JPH02201008A - Apparatus for driving valve of multiple valve engine - Google Patents

Abstract

PURPOSE:To enable smooth driving of each cam shaft by a method wherein in a multiple valve engine provided with three or more cam shafts, constitution is made so that driving force of the crank shaft is transmitted to a part of the cam shaft and the remaining cam shafts via belt drive type power transmission means respectively. CONSTITUTION:On an upper surface wall 15 formed in an approximate sphere at the upper end part of a combustion chamber 7, at an approximate center widthwise of an engine CE, first and second intake ports 4, 5 are arranged in one row lengthwise of the engine CE while a third intake port 6 is provided close to an intake side between both intake ports 4, 5. First and second exhaust ports 13, 14 are provided in one row lengthwise of the engine CE on an exhaust side half of the upper surface wall 15. The respective intake and exhaust ports 4 to 6, 13, 14 are opened and closed by intake and exhaust valves 1 to 3, 11, 12. In this case, an exhaust side intake valve cam shaft 22 is driven by a driving belt 96, and an exhaust side intake valve cam shaft 32 and an exhaust valve cam shaft 42 are driven by a driving belt 97 synchronized with a crank shaft 89 respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application J] The present invention relates to a valve train for a multi-valve engine, and more particularly to a valve train for a multi-valve engine equipped with three or more camshafts. This relates to a drive mechanism.

[Prior art] In order to reduce the passage resistance of the intake/exhaust boats, a plurality of intake boats or exhaust boats are provided in one combustion chamber, and intake/exhaust valves are provided to open and close each of these intake/exhaust boats, respectively. Multi-valve engines are generally known (for example, Japanese Utility Model Application Publication No. 1988-133, Japanese Utility Model Application Publication No. 62-34124, Japanese Patent Application Publication No. 58-47109, Japanese Patent Application Publication No. 62-26).
(See Publication No. 308).

For such a multi-valve engine, a large number of intakes and
In order to accurately open and close the exhaust valves at predetermined timing, a double overhead camshaft mechanism (DOHC mechanism) is used in which an intake valve camshaft and an exhaust valve camshaft are placed above the intake and exhaust valves, respectively. (For example, see the above-mentioned Japanese Patent Laid-Open No. 58-47109).

A crank pulley is attached coaxially to the crankshaft, an intake valve pulley is attached coaxially to the intake valve camshaft, and an exhaust valve is attached coaxially to the exhaust valve camshaft. A timing belt or chain is placed across the two pulleys, and each camshaft is driven to rotate synchronously by the crankshaft.

[Problem to be Solved by the Invention] By the way, if we take a multi-valve engine with three intake valves as an example, in order to ensure that the total flow cross section of the intake boats is as large as possible, the three intake boats Staggered arrangement (triangular arrangement) on the upper wall of the room (see Figure 2)
. In a multi-valve engine with three intake valves arranged in a staggered manner, in order to open and close the intake valve that is remote from the intake valve camshaft, a rocker arm is installed to transmit the power of the cam to the intake valve. Alternatively, it is necessary to form the bucket part (contact part with the cam) of the intake valve into a wide shape that can reach the cam, but if this is done, the power transmission mechanism from the cam to the intake valve becomes complicated, and especially There is a problem in that the smooth opening and closing operation of the intake valve is impaired at high speeds, making it impossible to sufficiently increase engine output. In addition,
Of course, similar problems occur when three or more exhaust valves are provided for one combustion chamber.

Therefore, a method has been considered in which an exhaust valve camshaft is provided for the exhaust valve, and separate intake valve camshafts are provided for the intake valve located on the exhaust side and the intake valve located on the opposite exhaust side. It will be done. According to this method, each intake valve can be directly driven by a cam, so the intake valves can be opened and closed smoothly with accurate timing even at high speeds, making it possible to increase the output of the engine. There is such a point.

However, in a multi-valve engine with three camshafts, one timing belt or chain is placed across the crank pulley and each camshaft boot, and each camshaft is driven to rotate by the crankshaft. In this case, the engagement circumferential length of the pulley of the intermediate camshaft with the timing belt (chain) becomes very short, resulting in a problem that the camshaft at the intermediate position cannot be reliably rotated.

