JP2516637Y2 - DOHC engine cylinder head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a cylinder head of a DOHC engine.

[Prior art] A camshaft for an intake valve and a camshaft for an exhaust valve are:
DOHC engines arranged in parallel in a cylinder head have been conventionally known. In such a DOHC engine, generally, both camshafts are provided with timing pulleys, respectively, and a timing belt is wound around both timing pulleys and crank pulleys, so that both camshafts directly rotate synchronously by the crankshafts. It is designed to be driven.

By the way, in recent years, in order to reduce the size of the engine, the intake valve and the exhaust valve are arranged so that the angle between the axes of these valve shafts is small, that is, a dynamic arrangement in which the valve shaft is arranged upright from the conventional engine. A valve mechanism has been proposed (hereinafter, such an improvement in the valve operating mechanism is referred to as narrowing of the valve operating angle). In order to narrow the valve operating angle in the DOHC engine, the two camshafts must be arranged at relatively narrow intervals. However, in the conventional DOHC engine, the necessary relationship between the timing pulley and the timing belt is required. The diameter of the timing pulley must be set to be relatively large in order to secure the length. Here, if the two camshafts are arranged at a narrow interval, the two timing pulleys interfere with each other, so the interval between the two camshafts cannot be made so narrow.

Therefore, a timing pulley is provided only on one of the two camshafts (hereinafter, referred to as a first camshaft), and the first camshaft is directly driven by the crankshaft, while the first camshaft is driven. A DOHC engine is proposed in which a gear set between cams that mechanically connects the shaft and the other cam shaft (hereinafter referred to as the second cam shaft) is provided, and the second cam shaft is driven by the first cam shaft. (See, for example, Japanese Utility Model Laid-Open No. 61-171807). In such a DOHC engine, the diameter of each gear of the cam-to-cam gear set can be made relatively small, and therefore the arrangement interval of both cam shafts can be narrowed, so that the valve operating angle can be narrowed and the engine can be made compact. be able to.

However, in the above-mentioned DOHC engine in which the timing pulley is provided only on the first camshaft, one timing pulley provided on the first camshaft receives the driving force for both camshafts. It is preferable to increase the engagement length of these in order to enhance the power transmission between the timing pulley and the timing pulley. Therefore, there has been proposed a DOHC engine in which an idler for restricting the timing belt is provided so that the engagement length becomes long, and an idler mounting boss is provided at the front end of the cylinder head below one of the camshafts (for example, Japanese Patent Laid-Open Publication No. Hei.
1-249944).

[Problems to be Solved by the Invention] However, in the above DOHC engine in which the timing pulley is provided only on the first camshaft and the idler mounting boss portion is provided at the front end of the cylinder head, the idler has a strong timing belt. Since tension is applied, this tension is transmitted to the camshaft bearing through the idler mounting boss that supports the idler and the front wall of the cylinder head. Therefore, the camshaft bearing is deformed,
There is a problem that so-called one-sided contact may occur in which the camshaft makes strong contact with only part of the camshaft bearing portion, and seizure may occur in the camshaft bearing portion.

The present invention has been made in view of the above-mentioned conventional problems. A timing pulley is provided only on one cam shaft, and an idler mounting boss portion that regulates a timing belt wound around the timing pulley is a cam. DO provided at the front end of the cylinder head below the shaft
In the HC engine, the camshaft bearing portion is effectively prevented from being deformed due to the belt tension acting on the idler,
An object of the present invention is to provide a cylinder head of a DOHC engine capable of preventing the occurrence of seizure.

[Means for Solving the Problems] In order to achieve the above object, the first invention is such that the first camshaft has a winding position such that the engagement length with the first camshaft is increased by the idler. The second camshaft is driven by the first camshaft via the driving force transmission means through the regulated winding member, the second camshaft is driven by the first camshaft, and the idler mounting boss portion is below the one camshaft. Installed on the front wall
In the DOHC engine, a case portion for housing the driving force transmission means is provided at the front end portion of the cylinder head, and one camshaft side as viewed in the cylinder head width direction is provided with a camshaft bearing portion. A cylinder head for a DOHC engine, characterized in that a water jacket bulging portion is provided on a deck, and an idler mounting boss portion is formed on the front side of the water jacket bulging portion.

A second aspect of the invention is, in the cylinder head of the DOHC engine according to the first aspect, rises from the bottom deck to the camshaft bearing portion formed on the rear wall behind the case portion, on the rear side of the water jacket bulging portion. Provided is a cylinder head of a DOHC engine, which is provided with an oil passage forming portion.

