Cover for internal combustion engine

Abstract

A chain cover (21) for an internal combustion engine is configured to be mounted to an engine body (10) and to cover a timing chain (20). The chain cover (21) includes a first member (30) formed of a hard resin material and a second member (40) formed of a material different from the hard resin material. The first member (30) is formed with the second member (40) embedded therein. A peripheral portion (45) of an insertion hole (43) has a first engaging surface engaged with the first member (30). The first engaging surface includes a first engaging portion and a second engaging portion, the first engaging portion having a recessed portion in a lattice pattern, and the second engaging portion having a plurality of grooves extending along an extension direction of the peripheral portion (45) and arranged in a cross direction intersecting the extension direction. The second engaging portion is located closer to a space adjacent to the peripheral portion (45) than the first engaging portion.

Description

Technical Field

[0001] The present disclosure relates to a cover for an internal combustion engine, which is configured to be mounted to an engine body and cover a timing chain or a timing belt. Background Art

[0002] Patent document 1 discloses a plastic timing belt cover for an internal combustion engine. The timing belt cover includes a plastic outer cover and a plastic inner cover. The inner cover is located between the outer cover and the engine body. The timing belt is accommodated between the inner cover and the outer cover.

[0003] The timing belt cover includes a soundproofing portion which is an elastic member made of, for example, a thermoplastic elastomer.

[0004] The sound insulating portion is accommodated in the timing belt cover near the tension pulley, which is arranged between the crank timing pulley and the cam timing pulley.

[0005] When the outer cover is manufactured, the sound insulating portion is molded continuously with the outer cover by injection molding.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 6-146915 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] The timing belt cover disclosed in Patent Document 1 includes a portion where a plastic cover and a soundproof portion as an elastic member made of, for example, a thermoplastic elastomer are joined to each other. There is a need to improve the joining strength of the members and the sealing performance at the joined portion.

[0011] Such a problem is caused not only at the joint of the outer cover and the soundproof part, but also at the joint of the members made of different materials. In addition, such a problem is caused not only in the timing belt cover for the internal combustion engine, but also in the timing chain cover.

[0012] An object of the present disclosure is to provide a cover for an internal combustion engine, which improves joint strength and sealing performance at a joint of members made of different materials.

[0013] Solutions for solving problems

[0014] In order to achieve the above-mentioned purpose, a cover for an internal combustion engine is provided. The cover is configured to be mounted to an engine body and cover a timing chain or a timing belt. The cover includes: a first member, which is made of hard plastic; and a second member, which is made of a material different from the hard plastic. The first member is formed by insert molding with the second member as an insert. The second member includes a joining surface in an edge of the second member. The first member is joined to the joining surface. The joining surface includes a first joining portion and a second joining portion. The first joining portion includes a lattice-shaped recess. The second joining portion includes a plurality of grooves. The plurality of grooves extend in an extension direction in which the edge extends. The plurality of grooves are arranged in an intersecting direction intersecting with the extension direction. The second joining portion is arranged to be closer to a space adjacent to the edge than the first joining portion.

[0015] According to this configuration, when the first member is formed by insert molding with the second member as an insert, the concave portion of the first engaging portion and the groove portion of the second engaging portion formed in the engaging surface of the second member are filled with molten plastic. Since the concave portion is lattice-shaped, a large contact area is ensured between the first engaging portion and the first member. This increases the joining strength of the first member and the second member.

[0016] Generally, blow-by gas in an internal combustion engine and oil splashed from an engine body may penetrate into a cover covering a timing chain or a timing belt through a small gap between joint surfaces of a first member and a second member.

[0017] In this regard, in the above-mentioned structure, the second joint is arranged to be closer to the space adjacent to the edge than the first joint. In addition, a plurality of grooves of the second joint are arranged along a cross direction intersecting with the extension direction of the edge of the second member. This prevents blowby gas or oil in the internal combustion engine from penetrating through a small gap between the joint surface of the second member and the first member. This improves the sealing performance between the first member and the second member. Since the sealing performance at the second joint is improved, blowby gas or oil in the internal combustion engine is prevented from penetrating into the first joint. Therefore, the joint strength at the first joint is maintained. Therefore, the joint strength and sealing performance at the joint of members made of different materials are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a front view of a chain cover for an internal combustion engine according to an embodiment, showing the chain cover mounted to an engine body.

[0019] Figure 2 It is a front view of the chain cover according to this embodiment.

[0020] Figure 3 is a rear view of the second member of the chain cover according to the embodiment.

[0021] Figure 4 is an enlarged rear view of the insertion hole of the second member.

