JPH04209907A - Assembling method of valve system in engine - Google Patents

Abstract

PURPOSE:To improve phase matching and assembling property of the driving wheel provided between cans of a cam shaft and a variable valve timing mechanism by matching phase between the variable valve timing mechanism and the driving wheel provided between the cams on an inner part side, and then matching phase between the variable valve timing mechanism and the cam shaft on an end part side. CONSTITUTION:In a case where a valve system is assembled on a cylinder head 3, firstly a lock nut 14 and a driving wheel 12 provided between cams of an exhaust side are inserted into the end part of a cam shaft 5 for exhaust, and then the cam shaft 5 for exhaust is set temporarily to the cylinder head 3. Phase between the driving wheel 12 provided between the cams of the exhaust side, and a driving wheel 13 which is provided between cams of an intake side and fixed on a cam shaft 6 for intake, is matched. After that, the cam shaft 6 for intake is set to the cylinder head 3. Then the mechanism main body 15 of a variable valve timing mechanism 16 is inserted into the inner circumference side of a ball bearing cap 18 on the top end part of the cam shaft 5. At this time, phase between the mechanism main body 15 and the driving wheel 12 provided between the cams of the exhaust side is matched while rotating the mechanism main body 15, so that a lock nut 14 is screwed into the screw part 15b of the top end.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of assembling a valve train for an engine in which a variable valve timing mechanism is attached to a camshaft of the engine.

(Prior art) Conventionally, a variable valve timing mechanism is attached to the camshaft drive mechanism of an engine's valve train, and the valve timing of the exhaust valve or intake valve is adjusted by changing the rotational phase of the crankshaft and camshaft. For example, a technology that changes the speed according to the operating condition is disclosed in Japanese Patent Application Laid-Open No. 62-19.
This is known as seen in Japanese Patent No. 1806.

Furthermore, regarding driving the camshafts, there is also a technology in which only one camshaft is driven from the crankshaft by a timing belt, etc., and the other camshaft is driven from one camshaft via a gear between cams, etc. Are known.

(Problem to be Solved by the Invention) However, when assembling the valve train as described above, a variable knob timing mechanism is disposed on the end side of the camshaft, and the variable knob timing mechanism is disposed on the end side of the camshaft. Assembling the inter-cam drive wheels that transmit power to the camshaft is a complicated process, as it requires reliable phase alignment of each part.

In other words, in order to match the opening and closing timing of the intake valve and exhaust valve, the phases of the camshafts on both sides are matched in the meshing of the driving wheels between the cams attached to each camshaft.
Further, it is necessary to align the variable valve timing mechanism mounted on the camshaft with both the inter-cam drive wheels and the camshaft. In the process of installing the variable valve timing mechanism, for example, when aligning the phases by positioning by engaging a pin and a groove, it is necessary to tighten the lock nut while the two are securely engaged. If the fastening members are not tightened, there is a risk that the assembly will be carried out with the phases shifted due to deformation of the pins, etc., and the desired engine performance will not be obtained.

In addition, in order to improve the work efficiency in the above-mentioned phase alignment confirmation and assembly, we will improve the processing efficiency.
The work of inserting and fastening the variable valve timing mechanism,
It is particularly complicated and inefficient because it involves multiple phase alignments.

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a method for assembling an engine valve train, which improves the ease of phasing and assembling a cam-to-cam drive wheel and a variable valve timing mechanism to a camshaft. The purpose is to

(Means for Solving the Problems) In order to achieve the above object, a method for assembling a valve train of the present invention provides an inter-cam drive that transmits power to one camshaft of a DOHC engine and to the other camshaft. In order to install a variable valve timing mechanism that changes the wheel and valve timing, a cam-to-cam drive wheel whose phase is aligned with the cam-to-cam drive wheel of the other camshaft and the cam-to-cam drive wheel are fixed to one of the camshafts. When inserting the lock nut and then inserting the variable valve timing mechanism into one of the above camshafts, first, align the phase between the variable valve timing mechanism and the drive wheel between the cams by positioning the mechanism body and the drive wheel between the cams. Then, after phasing the variable valve timing mechanism and one camshaft, attach the inter-cam drive wheel to the mechanism body using the lock nut, and set the variable valve timing mechanism to the end of one camshaft. This is to attach the mechanism.

