JP2015183717A - weight roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a weight roller excellent in fatigue strength.SOLUTION: A weight roller 1 is used in a V-belt automatic transmission, and comprises: a cylindrical roller body 2; and a cylindrical resin-based slide member 3 disposed to cover an outer circumferential surface 20 of the roller body 2. The roller body 2 functions as a weight and is formed of metal such as stainless steel, carbon steel, copper, copper alloy, aluminum, aluminum alloy, and a sintered metal. Polyamide resin is used as base resin for the resin-based slide member 3 and lubricant is added as needed for improving slide characteristics of PTFE, graphite or the like. Furthermore, a thickness T of the resin-based slide member 3 is set to 0.50 mm to 1.15 mm.

Description

  The present invention relates to a weight roller used in a V-belt type automatic transmission.

  In vehicles such as motorcycles, the groove width of the variable groove pulley is changed in accordance with the change in the engine speed, and the winding diameter of the V-belt spanned over the variable groove pulley is continuously changed. V-belt type automatic transmissions that enable stepless speed change are widely used.

  In a V-belt type automatic transmission, a variable groove pulley is constituted by a fixed pulley plate fixed to a rotating shaft and a movable pulley plate disposed on the rotating shaft so as to be movable in the axial direction. On the back side of the plate, there is a ramp plate that is fixed to the rotating shaft and that becomes closer to the outer side in the radial direction of the rotating shaft. A weight roller is arranged so as to be movable in the radial direction of the rotation shaft.

  When the centrifugal force acting on the weight roller increases as the engine speed increases, the weight roller moves outward in the radial direction of the rotating shaft and moves between the ramp plate and the movable pulley plate in the axial direction of the rotating shaft. Push out and push the movable pulley plate toward the fixed pulley plate. As a result, the distance between the movable pulley plate and the fixed pulley plate in the axial center direction of the rotating shaft, that is, the groove width of the variable groove pulley is reduced, and the V belt moves outward in the radial direction of the rotating shaft. As the diameter increases, the gear ratio (engine speed / tire speed) decreases. On the other hand, when the centrifugal force acting on the weight roller decreases as the engine speed decreases, the weight roller moves inward in the radial direction of the rotating shaft, and the movable pulley plate is pushed back toward the ramp plate. As a result, the distance between the movable pulley plate and the fixed pulley plate in the axial center direction of the rotating shaft, that is, the groove width of the variable groove pulley increases, and the V belt moves inward in the radial direction of the rotating shaft. The diameter becomes smaller and the gear ratio becomes larger.

  As described above, when the weight roller moves outward in the radial direction of the rotating shaft by the action of centrifugal force as the engine speed increases, the outer surface of the weight roller slides on the ramp plate fixed to the rotating shaft. It is required to have a certain amount of weight and to have excellent sliding characteristics and wear resistance. For this reason, the weight roller usually covers the surface of a metal roller body functioning as a weight with a resin-based sliding member having a polyamide resin as a base resin (Patent Document 1).

JP 2001-343055 A

  By the way, the weight roller is also required to have excellent fatigue strength because of repeated shocking vibration stress from the engine. In a conventional weight roller where the surface of the roller body is covered with a resin-based sliding member based on polyamide resin, the thickness (diameter thickness) of the resin-based sliding member is set to about 1.5 mm. Has been. However, this thickness may cause fatigue failure due to shocking and repeated vibration stress from the engine before the resin-based sliding member wears to an allowable wear amount from the viewpoint of the effect on the gear ratio, etc. there were.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a weight roller having excellent fatigue strength.

  In order to solve the above problems, the present invention provides a weight roller in which the outer peripheral surface of a roller body functioning as a weight is covered with a resin-based sliding member containing a polyamide resin, and the thickness of the resin-based sliding member is set to 0. It set to 50 mm-1.15 mm.

  Here, the roller body is preferably made of metal. The weight roller may be formed by press-fitting the roller body into a resin-based sliding member formed in a cylindrical shape in advance, or the resin-based sliding member may be formed on the surface of the roller body by insert molding. You may make it form integrally.

  When the resin-based sliding member containing polyamide resin is used as the resin-based sliding member that covers the surface of the roller body, the inventor improves the fatigue strength as the thickness of the resin-based sliding member is reduced. I found out. In particular, it can be seen that by reducing the thickness of the resin-based sliding member to 1.15 mm or less, the fatigue strength is dramatically improved compared to a conventional product in which the thickness is set to about 1.5 mm. It was. In general, the amount of wear allowed for the resin-based sliding member is set to about 0.50 mm in consideration of the influence on the gear ratio and the like. Therefore, the thickness of the resin-based sliding member is preferably 0.50 mm or more from the viewpoint of the amount of wear allowed for the resin-based sliding member.

