JP2006170368A - Cable protector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cable protector having sufficient stress reducing effects on a bent cable by effectively suppressing such stress that the cable receives from a fixed portion or the cable protector even at a lower temperature while improving the degree of freedom in setting the shape of a conical cable protecting part. <P>SOLUTION: The cable protector formed of an EPDM comprises a cylindrical held part 30 externally fitted to one end of a cable fixing clamp 60 and held thereon and the conical cable protecting part 40 continuously formed on the held part 30. The cable protecting part 40 has a stepped portion 43 first formed over a range from the boundary to the held part 30 to the front edge out of which the cable is put, and a diameter shrunk portion 44 then formed ranging from the stepped portion 43 to a diameter shrunk end 45 with its outer diameter being gradually shrunk. The formation of the stepped portion 43 improves the degree of freedom in setting the length or taper angle of the diameter contraction portion 44 and controls the stress on the cable 50 through the front end to an optimum. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is to fix a cable for remote control provided in various machines, automobiles, etc. to a predetermined member by a fixing tool, and particularly to fix a cable that is attached to the fixing tool and vibrates. The present invention relates to a cable protector that prevents a cable from being broken by relaxing the degree of bending at a tool portion.

  Such a cable is provided, for example, in a parking brake device of an automobile. As shown in FIG. 10, this apparatus often transmits the operating force of a manual brake lever 1 provided in a vehicle compartment to a parking brake unit provided in a wheel 3 by a parking brake cable 2. That is, the brake lever 1 and the parking brake unit are connected by the cable 2, and the cable 2 is connected to the predetermined position of the vehicle body via the clamp 4 with a moderate margin. And fixed to the parking brake unit.

  By the way, when the vehicle is running, the wheels always move up and down relatively with respect to the vehicle body. Therefore, in the cable 2 shown in FIG. The portion between the first fixed portion (the portion of the clamp 4) from the vehicle body side vibrates up and down and bends repeatedly. Such a cable that is forced to bend may be broken at the fixed portions at both ends of the bent portion due to long-term use.

  The reason why the cable is easily broken at the fixing portion is that the bending moment generated at the time of receiving stress from the fixing portion is the largest and the degree of bending becomes strong. In addition, since the fixing portion fixes the cable by caulking, there may be a case where deformation occurs when caulking occurs in the cable.

  Therefore, in order to prevent breakage of the cable at the fixed portion, a cable protector that relaxes stress received from the fixed portion is attached to the clamp. FIG. 11 shows a typical example of such a conventional cable protector together with dimensions, in which a conical cable protection part 12 extends continuously from the end of the cylindrical holding part 11. In the configuration, the clamp is press-fitted into the holding unit 11 to be held by the clamp, and the cable is inserted into the cable protection unit 12.

  The cable protector is made of elastic rubber such as EPDM (ethylene / propylene / diene terpolymer). The cable protector 12 covers the portion of the cable that is bent from the clamp. By being supported elastically, it is less susceptible to stress and prevents breakage. Moreover, as what supports the part which receives strong stress from a clamp with a rubber-made conical member, patent document 1 etc. are also known, for example.

Shokai 58-70953

  The cable protector using the EPDM bends relatively smoothly according to the curve of the cable at normal temperature, but tends to be difficult to bend due to an increase in the elastic modulus at low temperature. For this reason, the cable is subjected to stress from the distal end portion of the cable protector that is difficult to bend, and the cable may be bent at that portion, which may cause breakage. In order to solve such problems at low temperatures, it was considered to use a rubber such as silicon rubber whose elastic modulus is not affected by temperature changes as the material of the cable protector. However, since the fatigue resistance is inferior to that of EPDM, there is a risk of damage due to repeated stress from the cable even at room temperature.

  On the other hand, when the cable receives stress from the tip of the cable protector as described above, it can be said that stress is generated as a reaction force against the cable at the tip of the cable protector. In the conventional product as shown in FIG. 11 and the conical cable protector in which the cable protection part is formed in a conical shape as shown in Patent Document 1, the length of the conical portion, the degree of constriction, that is, the taper. If the corners are appropriately designed, the stress generated at the tip can be reduced even under low temperature conditions.

