JP3972640B2 - Cylinder head structure and assembly method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cylinder head that forms an upper part of an engine and accommodates a valve mechanism therein, and in particular, a camshaft support member is provided in the cylinder head body, and the camshaft support member is formed in parallel with the camshaft. The present invention relates to a cylinder head structure to which a rocker shaft is attached and an assembling method thereof.
[0002]
[Prior art]
The engine includes a cylinder head attached to the upper part of the main body and a head cover attached to the upper part of the cylinder head to form a sealed internal space of the cylinder head, which houses the valve operating mechanism.
For example, in the case of a single camshaft type valve operating mechanism (SOHC), as shown in FIG. 11, a plurality of camshaft support members are arranged inside the cylinder head body 100 at predetermined intervals along the longitudinal direction of the head (perpendicular to the paper surface). The cam journal 110 is formed so as to protrude.
[0003]
Cam shafts 120 having intake / exhaust cams (not shown) are attached to these cam journals 110, and rocker shafts 130, 140 for intake / exhaust are arranged in parallel on the upper surface of the cam journal 110 on both sides thereof. 180, the cam journal 110 is fastened. A rocker arm (not shown) that drives the intake / exhaust valves 150 and 160 is pivotally supported on each rocker shaft 130 and 140. The cylinder head body 100 has a cam-in type structure in which through holes 190 are respectively provided in an outer wall (not shown) and an internal cam journal 110, and the cam shaft 120 is inserted and pivoted into the through holes 190. .
[0004]
In the engine using the cylinder head body 100, when the intake / exhaust valves 150 and 160 are driven, a valve driving reaction force is applied to the rocker shaft fixing bolts 170 and 180 via the rocker arm and intake and exhaust rocker shafts 130 and 140 (not shown). . Here, since the rocker shaft fixing bolts 170 and 180 are screwed onto the upper portion of the cam journal 110, a substantially upward tensile force is applied in the vicinity of the screwed portion, so that the cam journal 110 is connected to the rocker shaft fixing bolts 170 and 180. It is necessary to ensure a sufficient strength in the vicinity of the threaded portion and maintain durability.
[0005]
In Japanese Utility Model Publication No. 2-40241, a camshaft is pivotally supported by a bearing wall of a cylinder head and a cap member that is fastened and coupled to the upper portion of the cylinder head. A cylinder head with a shaft attached is disclosed. Here, two intake rocker arms driven by two intake valves are pivotally supported on the intake rocker shaft, and one intake rocker arm driven by one valve is pivotally supported on the exhaust rocker shaft. A mechanism is disclosed.
[0006]
By the way, as a valve operating mechanism of an engine, there are a type that drives an intake / exhaust valve in a constant drive mode in the entire operation region, and a type that drives an intake / exhaust valve by changing the valve drive mode according to the engine operation region. A variable valve mechanism is known.
When a variable valve mechanism is adopted, the number of parts usually increases as the valve mechanism increases the need to secure the mounting space, which also increases the weight, which increases the valve drive reaction force. Tend to be. In particular, in recent years, there has been a tendency to increase the number of valves and the application of variable valve mechanisms, and accordingly, the engine speed range also tends to increase greatly, and the tendency to increase the valve drive reaction force at a higher speed range is further increased. ing.
[0007]
[Problems to be solved by the invention]
When the engine employs a variable valve mechanism, the cylinder head body must be provided with an operating oil passage for the variable valve mechanism and an oil control valve for switching the oil passage. In addition, the valve drive reaction force in the valve mechanism increases due to the increase in the frequency of use in the high speed range, and the cam of the cylinder head body that receives the valve drive reaction force via the intake / exhaust rocker shaft to cope with this. The need to sufficiently enhance the rigidity of journals and the like is increasing.
[0008]
However, if a rocker shaft with a variable valve mechanism (not shown) is mounted on the cam journal 110 of the cylinder head body 100 as shown in FIG. 11, the intake and exhaust rocker shafts 130 and 140 are placed on the upper surface of the cam journal 110. Since it is fastened and fixed by the shaft fixing bolts 170 and 180, valve driving reaction forces f1 and f2 are applied obliquely upward from the rocker shafts 130 and 140 to the rocker shaft fixing bolts 170 and 180, respectively. It is necessary to sufficiently strengthen the strength in the vicinity of the 180 screwed portions.
