Fastening structure of case

Abstract

To provide a fastening structure of a case which can enhance the stiffness of a fastening part of the case while suppressing an increase in number of fastening members.SOLUTION: In a fastening structure of a case 20 having a first case member 30 and a second case member 40 which is fastened to the first case member 30, (a) grooves 30b, 40b are formed at mating faces 30a, 40b to which the first case member 30 and the second case member 40 are fastened, and (b) a plate-shaped body 50 is inserted into the grooves 30b, 40b which are formed at the mating faces 30a, 40b of the first case member 30 and the second case member 40 so as to straddle the grooves. Since the plate-shaped body 50 is inserted into the grooves 30b, 40b which are formed at the mating faces 30a, 40a, the stiffness of the fastening part of the case 20 can be enhanced without increasing the number of bolts 80.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a fastening structure for a case that includes a first case member and a second case member fastened to the first case member. [Background technology]

[0002] There is known a case fastening structure in which case components are fastened together by bolts (=fastening means). For example, there is one described in Patent Document 1. Patent Document 1 discloses a structure in which the portions of the case components that come into contact with each other only via a liquid sealing material are integrally joined by the liquid sealing material being hardened. This makes it possible to suppress a decrease in rigidity in the fastening portion of the case even if the number of bolt parts is reduced. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-68822 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the case fastening structure described in Patent Document 1, the case members are integrally joined together by a hardened liquid sealing member, so it is difficult to disassemble the case members after they have been fastened together. On the other hand, a method of increasing the number of fastening bolts can be considered to suppress a decrease in rigidity at the fastening portion between the case members without using a liquid sealing member, but this method leads to an increase in the number of parts and an increase in assembly man-hours.

[0005] The present invention has been made against the background of the above circumstances, and its object is to provide a case fastening structure that can increase the rigidity at the fastening portion of the case while suppressing an increase in the number of fastening members. [Means for solving the problem]

[0006] The gist of the present invention is a fastening structure for a case comprising a first case member and a second case member fastened to the first case member, wherein (a) grooves are provided on mating surfaces where the first case member and the second case member are fastened, and (b) a plate-shaped body is inserted so as to straddle the grooves provided on the mating surfaces of the first case member and the second case member. Effect of the Invention

[0007] According to the fastening structure of the case of the present invention, (a) a groove is provided on each of the mating surfaces to which the first case member and the second case member are fastened, and (b) a plate-like body is inserted so as to straddle the grooves provided on the mating surfaces of the first case member and the second case member. By inserting a plate-like body into the grooves provided on each of the mating surfaces, the rigidity of the fastening portion of the case is increased without increasing the number of fastening members. This prevents the mating surfaces of the case from slipping, for example, even if a force is applied to slide the mating surfaces of the case. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view of a fastening structure for a case according to an embodiment. [Diagram 2] 2(a) is a view taken in the axial direction of the bolt; FIG. 2(b) is a cross-sectional view taken along the section line bb shown in FIG. 2(a); and FIG. 2(c) is a cross-sectional view taken along the section line cc shown in FIG. 2(a). [Diagram 3] FIG. 2 is an explanatory diagram of a case fastening structure according to an embodiment, showing a state before a second case member is fastened to a first case member by a bolt and a nut, as viewed in the axial direction of the bolt. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. EXAMPLES

[0010] Fig. 1 is a perspective view of the fastening structure of the case 20 according to the embodiment. Fig. 2 is an explanatory diagram of the fastening structure of the case 20 according to the embodiment, where (a) is a view seen in the axial direction of the bolt 80 (hereinafter, referred to as "bolt axial direction"), (b) is a cross-sectional view taken along the cutting line bb shown in Fig. 2(a), and (c) is a cross-sectional view taken along the cutting line cc shown in Fig. 2(a).

[0011] The case 20 is mounted on, for example, the vehicle 10, and accommodates therein power transmission members such as a gear pair 60 (see FIG. 3).

[0012] The case 20 includes a first case member 30 and a second case member 40. The second case member 40 is fastened to the first case member 30 by a bolt 80 and a nut 82. The first case member 30 and the second case member 40 are made of, for example, an aluminum alloy casting.