FIG. 1A is a front view of a weight roller 1 according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line AA of the weight roller 1 shown in FIG. FIG. 2 is a diagram for explaining the fatigue test. FIG. 3 is a diagram showing test results of a fatigue test performed on the specimens 4A to 4C shown in Table 2 under the conditions shown in Table 1. FIG. 4 is a diagram for explaining CAE analysis. FIG. 5 is a diagram showing the results of CAE analysis performed on the specimens 4A and 4C for Table 2 under the conditions shown in Table 3. FIG. 6 (A) is a diagram for explaining the location of occurrence of the maximum principal stress in the CAE analysis performed on the specimens 4A and 4C shown in Table 2 under the conditions shown in Table 3, FIG. 6B is a perspective view of the sliding member 3, and FIG. 6B is a view for explaining the mechanism of generation of the maximum principal stress, and is BB of the resin-based sliding member 3 shown in FIG. It is a fragmentary sectional view.

  An embodiment of the present invention will be described below.

  FIG. 1A is a front view of the weight roller 1 according to the present embodiment, and FIG. 1B is a cross-sectional view taken along line AA of the weight roller 1 shown in FIG.

  The weight roller 1 according to the present embodiment is used in a V-belt type automatic transmission, and is arranged so as to cover a cylindrical roller body 2 and an outer peripheral surface 20 of the roller body 2 as shown in the figure. The cylindrical resin-based sliding member 3 is prepared, and the roller main body 2 is press-fitted and fitted into the resin-based sliding member 3.

  The roller body 2 functions as a weight, and is formed of, for example, a metal such as stainless steel, carbon steel, copper, copper alloy, aluminum, aluminum alloy, and sintered metal. Since the specific gravity of the metal is large, the weight of the weight roller 1 can be increased, and the original function of the weight roller 1 that moves by centrifugal force can be enhanced.

  The resin-based sliding member 3 has annular protrusions 32 protruding from the inner peripheral surface 31 toward the inner side in the axis O direction of the weight roller 1 at both ends 30 thereof. By press-fitting the roller body 2 into the resin-based sliding member 3, the convex portion 32 comes into contact with the end 21 of the roller body 2, and the resin-based sliding member 3 covers the outer peripheral surface 20 of the roller body 2. To be fixed. In addition, a polyamide resin is used for the base resin of the resin-based sliding member 3, and a lubricant for improving sliding properties such as PTFE (polytetrafluoroethylene) and graphite (graphite) is added as necessary. The

  The inventor of the present invention uses the specimens 4A to 4C of the weight roller 1 having different thickness T of the resin sliding member 3 (the thickness in the radial direction of the resin sliding member 3: see FIG. 1B), respectively. A plurality of these specimens 4A to 4C were subjected to a fatigue test under the conditions shown in Table 1 below, and the occurrence time and location of fatigue failure (cracks) were observed.

  In the fatigue test, as shown in FIG. 2, the test bodies 4A to 4C into which the shaft 5 is inserted are arranged on the counterpart material (jig plate) 6 and the counterpart material 6 is placed in the W direction at the frequency shown in Table 1. By reciprocating, the load N in the W direction applied to the test specimens 4A to 4C is periodically changed within the load load range shown in Table 1, and the fatigue fracture of the test specimens 4A to 4C is observed.

  The produced test bodies 4A to 4C are as shown in Table 2 below. Here, the test body 4A is a comparative example for confirming the performance of the weight roller 1 according to the present embodiment, and the thickness T of the resin-based sliding member 3 is set to 1.5 mm, which is the same as the conventional product. Has been. On the other hand, in the test bodies 4B and 4C, the thickness T of the resin-based sliding member 3 is set to 1.15 mm and 1.0 mm, which are thinner than the conventional products, respectively. Further, in all the test bodies 4A to 4C, the thickness H of the convex portion 32 of the resin sliding member 3 is made the same, and the roller body 2 is press-fitted to the resin sliding member 3 with the same tightening allowance δ. doing.

  FIG. 3 is a diagram showing test results of a fatigue test performed on the specimens 4A to 4C shown in Table 2 under the conditions shown in Table 1. Here, the vertical axis represents the cumulative number of reciprocating motions of the counterpart material 6. The bar graphs 40A to 40C indicate the cumulative number of reciprocating motions of the counterpart material 6 required until the specimens 4A to 4C undergo fatigue failure. Note that a plurality of test bodies 4A to 4C are prepared, and bar graphs 40A to 40C indicate average values of test results of the plurality of test bodies 4A to 4C.

  As shown in the figure, the cumulative number of reciprocating motions of the mating member 6 required until fatigue failure is in the order of the specimens 4C, 4B, and 4A, and the thickness T of the resin-based sliding member 3 is set as follows. It has been found that the fatigue strength improves as the thickness decreases. In addition, the specimens 4B and 4C have a sharp increase in the number of reciprocating motions of the mating member 6 required until the fatigue failure compared to the specimen 4A of the comparative example, and the fatigue strength can be dramatically improved. I understood. In addition, the place where the fatigue fracture (crack) occurred was the end portion 30 of the resin-based sliding member 3 in any of the test bodies 4A to 4C.

  Next, the present inventor conducted CAE (Computer Aided Engineering) analysis under the conditions shown in Table 3 below in order to confirm the consistency of the test results of the fatigue tests described above, and the specimens shown in Table 2 above. The maximum principal stress values of the 4A and 4C resin-based sliding members 3 and the locations where they occurred were examined. In the CAE analysis, the interference δ of the specimens 4A and 4C is set to “0”.