[0009]
As a result, it is necessary to maintain a sufficient distance between the bearing portion 120 ′ of the camshaft 120 at the center of the cam journal 110 and the rocker shaft fixing bolts 170 and 180, and to take a sufficient thickness at this portion, so that a mounting space is reduced. In adopting a variable valve mechanism that needs to be secured, the need to secure further space is added.
In addition to this, it is necessary to provide a hydraulic oil passage for the variable valve mechanism and an oil control valve for switching the oil passage. In this respect, it is difficult to secure a mounting space.
[0010]
In Japanese Utility Model Publication No. 2-40241, a cylinder head provided with a valve mechanism with a relatively simple structure of an intake two-valve type is disclosed. No measures are disclosed. For this reason, in order to attach the variable valve mechanism to the cylinder head having such a structure, it is necessary to take measures such as attaching a hydraulic oil passage for the variable valve mechanism or an oil control valve for switching the oil passage outside the cylinder head. As a result, the assembly work is complicated, which causes a cost increase.
[0011]
The present invention is based on the above-described problems, and can easily be provided with a variable valve mechanism in the cylinder head while ensuring sufficient strength, and can reduce the machining of the cylinder head body. It is to provide a structure and an assembly method thereof.
[0012]
[Means for Solving the Problems]
  The invention according to claim 1 is a cylinder head structure of an engine having a variable valve mechanism, and a cylinder head body disposed on an upper part of the engine and pivotally supporting a camshaft, and attached to an upper part of the cylinder head body. Rocker shaft holder fitted with a rocker shaft that supports the variable valve mechanismWhen,
  An oil control valve that is attached to the rocker shaft holder and switches the hydraulic oil pressure of the variable valve mechanism;
A hydraulic oil passage formed in the rocker shaft holder and guiding the hydraulic oil from the oil control valve to the variable valve mechanism;Have
  The rocker shaft holder is formed of a material having higher strength than the cylinder head body.
  In this way, a separate rocker shaft holder is attached to the cylinder head body, and the rocker shaft holder is formed of a higher strength material than the cylinder head body. The shaft holder can stably receive the valve driving reaction force received by the rocker shaft with high durability, and the strength against the valve driving reaction force can be secured while maintaining the weight reduction of the cylinder head.In addition, since the oil control valve is attached to the rocker shaft holder by providing a hydraulic oil passage, the variable valve mechanism in the cylinder head can be easily deployed while ensuring sufficient strength. Processing on the main body side can be reduced. In particular, the oil control valve is assembled to the rocker shaft holder, the subassembly is temporarily assembled, and this subassembly is assembled to the cam journal of the cylinder head, so that the assembly work on the engine assembly line can be facilitated. .
[0013]
PreferablyThe rocker shaft holder is preferably attached so as to be in surface contact with the upper surface of the cylinder head body as a mating surface. In this case, since the frictional force is generated on the mating surfaces by the coupling process of the rocker shaft holder and the cylinder head body, the rocker shaft holder and the cylinder head body are surely integrated, and the effect of increasing the strength against the valve driving reaction force is further enhanced. Further, when a hydraulic oil passage or a lubricating oil passage is formed on the mating surfaces, the processing is facilitated and the cost can be reduced.
[0015]
  According to a second aspect of the present invention, in the cylinder head structure according to the first aspect, the cylinder head body is formed as a cam-in type in which a camshaft is pivotally attached to a through hole provided therein, and the rocker shaft holder is used for intake. The rocker shaft and the rocker shaft for exhaust are both held together.
  In this way, the rocker shaft holder holds both the intake and exhaust rocker shafts, so that the components of the valve drive reaction forces applied to the respective rocker shafts in the direction away from each other on the rocker shaft holder. It is possible to cancel each other, and in this respect as well, it can function to improve durability, and durability in this respect can be improved.In addition, the camshaft mounting structure is eliminated from the upper part of the cylinder head body, and the mounting structure can be simplified without interfering with the rocker shaft holder mounting structure.
  Preferably, the rocker shaft holder may have a fastening fixing point in the vicinity of each rocker shaft for intake and exhaust. In this case, the valve drive reaction force applied to the intake rocker shaft, which is frequently applied to the variable valve mechanism, is received at the fixed points on both the intake side and the exhaust side, so that the valve drive reaction force can be distributed. In this respect, durability can be secured.
