JPH06307463A - Flexible shaft coupling - Google Patents

Abstract

PURPOSE:To improve allowable torque by using one, or two or more of nylon, polyester, rayon and aromatic polyamide in twist yarn with large breaking elongation of combined yarn, and polybenzazole series in twist yarn with small thermal shrinkage. CONSTITUTION:This flexible shaft joint is formed by winding combined yarn by 10 layers inside a flange 6 formed at a collar 3, surrounding the whole part by rubber to embed it and use it as one element of a long and slender rubber elastic body 5, forming a mounting hole 1 in a short pipe 7 pressed in the collar 3, and combining these elements for 6 sets. A tension member 4 is combined yarn formed by twisting twist yarn with large breaking elongation and twist yarn with small thermal shrinkage together. The combined yarn is formed by taking up and twisting three of two polyester twist yarns 11 and one polybenzazole series twist yarn together. It is thus possible to improve allowable torque with little increase in bending spring constant at the time of heating and provide reduction in size and weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible shaft coupling for power transmission which is interposed between a drive shaft and a driven shaft and which is interposed in a propulsion shaft or the like for transmitting a rotational force. It is used to connect the propeller shaft that transmits the driving force of the steering wheel and the steering shaft that transmits the rotational force of the steering wheel.

[0002]

2. Description of the Related Art Generally, a joint for transmitting or cutting off torque from a drive shaft on a concentric shaft to a driven side is provided with flanges opposed to each other on both the drive shaft side and the driven shaft side. A joint is interposed, and examples of this kind of joint include those shown in FIGS. 3 and 4. What is shown in FIG. 3 is a so-called integral joint, while the type shown in FIG. 4 is an element type, each of which has four mounting holes for mounting on a flange (not shown) provided on the shaft. Or 6
It has one piece, and every other piece is alternately attached to the flanges on the drive shaft side and the driven shaft side.

In the example shown in the figure, there are six mounting holes 1a to 1c and 2a to 2c, but the mounting holes 1a, 1b and 1c are mounted on the driving side and the mounting holes 2a, 2b and 2c are mounted on the driven side. It is for. A collar 3 is attached to each of the mounting holes 1a to 1c and 2a to 2c.
The tensile body 4 is wound between the three. The collar 3 and the tensile body 4 are surrounded by a doughnut-shaped rubber elastic body 5 and the collar 3 and the tensile body 4 are embedded. This is called an integral joint. Surrounded by an elliptic rubber-like elastic body 5, one collar 3 is embedded in two elliptic rubber-like elastic bodies 5, and these six rubber-like elastic bodies 5 are used in combination. Is an element type joint.

Now, although these joints are mainly used for axles in many cases, there are some demanding performances because the places where they are used are extremely important.
For example, depending on the place of use, the rubber-like elastic body itself is required to have heat resistance and, in some cases, oil resistance because it is used in a considerably high temperature atmosphere. On the other hand, usually polyamide (nylon) is used as a tensile body.
Fiber, rayon fiber, polyester fiber, aromatic polyamide (amirad) fiber, etc. are selected and adopted in consideration of various conditions. In particular, since it is necessary to reliably transmit the torque from the driving side to the driven side, the tensile member wound between the adjacent collars must have a breaking strength that can withstand this torque. However, even if the breaking strength is high, a material having a small elongation until breaking cannot be said to be very good.

On the other hand, when the joint is used in a considerably high temperature range, it must have excellent thermal properties as a joint. That is, if the heat shrinkage is high, the vibration isolation performance is deteriorated and the product cannot be used. That is, if the elongation of the tensile member used is too small, it is disadvantageous in terms of durability. On the other hand, if the heat shrinkage is large, the vibration-proof properties at high temperatures deteriorate, and any of these causes the durability performance of the joint to be greatly reduced. .

Up to now, a tensile body using each of the above fibers alone has been used, but each performance required for a joint is not completely satisfied, and an improvement has been demanded.

[0007]

Therefore, the present invention is
An object of the present invention is to provide a flexible shaft joint that has a high breaking strength, a small heat shrinkability, and a moderately stretchable tensile body, in which the bending spring constant does not increase at a high temperature. Also,
It is an object of the present invention to provide a flexible shaft joint that is further miniaturized and reduced in weight and has improved allowable torque.

[0008]

In order to achieve the above-mentioned object, the present invention has a structure in which driving side and driven side collars are alternately arranged on the circumference, and a tension member is wound between adjacent collars. The rubber-like elastic body surrounds and embeds the collar and the tensile body, and the twisted thread having a large elongation at break as the tensile body and the twisted thread having a small heat shrinkability are further twisted together to form a composite thread. In the flexible shaft joint in which the above-mentioned collar is wound between the collars, one or more twisted yarns selected from nylon, polyester, rayon and aromatic polyamide are used as the twisted yarns having a large breaking elongation of the composite yarn, and the heat shrinkage of the composite yarn is performed. A polybenzazole-based twisted yarn is used as the twisted yarn having a low property.