Further, if three or more camshafts are provided and an attempt is made to make the engine more compact, the intervals between the camshafts will inevitably become narrower. On the other hand, the camshaft boob is
Since it requires twice the diameter (number of teeth) of the crankshaft pulley, the pulley diameter becomes relatively large. For this reason,
If you try to arrange the pulleys of each camshaft on the same plane so that they can be driven by one timing belt,
There is a problem in that the layout becomes very difficult, and even if it can be arranged, the width of the cylinder head becomes large, causing a problem in the connection of the engine to the vehicle.

The present invention has been made in view of the above conventional problems, and even when three or more camshafts are provided, the driving force of the crankshaft can be reliably transmitted to each camshaft, and each An object of the present invention is to provide a valve operating device for a multi-valve engine with a compact structure capable of opening and closing intake and exhaust valves at accurate timing.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an engine in which a plurality of intake and exhaust valves are provided in one combustion chamber, in which three or more camshafts that drive the intake and exhaust valves are provided. A multi-valve engine characterized in that the driving force of the crankshaft is transmitted to some of the camshafts and the remaining camshafts independently through winding type power transmission means. We provide valve train systems.

[Operations and Effects of the Invention] According to the present invention, some crankshafts (hereinafter referred to as the first
The driving force of the crankshaft is independently transmitted to the crankshaft set (hereinafter referred to as the crankshaft set) and the remaining crankshaft (hereinafter referred to as the second crankshaft set) via a wrap-type power transmission means such as a timing belt.

Therefore, since each camshaft boob has a relatively long contact circumference with the timing belt, it is possible to ensure sufficient contact force between the pulley of each camshaft and the timing belt, ensuring that each camshaft is Can be driven.

In addition, the first camshaft set and the second camshaft set have separate timing belts (winding type power transmission means).
Therefore, the boot of the first camshaft set and the pulley of the second camshaft center do not need to be arranged on the same plane. Therefore, if the bobbies of the first camshaft set and the pulleys of the second camshaft set are arranged offset in the axial direction of the crankshaft, interference between the bobbins will not occur, and the layout of the bobbles of each camshaft will be adjusted. This makes it easy to use, and it is possible to make the engine more compact.

[Implementation ρ11 Examples of the present invention will be specifically described below.

<First Embodiment> As shown in FIG. 1, a four-cylinder engine CE (only the first cylinder is shown) has a first cylinder. 2nd exhaust side intake valve! ,2
When the opposite U chain side intake valve 3 is opened, the first to third
Intake air is drawn into the combustion chamber 7 from the intake boats 4 to 6, compressed by a piston (not shown), and ignited and combusted by the spark plug 8, and the 1st and 2nd exhaust valves 11 and 12 are opened. The combustion gas is discharged from the first and second exhaust bows N3.14 when

As shown in FIG. The second intake boat 4°5 is
A top wall 15 formed in a substantially spherical shape at the upper end of the combustion chamber 7 (see FIG. 1) is provided with a wall C and an engine CE at approximately the center when viewed from the width direction of the engine CE (left side direction in FIG. 3). The first and second intake boats 4.5 are arranged in a row in the longitudinal direction (in the downward direction in FIG. 3), and the first and second intake boats 4.5 are connected to the first
．． It is opened and closed by a second exhaust side intake valve 1.2. Further, the third intake boat 6 is the first intake boat 6 when viewed from the same width direction of the engine CE. The first and second intake boats 4 and 5 are located at a position slightly on the intake side (right side (IFJ) in FIG. 3) of the second intake boats 4 and 5 when viewed in the longitudinal direction of the engine CE.
This third intake boat 6 is opened and closed by the intake valve 3 on the opposite exhaust side. In this way, the first to third intake boats 4 to 6 (i.e., the first
．． The second exhaust side intake valves 1 and 2 and the anti-υF air side intake valve 3) are
Since it is arranged in a staggered manner (triangular arrangement) on the top wall I5,
A large cross-sectional area of the intake passage can be ensured, making filling easier.
It is now possible to raise the level.

-・Director, 1st. The 218th air boat 13.14 is located in the exhaust side half of the upper wall 15 of the combustion chamber 7 (see FIG. 1).
These first . 2nd exhaust bow) 13.14 is the 1st. 2nd #
l: It is opened and closed by air valves 11 and 12.

A squish area 10 is provided at the upper end of the exhaust side of the combustion chamber 7 (see Fig. 1) to create strong turbulence (squish flow) of the air-fuel mixture in the combustion chamber 7 immediately before ignition, thereby improving the combustibility of the air-fuel mixture. I'm trying to increase that.

