Cover for internal combustion engine

Abstract

According to the present application, the chain cover (21) includes a first member (30) formed of a hard resin and having a back surface (31) facing the engine main body, and a second member (40) formed of a material different from that of the hard resin and joined to the first member (30). A groove portion (36) is formed only on the back surface (31) of the first member (30), and a sealing member for sealing a gap between the first member (30) and the engine main body is fitted in the groove portion (36).

Description

Technical Field

[0001] This disclosure relates to a cover for an internal combustion engine, which is mounted to the engine body and covers the timing chain or timing belt. Background Technology

[0002] Patent document 1 discloses a plastic timing chain cover (hereinafter referred to as the chain cover) that is mounted to the engine block of an internal combustion engine. The chain cover has a through hole for crankshaft insertion. The chain cover also has multiple through holes in its peripheral portion. These through holes receive bolts that fasten the chain cover to the engine block.

[0003] The chain guard has grooves in the surface facing the engine body. The grooves extend along the periphery of the chain guard.

[0004] The annular sealing member fits into the groove around the entire circumference to provide a seal between the engine body and the chain guard.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2015-102018 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] A chain guard is needed that comprises components made of different materials in order to, for example, partially improve the dimensional accuracy of the chain guard. However, since the aforementioned groove extends over two or more components, steps may form at the boundaries between the components. This can easily hinder tight contact between the sealing component and the groove, and thus may reduce sealing performance.

[0010] The purpose of this disclosure is to provide a cover for an internal combustion engine that maintains tight contact between the sealing member and the groove.

[0011] Solution for solving the problem

[0012] To achieve the above objectives, a cover for an internal combustion engine is provided. The cover is mounted to the engine body and covers the timing chain or timing belt. The cover includes a first component and a second component. The first component is made of rigid plastic and includes opposing surfaces. These opposing surfaces face the engine body. The second component is made of a material different from the rigid plastic and is joined to the first component. Grooves are provided only in the opposing surfaces of the first component. Sealing members are fitted into the grooves to provide a seal between the first component and the engine body.

[0013] Unlike the case where the groove extends through the first and second members, this design prevents the groove from creating steps on its inner surface. Therefore, a tight contact is maintained between the sealing member and the groove. Attached Figure Description

[0014] Figure 1 This is a front view of a chain cover for an internal combustion engine according to an embodiment, showing the chain cover mounted to the engine body.

[0015] Figure 2 This is a front view of the chain cover according to this embodiment.

[0016] Figure 3 This is a rear view of the chain guard according to this embodiment.

[0017] Figure 4 It is along Figure 2 The cross-sectional view taken from line 4-4. Detailed Implementation

[0018] Now refer to Figures 1 to 4 This describes a timing chain cover for an internal combustion engine according to an embodiment. In this embodiment, the timing chain cover (hereinafter referred to as the chain cover) of this disclosure is mounted on a reciprocating (piston) internal combustion engine mounted on a vehicle.

[0019] like Figure 1 As shown, the internal combustion engine includes an engine body 10 and a chain cover 21 mounted to the engine body 10.

[0020] (Engine body 10)

[0021] like Figure 1 As shown, the engine body 10 includes a cylinder head 11, a cylinder block 12, and a crankcase 13. The cylinder block 12 is arranged between the cylinder head 11 and the crankcase 13.

[0022] The cylinder head 11 rotatably supports the intake camshaft 14 and the exhaust camshaft 15.

[0023] The intake camshaft 14 and the exhaust camshaft 15 open and close the intake valve (not shown) and the exhaust valve (not shown), which serve as engine valves, respectively.

[0024] Camshafts 14 and 15 include end portions 14a and 15a located on one side of the camshafts 14 and 15 in the extending direction of the camshafts 14 and 15. End portions 14a and 15a protrude from the cylinder head 11.

[0025] Motor-driven variable valve timing mechanisms 91 and 92 are connected to the ends 14a and 15a of camshafts 14 and 15, respectively.

[0026] The variable valve timing mechanisms 91 and 92 each include motors 93 and 94 and actuators (not shown), which include a reduction mechanism and a linkage mechanism.

[0027] The actuators of the variable valve timing mechanisms 91 and 92 respectively include driven sprockets 16 and 17.

[0028] like Figure 1 As shown, the crankcase 13 rotatably supports the crankshaft 18. The crankshaft 18 includes an end portion 18a in its extending direction. The end portion 18a protrudes from the crankcase 13 in the same direction as the ends portions 14a and 15a of the camshafts 14 and 15. A drive sprocket 19 is coupled to the end portion 18a.