[Operation and Effect of the Invention] According to the first invention, the rigidity of the front end of the cylinder head is enhanced by the bulging portion of the water jacket provided at the front end portion of the cylinder head, and the boss for mounting the idler is also provided by the bulging portion of the water jacket. The supporting rigidity of the portion itself is increased, and the deformation of the idler mounting boss portion is prevented.
As a result, the deformation of the camshaft bearing portion is suppressed and the occurrence of seizure is prevented.

Further, the idler mounting boss portion is formed on the front side of the water jacket bulging portion provided at the front end portion of the cylinder head, and the water jacket bulging portion serves as a bracket for mounting the idler mounting boss portion.
Eliminates the need for brackets.

Furthermore, since the water jacket bulging part and the idler mounting boss part are arranged in the dead space below the case part, the space in the engine room can be effectively used, and in combination with the narrowed valve operating angle. Can be made compact.

According to the second invention, basically, the same operation and effect as those of the first invention can be obtained. Further, on the side where the idler is provided when viewed in the width direction of the cylinder head, an oil passage forming portion that rises from the bottom deck to the camshaft bearing portion behind the case portion is provided, and this oil passage forming portion serves as an idler mounting boss portion. Since it acts as a beam between the camshaft bearing portions, the rigidity of the cylinder head in this portion is enhanced, and the rigidity of the cylinder head front end portion is enhanced by the water jacket bulging portion provided on the front side of the oil passage forming portion. To be Therefore, it is possible to prevent the strong force acting on the idler mounting boss portion due to the belt tension from being transmitted to the camshaft bearing portion, preventing the camshaft bearing portion from being deformed and preventing the seizure thereof. To be done.

[Example] Hereinafter, an example of the present invention will be described specifically.

As shown in FIG. 8, in a 6-cylinder V-type DOHC engine VE with two exhaust valves and two intake valves, an exhaust valve camshaft 2 and an intake valve camshaft 3 are provided in the cylinder head 1 of the left bank L. Are arranged in parallel with their axes oriented in the longitudinal direction of the cylinder head 1. In the following description, the exhaust valve camshaft 2 side is simply referred to as the exhaust valve side, and the intake valve camshaft 3 side is simply referred to as the intake valve side, as viewed in the width direction of the cylinder head 1. The exhaust valve camshaft 2 is
It is rotatably supported by an exhaust valve camshaft bearing portion 6 formed by an exhaust valve camshaft receiving portion 4 and a cap 5 provided on the upper end of the cylinder head 1.
Further, the exhaust valve camshaft 2 is also supported by a front end exhaust valve camshaft bearing portion 7, which will be described later. Similarly, the intake valve camshaft 3 is also rotatable by the intake valve camshaft bearing portion 9 formed by the intake valve camshaft receiving portion 8 and the cap 5, and the front end intake valve camshaft bearing portion 11. It is supported by.

Then, a timing pulley 13 is attached to a front side end portion (left side end portion in FIG. 8) of the exhaust valve camshaft 2, and a timing belt 14 is provided between the timing pulley 13 and a crank pulley (not shown). Wrapped around,
The exhaust valve camshaft 2 is directly and synchronously driven by a crankshaft (not shown) at a rotational speed half the crankshaft rotational speed. In addition, an idler (not shown) that regulates the timing belt 14 so that the engagement length between the timing pulley 13 and the timing belt 14 is increased in order to enhance the power transmission between the timing pulley 13 and the timing belt 14. Is provided.

An exhaust valve-side cam gear 15 is provided on the exhaust valve camshaft 2 slightly on the rear side (right side in FIG. 8) of the timing pulley 13. On the other hand, the intake valve cam shaft 3 is provided with an intake valve side cam gear 16 having the same number of teeth as the exhaust valve side cam gear 15 and meshing with the exhaust valve side cam gear 15. I am configuring. Also,
A friction gear 18 is provided on the intake valve camshaft 3 in order to prevent backlash. The intake valve camshaft 3 is rotatably driven by the exhaust valve camshaft 2 via the inter-cam gear set 17 at the same rotational speed. Here, since the exhaust valve side inter-cam gear 15 and the intake valve side inter-cam gear 16 are formed to have a relatively small diameter, the exhaust valve cam shaft 2 and the intake valve cam shaft 3 have a relatively narrow interval. The valve is narrowed and the engine VE is made compact in the width direction. The inter-cam gear set 17 corresponds to the drive power transmission means described in claim 1.