[0013] For example, the first case member 30 is a cylindrical member with a bottom. For example, the first case member 30 has a bottom and a side wall extending in one direction from the outer periphery of the bottom, which are integrally formed by casting. The base of the side wall of the first case member 30 is connected to the bottom. The first case member 30 has an opening at the tip end where the side wall extends. The second case member 40 is a lid-like member fastened to the first case member 30 so as to close the opening of the first case member 30. In this specification, the direction around the opening of the first case member 30 is referred to as the "circumferential direction".

[0014] The first case member 30 has a mating surface 30a at the tip of its side wall. The second case member 40 has a mating surface 40a at its outer circumferential edge. The mating surfaces 30a and 40a are each made flat by flattening, for example, by cutting. When the first case member 30 and the second case member 40 are fastened together, the mating surfaces 30a and 40a are in contact with each other.

[0015] The first case member 30 has a plurality of fastening holes 32 extending in a direction perpendicular to the mating surface 30a. The fastening holes 32 are provided at predetermined intervals in the circumferential direction. The second case member 40 has a plurality of fastening holes 42 extending in a direction perpendicular to the mating surface 40a. The fastening holes 42 are provided at predetermined intervals in the circumferential direction. The fastening holes 32 and the fastening holes 42 are formed, for example, by drilling. The fastening holes 32 and the fastening holes 42 are holes through which a bolt 80, which will be described later, is inserted in order to fasten the first case member 30 and the second case member 40. The direction perpendicular to the mating surfaces 30a, 40a is the same as the bolt axial direction. The predetermined interval is an interval that is experimentally or design-wise determined in advance so that the variation in rigidity in the fastening portion of the case 20 due to the axial force of the bolt 80 falls within an allowable range when the first case member 30 and the second case member 40 are fastened together. The "fastening portion of the case 20" refers to a portion where the first case member 30 and the second case member 40 are fastened with a bolt 80 and a nut 82 described later, i.e., a portion where the first case member 30 and the second case member 40 are fastened at the mating surface 30a and the mating surface 40a. The "rigidity at the fastening portion of the case 20" refers to the resistance to deformation at the fastening portion when a force is applied to the case 20, for example, the resistance to slip of the mating surfaces 30a and 40a of the case 20 when a force that tries to slide the mating surfaces 30a and 40a of the case 20 (= a force that tries to move the mating surfaces 30a and 40a relatively) is applied. When the first case member 30 and the second case member 40 are fastened, the fastening hole 32 and the fastening hole 42 are provided at the same position when viewed in the bolt axis direction.

[0016] The bolt 80 and the nut 82 are members for fastening the first case member 30 and the second case member 40, i.e., fastening members. For example, the bolt 80 is inserted through the fastening hole 32 and the fastening hole 42 from the first case member 30 side, and the tip of the shaft of the bolt 80 is tightened with the nut 82, thereby fastening the first case member 30 and the second case member 40. In this embodiment, a washer 84 is provided between the nut 82 and the second case member 40.

[0017] The mating surface 30a of the first case member 30 is provided with a groove 30b having a depth in the bolt axial direction and a predetermined length and width. The groove 30b is, for example, a rectangular parallelepiped groove (in this embodiment, a rectangular parallelepiped shape with chamfered sides). The mating surface 40a of the second case member 40 is provided with a groove 40b having a depth in the bolt axial direction and a predetermined length and width. The groove 40b is, for example, a rectangular parallelepiped groove (in this embodiment, a rectangular parallelepiped shape with chamfered sides). The grooves 30b, 40b are formed, for example, by cutting after the mating surface 30a and the mating surface 40a are flattened. When the first case member 30 and the second case member 40 are fastened, the groove 30b and the groove 40b are provided at the same position when viewed in the bolt axial direction.

