ■, ■, Q=F/ (t anα+t anβ)... ...■
becomes.

Also, F2111m・ω = rIIWφω 7g・・・・・・
■It is. However, m is the mass of the weight roller, W is the same weight, W is the angular velocity, and 2g is the gravitational acceleration.

Therefore, the thrust force Q is finally given by the following formula.

Q=r*W*ω 7g (tana+tanβ) 4th
The figure is a graph illustrating the relationship between thrust and rotation speed calculated using the above formula in comparison with a conventional example.

In this embodiment, the spring 31 (first
When the initial set load (spring cent load) (see figure) is reached and this spring set load (30 kg) is overcome, the thrust continues to increase and the clutch is turned on with a thrust of approximately 53 kg.

On the other hand, in the conventional example, the spring set load is reached at about 3500 rotations, and the clutch is turned on with a thrust of about 46 kg. Therefore, assuming that the clutch is turned on in the conventional example at the same rotational speed as in this embodiment, the thrust when the clutch is turned on is approximately 35 kg, as shown by the dotted line, but in reality it is still below the spring set load. Therefore, it can be seen that the thrust force when the clutch is on in this example increases dramatically.

As a result, as shown in FIG. 5, a significant difference appears in the amount of torque transmitted after the clutch is turned on.

This means that belt slip is reduced and indicates improved start-up characteristics.

Further, FIG. 6 shows the relationship between the expansion angle of the weight roller 34 and the stroke of the movable pulley when it is half-off.

As is clear from this graph, the stroke amount can be reduced in this embodiment.

[Effects of the Invention] According to the present invention, the rise characteristics are greatly improved. In other words, the clutch is turned on with a small stroke, and a large transmission torque is applied to the belt. Therefore, belt slip during startup is reduced and fuel efficiency is improved. Furthermore, since the stroke required to turn on the clutch can be made smaller, the distance between the pulleys can be made smaller, and the device can be made more compact.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a drive pulley according to an embodiment of the present invention, Fig. 2 is an enlarged sectional view of the main parts, Fig. 3 is a schematic diagram showing how to calculate thrust, and Fig. 4 is a diagram showing the relationship between rotation speed and thrust. FIG. 5 is a correlation diagram between rotation speed and transmitted torque, and FIG. 6 is a correlation diagram between rotation speed and stroke. (Explanation of symbols) 3...Movable pulley half, 6...Pulley shaft, 8...
Fly weight, 34... Weight roller, 11...
・Pulley, 4...V belt, 15...cam surface, P・
...Support point. Patent applicant Honda Motor Co., Ltd. Patent applicant
Yamada Seisakusho Co., Ltd. Representative Patent Attorney
Kiyomitsu Komatsu 2nd figure rotation # 4th rotation (A rotation speed i5m rotation rotation

Claims (1)

[Claims] Consisting of a fixed pulley half and a movable pulley half provided on the same rotating shaft, a cam surface extending in the radial direction is formed on the back surface of the movable pulley half, and the rotating A flyweight is provided that expands while contacting the cam surface around a support point that rotates integrally with the shaft, and the cam surface has a point where the direction of inclination changes, and the cam surface rotates from the point where the direction of inclination changes. A clutch portion is provided on the axial side, and a speed change portion is provided on the outer circumferential side from the point where the inclination direction changes, and the distance between the cam surface and a line passing through the support point and perpendicular to the rotation axis is: In the direction of expansion of the flyweights,
A drive pulley for a V-belt type continuously variable transmission, characterized in that the drive pulley gradually increases in the clutch portion and gradually decreases in the transmission portion.