An exhaust valve side thrust flange 21 is provided on the exhaust valve cam shaft 2 slightly rearward of the exhaust valve side cam gear 15, and the exhaust valve side thrust flange 21 is
It is fitted in an exhaust valve side thrust flange receiving portion 23 formed by an exhaust valve side semicircular groove portion 22 formed in the upper end portion of the cylinder head 1 and the cap 5. By these, displacement of the exhaust valve cam shaft 2 in the thrust direction (axial direction) is restricted. Similarly, for the intake valve camshaft 3, the intake valve side thrust flange 24
And an intake valve side thrust flange receiving portion 26 formed by the intake valve side semicircular groove portion 25 and the cap 5.

FIGS. 1 to 7 are views showing the structure near the front end of the cylinder head 1, respectively. The cylinder head 1 will be described below with reference to these figures.

As shown in FIGS. 1 to 7, at the front end (the right end in FIG. 1 and the left end in FIGS. 3, 6 and 7) of the cylinder head 1, the inter-cam gear 15 is provided. A case portion 27 for accommodating 16 is provided so as to project in the front direction. As is clear from FIG. 5, the front wall 28 and the rear wall 29 of the case portion 27 are formed below the meshing portion of the inter-cam gear set 17 (see FIG. 8) at approximately the center of the cylinder head width direction. A rib 31 that connects the two is integrally provided with the upper deck 32, and the rigidity of the case portion 27 is enhanced by the rib 31.

An exhaust valve side receiving portion 33 is provided at a portion of the front wall 28 of the case portion 27 on the exhaust valve side so as to slightly project in the front direction.
The exhaust valve side receiving portion 33 and the front end cap 34 (see FIG. 8) form the front end exhaust valve camshaft bearing portion 7 (see FIG. 8). On the other hand, an intake valve side receiving portion 35 is provided at a portion of the front wall 28 on the intake valve side so as to project slightly in the front direction. The front end intake valve camshaft bearing portion 11 (see FIG. 8) is formed.

Further, on the rear side of the case portion 27, at the upper end portion of the cylinder head 1, the semicircular groove portions 22 and 25, the camshaft receiving portions 4 and 8, the head bolt boss portion 36, the tappet hole 37, and the plug hole 38 are provided. Etc. are provided.

An intake manifold flange 41 for attaching an intake manifold (not shown) is provided on the intake valve side surface 39 of the cylinder head 1 extending in the camshaft axial direction. The intake manifold flange 41 is provided so as to project obliquely downward from the side surface 39 of the cylinder head 1 toward the side.
Is provided with an intake passage 42 that communicates with a combustion chamber (not shown).

Then, from the side surface 39 near the front end of the cylinder head 1 to the front end surface on the intake valve side, a water jacket bulging portion 44 integrated with the water jacket 43 in the cylinder head 1 bulges outward from the cylinder head. The water jacket bulging portion 44 is provided with a cooling water outlet 45 for allowing the cooling water in the water jacket 43 to flow out. Further, below the camshaft 3 for the intake valve, the water jacket bulge 44
An idler mounting boss portion 47 for rotatably supporting an idler (not shown) is provided on the front end face of the. Here, since the water jacket bulging portion 44 functions as a bracket of the idler mounting boss portion 47, it is not necessary to provide a bracket.

Here, the water jacket bulging portion 44 and the idler mounting boss portion 47 are arranged in the dead space below the case portion 27. In this way, the dead space on the lower side of the case portion 27 is effectively utilized, so that the space in the engine room can be effectively utilized, and the engine VE is made compact in combination with the narrowed valve operating angle. be able to.

The water jacket bulging portion 44 has an upper end portion connected to the case portion 27, and a rear end portion connected to a front end surface of the cylinder head 1 and a front end portion of the intake manifold flange 41. Therefore, the supporting rigidity of the case portion 27 is increased, the rigidity of the exhaust valve side receiving portion 33 and the intake valve side receiving portion 35 provided on the front wall 28 of the case portion 27 is increased, and the exhaust valve camshaft 2 and the intake valve The valve camshaft 3 is firmly supported.

By the way, lubricating oil is supplied to the meshing portion of the inter-cam gear set 17, or the sliding contact portion between the thrust flanges 21 and 24 (see FIG. 8) and the thrust flange receiving portions 23 and 26 (see FIG. 8). Therefore, an oil supply system is provided. The oil supply system is provided with an exhaust valve side oil supply passage 51 and an intake valve side oil supply passage 52 extending in the longitudinal direction of the cylinder head 1 in the upper half of the cylinder head 1, and both oil supply passages 51 are provided. Front end portions of the and 52 are open to the case portion 27, and oil for lubricating the inter-cam gear set is supplied to the case portion 27.