[0022] Figure 5 yes Figure 4 An enlarged stereogram of portion A in FIG.

[0023] Figure 6 is along Figure 4 A cross-sectional view taken along line 6-6.

[0024] Figure 7 It is a cross-sectional view showing a joining state between the second joining portion of the second member and the first member.

[0025] Figure 8 It is a cross-sectional view showing a state in which a first engaging portion of a second member and a first member are engaged with each other. DETAILED DESCRIPTION

[0026] Now refer to Figures 1 to 8 A cover for an internal combustion engine according to an embodiment is described. In the present embodiment, a timing chain cover (hereinafter, referred to as a chain cover) of the present disclosure is mounted to a reciprocating (piston) internal combustion engine mounted on a vehicle.

[0027] 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 .

[0028] (Engine body 10)

[0029] 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.

[0030] The cylinder head 11 rotatably supports an intake camshaft 14 and an exhaust camshaft 15 .

[0031] The intake camshaft 14 and the exhaust camshaft 15 respectively open and close an intake valve (not shown) and an exhaust valve (not shown) as engine valves.

[0032] The cam shafts 14 and 15 include end portions 14a and 15a located on one side in the extending direction of the cam shafts 14 and 15. The end portions 14a and 15a protrude from the cylinder head 11.

[0033] Motor-driven variable valve timing mechanisms 91 , 92 are coupled to end portions 14 a , 15 a of camshafts 14 , 15 , respectively.

[0034] The variable valve timing mechanisms 91 , 92 include motors 93 , 94 , respectively, and an actuator (not shown) including a speed reduction mechanism and a link mechanism.

[0035] The actuators of the variable valve timing mechanisms 91 , 92 include driven sprockets 16 , 17 , respectively.

[0036] The crankcase 13 rotatably supports a crankshaft 18. The crankshaft 18 includes an end portion 18a in an extending direction. The end portion 18a protrudes from the crankcase 13. The end portion 18a protrudes in the same direction as the end portions 14a, 15a of the camshafts 14, 15.

[0037] A drive sprocket 19 is coupled to an end 18 a of the crankshaft 18 .

[0038] The timing chain 20 is looped around the driven sprockets 16, 17 and the driving sprocket 19. The driven sprockets 16, 17 are configured to rotate in conjunction with the rotation of the driving sprocket 19 by means of the timing chain 20. Therefore, the rotational force of the crankshaft 18 is transmitted to the camshafts 14, 15.

[0039] The intake-side variable valve timing mechanism 91 controls the rotation speed of the motor 93 so as to change the rotation phase of the intake camshaft 14 relative to the driven sprocket 16 .

[0040] The exhaust-side variable valve timing mechanism 92 controls the rotation speed of the motor 94 to change the rotation phase of the exhaust camshaft 15 relative to the driven sprocket 17 .

[0041] Controllers (not shown) are integrated with the motors 93, 94, respectively.

[0042] (Chain guard 21)

[0043] like Figure 1 As shown, the chain cover 21 is configured to be mounted to the engine body 10 and to cover the timing chain 20 .

[0044] The chain cover 21 includes a first member 30 made of hard plastic and a second member 40 made of a material different from the hard plastic.

[0045] The chain cover 21 of the present embodiment has a rectangular shape in a front view.

[0046] In the following description, the direction along the long side of the chain cover 21 (eg Figure 1 The up-down direction shown in FIG. 2 will be referred to as the length direction L, and the direction along the short side of the chain cover 21 (such as Figure 1 The transverse direction shown) will be referred to as the width direction W.

[0047] The chain cover 21 includes a plurality of cylindrical bushings 70 that receive bolts (not shown) for mounting the chain cover 21 to the engine body 10 .

[0048] like Figure 1 and Figure 2As shown, the first member 30 has a rectangular shape in a front view and forms the outer periphery of the chain cover 21. The second member 40 is joined to a portion of the front face 31 of the first member 30 in the length direction L (eg, Figure 1 and Figure 2 The second member 40 has a rectangular shape that is long in the width direction W in a front view.

[0049] First, the first member 30 will be described.

[0050] like Figure 1 and Figure 2 As shown, the first member 30 is covered with the second member 40 (eg Figure 1 and Figure 2 The upper portion shown in FIG. 1 includes two insertion holes 32 for receiving the motors 93 and 94, respectively. The two insertion holes 32 are spaced apart from each other in the width direction W.

[0051] The first member 30 is not covered with the second member 40 (eg Figure 1 and 2 A through hole 33 is provided in the lower portion (shown) for the crankshaft 18 to extend through.