[0029] The timing chain 20 surrounds the driven sprockets 16 and 17 and the drive sprocket 19. The driven sprockets 16 and 17 are configured to rotate in coordination with the rotation of the timing chain 20 and the drive sprocket 19. Therefore, the rotational force of the crankshaft 18 is transmitted to the camshafts 14 and 15.

[0030] The intake-side variable valve timing mechanism 91 controls the speed of the motor 93 in order to change the rotational phase of the intake camshaft 14 relative to the driven sprocket 16.

[0031] The exhaust-side variable valve timing mechanism 92 controls the speed of the motor 94 to change the rotational phase of the exhaust camshaft 15 relative to the driven sprocket 17.

[0032] The controller (not shown) is integrated with motors 93 and 94 respectively.

[0033] (Chain Cover 21)

[0034] like Figure 1 As shown, the timing chain cover 21 has a rectangular shape in the front view. The timing chain cover 21 is mounted to one side of the engine body 10, from which the ends 14a and 15a of the camshafts 14 and 15 and the end 18a of the crankshaft 18 protrude. The timing chain cover 21 is configured to cover the timing chain 20.

[0035] like Figures 1 to 3 As shown, the chain cover 21 includes a first member 30 and a second member 40 engaged with the first member 30.

[0036] First, the first component 30 will be explained.

[0037] like Figure 2 and Figure 3 As shown, the first member 30 has a rectangular shape in the front view. The first member 30 includes a rear surface 31 facing the engine body 10 and a front surface 32 located on the opposite side of the rear surface 31. The second member 40 is engaged with the front surface 32. The rear surface 31 corresponds to the opposing surface according to this disclosure.

[0038] The first component 30 includes two insertion holes 33 for receiving motors 93 and 94 respectively.

[0039] The first component 30 also includes a through hole 34 through which the crankshaft 18 extends. The through hole 34 is formed only in the first component 30.

[0040] like Figure 3 and Figure 4 As shown, the back surface 31 of the first component 30 includes a groove 36. The sealing component 50 is fitted into the groove 36 to provide a seal between the first component 30 and the engine body 10.

[0041] The groove 36 extends over the entire outer periphery of the back surface 31. The groove 36 is formed only in the first member 30.

[0042] The groove 36 includes a bottom wall 36a and side walls 36b and 36c, which extend from opposite sides in the width direction of the bottom wall 36a.

[0043] The first component 30 is made of rigid plastic. In this embodiment, the first component 30 is made of plastic having polyamide (PA-GF) as the main component.

[0044] The second component 40 will now be described.

[0045] like Figures 1 to 3 As shown, the second component 40 has a rectangular shape in the front view.

[0046] like Figure 4 As shown, the second member 40 includes a back surface 41 that is joined to the first member 30 and a front surface 42 located on the opposite side of the back surface 41.

[0047] The second component 40 includes insertion holes 43 for receiving motors 93 and 94 respectively. The insertion holes 43 are continuous with the insertion hole 33 of the first component.

[0048] Motors 93 and 94, integrated with the controller, are mounted on the front 42 of the second component 40.

[0049] The second component 40 has a plurality of mounting holes 44 in its peripheral portion surrounding each insertion hole 43. Bolts (not shown) for mounting motors 93, 94 to the second component 40 are screwed into the mounting holes 44. The mounting holes 44 correspond to mounting portions according to this disclosure.

[0050] The second component 40 is made of a rigid plastic with a lower coefficient of linear expansion and lower water absorption than the rigid plastic forming the first component 30. In this embodiment, the second component 40 is made of polyphenylene sulfide (PPS-GF).

[0051] like Figures 1 to 3As shown, the chain guard 21 includes a plurality of cylindrical sleeves 60, which receive bolts (not shown) for mounting the chain guard 21 to the engine body 10.

[0052] like Figure 3 and Figure 4 As shown, the second member 40 is engaged with the front surface 32 of the first member 30. When the sleeve 60 is used as an insert, the second member 40 is formed by insert molding. The second member 40 includes a plurality of cylindrical portions 45 that respectively surround the sleeve 60.

[0053] like Figures 1 to 3 As shown, in this embodiment, each side of the chain cover 21 in the width direction is provided with two cylindrical portions 45.