  Incidentally, it has been found that the longer the conical portion and the greater the taper angle, the greater the stress. If this stress is too large, the cable will be bent at the tip of the cable protector. If it is too small, the cable protector will not protect the cable, and the cable will be bent at the fixed portion. Therefore, this stress must be set in an appropriate range.

  However, the cable protector of a conventional cable protector is a simple cone that linearly connects the maximum outer diameter of the clamp-side holding part to the minimum outer diameter of the tip part. The degree of freedom with which the taper angle, which is the degree of diameter, is an optimum dimension that does not break the cable is low, and therefore, it is difficult to obtain a sufficient stress relaxation effect.

  Therefore, according to the present invention, in the cable protector in which the cable protection portion is conical, the degree of freedom in setting the shape of the conical portion is increased, and thereby the stress that the cable receives from the fixing portion or the cable protector even at a low temperature. An object of the present invention is to provide a cable protector that can be effectively suppressed and can sufficiently obtain a stress relaxation effect of a bent cable.

  The present invention is a cylindrical cable protector made of an elastic material that is fixed to an end of a cylindrical fixture fixed to a predetermined member, and through which a cable is inserted together with the fixture, and the end of the fixture And a conical cable protection part connected to the holding part. The cable protection part is formed with a step part from a boundary part with the holding part. It is characterized in that it has a shape having a reduced diameter portion that gradually decreases from the portion to the reduced diameter end portion.

  According to the cable protector of the present invention, the fixed end of the bent cable, which is the portion that comes out of the fixture, is elastically supported by the conical cable protector, thereby relieving the stress that the cable receives from the fixture. As a result, bending is less likely to occur, and breakage can be prevented.

  Here, the cable protector of the cable protector according to the present invention is not a simple cone in which the tip is linearly connected from the boundary with the holding portion as in the prior art, but first a stepped portion from the boundary to the tip. And has a conical shape in which a reduced diameter portion with an outer diameter gradually decreasing from the step portion toward the tip portion is formed.

  As described above, the length of the conical portion of the cable protector (taper length) and the taper angle need only be set to the optimal dimensions that do not break the cable. It was difficult. However, in the present invention, by providing the stepped portion, the length and taper angle of the cable protection portion can be arbitrarily set without being restricted by the maximum outer diameter by the holding portion and the minimum outer diameter of the tip portion. That is, the shape of the conical portion of the cable protection part can be set with a high degree of freedom.

  In the present invention, the length of the taper portion of the cable protection portion is from the boundary portion between the holding portion and the cable protection portion to the reduced diameter end that is the end of the reduced diameter, and the taper angle is the end of the stepped portion and the reduced diameter end. It is defined as the inclination angle with respect to the axial direction between the two parts.

  Depending on the outer diameter and physical properties of the cable to which the cable protector of the present invention is applied, there is an optimum combination of taper length and taper angle, and the range of the combination is greatly increased by providing the step portion in the present invention. can do. For example, when the taper length is relatively long, the stress generated at the tip of the cable protector can be reduced by reducing the taper angle. For that purpose, the step is deepened, that is, the step The width (length in the radial direction) is increased. On the contrary, when the taper length is relatively short, if the taper angle is relatively large accordingly, an appropriate stress can be generated at the tip of the cable protector. Is relatively shallow.

  The stress generated at the tip of the cable protector varies not only in the conical shape of the cable protector due to the taper length and taper angle, but also in the cable protector's minimum outer diameter, maximum outer diameter, inner diameter, cable protector elastic modulus, etc. Factors affect it. According to the present invention, a cable protector in which a specific range of stress is generated at the tip under a certain condition is a preferred embodiment, which is as follows.