[0052] The first member 30 has a plurality of fastening holes 34 in a portion not covered with the second member 40. Each fastening hole 34 receives a metal sleeve 80.

[0053] In the present embodiment, four fastening holes 34 are provided on each side portion in the width direction W of the chain cover 21. In each side portion, the four fastening holes 34 are spaced apart from each other in the length direction L. In addition, the four fastening holes 34 are arranged on the outer periphery of the through hole 33. Figure 1 In the embodiment, the bolts inserted into the fastening holes 34 are omitted.

[0054] The first member 30 is made of hard plastic. In the present embodiment, the first member 30 is made of plastic having polyamide (PA-6GF) as a main component.

[0055] The second member 40 will now be described.

[0056] like Figures 1 to 3 As shown, the second member 40 includes a back surface 41 and a front surface 42 , the back surface 41 being joined to the front surface 31 of the first member 30 , and the front surface 42 being located on the opposite side of the back surface 41 .

[0057] like Figure 1 and Figure 2 As shown, the second member 40 includes two insertion holes 43 that respectively receive the motors 93 , 94 . The two insertion holes 43 are spaced apart from each other in the width direction W. Each insertion hole 43 is continuous with the corresponding insertion hole 32 of the first member 30 .

[0058] Motors 93 , 94 integrated with a controller are mounted to the front face 42 of the second member 40 .

[0059] like Figures 1 to 3 As shown, the second member 40 has a plurality of mounting holes 44 in a peripheral portion 45 around each insertion hole 43. Bolts (not shown) for mounting the motors 93, 94 to the second member 40 are screwed into the mounting holes 44. The mounting holes 44 correspond to mounting portions according to the present disclosure.

[0060] like Figure 3 As shown, the second member 40 has a plurality of cylinders 46 protruding from the back surface 41. The plurality of cylinders 46 respectively surround the plurality of sleeves 70. Figure 3 As shown, in the present embodiment, two cylindrical portions 46 are provided on each side portion in the width direction W of the back surface 41. In each side portion, the two cylindrical portions 46 are spaced apart from each other in the length direction L.

[0061] The second member 40 is made of hard plastic having a lower linear expansion coefficient and water absorption than the hard plastic forming the first member 30. In the present embodiment, the second member 40 is made of polyphenylene sulfide (PPS-GF).

[0062] In the case where the plurality of sleeves 70 are used as inserts, the second member 40 is formed by insert molding.

[0063] With the second member 40 and the plurality of sleeves 80 as inserts, the first member 30 is formed by insert molding.

[0064] like Figure 3 As shown, the rear surface 41 of the second member 40 includes a first engaging surface 50 and a second engaging surface 60 that are engaged to the first member 30 .

[0065] The first joint surface 50 is formed in the peripheral portion 45 around each insertion hole 43. In the present embodiment, each first joint surface 50 is formed on the entire circumference of the corresponding peripheral portion 45. The first joint surface 50 corresponds to the joint surface according to the present disclosure. In addition, the peripheral portion 45 around the insertion hole 43 corresponds to the edge of the second member 40 according to the present disclosure.

[0066] like Figures 4 to 6 As shown, each first joint surface 50 includes a first joint portion 51 and a second joint portion 52, the first joint portion 51 includes a lattice-shaped recessed portion 53, and the second joint portion 52 includes a plurality of grooves 54. The plurality of grooves 54 extend in the direction in which the peripheral portion 45 extends (i.e., in the circumferential direction of the insertion hole 43), and are arranged in a direction perpendicular to the extending direction or in a radial direction of the insertion hole 43. The recessed portion 53 and the groove 54 are formed, for example, by a laser device.

[0067] like Figure 4 As shown, the first engaging portion 51 and the second engaging portion 52 are provided over the entire circumference of the peripheral edge portion 45 .

[0068] The second engaging portion 52 is disposed closer to the insertion hole 43 than the first engaging portion 51. That is, the second engaging portion 52 is disposed closer to the space adjacent to the peripheral edge portion 45 than the first engaging portion 51.

[0069] like Figure 5 As shown, the recessed portion 53 forming the first engaging portion 51 includes a plurality of first grooves 53 a extending parallel to each other and a plurality of second grooves 53 b respectively orthogonal to the first grooves 53 a .

[0070] like Figure 3 As shown, the second joint surface 60 is formed in the peripheral portion of the second member 40 and the end surface of the cylindrical portion 46. In the present embodiment, the second joint surface 60 is formed on the entire circumference of the peripheral portion of the second member 40. In addition, the second joint surface 60 is formed on the entire end surface of each cylindrical portion 46.

[0071] The operation of this embodiment will now be described.

