JPS6235963Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a belt tensioner in a belt transmission mechanism.

(Prior art) Conventionally, in order to make the structure of a belt tensioner more compact so that the installation space can be reduced, and at the same time to be able to apply sufficient tension force, a belt tensioner has been developed as shown in, for example, Japanese Utility Model Publication No. 58-56446. A tension pulley is rotatably held by a shaft (pulley holding member) rotatably supported around an eccentric shaft, and a coil spring having a coil diameter larger than the outer diameter of the shaft is externally mounted on the shaft. It is known that the shaft is biased around the eccentric axis by fitting and attaching the shaft. However, with this belt tensioner, when the coil spring is twisted and elastically deformed when the shaft rotates around the eccentric shaft, the coil spring tends to tilt with respect to the axis of the shaft, and the upper end of the coil spring There is a risk that the lower surface of the tension pulley may come into contact with the lower surface of the tension pulley, and in order to prevent this, it is necessary to provide sufficient space between the tension pulley and the coil spring. I couldn't achieve it.

In addition, in order to prevent the coil spring from tilting, the inner diameter of the coil spring and the outer diameter of the shaft are made approximately equal, and the entire coil spring is attached to the outer circumference of the shaft, as shown in, for example, Japanese Utility Model Application Publication No. 58-151738. By attaching the shaft close to a surface, the shaft is used as a guide member to prevent the coil spring from tilting. However, with this configuration, it is difficult to set a large spring torque because the coil diameter of the coil spring is small.Moreover, the coil spring tends to come into contact with the outer peripheral surface of the shaft, and due to the frictional resistance, the predetermined spring torque is There is a problem that the tension action is likely to become unstable.

(Purpose of the invention) The present invention has been made in order to solve the above-mentioned problems, and has a simple and compact structure that prevents the coil spring from inclining. An object of the present invention is to provide a belt tensioner that can prevent a coil spring from coming into contact with a pulley holding member by providing a sufficient distance between the coil spring and the outer circumferential surface of the belt tensioner.

(Structure of the invention) The invention consists of an eccentric shaft installed upright on a fixed member, a pulley holding member rotatably supported by the eccentric shaft, and a pulley holding member rotatably held at the end of the pulley holding member. The tension pulley is fitted between the tension pulley, the fixing member of the pulley holding member, and the tension pulley, and one end is locked to the pulley holding member, and the other end is attached to the fixing member. In a belt tensioner equipped with a coil spring that is locked, the coil diameter of the coil spring is made larger than the outer diameter of the pulley holding member, and the coil spring is arranged closer to the fixed member than the tension pulley of the pulley holding member. It has a protruding flange that abuts on the upper end and holds it to prevent it from falling.

With this configuration, the upper end of the coil spring comes into contact with the flange and is locked, so that even if the coil spring is twisted and elastically deformed, it can be prevented from inclining.

(Embodiment) FIGS. 1 and 2 show an embodiment of the belt tensioner according to the present invention, and in these figures,
Reference numeral 1 denotes an eccentric shaft consisting of a stud bolt or the like installed upright on a fixed member 2, 3 a pulley holding member rotatably supported around this eccentric shaft 1, and 4 a bearing 5 attached to this pulley holding member 3. The tension pulley 6 rotatably held via the pulley holding member 3 is a coil spring having a larger coil diameter than the pulley holding member 3 and is attached to the holding member 3 by being fitted onto the outside thereof.

One end 7 connected to the lower end of the coil spring 6 is bent toward the center of the coil at a first bend 7a, and bent at a substantially right angle at a second bend 7b near the center of the coil. The first bent portion 7a and the tip portion 7c extend outward, and the engagement grooves 3a, 3b are formed in the outer peripheral portion of the lower end of the pulley holding member 3.
It is fitted inside and locked. The other end 8 connected to the upper end of the coil spring 6 is bent downward, and its tip is fitted into the engagement hole 2a formed in the fixing member 2 and locked. As a result, rotational force is applied to the pulley holding member 3 about the eccentric shaft 1, which is provided eccentrically by a predetermined distance from the central axis of the pulley holding member 3. When the coil spring 6 is twisted and elastically deformed by the driving force of the belt 9, the restoring force presses the outer peripheral surface of the tension pulley 4 against the belt 9, so that a predetermined tension is applied to the belt 9. It is composed of

Further, a flange 10 is provided on the circumferential surface of the pulley holding member 3 located below the bearing 5, and extends in a direction perpendicular to the central axis of the pulley holding member 3.
By abutting the upper end of the coil spring 6 against the lower surface of the coil spring 6, the coil spring 6 is held to prevent it from falling.