Further, the mechanism body of the variable valve timing mechanism and the inter-cam driving wheel are aligned in phase, and the inter-cam driving wheel is temporarily tightened to the mechanism body using a lock nut, and then the variable valve timing mechanism and one camshaft are temporarily tightened. It is preferable to fully tighten the lock nut when the variable valve timing mechanism is attached to one end of the camshaft by tightening the fastening member.

(Operations and Effects) In the method for assembling a valve train as described above, a variable valve timing mechanism is inserted into one of the camshafts and the cam-to-cam drive wheel is aligned in phase with the other cam-to-cam drive wheel. Sometimes, the variable valve timing mechanism and the cam drive wheel are first aligned on the inside, and then the variable valve timing mechanism and the camshaft are aligned on the end side before assembly. In fact, the next phase alignment cannot be performed unless the phase alignment of the previous stage is completed, and furthermore, the status of the phase alignment of the latter stage can be visually confirmed on the front end side, so the phase alignment as a whole remains incomplete. By assembling the engine, accurate phase alignment can be performed without deforming the positioning member, etc., and a predetermined engine performance can be ensured with good work efficiency.

In addition, after the main body of the variable valve timing mechanism is aligned with the drive wheel between the cams, the lock nut is temporarily tightened, and then the lock nut is fully tightened when tightening the fastening member after the variable valve timing mechanism is aligned with the camshaft. By doing this at the same time, the lock nut, which has low workability, can be tightened efficiently, and good assembly results in efficiency.

(Example) The present invention will be described in detail below with reference to the drawings.

Fig. 1 shows a schematic front configuration of a V-type engine equipped with a valve train to which an assembly method according to an embodiment of the present invention is applied, and Fig. 2 shows a valve train of the first bank (left side in Fig. 1). FIG. 3 shows the cross-sectional side structure of the main part of the device, and FIG. 3 shows the cross-sectional planar structure of the main part.

In the V-type engine 1, a first cylinder head 3 and a second cylinder head 4 are arranged obliquely on a cylinder block 2 at the lower center, forming first and second banks IA and IB. Two camshafts 5.6 are installed in each as a valve train. The center side is an intake camshaft 6, and the outside side is an exhaust camshaft 5, which are driven by a crankshaft 7 via a timing belt 8. That is, the crank pulley 7a at the end of the crankshaft 7 disposed at the bottom of the cylinder block 2, and the driving force transmission wheels 9, 9 (cam pulleys) at the ends of the camshafts 5, 5 on the exhaust side of both banks IA, 1B. ) is connected to the timing belt 8 via idlers lla to 11d, and the driving force is transmitted to the camshaft 6 on the intake side by inter-cam drive wheels 12 and lj (inter-cam gear), synchronizing with engine rotation. It is driven by

In the case of the illustrated engine, each cylinder is provided with four valves (two intake valves and two exhaust valves), and for example, the exhaust valve 10 (see FIG. 2) is driven to open and close by each cam portion 5a of the exhaust side camshaft 5. be done.

To be more specific, the driving force transmission wheel 9 is installed on the outer periphery of the shaft portion at the tip of the exhaust camshaft 5;
The driving force transmission wheel 9 is attached to the mechanism main body 15 side of a variable valve timing mechanism 16 that changes the overlapping period with the intake valve 4 by changing the opening and closing timing of the exhaust valve 10 by changing the rotational phase of the exhaust camshaft 5. It is being

Further, an exhaust-side inter-cam drive wheel 12 disposed around the outer periphery of the exhaust camshaft 5 is attached to the rear end side of the mechanism body 15 by fastening a lock nut 14. An intake-side cam-to-cam drive wheel 13 that meshes with the exhaust-side cam-to-cam drive wheel 12 is fixed to the end of the intake-side camshaft 6 to transmit rotational force. A friction gear 17 for reducing backlash is attached to the intake side inter-cam drive wheel 13.