[0018] When the first case member 30 and the second case member 40 are fastened, a rectangular parallelepiped space S is formed by the grooves 30b and 40b, and the plate-like body 50 is inserted in the space S so as to straddle the grooves 30b and 40b. The plate-like body 50 is a plate-like member that can be inserted into the space S, for example, a rectangular parallelepiped plate (in this embodiment, a rectangular parallelepiped with its longitudinal sides chamfered). The plate-like body 50 is fitted into the space S. For example, a pair of opposing side surfaces of the plate-like body 50 are in contact with the opposing groove side surfaces of the grooves 30b and 40b, respectively. Even when the plate-like body 50 is inserted, both ends of the space S in the direction in which the grooves 30b and 40b extend are open. That is, the length in the direction in which the grooves 30b and 40b extend is longer than the length in the direction in which the plate-like body 50 extends. This makes it easier for the plate body 50 to be inserted into the space S.

[0019] The plate-like body 50 has a necessary strength. The "necessary strength" means a strength that does not deform even when an expected force is applied to the case 20. The plate-like body 50 may be made of the same aluminum alloy as the first case member 30 and the second case member 40, but may be made of a material having a higher strength than the first case member 30 and the second case member 40, such as iron. By inserting the iron plate-like body 50 into the space S, the rigidity of the fastening portion of the case 20 is reinforced.

[0020] For example, the plate-like body 50 inserted into the space S between the bolts 80 and nuts 82 that are adjacent to each other in the circumferential direction is arranged to extend in a tangential direction of the circumferential direction. As a result, when a force is applied to slide the mating surfaces 30a, 40a of the case 20, the plate-like body 50 prevents the mating surfaces 30a, 40a from sliding in a direction other than the direction in which it extends (= other than the tangential direction of the circumferential direction). Preferably, the case 20 is provided with a plurality of grooves 30b, 40b and plate-like bodies 50 inserted therein, and the directions in which the plurality of plate-like bodies 50 extend are different from each other. In such a case, regardless of the direction in which a force is applied to slide the mating surfaces 30a, 40a of the case 20, at least one of the plurality of plate-like bodies 50 prevents the mating surfaces 30a, 40a from sliding.

[0021] The mating surface 30a of the first case member 30 is provided with an annular groove 30c having a depth in the bolt axial direction and a predetermined width. For example, the annular groove 30c is a groove having a U-shaped cross section. The mating surface 40a of the second case member 40 is provided with an annular groove 40c having a depth in the bolt axial direction and a predetermined width. For example, the annular groove 40c is a groove having a U-shaped cross section. The annular groove 30c and the annular groove 40c are formed, for example, by cutting the mating surface 30a and the mating surface 40a after flattening. When the first case member 30 and the second case member 40 are fastened, the annular groove 30c and the annular groove 40c are provided at the same position as viewed in the bolt axial direction. When the first case member 30 and the second case member 40 are fastened, an O-ring 70 is press-fitted into the space formed by the annular groove 30c and the annular groove 40c. As a result, the case 20 to which the first case member 30 and the second case member 40 are fastened is made oil-tight.

[0022] FIG. 3 is an explanatory diagram of the fastening structure of the case 20 according to the embodiment, and is a diagram viewed in the bolt axial direction showing the state before the second case member 40 is fastened to the first case member 30 by the bolt 80 and nut 82.

[0023] As shown in FIG. 3, the gear pair 60 is housed in the case 20. The gear pair 60 includes a gear 60a and a gear 60b that mesh with each other, one of which is a drive gear and the other is a driven gear. For example, when the driving power is transmitted from the drive gear to the driven gear in the gear pair 60, a reaction force is generated in each of the gears 60a and 60b due to the meshing of the gear pair 60. The case 20 is filled with oil as a lubricant. In order to prevent oil leakage, the mating surfaces 30a and 40a are fastened with fastening members (=bolts 80 and nuts 82) and an O-ring 70 is sandwiched between the mating surfaces 30a and 40a, making the case 20 oil-tight. The plate-shaped body 50 suppresses the slippage of the mating surfaces 30a and 40a without increasing the number of bolts 80, thereby improving the oil-tightness of the case 20. When the first case member 30 and the second case member 40 are fastened together with fastening members (=bolts 80 and nuts 82), flanges (=flanges) are provided as fastening regions on the mating surface 30a side of the first case member 30 and the mating surface 40a side of the second case member 40. Therefore, the rigidity of the fastening portion of the case 20 can be increased simply by ensuring a space for the grooves 30b, 40b and the plate-like body 50 inserted therein on the outer circumferential side of the O-ring 70 at the flanges on the mating surfaces 30a, 40a.