In this way, since the upper end of the coil spring 6 is in contact with and locked to the lower surface of the flange 10, the coil diameter of the coil spring 6 is larger than the outer diameter of the pulley holding member 3. Even when the spring 6 is twisted, it is possible to effectively prevent the coil spring 6 from tilting with respect to the axis of the pulley holding member 3. Therefore, sufficient spring torque can be obtained by making the coil diameter of the spring 6 larger than the outer diameter of the pulley holding member 3, and a predetermined distance 〓 is provided between the coil spring 6 and the pulley holding member 3. In addition, it is possible to prevent the coil spring 6 from inclining and causing its upper end to contact the tension pulley 4 or the like and inhibiting its rotational action.

Further, in the above embodiment, one end 7 of the coil spring 6 which is bent at a substantially right angle at the second bent portion 7b is connected to the engagement groove 3a of the pulley holding member 3.
3b, and this coil spring 6 is also held at its lower end to prevent it from falling. For this reason, the coil spring 6 is held to prevent it from collapsing at both the upper end portion that is locked to the flange 10 and the lower end portion that is locked to the locking grooves 3a and 3b, and as a result, the pulley holding member There is an advantage that it is possible to more reliably prevent the coil spring 6 from tilting with respect to the axis of FIG.

Note that one end of the coil spring 6 is not necessarily bent into the shape described above to form the engaging grooves 3a, 3b.
There is no need to configure the coil so that it is locked inside, but one end that is bent so as to extend straight toward the center of the coil is inserted into the engagement hole formed on the circumferential surface of the pulley holding member 3 and locked. You may also do so.

(Effect of the invention) As explained above, the belt tensioner according to the invention has a flange protruding from the peripheral surface of the pulley holding member rotatably supported around the eccentric shaft, and the pulley holding member is By bringing the upper end of the coil spring that urges around the eccentric shaft into contact with the flange and locking it, the coil spring is held to prevent it from falling, so the pulley cannot be held as with conventional products. The coil spring is tilted with respect to the axis of the pulley holding member without adopting means such as bringing the coil spring close to the outer peripheral surface of the pulley holding member in order to use the member itself as a guide member for preventing coil spring inclination. This can definitely be prevented. Therefore, by setting the coil diameter of the coil spring to be larger than the outer diameter of the pulley holding member by a predetermined amount, sufficient spring torque can be obtained from the spring, and the inner peripheral surface of the coil spring and the pulley holding member can be It is possible to prevent the occurrence of frictional resistance due to contact between the outer circumferential surface of the member, and it is possible to always exert a stable tension action.

In addition, since the above-mentioned flange prevents the coil spring from tilting, it is possible to prevent contact between the tension pulley and the coil spring without providing a large gap between the two, allowing for a more compact configuration. At the same time, it is possible to simultaneously achieve effects such as stabilizing the rotation of the tension pulley field.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a view taken along the - line in FIG. 1. DESCRIPTION OF SYMBOLS 1...Eccentric shaft, 2...Fixing member, 3...Pulley holding member, 4...Tension pulley, 6...Coil spring, 7...One end of the coil spring, 8...The other end of the coil spring , 10...
flange.

Claims (1)

[Scope of utility model registration request] An eccentric shaft erected on a fixed member, a pulley holding member rotatably supported by the eccentric shaft, a tension pulley rotatably held at an end of the pulley holding member, and the pulley holding member A coil spring is fitted between the fixing member and the tension pulley, and has one end locked to the pulley holding member and the other end locked to the fixing member. In the belt tensioner, the coil diameter of the coil spring is made larger than the outer diameter of the pulley holding member, and the pulley holding member is placed closer to the fixed member than the tension pulley and comes into contact with the upper end of the coil spring. A belt tensioner characterized by a protruding flange that is held to prevent it from falling.