[0009]

In the present invention, a polybenzazole (PBO) twisted yarn is used as the twisted yarn having a small heat shrinkability, and this PBO fiber has a unit weight of Kevlar (registered trademark).
Fiber is 20 to 25 g / d, while 35 to 45 g / d
It has a strength of d (d is denier). Therefore,
The strength is about 80% higher than that using Kevlar fiber, and the allowable torque can be improved. Further, by using the PBO fiber, the strength does not decrease even if the number of windings of the fiber is reduced, so that the size and the weight can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an enlarged cross-sectional view of a central portion of one element of an element type flexible shaft coupling. 55 mm between centers of collars 3 and 3
Then, 10 layers of the composite yarn are wound around the flanges 6 and 6 formed on the collar 3. 11 between the flanges 6 and 6
mm. Thereafter, the whole is surrounded and embedded with rubber to form an element of the elliptic rubber-like elastic body 5,
The mounting hole 1 is formed in the short pipe 7 press-fitted in the collar 3. Six of these elements are combined to complete a flexible shaft joint as shown in FIG. Here, the tensile body 4 is formed by further twisting a twisted yarn having a large elongation at break and a twisted yarn having a small heat shrinkability into a composite yarn, which is wound around the collars 3 and 3. Here, as shown in FIG. 2, the composite yarn includes two polyester twisted yarns (twisted yarns having a large breaking elongation) 11,
1 PBO twisted yarn (twisted yarn with high heat shrinkability) 1
A total of three books are picked up and twisted together.
Examples of the polybenzazole type include polybenzoxazole, more specifically, polyparaphenylenebenzbisoxazole (cis type) and polybenzthiazole.
The number of each twisted yarn is not limited to two and one, and two or more types of twisted yarns 11 having a larger breaking elongation can be used in combination.

Experiment 1 Here, a characteristic test of various yarns used for each twisted yarn was conducted. The respective test yarns are as follows. Polyamide raw yarn: 6-nylon (1000 denier) Polyester raw yarn: 1000 denier Aromatic polyamide raw yarn: Kevlar (registered trademark) (10
00 denier) PBO raw yarn: polyparaphenylene benzbisoxazole (cis type) (1000 denier) Table 1 shows the test results of elongation at break (elongation rate% until pulling to break) and heat shrinkage. The heat shrinkage test was judged by the shrinkage when the raw yarn was left in an atmosphere of 150 ° C. for 30 minutes.

[0013]

[Table 1]

As can be seen from the test results, the breaking elongations of the polyamide raw yarn and the polyester raw yarn are large, and the breaking elongation of the polyester raw yarn is suitable for the shaft coupling. On the other hand, the aromatic polyamide raw yarn and the PBO-based raw yarn have almost no heat shrinkability,
Suitable as a tensile member for shaft joints in high temperature range. However, since the elongation at break is small, it is found that the tensile body of the shaft joint has a problem in durability.

Experiment 2 Next, a polyester yarn and an aromatic polyamide yarn were selected from the above-mentioned raw yarns, and a characteristic test was carried out when these yarns were made into a composite yarn. Here, as in the case of the composite yarn shown in FIG. 2, two polyester twisted yarns 11 and one aromatic polyamide (Kevlar) twisted yarn are picked up and twisted together for a total of three. The number of lower twists of the polyester twisted yarn 11 used in such an experiment is 38 (T / 10cm), the number of lower twists of the Kevlar twisted yarn is 45 (T / 10cm), and the number of twists of the composite yarn is 45 (T / 10cm). )Met. Note that a
Is the number of Kevlar twisted yarns, b is the number of all original yarns, and the ratio is shown in Table 2 as a / b. Here, the same test as in Experiment 1 was performed, and the results are shown in Table 2. In addition, the test results are set such that the breaking elongation of the polyester twisted yarn 11 is 1, and the heat shrinkage of the Kevlar twisted yarn is 1, and how much the composite yarn shows the breaking elongation with respect to such breaking elongation 1. The ratio of the heat shrinkage of the composite yarn to the heat shrinkage of 1 is shown as a ratio.

[0016]

[Table 2]

As can be seen from these results, the composite yarn exhibits not only the characteristics of the respective original threads but also the characteristics of both of them, and it is proved that it is suitable for use as a tensile body of the shaft coupling. did. However, when a Kevlar twisted yarn is used as the twisted yarn having a small heat shrinkability, there is a limit in terms of downsizing and weight reduction. Therefore, in the present invention, the PBO twisted yarn 12 using a PBO-based fiber having a strength higher than that of Kevlar is used as a twisted yarn having a small heat shrinkability, thereby achieving miniaturization and weight reduction. In Experiment 2, the number of windings of the composite yarn per element was 153, but the PBO twisted yarn 1
75-85 to maintain comparable performance using 2
Was enough.