[0016]
  Claim 3In the method of assembling a cylinder head of an engine having a variable valve mechanism, a hydraulic oil passage for supplying hydraulic oil to the variable valve mechanism is formed, and the method invention is formed of a material having higher strength than the cylinder head body. The rocker shaft holder supports the variable valve mechanism and the rocker shaft and the hydraulic oil passageSwitch hydraulic oil pressureAfter assembling the oil control valve, the rocker shaft holder is assembled to the cylinder head body at the upper part of the engine.
  In this way, after assembling the rocker shaft and the oil control valve to the rocker shaft holder that has a hydraulic oil passage and is stronger than the cylinder head, this rocker shaft holder is assembled to the cylinder head body at the top of the engine. The main part of the variable valve mechanism can be assembled to the rocker shaft holder to make a sub-assembly, and the variable valve mechanism can be easily installed in the cylinder head and assembled on the engine assembly line. Work can be facilitated. Moreover, since the rocker shaft holder is formed before assembling the hydraulic oil passage, processing of the hydraulic oil passage is facilitated.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
1 to 3 show a cylinder head to which the cylinder head structure of the present invention is applied. The cylinder head 1 is employed in a V-type 6-cylinder engine (hereinafter simply referred to as an engine) 2. The cylinder block 3 of the right bank that accommodates the cylinders (not shown) for the three cylinders of the engine 2 is overlaid with a cylinder head 1 for the right bank that is fastened by a plurality of head bolts 4. In addition, the left bank (not shown) of the engine 2 is also formed substantially symmetrically, and a duplicate description is omitted.
An inner space 6 sealed in the longitudinal direction X of the cylinder head is formed by the cylinder head 1 of the right bank and the head cover 5 fastened with a bolt (not shown) on the top of the cylinder head 1, and the right side is formed in the right side. The bank side variable valve mechanism A is accommodated.
[0018]
Cylinder head bodies such as the cylinder block 3, the cylinder head 1, and the head cover 5 are each cast from an aluminum alloy to reduce the weight.
The cylinder head 1 forms an upper wall of a combustion chamber for three cylinders (not shown) by a lower wall portion overlapping the cylinder block 3, and the front and rear vertical walls 7 and 8 and the left and right vertical walls 9 and 10 are integrated from the peripheral portion of the lower wall portion. After being connected, they extend upward and are formed so as to cover the side portion of the internal space 6. The front and rear vertical walls 7 and 8 and the left and right vertical walls 9 and 10 are formed with an upward facing surface at the upper end thereof, and a peripheral flange 501 of the head cover 5 is overlapped on the upward facing surface, and the inner space 6 is defined by bolting. It is formed so that it can be sealed. The head cover 5 is a lid-like member, and has a shape capable of tightly closing the internal space 6, and is formed with an oil suction port sealed with a cap (not shown) and a through hole 12 of an oil control valve 11 described later.
[0019]
The cylinder head 1 is formed with a plurality of cam journals 13 (see FIG. 2), which are camshaft support members, protruding from the upper surface of the lower wall along the longitudinal direction X, which is the longitudinal direction of the head, at predetermined intervals. 13 also forms part of the cylinder head body. A plurality of cam journals 13 and front vertical walls 7 arranged in the front-rear direction X are formed with through holes 14 as shown in FIGS. 2 and 3, and a camshaft 15 having an intake / exhaust cam described later is a bearing. It is pivotally attached via a member. The front end of the camshaft 15 protrudes from the front vertical wall 7, and a timing gear (not shown) is integrally coupled to the protruding end 151, and the rotational force is transmitted to the engine shaft at a speed half that of the engine.
[0020]
The upper part of each cam journal 13 is formed with an upward facing surface fa (see FIG. 2), where block-shaped rocker shaft holders 16a and 16b are superposed and fastened to the upper part of each cam journal 13 with a plurality of bolts b. The
As shown in FIGS. 1 and 3, the front and rear cam journals 13 are L-shaped rocker shaft holders 16a in plan view, and the intermediate cam journals 13 are T-shaped rocker shaft holders 16b in plan view. Fastened with b. These rocker shaft holders 16a and 16b are made of steel, and the strength thereof can be sufficiently strengthened from the side of the cam journal 13 made of aluminum alloy, and the mounting space can be made relatively small.