The exhaust side and intake side camshafts 5, 6 as described above are mounted on the upper surface of the cylinder head 3, and the front end portions of the respective camshafts 7) 5, 6 are supported on the cylinder head 3. Bearing caps 18 (see FIG. 2) are attached from above to the end bearings 21a, 21b on both sides. An intermediate bearing portion 22 that supports the intermediate portion is provided, and a cam cap 19 is attached to this intermediate bearing portion 22.

The exhaust side end bearing portion 21a supports the exhaust camshaft 5 via the mechanism body 15 of the variable valve timing mechanism 16, and the mechanism body 15 has a flange-shaped front portion. The rear portion extends in a cylindrical shape along the exhaust camshaft 5, and the middle portion of this cylindrical portion is formed as a journal portion 15a supported by the bearing portion formed by the end bearing portion 21a and the bearing cap 18,
The front stage portion of the longitudinal portion 15a abuts the bearing portion formed by the end bearing portion 21a and the bearing cap 18 from the front. Further, the exhaust side inter-cam drive wheel 12 is fitted behind the journal portion 15a, and a threaded portion 15b (screw) for threading the lock nut 14 is formed on the outer periphery of the rear end portion. .

On the other hand, the exhaust side inter-cam drive wheel 12 is connected to the mechanism main body 1.
The boss part 12a has a central boss part 12a that is fitted behind the journal part 15a of the mechanism body 15. It is fixed in a state of contact. Further, the tip of the boss portion 12a of the exhaust-side inter-cam drive wheel 12 is connected to the bearing cap 18 and the end bearing portion 21 of the cylinder head 3.
It is inserted into a cylindrical portion G formed in a step shape on the inner circumferential side of the rear end of a. The above structure restricts the front and rear thrust movement of the mechanism body 15 with respect to the end bearing portion 21a of the cylinder head 3.

Furthermore, a positioning pin 23 and a groove 12b are formed between the mechanism main body 15 and the boss portion 12a of the exhaust-side inter-cam drive wheel 12 to match the mutual phases. That is, a positioning pin 23 is provided upright on the rear outer periphery of the mechanism body 15, and a vertical groove 12b that engages with the positioning pin 23 is formed at a predetermined position in the boss portion 12a of the exhaust-side inter-cam drive wheel 12. There is.

Further, a ring-shaped seal member 24 is inserted into the ring-shaped recess F on the inner peripheral side of the front end of the bearing cap 18 and the end bearing portion 2-1a of the cylinder head 3. Furthermore, the bearing cap 18 has a flange portion 18a extending forward.
A belt cover 41 that covers the front of the cylinder head 3 is disposed at the tip of the flange portion 18a.

On the other hand, from the rear end of the bearing cap 18 to the cylinder head 3
A head cover 42 is disposed to cover the upper part of the head.

In the tip shaft portion of the exhaust camshaft 5 located inside the mechanism body 15 as described above, the portion 5 is the portion where the tip shaft portion of the camshaft 5 comes into contact with the inner surface of the mechanism body 15.
b is formed with a predetermined width between the journal portion 15a of the mechanism body 15 and the threaded portion 5b into which the lock nut 14 is threaded.

That is, the bearing portion 5b is in contact with the inner circumferential surface of the mechanism main body 15 with a small clearance, and the other end shaft portions of the camshaft 5 are formed to have a small diameter so as to have a larger clearance than this.

Note that a hexagonal portion 5C is formed in the middle of the exhaust camshaft 5 so that it can be rotated with a tool.

The variable valve timing mechanism 16 is hydraulically operated, and engine lubricating oil from an oil pump (not shown) of the engine is supplied from the other end of the camshaft 5 depending on the operating condition. The detailed structure of the valve timing mechanism 16 will be explained.

A cylindrical front case 25 is fixed to the flange-shaped front end of the mechanism main body 15 into which the distal end shaft of the exhaust camshaft 5 is fitted, and the driving force transmission wheel 9 (
The inner circumference of the cam pulley is fixed. front case 2
A ring member 26 is attached to the tip of the ring member 5, and a lid member 38 is fixed to the tip of the ring member 26.

Further, the exhaust camshaft 5 is integrally fixed to the distal end thereof by a fastening member 29 (mounting bolt) via a cylindrical spacer 27 and a stopper member 28 . This fastening member 2
Reference numeral 9 attaches the variable valve timing mechanism 16 to the camshaft 5.