In the analysis model in which the cable is stretched in a cantilevered state via a fixture equipped with a cable protector,
L: Cable length P: Load required to deflect the cable δ (mm) (N)
δ: Cable deflection (mm)
L ₁ : Length of conical part of cable protection part (mm)
E ₁ : Elastic coefficient of cable protector (N / mm ² )
I ₁ : Cross-sectional secondary moment of the reduced diameter portion (the outer diameter of the reduced diameter portion when obtaining I ₁ is the average outer diameter of the reduced diameter portion)
E ₂ : Elastic modulus of cable (N / mm ² )
I ₂ : Sectional moment of the cable (mm ⁴ )
d: Cable outer diameter = Cable protector inner diameter (mm)
x: When the position is from the cable fixing end
The load P (N) necessary to deflect the cable by δ (mm) is expressed by the following equation (1). When the load P calculated by the equation (1) is added to the analysis model, the cable The stress generated in the cable protector unattached part is expressed by the following equation (3):
δ: 52.5 (mm)
L: 212 (mm)
E ₂ : 885 (N / mm ² )
I ₂ : 191.3 (mm ⁴ )
When the value is substituted, the stress generated at the tip of the cable protector calculated from the following formula (1) and the following formula (3) satisfies 15.3 (N / mm ² ) or less.

  In the cable protector of the present invention, the axial distance between the boundary portion between the holding portion and the cable protection portion and the back end surface of the insertion hole of the fixture in the holding portion is secured as a predetermined length as the damper portion. It is a preferable form. This means that a predetermined distance is interposed between the end portion of the fixture and the step portion that is susceptible to a large bending moment, and the rigidity of the cable protector can be increased as compared with the case where there is no such distance.

  When the cable is fixed to the fixture by caulking, the cable may be deformed due to caulking stress, and this deformation becomes a weak point that the cable is easily bent. In addition, the cable protector receives a large bending moment due to the bending cable. However, the function of protecting the cable is sufficiently achieved by improving the rigidity of the damper portion.

  Moreover, in the cable protector of this invention, it is set as the preferable form that the outer diameter of the front-end edge which is a part from which the inserted cable goes out is set to 125% or less of the outer diameter of a cable. The part of the cable that is protected by the cable protector is elastically supported by the cable protector and is in a state of being supplemented with rigidity. If the difference in rigidity between this portion and the portion where the cable protector is not mounted is too great, the cable is liable to be bent due to the stress received from the tip portion of the cable protector.

  In order to prevent this problem, the outer diameter of the tip edge of the cable protector should be as close as possible to the outer diameter of the cable. However, in the present invention, in consideration of practical aspects such as productivity, assemblability, and handleability. As described above, it is set to 125% or less of the outer diameter of the cable.

  According to the cable protector of the present invention, by providing a step portion in the cable protection portion that substantially exhibits a conical shape and protects the cable, the degree of freedom in setting the shape of the cable protection portion can be increased. Even at a low temperature, the stress relaxation effect of the bent cable can be sufficiently obtained. As a result, the durability of the cable and the cable protector itself can be greatly improved.

  In addition, by forming the stepped portion, the thickness of the cable protector can be reduced by reducing the wall thickness, and therefore, it is possible to reduce the amount of material used and to produce it at a low cost. Moreover, the weight can be reduced.

  In addition, the reduced capacity reduces the overall cable rigidity of the cable protector, especially at low temperatures, reducing the stress applied to the fixture, which eliminates the need for additional ribs to reinforce the fixture. can do. As a result, cost reduction and weight reduction can be achieved by thinning the fixture.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a cable protector (hereinafter abbreviated as a protector) 20 according to an embodiment applied to a parking brake cable as shown in FIG. 10, and FIG. 2 shows a use state of the protector 20. Reference numeral 50 in FIG. 2 is a cable, and this cable 50 is fixed to a fixed portion such as a vehicle body or a parking brake unit via a clamp (fixing tool) 60, and the protector 10 is attached to the clamp 60. .

  The clamp 60 is, for example, a metal plate such as a thin steel plate formed into a cylindrical shape, and a flat bracket portion 61 is integrally provided. The cable 50 is inserted through the clamp 60 and fixed to the clamp 60 by caulking, and the bracket portion 61 is fixed to the fixing portion, so that the cable 50 is routed and fixed at a predetermined position via the clamp 60.