[0021]
As shown in FIGS. 1 and 3, a lower vertical inflow passage 17 is formed in the front portion of the lower wall of the cylinder head 1, and an oil main gallery 18 on the cylinder block 3 side communicates there. Further, a front side of the lower wall of the cylinder head 1 is bent and extended from the lower vertical inflow path 17, and extends in the vehicle width direction Y that is the width direction of the cylinder head 1. A vertical inflow path and 20 are formed that extend upward in the cam journal 13 at the front end from the deepest part and reach the L-shaped rocker shaft holder 16a. Further, a part of the lateral inflow passage 19 branches off, and extends from the deepest portion of the connecting passage 21 extending rearward in the lower wall to the inside of the cam journal 13 (see FIG. 2). A vertical inflow path 22 reaching the rocker shaft holder 16b of the mold is formed.
[0022]
As shown in FIGS. 6A to 6C, the L-shaped rocker shaft holder 16a is formed of an intake side fitting portion 23, an exhaust side fitting portion 24, and a body portion 25 connecting the two portions. An end portion of the exhaust side rocker shaft 26 is fitted into the exhaust side fitting portion 24, and this portion is fastened to the cam journal 13 together with the exhaust side fitting portion 24 with a bolt b.
The tip of the intake side first rocker shaft is rotatably fitted to the intake side fitting portion 23, and the exhaust side fitting portion that avoids interference with the first rocker shaft is fastened to the cam journal 13 with a bolt. Is done. The L-shaped rocker shaft holder 16a at the front end is formed with a communication path 28 that communicates with the longitudinal inflow path 20 on the cam journal 13 side, and this communicates with a lubricating oil path 27 formed at the axis of the exhaust-side rocker shaft 26. To do.
[0023]
The exhaust-side rocker shaft 26 is a single shaft member and is formed so as to guide the lubricating oil to the rocker shaft holders 16a and 16b between the cylinders. The L-shaped rocker shaft holder 16a at the front end is formed with an oil distribution branch 30 that communicates with a distribution hole 29 formed in the exhaust-side rocker shaft 26, and part of the oil distribution branch 30 passes through the body 25. Thus, the lubricating oil can be supplied also to the bearing portion on the outer periphery of the intake side first rocker shaft 31 (see FIG. 5A). Note that an adjuster support portion 33 that accommodates the lash adjuster 32 (see FIG. 5B) protrudes from the body portion 25. This part will be described with a variable valve mechanism A described later.
As shown in FIG. 5A, the intake-side first rocker shaft 31 with the tip inserted into the intake-side fitting portion 23 is formed with a control oil passage 34 that receives the control oil pressure at its axis. The control oil passage 34 is formed so as to receive the control oil pressure from the oil control valve 11 from the opposite end side to a second rocker shaft 35 (see FIG. 7B) described later.
[0024]
The first rocker shaft 31 is pivotally supported by an L-shaped rocker shaft holder 16a at the front end and a T-shaped rocker shaft holder 16b at an intermediate front portion behind the first rocker shaft 31, and supports the movable portion of the variable valve mechanism A.
Here, the T-shaped rocker shaft holder 16b at the middle front is placed on the cam journal 13 (see FIG. 2) at the middle front and is integrally coupled.
As shown in FIGS. 2 and 7 (a) to (d), the T-shaped rocker shaft holder 16b is formed by an intake side fitting portion 36, an exhaust side fitting portion 37, and a body portion 38 connecting the two portions. Is done. The exhaust side fitting part 37 forms a bearing part having a relatively large width, and the exhaust side rocker shaft 26 is fitted and inserted into the cam journal 13 together with the exhaust side fitting part 37 with bolts b. It is concluded.
[0025]
As shown in FIG. 7 (b), the end portions of the first and second rocker shafts on the intake side are rotatably fitted to the front and rear opening ends of the intake side fitting portion 36. The intake side fitting portion 36 is fastened to the cam journal 13 with the bolt b while avoiding interference with the end portions of the second rocker shafts 31 and 35.
An oil distribution branch 39 is formed in the T-shaped rocker shaft holder 16 b, and communicates with the lubricating oil passage 27 of the exhaust-side rocker shaft 31 through the distribution hole 29. A part of the oil distribution branch 39 passes through the body portion 38 and is configured to be able to supply lubricating oil to the bearing portions 36 on the outer periphery of the first and second rocker shafts 31 and 35 on the intake side.
