JP2020060117A - Front cover of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fix another member in the vicinity of a VVT device without causing misalignment between the VVT device and a camshaft in a front cover having a VVT device mounting portion formed on the upper portion. SOLUTION: A window hole 11 is opened in an upper portion of a front cover 3 to form a VVB device mounting portion 12 for an intake valve, and an auxiliary boss portion for fixing another member such as an EGR valve is next to the VVB device mounting portion 12. 16 is projected. A rib 26 is formed on the front cover 3 so as to connect the auxiliary boss portion 16 and one main boss portion 16 located below the auxiliary boss portion 16. Even if a bending moment acts on the auxiliary boss portion 16 due to the weight of the member, the rib 26 prevents the deformation, so that the strain does not spread to the intake valve VVB device mounting portion 12. Therefore, there is no misalignment between the intake valve VVB device and the intake gum shaft. [Selection diagram] Fig. 3

Description

  The present invention relates to a front cover that covers a timing chain in an internal combustion engine.

  A timing chain of an internal combustion engine is covered with a shallow shell-shaped front cover that is fixedly stacked on a cylinder block and a cylinder head. On the other hand, in driving the cam shaft by the timing chain, in particular for the intake cam shaft, the VVT device (variable valve timing device) is used to advance or retard the valve opening / closing timing.

  This VVT device is classified into a hydraulic type and an electric type, and as an arrangement structure of the electric VVT device, Patent Document 1 discloses that the VVT device is attached to a front cover. The VVT device includes a rotating member connected to the cam shaft, and advances or retards the rotating member with respect to the rotation of the sprocket, thereby advancing or retarding the valve. There is.

  Therefore, the VVT device (the rotating member thereof) and the cam shaft need to be held concentrically, and when misalignment occurs between the cam shaft and the VVT device, the VVT device has the rotating member and the cam shaft. There is a problem that the twisting occurs, which hinders the control of the cam shaft and reduces the durability.

JP, 2008-215314, A

  Now, there are many auxiliary members in the internal combustion engine. The VVT device can be said to be an auxiliary member, but there are cases where other members other than the VVT device must be fixed to the auxiliary boss portion provided on the front cover. In this case, if the weight of the other member is heavy, if it is fixed near the VVT device in the front cover, the strain generated in the auxiliary boss portion due to the weight of the other member reaches the mounting portion of the VVT device, and There is concern that misalignment with the cam shaft may occur.

  The present invention has been made to improve the present situation.

As described in claim 1, the present invention relates to a front cover that covers the timing chain, in which both left and right sides as viewed from the crank axis direction are overlapping portions that overlap the cylinder head and the cylinder block,
"A mounting portion of the VVT device and an auxiliary boss portion for mounting another member are formed on the upper portion so that the auxiliary boss portion protrudes outside one overlapping portion,
A main boss portion for fixing the one overlapping portion to the cylinder head is formed in a portion of the one overlapping portion below the auxiliary boss portion,
The auxiliary boss portion and the main boss portion are connected by a rib protruding outside the overlapping portion. "
It is configured as.

The present invention also includes the configuration of claim 2. According to the invention of claim 2, in claim 1,
"The cylinder head has a laminated structure of a head main body having an intake port and a cam carrier fixed to the upper surface thereof, and the rib is formed between the upper end and the lower end of the head main body and the cam carrier. It is formed so that the mating surfaces are located. "
It is configured as.

  In the present invention, even if a load is applied to the auxiliary boss by fixing the other member to the auxiliary boss, the load is supported by the ribs, so that the weight of the other member causes strain (deformation) in the auxiliary boss. It can be prevented or significantly suppressed.

  Therefore, even if the auxiliary boss portion is provided near the VVT device mounting portion, strain does not spread to the VVT device mounting portion, and as a result, misalignment between the VVT device and the cam shaft is prevented, It is possible to prevent the occurrence of problems such as malfunction and uneven wear due to twisting at the connecting portion between the VVT device and the cam shaft. In other words, a heavy member can be attached to the front cover near the VVT device without adversely affecting the VVT device.

  By the way, the cylinder head is configured to have a laminated structure of a head body having an intake port formed therein and a cam carrier that rotatably holds a cam shaft. In this case, the front cover includes a cam carrier. It overlaps with both the head body.

  If the head main body and the cam carrier are separate bodies, a slight difference in vibration may occur between the two when the engine is operating. Then, due to the difference in vibration, the VVT device mounting portion is caused. May be distorted.

  On the other hand, when the second aspect is adopted, since the supporting function of the rib acts on both the head body and the cam carrier, it is possible to greatly suppress the occurrence of a difference in vibration between the head body and the cam carrier. As a result, it is possible to prevent or suppress vibration acting on the VVT device mounting portion, and prevent or significantly suppress the occurrence of strain in the VVT device mounting portion. Therefore, the operation of the VVT device can be ensured.