  The protector 20 is formed by molding rubber having a predetermined range of elasticity. The protector 20 is detachably held at the end of the clamp 60, and is connected to the end of the hold 30 so that only the cable 50 is inserted. And a cable protector 40 that substantially protects the fixed end of the cable 50. A synthetic rubber such as EPDM is preferably selected as the rubber material.

  The holding portion 30 is formed in a cylindrical shape having both an inner diameter and an outer diameter that are substantially constant. The inner diameter is slightly smaller than the outer diameter of the clamp 60, and one end of the clamp 60 is press-fitted into the inner insertion hole 31 so as to be detachable. Then, as shown in FIG. 2, it is caulked and fixed to one end of the clamp 60 by caulking ring 72 in an externally fitted state.

  The cable protection unit 40 has a generally conical shape that tapers from an annular edge 41 that is a boundary portion with the holding unit 30 to a tip edge that is a portion from which the cable 50 exits, and is integrated with the holding unit 30 and , Is formed coaxially with the holding portion 30. An inner diameter of the cable insertion hole 42 through which the cable 50 is inserted and communicates with the insertion hole 31 of the holding section 30 is approximately equal to or slightly smaller than the outer diameter of the cable 50.

  The cable protection portion 40 is not a simple conical shape, but a short step portion 43 is first formed from the edge 41 to the leading edge, and then the conical diameter reduction from the step portion 43 is gradually reduced in outer diameter. A portion 44 is formed, and a tip cylindrical portion 46 having a short constant outer diameter is formed from the reduced diameter end portion 45, which is the end of the reduced diameter portion 44, to the tip edge.

  The cross-sectional shape of the stepped portion 43 is not limited. For example, as shown in FIG. Examples include a tapered shape that is straightly inclined to the diameter portion 44, and a shape in which the transition portion from the edge 41 and the stepped portion 43 to the reduced diameter portion 44 is formed in R as shown in FIG.

  In the holding part 30, a meat part between the cable protection part 40 and the back end face 31 a of the insertion hole 31 is formed as a damper part 32. That is, the axial distance between the edge 41 and the back end surface 31 a of the insertion hole 31 in the holding portion 30 is ensured by the predetermined thickness as the damper portion 32. Further, the outer diameter of the tip cylindrical portion 46 which is the minimum outer diameter of the cable protection portion 40 is set to 125% or less of the outer diameter of the cable 50.

In the protector 20 of the present embodiment, the taper length (L ₁ ), the minimum outer diameter (d ₁ ) and the maximum outer diameter (d ₂ ) of the cable protector 40, the inner diameter of the protector 20 = the inner diameter of the taper section. (D ₃ ), the outer diameter (d ₄ ) of the holding portion 30, and the taper angle (θ) are set to optimum dimensions according to the outer diameter and physical properties of the cable 50.

Here, in this embodiment, as shown in FIG. 1, the taper length (L ₁ ) is the length of the conical portion of the cable protection portion 40, the length from the edge 41 to the reduced diameter end portion 45, and the taper. The minimum outer diameter (d ₁ ) of the portion is the inner diameter of the cable insertion hole 42, and the maximum outer diameter (d ₂ ) of the taper portion is the outer diameter at the boundary portion between the step portion 43 and the reduced diameter portion 44 (the end of the step portion 43). The taper angle (θ) is defined as an inclination angle with respect to the axial direction between the end of the stepped portion 43 and the reduced diameter end portion 45.

  The tapered portion in the illustrated example has a conical shape that is inclined while linearly reducing the diameter from the end of the stepped portion 43 to the reduced diameter end portion 45. However, in the present invention, the tapered portion is not limited to a linear inclination and is curved. It also includes a shape that is reduced in diameter.

Examples of the dimensions of the protector 20 include the following dimensions.
・ Minimum outer diameter (d ₁ ) of taper part: 11.8 mm
・ Maximum outer diameter (d ₂ ) of the taper part: 16 mm
-Inner diameter (d ₃ ) of the protector 20: 9.8 mm
-Outer diameter (d ₄ ) of holding part 30: 20 mm
・ Taper angle: (θ): About 4.4 °

  Next, the stress generated in the cable 50 when the shape of the cable protector according to the above dimensions of the protector is changed is analyzed by the following procedure.