[0054] like Figure 4 As shown, the first member 30 includes a surrounding portion 35 that surrounds the cylindrical portion 45. In this embodiment, a portion of the surrounding portion 35 forms a portion of the outer sidewall 36c of the groove portion 36.

[0055] like Figures 1 to 3 As shown, the first member 30 has a plurality of fastening holes 37 in the portion not covered by the second member 40. Each fastening hole 37 receives a metal sleeve. In this embodiment, each side of the chain guard 21 in the width direction is provided with four fastening holes 37. Furthermore, the four fastening holes 37 are arranged around the through hole 34. Figure 1 The bolt inserted into the fastening hole 37 is omitted in the text.

[0056] The function of this implementation method will now be explained.

[0057] When the second member 40 is used as an insert, the chain cover 21 is obtained by insert molding to form the first member 30. In this case, the groove 36 for the sealing member 50 to fit into is formed only in the first member 30. With this configuration, unlike the case where the groove 36 extends through the first member 30 and the second member 40, the groove 36 does not include the boundary between the members. This prevents the groove 36 from forming a step on its inner surface.

[0058] This implementation method has the following advantages.

[0059] (1) The chain guard 21 includes a first component 30 made of rigid plastic and a second component 40 made of a material different from the rigid plastic. The first component 30 includes a back surface 31 facing the engine body 10. The second component 40 engages with the first component 30. Only the back surface 31 of the first component 30 includes a groove 36 for receiving a sealing component 50. The sealing component 50 provides a seal between the first component 30 and the engine body 10.

[0060] This structure functions in the manner described above. Therefore, a tight contact is maintained between the sealing member 50 and the groove 36.

[0061] (2) The second component 40 includes an insertion hole 43 and a mounting hole 44 disposed in the peripheral portion surrounding each insertion hole 43. The insertion hole 43 receives variable valve timing mechanisms 91, 92 connected to camshafts 14, 15. More specifically, the insertion hole 43 receives motors 93, 94 of the variable valve timing mechanisms 91, 92. The variable valve timing mechanisms 91, 92 (more specifically, motors 93, 94 of the variable valve timing mechanisms 91, 92) are mounted to the mounting hole 44. The second component 40 is made of PPS-GF, which satisfies both the condition of having a coefficient of linear expansion lower than PA6-GF and the condition of having a water absorption lower than that of the rigid plastic.

[0062] In the chain cover 21, motors 93 and 94 are mounted into mounting holes 44, which are located in the periphery surrounding insertion holes 43 into which motors 93 and 94 are inserted. To ensure the positional accuracy of motors 93 and 94, mounting holes 44 are expected to have material properties that resist deformation caused by heat transferred from the engine body 10 and collected water.

[0063] With the above-described structure, the second component 40, including the mounting hole 44, is made of a material that satisfies both the condition that its coefficient of linear expansion is lower than that of the rigid plastic forming the first component 30 and its water absorption is lower than that of the rigid plastic. This limits deformation of the mounting hole 44 due to heat transferred from the engine body 10 and water collected therefrom. This prevents a decrease in the positional accuracy of the motors 93, 94 mounted to the mounting hole 44.

[0064] (3) Only the first component 30 includes a through hole 34 through which the crankshaft 18 extends.

[0065] Compared to the second component 40, which includes an insertion hole 43 for inserting motors 93 and 94 and a mounting hole 44 for mounting motors 93 and 94, as well as a through hole through which the crankshaft 18 extends, this configuration reduces the size of the second component 40. Therefore, the size and weight of the chain guard 21 are reduced.

[0066] (4) When the second component 40 is an insert, the first component 30 is formed by insert molding.

[0067] In this type of construction, if the groove 36 extends over the first member 30 and the second member 40, it may be easy to form a step at the boundary between the members in the groove 36.

[0068] If this disclosure is applied to this type of construction, a tight contact is maintained between the sealing member 50 and the groove 36.

[0069] (5) The chain guard 21 includes a plurality of cylindrical sleeves 60, which receive bolts for mounting the chain guard 21 to the engine body 10. A second member 40 engages with the front face 32 of the first member 30, which is located on the opposite side of the back face 31. When the sleeve 60 is used as an insert, the second member 40 is formed by insert molding and includes a plurality of cylindrical portions 45 respectively surrounding the sleeve 60. The first member 30 includes a plurality of surrounding portions 35 respectively surrounding the cylindrical portions 45.