[0026]
Further, as shown in FIG. 7 (b), an adjuster supporting portion 40 for accommodating a lash adjuster (see FIG. 5 (b)) 32 and an oil in the body portion 38 of the T-shaped rocker shaft holder 16b at the middle front portion. A valve support 41 of the control valve 11 is formed to protrude. As shown in FIG. 2, the valve support 41 is formed with an internal thread 42 for screwing the small diameter portion of the oil control valve 11 in the vertical direction, and the inflow opening c1 at the distal end surface of the small diameter portion is on the cam journal 13 side immediately below. It communicates with a bent communication path 43 that communicates with the vertical inflow path 22. Moreover, an outflow opening c2 is formed on the side wall of the small diameter portion, and the outflow opening c2 communicates with a discharge passage 44 that opens to the inner screw portion 42 of the valve support portion 41. The discharge passage 44 passes through the body portion 38 and reaches a position (near the bolt fastening position) avoiding interference with the end portions of the first and second rocker shafts 31 and 35 of the intake side fitting portion 36. The first and second rocker shafts 31 and 35 communicate with the control oil passages 34 and 45 of the respective shaft cores.
[0027]
The oil control valve 11 opens between the inflow opening c1 and the outflow opening c2 when it is off to maintain the control hydraulic pressure of the discharge passage 44 and the control oil passages 34 and 45 at a high level, and when on, between the inflow opening c1 and the outflow opening c2. The discharge passage 44 and the control oil passages 34 and 45 are switched to a low level oil pressure.
[0028]
The first rocker shaft 34 supports the variable valve mechanism on the intake side of the cylinder at the front end of the right bank, and the second rocker shaft 34 supports the variable valve mechanism on the intake side of the center cylinder in the right bank. A third rocker shaft (not shown) supports a variable valve mechanism on the intake side of the rear end cylinder of the right bank, and is shown in FIG. 7 (d) with a T-shaped rocker shaft holder 16b. It is pivotally supported by an L-shaped rocker shaft holder 16a. Here, the T-shaped rocker shaft holder 16b shown in FIG. 7 (d) has substantially the same configuration except that the valve support 41 is excluded from the T-shaped rocker shaft holder 16b shown in FIG. 7 (b). The L-shaped left and right symmetrical rocker shaft holder 16a shown in Fig. 1 adopts a left-right symmetrical shape with the L-shaped left and right symmetrical rocker shaft holder 16a shown in Figs.
Since the variable valve mechanism A of each cylinder has the same configuration, the variable valve mechanism A of the front end cylinder will be described as a representative with reference to the function explanatory diagram shown in FIG.
[0029]
Here, on the exhaust side, a double-headed exhaust rocker arm 47 pivotally supported on the rocker shaft 26 simultaneously drives the exhaust two valve 48 (see FIG. 2), and a roller 49 is pivotally supported on the camshaft facing portion 481. . The exhaust rocker arm roller 49 is in contact with the exhaust cam 50 of the camshaft 15 so that the exhaust valve lift pattern m is shown in FIGS. 8 (a) and 8 (b). Thus, the exhaust 2 valve 48 can be opened and closed.
On the intake side, the intake two valve 53 is driven by fixed and variable intake rocker arms 51 and 52 which are supported by the first rocker shaft 31 and relatively displaced. The first intake valve 53a can open and close the swirl port, and the second intake valve 53b can open and close the normal port.
[0030]
The front and rear ends of the first rocker shaft 31 are pivotally supported by an L-shaped rocker shaft holder 16a having a front end and a T-shaped rocker shaft holder 16b having an intermediate front portion. The relatively large-diameter shaft portion 311 of the first rocker shaft 31 protrudes and forms an extension portion 312 on the L-shaped rocker shaft holder 16a side, and as shown in FIG. A sliding contact piece 64 is integrally coupled to the rotating end, and the sliding contact piece 64 is always in contact with the high-speed cam 54 of the camshaft 15.
[0031]
Further, a switching rocker arm 52 is pivotally attached to the shaft portion 311 on the extending portion 312 side, and a normally driven non-switching rocker arm 51 is pivotally attached to the opposite end side. Both the rocker arms 52 and 51 are configured to always receive the pressing force of the spring 55 so as to keep the distance between them constant.