  As shown in FIG. 4, a cable 50 having both ends fixed is modeled as a both-end fixed beam, and the length of the cable 50 is 2L and the deflection (amplitude) of the cable 50 is 2δ. Furthermore, since this model can be regarded as a continuation of symmetrical left and right cantilever beams, the analysis is performed using the analysis model shown in FIG.

  A load (stress) P necessary to bend the cable 50 shown in FIG. 5 is expressed by the following equation (1).

here,
L: Cable length P: Stress required to deflect the cable δ (mm) (N)
δ: Cable deflection (mm)
L ₁ : Length of the conical portion of the cable protection portion = taper length (mm)
E ₁ : Elastic coefficient of cable protector (N / mm ² )
I ₁ : Cross-sectional secondary moment of reduced diameter portion E ₂ : Elastic modulus of cable (N / mm ² )
I ₂ : Sectional moment of the cable (mm ⁴ )
It is.

  Further, the stress generated when the load P calculated by the above equation (1) is added to the analysis model shown in FIG. 5 is calculated separately for the mounting portion and the non-mounting portion of the protector of the cable. The cable mounting portion is represented by the following formula (2), and the unmounted portion is represented by the following formula (3).

Stress at the protector attachment (0 ≦ x <L ₁ )

Stress of the part without protector (L ₁ ≦ x ≦ L)

In the above equations (2) and (3), d and x are
d: Cable outer diameter = Cable protector inner diameter (mm)
x: Position from the cable fixing end.

  When the cable is bent with the cable attached to the clamp, the portion where the cable is bent and possibly broken is a portion corresponding to the end portion of the protector, that is, the portion coming out of the cable protection portion of the protector. Therefore, by substituting each variable set as follows to the above equations (1), (2) and (3), the stress generated at the tip of the protector (corresponding to the reaction force of the stress received from the cable) Asked). The following formulas (1) ′, (2) ′ and (3) ′ are the calculation formulas.

δ: 52.5 (mm)
L: 212 (mm)
E ₁ : 79.3 (N / mm ² ) at −40 ° C. (9 (N / mm ² ) at normal temperature)
E ₂ : 885 at −40 ° C. (N / mm ² ) <441 (N / mm ² ) at normal temperature>
I ₂ : 191.3 (mm ⁴ )

  Load P required to deflect the cable δ

Stress at the protector attachment (0 ≦ x <L ₁ )

Stress of the part without protector (L ₁ ≦ x ≦ 212)

Furthermore, the protector tip is from x = L ₁

The protector of the present invention is one in which the stress generated at the tip of the protector calculated from the above formulas (1) ′ and (3) ′ is 15.3 (N / mm ² ) or less. The stress generated at the tip of the protector varies not only in the conical shape of the cable protector due to the length and angle of the taper, but also in the cable protector's minimum outer diameter, maximum outer diameter, inner diameter, and the elastic modulus of the protector. Factors to influence. The present invention provides a protector in which the stress generated at the tip of the protector is 15.3 (N / mm ² ) or less, even if these variable factors fluctuate, using the above-mentioned formulas (1) 'and (3)' as constant conditions It is.

Table 1 shows the stress at the tip of the protector obtained as described above, the taper length (L ₁ ), the minimum outer diameter (d ₁ ) of the taper portion, the maximum outer diameter (d ₂ ) of the taper portion, protector inner diameter _(d 3), shows the protector of varying elastic modulus _{(E 1).} In this table, in addition to the conventional product shown in FIG. 11, Comparative Examples 1 to 3 that depart from the present invention and Examples 1 to 3 that are the product of the present invention are applied to the above formula, and the tip of the protector The result of obtaining the stress is shown.

In obtaining the tip stress of the protector by the above formulas (1) ′ and (3) ′, the taper length (L ₁ ), the minimum outer diameter (d ₁ ) of the taper, If the values of the maximum outer diameter (d ₂ ), protector inner diameter (d ₃ ), and elastic modulus (E ₁ ) are determined, the stress is obtained, and the stress shown in Table 1 is calculated based on the stress. ing. Therefore, the numerical values of these factors used in the calculation in this embodiment will be described.