The spacer 27 is provided inside the front case 25'.
A ring-shaped piston 30 is installed between the two.

The piston 30 has a structure in which it is divided into two parts in the axial direction, and both parts are fixed to each other by a plurality of pins 31 arranged at equal intervals in the circumferential direction. Helical splines in opposite directions are formed on the inside and outside of the piston 30.

A helical spline is formed on the outside of the spacer 27 corresponding to the helical spline on the inside of the piston 30, and a helical spline is formed on the inner periphery of the front case 25 in correspondence to the spline on the outside of the piston 30. Further, the piston 30 is urged toward the distal end side by a spring 36 installed between the piston 30 and the end surface of the mechanism main body 15.

Further, a knock pin 32 and a groove 27a are formed between the exhaust camshaft 5 and the spacer 27 of the variable valve timing mechanism 16 to match the mutual phases. That is, a knock pin 32 that projects in the axial direction is provided upright at the tip of the camshaft 5, and a vertical groove 27a that engages with the knock pin 32 is formed at a predetermined position in the inner peripheral portion of the spacer 27.

On the other hand, an oil passage (not shown) is formed along the axis of the exhaust camshaft 5, and passes through the inside of the fastening member 29 and passes through the groove of the ring member 26 from inside the tip to the head of the piston 30. When the piston 30 compresses the spring 36 and moves in the axial direction when hydraulic pressure is introduced, the spacer 27 that fits with the helical splines in the opposite direction formed on the inner and outer circumferences of the piston 30 is connected to the front case. 25, that is, rotates relative to the driving force transmission wheel 9. This changes the phase between the exhaust camshaft 5 and the driving force transmission wheel 9, that is, the valve timing.

Next, to explain how to assemble the above-mentioned valve train to the cylinder head 3, first, after inserting the lock nut 4 and the drive wheel 12 between the exhaust side cams into the end of the V1 camshaft 5, Temporarily set the camshaft 5 to the cylinder head 3. And the drive wheel 1 between the exhaust side cams
2 and the intake side inter-cam drive wheel 13 fixed to the intake camshaft 6, the intake camshaft 6 is set in the cylinder head 3. The above phase matching is performed in advance between the drive wheel 12 between the exhaust side cams and the drive wheel 1 between the intake side cams.
This is done by aligning the punch marks formed in 3 and 3.

Subsequently, the end bearing portions 21a, 21 of the cylinder block 3
At the same time, a cam cap 19 is attached to the intermediate bearing portion 22 to fix each of the camshafts 5 and 6 to the cylinder head 3. At this time, the lock nut 14 and the exhaust-side inter-cam drive wheel 12 are located at the rear of the bearing cap 18, but the assembled bearing cap 18 and the end bearing portion 21a of the cylinder block 3 allow the bearing cap 18 to A cylindrical portion G is formed on the rear side, and the tip of the boss portion 12a of the exhaust-side inter-cam drive wheel 12 is inserted into this cylindrical portion G, and is concentrically arranged with a gap around the outer periphery of the camshaft 5. I will support you.

Similarly, a ring-shaped recess F is formed on the front side of the bearing cap 18 by the bearing cap 18 and the end bearing part 21a of the cylinder block 3, and a ring-shaped seal member is inserted into the ring-shaped recess F from the front. 24 (oil seal) is press-fitted.

Thereafter, the mechanism body 15 of the variable valve timing mechanism 16 is inserted into the tip of the camshaft 5 and into the inner circumferential side of the bearing cap 18. Since the exhaust side inter-cam drive wheel 12 is concentrically supported at the tip of the mechanism main body 15,
It can also be easily inserted inside. At that time, the mechanism body 15
While rotating the mechanism body 15, that is, the variable valve timing mechanism 16, so that the positioning pin 23 at the tip of the exhaust side cam drive wheel 12 is engaged with the groove 12b of the exhaust side cam drive wheel 12, the phase alignment with the exhaust side cam drive wheel 12 is performed. When the lock nut 14 can be screwed onto the screw of the threaded portion 15b at the tip by inserting the mechanism body 15, the lock nut 14 is temporarily tightened.