The non-switching rocker arm 51 pivotally supports a roller 56 at its camshaft facing end, and abuts the stem of the first intake valve 53a at the opposite valve facing end. The non-switching rocker arm 51 abuts the roller 56 against the low speed cam 57 on the camshaft 15 side, and follows the lift pattern n of the low speed cam 57 as shown in FIG. 8A in the constant intake valve drive mode. 1 The intake valve 53a can be driven to open and close.
[0032]
The switching rocker arm 52 pivotally supports a roller 58 at its camshaft facing end, abuts against a minimal lift cam 62, a valve facing end on the opposite side abuts the stem of the second intake valve 53b, and a shaft portion 311 with a boss portion 521 is formed. For this reason, the switching rocker arm 52 can open and close the second intake valve 53b along the lift pattern n2 of the minimum lift cam 63 as shown in FIG. On the other hand, when the switching rocker arm 52 is driven by the high-speed cam 54 via the sliding contact piece 64 at the rotation end of the extending portion 312, along the lift pattern n 1 of the high-speed lift cam 54 as shown in FIG. The second intake valve 53b can be opened and closed. The lift pattern n1 of the high-speed lift cam 54 is set to be larger than that of the other cams in terms of valve opening timing and lift amount.
[0033]
As shown in FIGS. 10A to 10C, a fitting hole 60 is formed in the shaft portion 311 in the radial direction in communication with the control oil passage 34, and a switching pin 59 is fitted therein. The fitting hole 60 has such a length that the switching pin 59 can be completely retracted into the shaft portion 311, and the spring 62 disposed between the step portion e of the fitting hole 60 and the locking portion g of the switching pin 59. It is accommodated in the fitting hole 60 by elastic force. When the fitting hole 60 receives control oil pressure from the oil control valve 11 via the control oil passage 34, the switching pin 59 protrudes and is urged against the elastic force of the spring 62, and is provided in the boss portion 521 of the switching rocker arm. The engagement hole 61 can be inserted and fitted.
[0034]
  A method for assembling such a cylinder head 1 will be described. Here, first, a rocker shaft holder in which hydraulic oil passages 34 and 45 for supplying hydraulic oil to the variable valve mechanism A are formed.16a, 16bThen, the rocker shafts 31, 35, 27 and the oil control valve 11 are assembled thereto, and the sub-assembly in which the main part of the variable valve mechanism A is assembled to the rocker shaft holders 31, 35 is temporarily assembled. . Then rocker shaft holder16a, 16bThe sub-assembly on the side is placed from above the cylinder head 1 and tightened with the bolt b.
[0035]
  In such an assembly method of the cylinder head 1, the hydraulic oil passages 34 and 45 are formed, and the rocker shaft holder that can secure sufficient strength.16a, 16bOn the other hand, the rocker shafts 31, 35, 27 and the oil control valve 11 are assembled, the subassembly is temporarily assembled, and the subassembly is assembled on the plurality of cam journals 13 above the cylinder head 1. In addition, the variable valve mechanism A in the cylinder head 1 can be easily provided, and the assembly work on the engine assembly line can be facilitated.
  In such a variable valve mechanism A, the first intake valve 53 a on the intake side is always opened and closed by the lift pattern n of the low speed cam 57.
[0036]
At the same time, when the control oil pressure is received when the oil control valve 11 is turned off, the switching pin 59 engages with the engagement hole 61 of the switching rocker arm 52, and the shaft portion 311 integrated with the extending portion 312 is integrated. The switching rocker arm 52 can be driven by the lift pattern n1 of the high speed cam 54 shown in FIGS.
Conversely, when the control oil pressure is removed when the oil control valve 11 is turned on, the switching pin 59 is detached from the engagement hole 61 by the elastic force of the spring 62 and is accommodated in the fitting hole 60. As a result, the switching rocker arm 52 is pivotally supported by the shaft portion 311, and the second intake valve is driven to open and close via the switching rocker arm by the lift pattern n 2 of the minimal lift cam 63.
[0037]
In an engine equipped with such a variable valve mechanism A, the first intake valve 53a is driven by the lift pattern n of the low-speed cam 57 in the low rotation range, releases the swirl port, and generates swirl into the combustion chamber. In addition, lean combustion can be performed stably. At this time, the oil control valve 11 is on, the switching pin 59 is disengaged from the engagement hole 61 of the switching rocker arm 52, the second intake valve 53b is driven by the lift pattern n2 of the minimal lift cam 63, and the fuel on the port side Is released slightly to the extent that does not stay.