It is the side view which looked at embodiment from the side of the air intake side. It is a partial front view. It is a rear view of a front cover. It is a front view of a front cover. It is a partial perspective view seen from the front upper part. It is the perspective view seen from the intake side lower part.

  Next, an embodiment of the present invention will be described with reference to the drawings. The internal combustion engine is arranged in the engine room provided in the front part of the automobile, but in the present embodiment, the internal combustion engine is arranged in a horizontal position in which the crankshaft is arranged in a long posture in the left-right direction of the vehicle body. Is. Further, the relationship between the intake air and the exhaust air is a front exhaust air / rear intake air with the exhaust side surface positioned on the front side in the traveling direction with reference to the forward traveling direction of the vehicle.

  On the other hand, in the internal combustion engine, it is generalized that the side on which the timing chain is arranged is called the front and the side on which the mission is arranged is called the rear, with the crank axis direction as the front-rear direction in order to specify the direction. The cover that covers the timing chain is called the front cover.

  Also in this embodiment, this general usage is used for the direction of the internal combustion engine, but as described above, since the internal combustion engine of the embodiment is horizontal, the front-rear direction of the vehicle and the front-rear direction of the internal combustion engine are 90 degrees. ° Different. The direction is clearly shown in FIG. The left-right direction is a direction orthogonal to the crank axis and the cylinder bore axis.

  The basic mode of the internal combustion engine of this embodiment is the same as before, and as shown in FIG. 1, a cylinder block 1 and a cylinder head 2 fixed to the upper surface thereof, and a front surface of the cylinder block 1 and the cylinder head 2 are provided. The front cover 3 is fixed. An oil pan (not shown) is fixed to the lower surface of the cylinder block 1, while a head cover 4 (see FIGS. 2 and 5) is fixed to the upper surface of the cylinder head 2.

  The cylinder head 2 of the present embodiment is composed of a head main body 2a located below and a cam carrier 2b which is superposed and fixed on the upper surface of the head main body 2a. The cam carrier 2b has an intake cam shaft and an exhaust cam shaft. The cam shaft is rotatably held. The upper surface of the cam carrier 2b is indicated by reference numeral 6, the overlapping surface between the cam carrier 2b and the head main body 2a is indicated by reference numeral 7, and the boundary surface between the head main body 2a and the cylinder block 1 is indicated by reference numeral 8.

  As shown in FIGS. 5 and 6, the head main body 2a is formed with an intake side surface 9 in which an intake boat 9a is opened, and the intake manifold 10 shown in FIGS. 1 and 2 is fixed to the intake side surface. As shown in FIG. 1, a flange 10a having an intake outlet is formed in the upper part of the intake manifold 10, and the flange 10a is fixed to the intake side surface 9 with a bolt.

  As can be understood from the form of the intake manifold 10 shown in FIG. 1, the internal combustion engine of this embodiment has four cylinders. The intake manifold 10 has a built-in surge tank, and the intake air is swirled clockwise in the front view of the intake manifold 10 as shown by a dotted arrow in FIG. 2, and is discharged from the upper flange 10a.

  As shown in FIGS. 3 and 4, an intake valve VVB device mounting portion 12 having a circular window hole 11 is formed in a portion of the upper portion of the front cover 3 near the intake side surface, and the intake valve VVT device mounting portion 12 is formed. A plurality of boss portions 13 for fixing the VVT device are formed in the device mounting portion 12 along the circumferential direction.

  The front cover 3 has a shallow shell shape that opens toward the cylinder block 1 and the cylinder head 2. Therefore, as shown in FIG. Left and right vertically long side walls 14a and 14b are formed as overlapping portions overlapping the head 2, and a large number of main boss portions 15 for fixing the side walls 14a and 14b with bolts are formed on the side walls 14a and 14b. .

  Then, an auxiliary boss portion 16 projecting to the outside of the side wall 14a is formed at the intake side end of the upper end of the front cover 3, and an EGR valve 18 is provided on the upper surface of the auxiliary boss portion 16 via a bracket 17. It is fixed. Therefore, in this embodiment, the EGR valve 18 is the other member described in the claims. The EGR valve 18 is controlled by an electromagnetic solenoid, and is provided with a connector 18a to which a plug is connected as shown in FIG. 5, for example.

  The bracket 17 is composed of a tubular portion 17a and an arm portion 17b branched from an upper portion of the tubular portion 17a. The tubular portion 17a is screwed into the auxiliary boss portion 16 and a stud bolt 19 screwed into the stud bolt 19. It is fixed to the upper surface of the auxiliary boss portion 16 with the nut 20.