Material of elastic modulus protector material is from EPDM is conventionally used, its modulus (100% modulus) is 1 to 10 N ^/ mm 2 when 30 ℃, 70~110N / mm ² when the -40 ℃ Degree. In the present embodiment, since the elastic modulus was EPDM of about 79.3 N / mm ² at −40 ° C., this numerical value was applied in the calculation.

-Inner diameter of the protector A state where there is no gap between the cable and the protector is preferable because a sense of unity between them can be obtained. Therefore, in this embodiment, since a cable having an outer diameter of 9.8 mm is used, the inner diameter of the tapered portion, that is, the inner diameter of the protector is set to an optimum value in the calculation.

・ Minimum outer diameter of the taper part It is desirable that the minimum outer diameter of the taper part is equal to the outer diameter of the cable so that the difference in rigidity between the protector attachment part and the non-attachment part of the cable does not increase. However, in consideration of practical aspects such as productivity, ease of assembly, and handleability, the thickness of the tip portion is set to 1 mm, and therefore the minimum outer diameter of the tapered portion is set to 11.8 mm.

Tapered part length and taper angle FIGS. 6 and 7 show the calculation results when the taper part length and the stress at the tip of the protector are changed in combination with the taper angle and the elastic coefficient. As shown in these drawings, when the taper portion becomes longer at −40 ° C., the stress increases, which indicates that the reaction force from the cable applied to the clamp that holds the cable increases. When the reaction force becomes large, the clamp is required to have a reinforcing measure such as a complicated shape due to the addition of a rib or the like, or a thicker material. Further, when the taper angle is increased at −40 ° C., the stress generated in the cable is increased. Taking these into account, the length of the tapered portion and the taper angle are appropriately determined.

The above-mentioned factors are examples that satisfy the present invention. In the protector in this case, for example, as shown in FIG. 1, the outer diameter of the holding portion is used to reduce the bending moment received from the cable. d ₄ is set to about 20 mm, and the axial length L _{3 of the} damper portion 32 is set to about ₃ mm.

As described above, the shape of the protector according to the present invention is designed by determining each variation factor so that the stress at the tip of the protector is 15.3 N / mm ² or less. In particular, the length of the tapered portion and the maximum of the tapered portion are designed. The outer diameter has a high degree of freedom in setting, and FIG. 8 shows these relationships. In the figure, the shaded area represents the range where the stress at the tip of the protector is 15.3 N / mm ² or less and the step needs to be provided.

As shown in Table 1, when the maximum outer diameter of the tapered portion is larger than 20 mm as in the conventional products and Comparative Examples 1 to 3, in other words, when the taper portion cannot be smaller than 20 mm, the stress is within the shaded area in FIG. In order to be inside, it is necessary to make the length of the taper portion 2.2 mm or less. However, if the length of the taper portion is shortened, the area where the cable comes into contact with the inner diameter of the protector (the inner peripheral surface of the cable insertion hole) is reduced, the sense of unity between the protector and the cable is impaired, and the rigidity is lowered. In addition, it is necessary to set dimensional tolerances for the outer diameter of the cable, the inner diameter of the protector, and the length of the tapered portion, which is not practical. Accordingly, it is effective to provide a stepped portion in order to set a dimension with a small variation due to an error with a stress of 15.3 N / mm ² or less.

Next, examples that demonstrate the effects of the present invention will be described.
-Vibration test Ten protectors each showing the numerical values of the conventional products shown in Table 1, Comparative Examples 1 to 3 and Examples 1 to 3 were prepared. As shown in FIG. 9 (the protector 20 of the present invention is illustrated in FIG. 9), these protectors are attached to clamps 60 fixed to both ends of the cable 50, and the clamp 60 at one end is fixed. On the other hand, the other end was vibrated. Table 2 shows the coordinates in the three-dimensional direction: X, Y, and Z directions at points A to H shown in FIG. The length of the cable 50 was set to 424 mm, and the vibration frequency was set to 3 Hz.