[0038]
In a high engine speed range, the oil control valve 11 is off, the switching pin 59 is engaged with the engagement hole 61 of the switching rocker arm 52 by the control hydraulic pressure, and the second intake valve 53b is in the lift pattern n1 of the high speed lift cam 54. And the intake air with the maximum flow rate is caused to flow into the combustion chamber from this port side. For this reason, the airflow from the swirl port side of the first intake valve 53a is quantitatively reduced, the swirl is eliminated, and suction is performed in a state where the flow resistance is minimized, thereby improving fuel efficiency.
[0039]
As described above, when the cylinder head 1 to which the cylinder head structure of FIG. 1 is applied, the rocker shaft holder 16b is made of a steel material higher in strength than the cam journal 13 side which is the cylinder head main body side. The strength can be sufficiently enhanced from the side of the cam journal 13 made of aluminum alloy, durability can be ensured, and the mounting space can be made relatively small. Further, since the rocker shaft holders 16a and 16b are made of a material having higher strength than the cylinder head body, the rocker shaft holder can stably and stably withstand the valve driving reaction force received by the rocker shafts 31 and 35. It is possible to secure a high strength against the valve drive reaction force while maintaining the weight reduction of the cylinder head 1.
[0040]
In addition, it is possible to manufacture the bending communication path 43, the discharge path 44, and the valve support portion 41 of the oil control valve 11 that are hydraulic oil paths independently, and the processing is facilitated and the accuracy is easily improved. It is also possible to reduce costs. In addition, since the bent communication path 43 is formed on the lower surface, which is the mating surface with the cam journal 13, the processing of this portion is facilitated and the cost can be reduced.
A cylinder head 1 to which the cylinder head structure of FIG. 1 is applied is a cam-in type in which a cam shaft 15 is pivotally attached to a through hole 14 provided in a cam journal 13 on the cylinder head main body side. However, it can be easily avoided that the rocker shaft holders 16a and 16b are attached to the mounting structure portion, and the assembly structure can be simplified. Since the rocker shaft holders 16a and 16b are coupled with the upper surface of the cam journal 13 as the mating surface, friction force is likely to be generated on the mating surface, so that the rocker shaft holders 16a and 16b and the cam journal 13 are reliably integrated, and the valve drive The effect of increasing the strength against the reaction force is further increased.
[0041]
Further, since the rocker shaft holders 16a and 16b hold the intake rocker shafts 31 and 35 and the exhaust rocker shaft 27 together, the components of the valve drive reaction force applied to the rocker shaft in the direction away from each other are included. The holders 16a and 16b can cancel each other, and this point can also function to improve durability.
[0042]
Further, since the rocker shaft holders 16a and 16b have tightening fixing points p1 and p2 (see FIG. 7B) in the vicinity of the intake and exhaust rocker shafts 31, 35 and 27, respectively, the variable valve mechanism A The valve drive reaction force applied to the rocker shafts 31 and 35 for the intake rocker shaft to which is applied is received at the fixed points p1 and p2 on both the intake side and the exhaust side, so that the valve drive reaction force can be distributed. Durability can also be secured in this respect.
[0043]
【The invention's effect】
  As described above, the present invention attaches a separate rocker shaft holder to the cylinder head body, and when the rocker shaft holder is made of a material having higher strength than the cylinder head body, The rocker shaft holder made of the above material can stably receive the valve driving reaction force received by the rocker shaft with high durability, and can secure high strength against the valve driving reaction force while maintaining the weight reduction of the cylinder head.
  In addition, since the oil control valve is attached to the rocker shaft holder by providing a hydraulic oil passage, the variable valve mechanism in the cylinder head can be easily deployed while ensuring sufficient strength. Processing on the main body side can be reduced. In particular, the oil control valve is assembled to the rocker shaft holder, the subassembly is temporarily assembled, and this subassembly is assembled to the cam journal of the cylinder head, so that the assembly work on the engine assembly line can be facilitated. .
[0044]
  Further, when the rocker shaft holder holds both the intake and exhaust rocker shafts, the components of the valve driving reaction forces applied to the respective rocker shafts in the direction away from each other cancel each other on the rocker shaft holder. In this respect, it can function to improve durability, and durability in this respect can be improved.In addition, the camshaft mounting structure is eliminated from the upper part of the cylinder head body, and the mounting structure can be simplified without interfering with the rocker shaft holder mounting structure.