[0070] With this configuration, the multiple cylindrical portions 45 of the second member 40, which respectively surround the multiple sleeves 60, are respectively surrounded by the multiple surrounding portions 35 of the first member 30. The chain guard 21 is mounted to the engine body 10 using bolts inserted into the sleeves 60. Thus, except at the joint, the first member 30 and the second member 40 are fixed to each other at the multiple cylindrical portions 45 and the surrounding portions 35. This limits the deformation of the first member 30 due to heat transferred from the engine body 10 and water collected, and thus effectively limits the deformation of the second member 40.

[0071] <Variation>

[0072] This embodiment can be modified as follows. As long as the combined modifications do not contradict each other technically, this embodiment and the following modifications can be combined.

[0073] The number and position of the fastening holes 37 are not limited to those in the above embodiments, but can be changed.

[0074] The number and position of the cylindrical portion 45 of the second component 40 and the surrounding portion 35 of the first component 30 are not limited to the number and position in the above embodiment, but can be changed.

[0075] Both the cylindrical portion 45 of the second component 40 and the surrounding portion 35 of the first component 30 can be omitted.

[0076] The first component 30 does not necessarily need to be formed by insert molding when the second component 40 is an insert. That is, the chain cover 21 can be formed by joining the separately molded first component 30 and second component 40 together.

[0077] The chain guard 21 is not limited to a chain guard in which only the first member 30 includes the through hole 34. For example, the second member 40 may include a hole through which the crankshaft 18 extends, such that the hole and the through hole 34 form a through hole in the chain guard 21 for the crankshaft 18 to extend through.

[0078] The variable valve timing mechanisms 91 and 92 are not limited to the electric type with motors 93 and 94 as described in the above embodiments, but can be hydraulic type.

[0079] The second component 40 is not limited to the second component made of polyphenylene sulfide (PPS-GF) as described in the above embodiments, but can be made of a metal such as aluminum instead of PPS. Instead of PPS, any of the following rigid plastics can be selected and used: liquid crystal polymer (LCP), polyetheretherketone (PEEK), polyethylene naphthalate (PEN), polyamide 6T (PA6T), polyamide 9T (PA9T), polyethylene terephthalate (PBT), or polyacetal (POM).

[0080] The first component 30 is not limited to the first component made of polyamide 6 (PA6-GF) as described in the above embodiments, but may be made of a plastic having a polyamide as the main component instead of polyamide 6.

[0081] The groove 36 does not necessarily need to be provided on the entire outer periphery of the first member 30 as described in the above embodiments, but may include the end in the extension direction.

[0082] The shapes of the chain cover 21, the first component 30, and the second component 40 are not limited to the rectangular shape shown in the front view of the above embodiment, but can be changed according to the requirements that need to be met when the chain cover 21 is installed on the engine body 10.

[0083] The cover according to this disclosure is not limited to chain cover 21, but may be a timing belt cover.

Claims

1. A cover for an internal combustion engine, the cover being mounted to an engine main body and covering a timing chain or a timing belt, the cover comprising: a first member made of a hard plastic and including an opposing surface facing the engine main body; and a second member made of a material different from the hard plastic and joined to the first member, wherein a groove portion is provided only in the opposing surface of the first member, and a sealing member is fitted in the groove portion to provide a seal between the first member and the engine main body, wherein the second member includes: an insertion hole receiving a mechanism coupled to a camshaft and changing a manner of engine valve operation; and a mounting portion provided in a peripheral portion around the insertion hole, the mechanism being mounted to the mounting portion, and the second member is made of a hard plastic satisfying both a condition that a linear expansion coefficient is lower than that of the hard plastic of the first member and a condition that water absorption is lower than that of the hard plastic of the first member. Only the first member includes a through hole through which a crankshaft extends.

2. The cover for an internal combustion engine according to claim 1, characterized by In a case where the second member is an insert, the first member is formed by insert molding.

3. The cover for an internal combustion engine according to claim 1, characterized by 4. The cover for an internal combustion engine according to any one of claims 1 to 3, characterized in that the cover includes a plurality of sleeve tubes that are cylindrical and receive bolts for mounting the cover to the engine main body, the second member is joined to a surface of the first member on an opposite side from the opposing surface, in a case where the sleeve tubes are inserts, the second member is formed by insert molding, and the second member includes a plurality of cylindrical portions that respectively surround the sleeve tubes, and the first member includes a plurality of surrounding portions that respectively surround the cylindrical portions. ​

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