[0072] like Figure 7 and Figure 8 As shown, when the first member 30 is formed by insert molding with the second member 40 as an insert, the recessed portion 53 of the first engaging portion 51 and the groove portion 54 of the second engaging portion 52 formed in each first engaging surface 50 of the second member 40 are filled with molten plastic. Since the recessed portion 53 is lattice-shaped, a large contact area is ensured between the first engaging portion 51 and the first member 30. This increases the joining strength between the first member 30 and the second member 40.

[0073] In the chain cover 21, when the recessed portion 53 of the first engaging portion 51 and the groove portion 54 of the second engaging portion 52 are filled with molten plastic, a small first gap S1 and a small second gap S2 are respectively generated between the first engaging portion 51 and the first member 30 and between the second engaging portion 52 and the first member 30. For the purpose of explanation, the gaps S1, S2 are partially enlarged and simplified.

[0074] like Figure 8 As shown, at the bottom of the grid-shaped recess 53 (as shown in Figure 8In the lower part shown in FIG. 1 , the first gap S1 connects the first groove 53a and the second groove 53b to each other at the intersection of the first groove 53a and the second groove 53b. Therefore, for example, if the first joint portion 51 is arranged closer to the insertion hole 43 than the second joint portion 52, that is, closer to the space adjacent to the peripheral portion 45 than the second joint portion 52, the blow-by gas in the internal combustion engine and the oil splashed from the engine body 10 will easily penetrate from the inner periphery to the outer periphery of the insertion hole 43 through the intersection of the first gap S1. The infiltrated blow-by gas or oil will reduce the bonding strength at the first joint portion 51.

[0075] In this regard, the second joint portion 52 of the chain cover 21 according to the present embodiment is closer to the insertion hole 43 than the first joint portion 51. In addition, a plurality of groove portions 54 are arranged along a cross direction that crosses the extension direction of the peripheral edge portion 45 around the insertion hole 43. This prevents blowby gas or oil from penetrating through the small second gap S2 between the second joint portion 52 and the first member 30. This is because the second gap S2 formed along the top and bottom of the plurality of groove portions 54 of the second joint portion 52 hinders the movement of blowby gas and oil. This improves the sealing performance between the first member 30 and the second member 40. Since the sealing performance at the second joint portion 52 is improved, blowby gas or oil is prevented from penetrating into the first joint portion 51. Therefore, the joint strength at the first joint portion 51 is maintained.

[0076] This embodiment has the following advantages.

[0077] (1) The peripheral edge portion 45 around each insertion hole 43 as the edge of the second member 40 includes a first joint surface 50 joined to the first member 30. Each first joint surface 50 includes a first joint portion 51 and a second joint portion 52, the first joint portion 51 includes a grid-shaped recessed portion 53, and the second joint portion 52 includes a plurality of grooves 54. The plurality of grooves 54 extend along the direction in which the peripheral edge portion 45 or the edge extends, and are arranged in a cross direction intersecting the extending direction. The second joint portion 52 is arranged to be closer to the space adjacent to the peripheral edge portion 45 as the edge than the first joint portion 51.

[0078] This configuration functions in the above-described manner. Therefore, the joint strength and sealing performance at the joint portion of components made of different materials are improved.

[0079] (2) Each first engaging surface 50 is formed over the entire circumference of the corresponding peripheral edge portion 45 as an edge portion. The first engaging surface 50 includes a first engaging portion 51 and a second engaging portion 52 extending over the entire circumference of the peripheral edge portion 45 as an edge portion.

[0080] This configuration improves the joint strength and sealing performance at the joint of components made of different materials.

[0081] (3) The first member 30 and the second member 40 include insertion holes 32, 43 for receiving the variable valve timing mechanisms 91, 92, respectively. The second member 40 includes mounting holes 44, which are provided in the peripheral edge portion 45 around each insertion hole 43, or in the edge portion of the second member 40. The mounting holes 44 receive the variable valve timing mechanisms 91, 92, respectively. The second member 40 is made of PPS-GF, which satisfies both the condition that the linear expansion coefficient is lower than that of PA6-GF and the condition that the water absorption is lower than that of PA6-GF.

[0082] The chain cover 21 includes insertion holes 32, 43 that respectively receive the variable valve timing mechanisms 91, 92. The variable valve timing mechanisms 91, 92 are mounted to mounting holes 44 that are provided in a peripheral portion 45 around each insertion hole 43 or in an edge portion of the second member 40. In order to ensure positional accuracy of the variable valve timing mechanisms 91, 92, it is desirable that the mounting holes 44 have material properties that resist deformation due to heat transferred from the engine body 10 or collected water.