Experiment 3 The same experiment as in Experiment 2 was conducted on a composite yarn of a polyamide twisted yarn and a PBO twisted yarn. The number of windings of the composite yarn per element was 153. The experimental results are shown in Table 3.

[0019]

[Table 3]

From these results, it was found that the composite yarn obtained by twisting two kinds of raw yarns together is suitable as the tensile body for the shaft coupling.

Experiment 4 The tensile body 4 shown in FIG. 1 was formed from the composite yarn used in Experiment 3 to make the flexible shaft joint shown in FIG. A constant torsion torque was repeatedly applied to the short pipe 7 of such a flexible shaft coupling, and the number of times until breakage was measured. In Table 4, a / b is 0 /
The number of times until breakage of 3 in the related art is set to 1 and the ratio is shown as the durable life.

[0022]

[Table 4]

A / b according to the invention is 2/3 and 1/3
It can be seen that the shaft coupling using the composite yarn of No. 2 has a markedly increased durability life. In case of PBO only (3/3)
It was also found that the endurance life was extremely poor. Also, as a shaft coupling, in some cases there is heat generation due to use,
On the other hand, the atmosphere of the operating environment is often in a high temperature range, and it is inconvenient if the spring characteristics change significantly in the high temperature range.
In consideration of this point, the bending spring characteristics of the shaft coupling at room temperature and the bending spring characteristics at the time of temperature increase (80 ° C.) were compared. The results are shown in Table 4, and it can be seen that the conventional twisted yarn in which a / b is 0/3 changes greatly, whereas the yarn of the present invention can withstand use in a sufficiently high temperature range.

Here, the bending spring characteristic means that the short pipe 7 which is one end of the shaft joint is fixed and held horizontally, and the short pipe at the other end of the shaft joint facing the held short pipe 7 is held. 7 is applied to measure the load required to bend 1 ° from the horizontal line of the horizontally held shaft coupling, and this load and the short pipe at the one end and the short pipe at the other end are measured. Bending spring constant obtained by the product with the distance from the center of 7 (hereinafter referred to as arm length). The bending spring constant is expressed in Kg · cm / deg. In this experiment, a shaft coupling with an arm length of 14.3 cm was manufactured, and ± 2.5 mm (1
The load required to bend (equivalent to a deflection of ° minutes) (Kg,
The average value was measured, and the bending spring constant was determined by the load (Kg) × 14.3 (cm).

[0025]

As described above, according to the present invention, the twisted yarn having a large elongation at break of the composite yarn is selected from 1 or 2 selected from nylon, polyester, rayon and aromatic polyamide.
The above-mentioned twisted yarn is used, and the twisted yarn of the polybenzazole type is used as the twisted yarn of the composite yarn having a small heat shrinkability. The tensile body was obtained,
By applying this to a shaft coupling, durability is improved. Further, since the composite yarn of the present invention has a higher strength than a yarn using Kevlar as a twisted yarn combined with a twisted yarn having a large breaking elongation, if a flexible shaft coupling having a similar strength is made, it is downsized and lightweight. Can be realized. If they are made of the same size and weight, they can handle about 80% more torque than those using Kevlar. When the weight was reduced, the weight of the joint as a whole could be reduced by about 7% as compared with the case where Kevlar was used.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a tensile body used in a flexible shaft coupling of the present invention.

FIG. 2 is a sectional view of a composite yarn.

FIG. 3 is a plan view of an integral type flexible shaft coupling.

FIG. 4 is a plan view of an element type flexible shaft coupling.

[Explanation of symbols] 3 Color 4 Tensile body 5 Rubber-like elastic body 11 Twisted yarn with large elongation at break 12 Twisted yarn with small heat shrinkability

Claims (1)

[Claims] 1. A collar on the driving side and a collar on the driven side are alternately arranged on the circumference, and a tension body is wound between adjacent collars, and a rubber-like elastic body surrounds the collar and the tension body. A flexible shaft joint in which a twisted yarn which is embedded and has a large breaking elongation as the tensile body and a twisted yarn having a small heat shrinkability are further twisted to form a composite yarn, which is wound between the collars. 1 selected from nylon, polyester, rayon and aromatic polyamide
Alternatively, a flexible shaft joint is characterized in that two or more twisted yarns are used, and a polybenzazole-based twisted yarn is used as the twisted yarn of the composite yarn having a small heat shrinkability.