  In the CAE analysis, as shown in FIG. 4, the roller body 2 of the test bodies 4A and 4C is completely fixed, and the mating material 6 is pressed against the test bodies 4A and 4C, thereby applying the load N shown in Table 3 to the test body. In addition to 4A and 4C, the stress value and occurrence location of the maximum principal stress are analyzed.

  FIG. 5 is a diagram showing an analysis result of CAE analysis performed on the specimens 4A and 4C shown in Table 2 under the conditions shown in Table 3. Here, the left vertical axis indicates the stress value of the maximum principal stress, and the right vertical axis indicates the amount of displacement at the location where the maximum principal stress is generated. The bar graphs 41A and 42A show the maximum principal stress value of the resin sliding member 3 of the specimen 4A and the amount of displacement at the place where the maximum principal stress is generated, and the bar graphs 41C and 42C show the resin series of the specimen 4C. The maximum principal stress value of the sliding member 3 and the displacement amount at the location where the maximum principal stress is generated are shown. FIG. 6 (A) is a diagram for explaining the location where the maximum principal stress occurs in the CAE analysis performed under the conditions shown in Table 3 for the specimens 4A and 4C shown in Table 2. FIG. 6B is a perspective view of the resin-based sliding member 3, and FIG. 6B is a diagram for explaining the mechanism of generation of the maximum principal stress, and B of the resin-based sliding member 3 shown in FIG. FIG.

  As shown in FIG. 5, the specimen 4C has a reduced maximum principal stress value and displacement amount of the resin-based sliding member 3 compared to the test body 4A of the comparative example, and the thickness of the resin-based sliding member 3 is reduced. It shows that the thinner the thickness T, the more advantageous the fatigue strength. Further, as shown in FIG. 6A, the maximum principal stress of the resin sliding member 3 is generated at both end portions 30 (convex portions 32) in the contact region C between the resin sliding member 3 and the counterpart material 6. doing. As shown in FIG. 6B, the thickness T of the resin sliding member 3 is compressed by the pressing force of the mating member 6 in the contact region C between the resin sliding member 3 and the mating material 6. As a result, the resin-based sliding member 3 is displaced in the direction in which the length L extends (displacement E) and is formed at both end portions 30 of the resin-based sliding member 3. This is because tensile stress is generated in the S portion of the convex portion 32. This tensile stress is the maximum principal stress.

  By this CAE analysis, the consistency of the test results of the above-described fatigue test, that is, the resin-based sliding member 3 having a polyamide resin as a base resin is used as the resin-based sliding member 3 that covers the surface 20 of the roller body 2. In this case, it was confirmed that the fatigue strength was improved as the thickness T of the resin-based sliding member 3 was reduced.

  The analysis result of this CAE analysis is for the specimens 4A and 4C having a diameter D of 20 mm. However, the tendency of the fatigue strength to increase as the thickness T of the resin-based sliding member 3 is reduced does not depend on the diameter D of the weight roller 1, and the weight roller 1 having another diameter D (for example, 15 mm to 75 mm). The same analysis result was obtained in the CAE analysis.

  In general, the amount of wear allowed for the resin-based sliding member 3 is set to about 0.50 mm in consideration of the influence on the gear ratio of the V-belt type automatic transmission. Therefore, the thickness T of the resin-based sliding member 3 is preferably 0.50 mm or more from the viewpoint of the amount of wear allowed for the resin-based sliding member 3.

  The embodiment of the present invention has been described above.

  According to the present embodiment, by setting the wall thickness T of the resin-based sliding member 3 to 0.50 mm to 1.15 mm, it is possible to cope with the general wear amount allowed for the resin-based sliding member 3. The weight roller 1 having excellent fatigue strength can be provided.

  In this embodiment, the weight roller 1 is formed by press-fitting the roller body 2 to the resin-type sliding member 3 formed in a cylindrical shape, but the present invention is not limited to this. The weight roller 1 may be manufactured by integrally forming the resin sliding member 3 on the surface 20 of the roller body 2 by insert molding. In the above-described CAE analysis, in the test bodies 4A and 4C in which the interference δ is set to “0”, the effect of improving the fatigue strength as the thickness T of the resin sliding member 3 is reduced was confirmed. Therefore, the same effect can be expected also in the weight roller 1 formed by insert molding without the interference δ.

  1: Weight roller, 2: Roller body, 3: Resin sliding member, 20: Outer peripheral surface of roller body, 21: End of roller body, 30: End of resin sliding member, 31: Resin sliding Inner peripheral surface of moving member, 32: convex portion of resin-based sliding member

Claims (2)

A weight roller used in a V-belt type automatic transmission,
A roller body that functions as a weight;
A resin-based sliding member that covers the outer peripheral surface of the roller body,
The resin-based sliding member is
A weight roller comprising a polyamide resin and having a thickness of 0.50 mm to 1.15 mm. The weight roller according to claim 1,
The weight roller, wherein the roller body is made of metal.

Images