[0024] According to this embodiment, (a) the mating surfaces 30a, 40a to which the first case member 30 and the second case member 40 are fastened are provided with grooves 30b, 40b, respectively, and (b) the plate-like body 50 is inserted so as to straddle the grooves 30b, 40b provided in the mating surfaces 30a, 40a of the first case member 30 and the second case member 40. By inserting the plate-like body 50 into the grooves 30b, 40b provided in the mating surfaces 30a, 40a, respectively, the rigidity of the fastening portion of the case 20 is increased without increasing the number of bolts 80. As a result, for example, even if a force is applied to slide the mating surfaces 30a, 40a of the case 20, the mating surfaces 30a, 40a of the case 20 are prevented from slipping. In addition, when it is not necessary to increase the rigidity of the fastening portion of the case 20, it is only necessary not to insert the plate-like body 50 into the grooves 30b, 40b, and the specification can be easily changed.

[0025] According to this embodiment, the plate-like body 50 is made of a material having a higher strength than the first case member 30 and the second case member 40. For example, when the first case member 30 and the second case member 40 are made of an aluminum alloy and the plate-like body 50 is made of iron, the volume of the plate-like body 50 required to ensure the necessary strength can be about 1 / 3 compared to when the plate-like body 50 is made of an aluminum alloy. Therefore, it is easy to ensure the space for providing the grooves 30b, 40b and the plate-like body 50 inserted therein.

[0026] According to this embodiment, the groove 30b is provided on the mating surface 30a, the groove 40b is provided on the mating surface 40a, and the plate-like body 50 is inserted into the grooves 30b, 40b, thereby increasing the rigidity of the fastening portion of the case 20. For example, in the case where a protrusion is provided on the mating surface 30a and a groove into which the protrusion is fitted is provided on the mating surface 40a, the machining time for cutting the mating surface 30a to provide the protrusion is longer than that for providing the groove 30b as in this embodiment. In addition, the protrusion provided on the mating surface 30a cannot be changed to a material different from that of the first case member 30, as in the plate-like body 50 in this embodiment. On the other hand, in this embodiment, the machining time for cutting the groove 30b is relatively short, and it is easy to change the positions of the grooves 30b, 40b and the plate-like body 50 inserted therein, i.e., the reinforcing positions, and it is possible to use a material for the plate-like body 50 different from that of the case 20.

[0027] It should be noted that the above is an embodiment of the present invention, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

[0028] In the above embodiment, even when the plate-like body 50 is inserted, the space S is open at both ends in the direction in which the grooves 30b, 40b extend, but the present invention is not limited to this. For example, the plate-like body 50 may have both ends in the longitudinal direction in contact with the opposing side surfaces in the direction in which the grooves 30b, 40b extend. In this case, even if a force that tries to slide the mating surfaces 30a, 40a of the case 20 is applied in any direction including the direction in which the plate-like body 50 extends, the mating surfaces 30a, 40a are prevented from sliding by the plate-like body 50 alone.

[0029] In the above embodiment, the space S and the plate-like body 50 are each a rectangular parallelepiped, but the present invention is not limited to this and may be of another shape. [Explanation of symbols]

[0030] 20: case, 30: first case member, 30a: mating surface, 30b: groove, 40: second case member, 40a: mating surface, 40b: groove, 50: plate-like body

Claims

[Claim 1] A fastening structure for a case including a first case member and a second case member fastened to the first case member, A groove is provided on each of the mating surfaces to which the first case member and the second case member are fastened, A plate-shaped body is inserted so as to straddle the grooves provided on the mating surfaces of the first case member and the second case member. A case fastening structure characterized by the above.

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