The cable was vibrated while counting the frequency, and the frequency when the cable was broken was measured as the durability. The results are shown in Table 3. According to this result, Examples 1 to 3 in which the stress at the tip of the protector showed 15.3 N / mm ² or less exhibited no excellent cable breakage even after 2.3 million times and exhibited excellent durability. . On the other hand, the case where the stress at the tip of the protector shows 15.3 N / mm ² or more is extremely inferior to the endurance compared to the examples, and thus the effect of the present invention has been demonstrated.

It is a partial cross section side view of the cable protector which concerns on one Embodiment of this invention. It is a partial cross section side view which shows the attachment state of the cable protector of one Embodiment. It is sectional drawing which shows the example of the form of the step part formed in a cable protector. This is a doubly-supported analysis model for analyzing the stress generated at the tip of the cable protector. This is a cantilever type analysis model for analyzing the stress generated at the tip of the cable protector. It is a diagram which shows the calculation result at the time of changing the combination of a taper angle and an elastic coefficient about the relationship between a taper part length and the front-end | tip part stress of a protector. It is the diagram which expanded the data of -40 degreeC of FIG. It is a diagram which shows the relationship between a taper part length and the largest outer diameter of a taper part. It is a figure which shows the method of the vibration test of an Example. It is a perspective view which shows an example of the parking brake apparatus of a motor vehicle. It is a side view which shows one conventional product of a cable protector.

Explanation of symbols

20 ... Cable protector, 30 ... Holding part, 31 ... Insertion hole of holding part, 31a ... Back end surface,
32 ... Damper part, 40 ... Cable protection part, 41 ... Edge (boundary part), 43 ... Step part,
44 ... Reduced diameter part, 45 ... Reduced diameter end part, 50 ... Cable, 60 ... Clamp (fixing tool).

Claims (4)

A cylindrical cable protector made of an elastic material fixed to an end portion of a cylindrical fixture fixed to a predetermined member, and a cable inserted through the fixture.
A holding portion held in an externally fitted state at an end of the fixture;
A conical cable protection part connected to the holding part,
The cable protection part has a stepped part formed from a boundary part with the holding part, and has a shape having a reduced diameter part from the stepped part to an outer diameter gradually decreasing to reach a reduced diameter end part. Cable protector characterized by that. In the analysis model in which the cable is stretched in a cantilever state via the fixture equipped with the cable protector,
L: Cable length P: Load required to deflect the cable δ (mm) (N)
δ: Cable deflection (mm)
L ₁ : Length of conical part of cable protection part (mm)
E ₁ : Elastic coefficient of cable protector (N / mm ² )
I ₁ : Cross-sectional secondary moment of the reduced diameter portion (the outer diameter of the reduced diameter portion when obtaining I ₁ is the average outer diameter of the reduced diameter portion)
E ₂ : Elastic modulus of cable (N / mm ² )
I ₂ : Sectional moment of the cable (mm ⁴ )
d: Cable outer diameter = Cable protector inner diameter (mm)
x: When the position is from the cable fixing end
When the load P (N) necessary for bending the cable by δ (mm) is expressed by the following equation (1), and the load P calculated by the equation (1) is added to the analysis model, The stress generated in the cable unattached part of the cable is expressed by the following equation (3),
δ: 52.5 (mm)
L: 212 (mm)
E ₂ : 885 (N / mm ² )
I ₂ : 191.3 (mm ⁴ )
When the value is substituted, the stress generated at the tip of the cable protector calculated from the following formula (1) and the following formula (3) satisfies 15.3 (N / mm ² ) or less. Item 3. A cable protector according to Item 1.

  A predetermined length is secured as a damper portion in an axial distance between a boundary portion between the holding portion and the cable protection portion and a back end surface of the insertion hole of the fixture in the holding portion. The cable protector according to claim 1 or 2.   The cable protector according to any one of claims 1 to 3, wherein an outer diameter of the leading edge, which is a portion where the inserted cable comes out, is set to 125% or less of an outer diameter of the cable.

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