Further, after the mechanism main body 15 is inserted and the phase is aligned with the exhaust side inter-cam drive wheel 12, the knock pin 32 at the tip of the exhaust camshaft 5 comes into contact with the spacer 27, and the hexagonal part 5c of the camshaft 5 is inserted into the hexagonal part 5c. While applying and rotating the spacer 27? By engaging the knock pin 32 with g 27 a, the exhaust camshaft 5 and the variable valve timing mechanism 16 are aligned in phase. At this time, the lid member 38, fastening member 29, and stopper member 28 of the variable valve timing mechanism 16 are removed, and the knock pin 32 and the groove 2 are removed.
7a is visually confirmed from the front, and after confirming the engagement between the two, the fastening member 2 is
Tighten 9.

Then, a jig is set on the lock nut 4 to fix the rotation of the lock nut 14. Thereafter, the fastening member 29 is fully tightened to a predetermined torque using a torque wrench, thereby attaching the variable valve timing mechanism 16 to the camshaft 5, and the lock nut 14 is also fully tightened to tighten the drive wheel 12 between the exhaust side cams. is fastened to the mechanism body 15.

Subsequently, the lid member 38 is attached to complete the assembly.

The hydraulic pressure is introduced under the control of a controller that operates a valve mechanism (not shown), and the hydraulic pressure is introduced into the variable valve timing mechanism 16 in a high rotation and high load region based on the engine load (for example, throttle opening) and engine speed. When this hydraulic pressure is introduced, the opening/closing timing of the exhaust valve is delayed to increase the overlap period during which both the exhaust valve and the intake valve are open. In addition, the introduction of hydraulic pressure to the variable valve timing mechanism 16 is stopped in the low-load, low-speed region, and the opening/closing timing of the exhaust valve is advanced to shorten the overlap period in which both the exhaust valve and the intake valve are open at the same time.

In the above embodiment, the variable valve timing mechanism 16 is installed on the exhaust camshaft 5 to change the opening and closing timing of the exhaust valve, but this variable valve timing mechanism is installed on the intake camshaft 6. The opening/closing timing of the intake valve may also be changed.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view of a V-type engine equipped with a valve train to which an assembly method according to an embodiment of the present invention is applied; FIG. 2 is a cross-sectional side view of a main part of a first bank valve train; FIG. 3 is a sectional plan view of the main part thereof. 1...Engine, 3,4...Cylinder head, 5゜6...Camshaft, 9...
... Drive force transmission wheel, 12° 13 ... Drive wheel between cams, 12b ... Groove, 14 ... Lock nut, 15 ... Mechanism body, 16. ...Variable valve timing mechanism, 23...Positioning pin,
27a... Groove, 29... Fastening member, 3
2...Dowel pin. Figure 2 Figure 3/l j 13

Claims (2)

[Claims] (1) In a valve train for a DOHC engine, in which one camshaft is provided with an inter-cam drive wheel that transmits power to the other camshaft, and a variable valve timing mechanism capable of changing valve timing is provided. ,
An inter-cam drive wheel that is in phase with the inter-cam drive wheel of the other camshaft and a lock nut that fixes the inter-cam drive wheel are inserted into the one camshaft, and a variable valve timing is inserted into the one camshaft. When inserting the mechanism, first align the variable valve timing mechanism and the cam drive wheel by positioning the mechanism body and the cam drive wheel, and then align the variable valve timing mechanism and one camshaft. After performing phase matching, the inter-cam driving wheel is attached to the mechanism body using the lock nut, and the variable valve timing mechanism is attached to one end of the camshaft. Attachment method. (2) Phase-align the mechanism body of the variable valve timing mechanism and the inter-cam drive wheel, temporarily tighten the inter-cam drive wheel to the mechanism body with a lock nut, and then connect the variable valve timing mechanism and the inter-cam drive wheel temporarily. After adjusting the phase with the camshaft, when attaching the variable valve timing mechanism to the end of one camshaft by tightening the fastening member,
2. The method of assembling a valve train for an engine according to claim 1, wherein said lock nut is fully tightened at the same time.