[0083] With the above configuration, the second member 40 including the mounting hole 44 is made of a material that satisfies both the condition that the linear expansion coefficient is lower than the linear expansion coefficient of the hard plastic forming the first member 30 and the condition that the water absorption is lower than the water absorption of the hard plastic. This restricts deformation of the mounting hole 44 due to heat transferred from the engine body 10 or collected water. This prevents the positional accuracy of the mechanism mounted to the mounting hole 44 from being degraded.

[0084] (4) The edge portion of the second member 40 is the peripheral edge portion 45 around the insertion hole 43 of the second member 40 .

[0085] Since the insertion hole 43 connects the inside and the outside of the internal combustion engine to each other, the peripheral edge portion 45 around the insertion hole 43 is always exposed to the blow-by gas and oil of the internal combustion engine.

[0086] The above configuration prevents the blow-by gas and oil of the internal combustion engine from penetrating through the small gaps S1 , S2 between the first joint surface 50 of the second member 40 and the first member 30 in the peripheral edge portion 45 around the insertion hole 43 .

[0087] <Variation>

[0088] The above-described embodiment may be modified as follows. The above-described embodiment and the following modifications may be combined as long as the combined modifications remain technically consistent with each other.

[0089] Each of the first engaging surfaces 50 does not necessarily need to be provided over the entire circumference of the peripheral edge portion 45 around the corresponding insertion hole 43 .

[0090] The engagement surface of the present disclosure is not limited to the first engagement surface 50 formed in the peripheral edge portion 45 around the insertion hole 43. Figure 3 The present disclosure may be employed in a portion of the second joint surface 60 in the peripheral portion 50A located on the back surface 41 of the second member 40 , or in a portion of the second joint surface 60 formed in the peripheral portion of the cylinder portion 46 .

[0091] The number and positions of the fastening holes 34 are not limited to those in the above-described embodiment but may be changed.

[0092] The number and position of the cylindrical portions 46 of the second member 40 are not limited to those in the above-described embodiment, but may be changed.

[0093] The cylindrical portion 46 of the second member 40 may be omitted.

[0094] The chain cover 21 is not limited to a chain cover in which only the first member 30 includes the through hole 33. For example, the second member 40 may include a hole through which the crankshaft 18 extends, so that the hole and the through hole 33 form a through hole in the chain cover 21 through which the crankshaft 18 extends.

[0095] The second member 40 is not limited to the second member made of polyphenylene sulfide (PPS-GF) as described in the above embodiment, but may be made of a metal such as aluminum instead of PPS. Instead of PPS, any of the following hard plastics may 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).

[0096] The first member 30 is not limited to the first member made of polyamide 6 (PA6-GF) as described in the above embodiment, but may be made of a plastic having polyamide instead of polyamide 6 as a main component.

[0097] The shapes of the chain cover 21 , the first member 30 and the second member 40 are not limited to the rectangular shape in the front view as described in the above embodiment, but may be changed according to requirements to be satisfied when the chain cover 21 is mounted on the engine body 10 .

[0098] The cover according to the present disclosure is not limited to the chain cover 21 but may be a timing belt cover.

Claims

1. A cover for an internal combustion engine, the cover being configured to be mounted to an engine body and covering a timing chain or a timing belt, the cover comprising: A first member made of hard plastic; as well as The second member is made of a material different from the hard plastic, wherein: The first member is formed by insert molding with the second member as an insert, The first member and the second member each include an insertion hole, wherein the insertion hole receives a mechanism for changing the operation mode of the engine valve, the second member includes a joining surface in a peripheral portion around the insertion hole of the second member, the first member being joined to the joining surface, The engagement surface comprises: A first engaging portion including lattice-shaped recesses; and a second engaging portion including a plurality of grooves extending in a circumferential direction of the insertion hole of the second member and arranged in a radial direction of the insertion hole of the second member, the radial direction intersecting the circumferential direction, and The second engaging portion is provided closer to a space adjacent to the peripheral portion than the first engaging portion.

2. The cover for an internal combustion engine according to claim 1, characterized in that The engagement surface is provided over the entire circumference of the peripheral portion, and The first engaging portion and the second engaging portion are provided over the entire circumference of the peripheral edge portion.

3. The cover for an internal combustion engine according to claim 1 or 2, characterized in that: The second member includes a mounting portion provided in the peripheral portion around the insertion hole of the second member, the mechanism being mounted to the mounting portion, and The second member is made of a material satisfying at least one of a condition that a linear expansion coefficient is lower than a linear expansion coefficient of the hard plastic and a condition that a water absorption is lower than a water absorption of the hard plastic.

Images