  Furthermore, in the present invention, after the rocker shaft and the oil control valve are assembled to the rocker shaft holder having a hydraulic oil passage formed and having a strength higher than that of the cylinder head, the rocker shaft holder is attached to the cylinder head body at the upper part of the engine. Because it is assembled, the main part of the variable valve mechanism can be assembled to the rocker shaft holder and sub-assembled, and the variable valve mechanism can be easily installed in the cylinder head. Assembling work can be facilitated. Moreover, since the rocker shaft holder is formed before assembling the hydraulic oil passage, processing of the hydraulic oil passage is facilitated.
[Brief description of the drawings]
FIG. 1 is a schematic plan view of a cylinder head to which a cylinder head structure and its assembling method according to an embodiment of the present invention are applied and a variable valve mechanism A in the cylinder head.
FIG. 2 is a cross-sectional view of the main part of the cylinder head structure of FIG.
3 is a front side view of the cylinder head structure of FIG. 1. FIG.
4 is a functional explanatory diagram of a variable valve mechanism that is accommodated in the cylinder head structure of FIG. 1; FIG.
5 shows an L-shaped rocker shaft holder and a rocker shaft used in the cylinder head structure of FIG. 1, wherein (a) is an assembly plan view, and (b) is a sectional view taken along line BB.
6 shows an L-shaped rocker shaft holder used in the cylinder head structure of FIG. 1, wherein (a) is a left side view, (b) is a plan view, and (c) is a right side view.
7 shows a T-type rocker shaft holder used in the cylinder head structure of FIG. 1, wherein (a) is a left side view, (b) is a plan view, (c) is a right side view, and (d) is a T-type rocker. It is a top view in other forms of a shaft holder.
8A and 8B are cam lift pattern diagrams of the variable valve mechanism housed in the cylinder head structure of FIG. 1, wherein FIG. 8A shows a low rotation time and FIG. 8B shows a high rotation time.
9 is an assembled plan view of a first rocker shaft and a switching rocker arm used in the cylinder head structure of FIG. 1. FIG.
10 shows the first rocker shaft and the switching rocker arm of FIG. 9, wherein (a) is a cross-sectional view taken along line CC, (b) is a cross-sectional view taken along line DD, and (c) is a cross-sectional view taken along line EE. is there.
FIG. 11 is a cross-sectional view of a main part of a conventional cylinder head.
[Explanation of symbols]
1 Cylinder head
2 Engine
6 Internal space
11 Oil control valve
13 Cam journal (part of cylinder head body)
15 Camshaft
16a Rocker shaft holder
16b Rocker shaft holder
26 Rocker shaft for exhaust
31 1st rocker shaft
35 Second rocker shaft
39 Oil distribution branch (hydraulic oil passage)
43 Bent communication path (hydraulic oil path)
44 Discharge path (hydraulic oil path)
60 Insertion hole
A Variable valve mechanism
X longitudinal direction

Claims (3)

In a cylinder head structure of an engine having a variable valve mechanism,
A cylinder head body that is disposed at the top of the engine and pivotally supports a camshaft;
A rocker shaft holder fitted with a rocker shaft attached to an upper portion of the cylinder head body and supporting the variable valve mechanism ;
An oil control valve that is attached to the rocker shaft holder and switches the hydraulic oil pressure of the variable valve mechanism;
A hydraulic oil passage formed in the rocker shaft holder and guiding the hydraulic oil from the oil control valve to the variable valve mechanism ;
2. The cylinder head structure according to claim 1, wherein the rocker shaft holder is made of a material having a strength higher than that of the cylinder head body. The cylinder head structure according to claim 1,
The cylinder head body is formed as a cam-in type in which a cam shaft is pivotally attached to a through hole provided therein,
The cylinder head structure, wherein the rocker shaft holder holds both an intake rocker shaft and an exhaust rocker shaft . In a cylinder head assembling method of an engine having a variable valve mechanism, a rocker shaft holder in which a hydraulic oil passage for supplying hydraulic oil to the variable valve mechanism is formed and made of a material having a strength higher than that of the cylinder head body is provided. The rocker shaft for supporting the variable valve mechanism and the oil control valve for switching the hydraulic oil pressure of the hydraulic oil passage are assembled, and then the rocker shaft holder is assembled to the cylinder head main body of the engine. Cylinder head assembly method.

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