The first branch oil passage 53 extending in the cylinder head width direction is connected to the exhaust valve side oil supply passage 51, and the intake valve side oil supply passage 52 also has a second branch oil passage 56 extending in the cylinder head width direction. Are connected. Further, in the first branch oil passage 53, the exhaust valve side semicircular groove portion 22
An exhaust valve side thrust flange oil passage 54 for supplying oil for thrust flange lubrication is connected to the second branch oil passage 56 and an intake valve side semicircular groove portion 25 for supplying thrust flange lubrication oil. The intake valve side thrust flange oil passage 55 is connected.

Further, in a bottom deck 57 provided near the lower end of the cylinder head 1, a lower oil supply passage 58 extending in the cylinder head longitudinal direction is provided. An oil passage forming portion 59 that rises from the bottom deck 57 toward the intake valve camshaft bearing portion 9 (see FIG. 8) is provided in the cylinder head 1 just behind the water jacket bulging portion 44. A connection oil passage 61 that connects the lower oil supply passage 58 and the first and second branched oil passages 53 and 56 is provided in the oil passage formation portion 59.

Here, the lower portion of the oil passage forming portion 59, the water jacket bulging portion 44, and the idler mounting boss portion 47 are provided adjacent to each other in the cylinder head longitudinal direction, and the upper end portion of the oil passage forming portion 59 is Since it rises in the direction of the intake valve camshaft bearing 9 (see FIG. 8) and is connected thereto, the oil passage forming portion 59 has the idler mounting boss 47 and the intake valve side camshaft bearing 9 (see (See FIG. 8), and the rigidity of the cylinder head 1 in this portion is increased. Moreover, the rigidity of the front end portion of the cylinder head 1 is also increased by the water jacket bulging portion 44. Therefore, it is possible to prevent the strong force acting on the idler mounting boss portion 47 due to the belt tension from being transmitted to the intake valve camshaft bearing portion 9 (see FIG. 8), and the intake valve side camshaft bearing. Part 9 (see Figure 8)
It is possible to prevent the deformation and to prevent the image sticking.

[Brief description of drawings]

FIG. 1 is a side view of a cylinder head of a DOHC engine showing an embodiment of the present invention. FIG. 2 is a front elevational view of the cylinder head shown in FIG. FIG. 3 is a plan view of the cylinder head shown in FIG. FIG. 4 is a cross-sectional view taken along the line AA of the cylinder head shown in FIG. FIG. 5 is a cross-sectional view taken along the line BB of the cylinder head shown in FIG. FIG. 6 is a sectional view of the cylinder head shown in FIG. 5 taken along the line CC. FIG. 7 is a cross-sectional view taken along the line D-D of the cylinder head shown in FIG. FIG. 8 is a V-type DO equipped with the cylinder head shown in FIG.
It is a plane explanatory view of a front side portion of a left bank of a HC engine in a state where a cylinder head cover is removed. VE ... Engine, L ... Left bank, 1 ... Cylinder head, 2 ... Exhaust valve camshaft, 3 ... Intake valve camshaft, 13 ... Timing pulley, 14 ... Timing belt, 15 ... Exhaust valve side cam gear, 16 …… Intake valve side cam gear, 17 …… Cam gear set, 27 …… Case part, 28 …… Front wall, 29 …… Rear wall, 43 …… Water jacket, 44… … Water jacket bulge, 47 …… Idler mounting boss, 59 …… Oil passage forming part, 61 …… Connecting oil passage.

Claims (2)

(57) [Scope of utility model registration request] 1. A first camshaft is driven by a crankshaft via a winding member whose winding position is regulated by an idler so that an engagement length with the first camshaft is long, and a second cam is provided. In a DOHC engine in which the shaft is driven by the first camshaft via the driving force transmitting means and the idler mounting boss portion is provided on the front wall of the cylinder head below one of the camshafts, a case portion for housing the driving force transmitting means. Is provided at the front end of the cylinder head, and on one camshaft side as viewed in the cylinder head width direction, a water jacket bulge is provided from the rear wall behind the case part where the camshaft bearing is formed to the bottom deck. The idler mounting boss is formed on the front side of the bulging part of the jacket. Cylinder head. 2. A cylinder head for a DOHC engine as set forth in claim 1, wherein an oil passage that rises from a bottom deck to a camshaft bearing portion formed on a rear wall behind the case portion is provided on the rear side of the water jacket bulging portion. It is characterized in that a forming portion is provided.
Cylinder head for DOHC engine.