  As shown in FIG. 5, the arm portion 17b of the bracket 17 extends rearward, and the EGR valve 18 is fixed to the rear end of the bracket 17 via a boss body 18b and a bolt 18c. Further, as shown in FIG. 1, an EGR cooler 21 is fixed to the EGR valve 18, and an EGR pipe 22 and cooling water ports 23, 24 are connected to the EGR cooler 21.

  Further, the EGR valve 18 is connected to a distribution passage 25 for distributing the EGR gas to each branch pipe of the intake manifold 10. The distribution passage 25 is formed in a tournament shape having a primary branch portion 25a and a secondary branch portion 25b, and the primary branch portion 25a and the secondary branch portion 25b are welded to the intake manifold 10. Therefore, both the intake manifold 10 and the distribution passage 25 are made of synthetic resin.

  As shown in FIGS. 3 to 5, the auxiliary boss portion 16 projects outward in the left-right direction, while the arm portion 17b of the bracket 17 extends rearward, which is caused by the weight of the EGR valve 18 (and the EGR cooler 21). The generated moment acts on the auxiliary boss portion 16 as an external force that causes a twist in the front view and the side view, as indicated by the white arrow in FIGS.

  Therefore, in order to prevent deformation of the auxiliary boss portion 16, the lower surface of the auxiliary boss portion 16 and the side wall 14a on the intake side are connected by a plate-shaped rib 26. The rib 26 is formed in a state of connecting with one main boss portion 15 located below the auxiliary boss portion 16. The outer surface of the rib 26 is a curved surface that is recessed toward the intake side in front view and rear view, but as shown by the alternate long and short dash line in FIG. 3, the auxiliary boss portion 16 and the main boss portion 15 are separated from each other. A mode of connecting in a straight line can also be adopted.

  Even if a bending moment acts on the auxiliary boss portion 16 due to the weight of the EGR valve 18 and the EGR cooler 21, the ribs 26 prevent the auxiliary boss portion 16 from being deformed. It does not affect the device mounting portion 12. Therefore, the EGR valve 18 can be supported by the auxiliary boss portion 16 without causing a problem of misalignment between the intake valve VVT device and the intake camshaft.

  By providing the ribs 26 on the lower surface of the auxiliary boss portion 16, the rigidity of the intake side upper portion 27 (see FIGS. 3 and 4) of the front cover 3 is significantly improved. On the other hand, as clearly shown in FIGS. 3 and 4, the overlapping surface 7 of the head body 2a and the cam carrier 2b is located behind the intake side upper portion 27 reinforced by the ribs 26. Therefore, the head main body 2a and the cam carrier 2b are firmly supported by the intake-side upper portion 27 reinforced by the ribs 26.

  Therefore, it is possible to remarkably suppress independent vibration of the head body 2a and the cam carrier 2b, and prevent the vibration from spreading to the intake valve VVT device mounting portion 12. In this respect, as a result, it is possible to prevent the misalignment between the intake valve VVT device and the intake camshaft.

  The present invention can be embodied in various forms other than the illustrated form. For example, in the above embodiment, the auxiliary boss portion is provided on the intake side, but the auxiliary boss portion may be provided on the exhaust side. Further, other members are not limited to the EGR valve, and various other members can be adopted. Furthermore, other members do not necessarily need to be fixed via the bracket, but may be fixed directly.

  The present invention can be embodied in an internal combustion engine for automobiles. Therefore, it can be used industrially.

1 Cylinder Block 2 Cylinder Head 2a Head Body 2b Cam Carrier 3 Front Cover 5 Intake Manifold 11 Window Hole 12 Intake Valve VVB Device Attachment 14a, 14b Side Wall of Front Cover (Overlap)
15 Main Boss Section 16 Auxiliary Boss Section 17 Bracket 18 EGR Valve 19 as One Example of Other Member 19 EGR Cooler 26 Rib
27 Upper part of intake side

Claims (2)

Left and right sides as viewed from the crank axis direction are overlapping parts that overlap the cylinder head and the cylinder block, and are front covers that cover the timing chain,
A mounting portion of the VVT device and an auxiliary boss portion for mounting another member are formed on the upper portion such that the auxiliary boss portion protrudes outside one overlapping portion,
A main boss portion for fixing the one overlapping portion to the cylinder head is formed in a portion of the one overlapping portion below the auxiliary boss portion,
The auxiliary boss portion and the main boss portion are connected by a rib protruding outside the overlapping portion,
Front cover of internal combustion engine. The cylinder head has a laminated structure of a head main body having an intake port and a cam carrier fixed to an upper surface thereof, and the rib is formed between the upper end and the lower end of the head main body and the cam carrier. Formed so that the surface is located,
A front cover for an internal combustion engine according to claim 1.

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