As shown in FIG. 1 again, the first exhaust side intake valve l is
A valve section 16 that opens and closes the intake boat 4, and the valve section 1
6, a valve guide section 8 that supports the valve shaft 17 so as to be slidable in the axial direction, a bucket section I9, which will be described later, and the first exhaust side intake valve l. It is composed of a coil-shaped spring 21 that is always biased in the valve direction (upward). The upper end surface of the bucket part 9 is always in contact with the exhaust-side intake valve cam 23 attached to the exhaust-side intake valve camshaft 22, and as the exhaust-side intake valve camshaft 22 rotates, When the exhaust-side intake valve cam 23 pushes down the first exhaust-side intake valve 1 against the biasing force of the spring 21, the first intake boat 4 is opened at a predetermined timing, and intake air flows into the combustion chamber 7. It is meant to be inhaled.

Although not shown, the second exhaust side intake valve 2 is also connected to the first intake valve 2.
It has the same configuration as the exhaust side intake valve 1, and opens and closes the second intake boat 5 at the same timing as the first exhaust side intake valve 1.

Similarly to the first exhaust side intake valve l, the counter-exhaust side intake valve 3 is also composed of a valve part 25, a valve shaft 26, a valve guide part 27, a bucket part 28, and a spring 29. The valve 3 is opened and closed at predetermined timing by a cam 33 for an intake valve on the opposite exhaust side that is attached to a camshaft 32 for an intake valve on the opposite exhaust side.

Furthermore, like the first exhaust side intake valve l, the first exhaust valve II also includes a valve portion 35, a valve shaft 36, a valve guide portion 37, a bucket portion 38, and a spring 39.
The exhaust valve 11 is opened and closed at predetermined timing by an exhaust valve cam 43 attached to an exhaust valve camshaft 42. Although not shown, the second
The exhaust valve 12 also has the same configuration as the first exhaust valve 11, and the second exhaust boat 1 is opened at the same timing as the first exhaust valve 11.
4 to open and close.

The exhaust-side intake valve camshaft 22 has a bearing part 45 formed integrally with the upper end of the cylinder head (1), and a bearing cap 47 attached to the upper side of the part 45 with a bolt 46. It is rotatably supported by an exhaust-side intake valve bearing 48 composed of. Similarly, the camshaft 32 for the intake valve on the opposite exhaust side is rotatably supported by a bearing 53 for the intake valve on the opposite exhaust side, which is constituted by a bearing portion 51 and a bearing cap 52 . In addition, the bearing cap 47 of the exhaust side intake valve bearing 48 and the bearing 5 for the opposite exhaust side intake valve
The bearing cap 52 of No. 3 is integrally formed as will be explained in detail later.

Further, the exhaust valve camshaft 42 is rotatably supported by an exhaust valve bearing 56 that includes a bearing portion 54 and a bearing cap 55.

Here, the exhaust valve camshaft 42, the exhaust side intake valve camshaft 22, and the non-exhaust side intake valve camshaft 32 have their respective axes located on a plane P formed on the upper end surface of the cylinder head H. so that engine C
They are arranged linearly in the width direction of E. Each bearing formed at the upper end of the cylinder head H has portions 54 and 45.
．． The upper end surface of portion 54. ,4.5,
The entire upper end surface of the cylinder head H including the upper end portion of the cylinder head 51 is flat. Therefore, each of the bearing caps 55, 47, and 52 can be attached by screwing the bolts 46 vertically downward, resulting in good workability during attachment.

In addition, the plane P forming the upper end surface of the cylinder head I, which includes the upper end surfaces of the parts 54, 45, and 51 of each bearing, becomes higher toward the intake side (right side in FIG. 1) when viewed in the width direction of the engine CE. It is formed on a plane with such an inclination. Therefore, the length between the upper surface of the bucket portion 19 and the lower surface of the valve portion 16 of the first exhaust-side intake valve l (valve stem length) can be set relatively large. Therefore, since a sufficient length of the valve shaft I7 can be ensured, the length of the valve guide portion 18 that pivotally supports the valve shaft 17 can also be set to a sufficient length.
The first exhaust-side intake valve 1 can be firmly supported, and rattling can be effectively prevented from occurring. Of course, the same applies to the second exhaust side intake valve 2.

Note that since the valve stem length of the opposite-exhaust side intake valve 3 is also increased, it goes without saying that the same rattling prevention effect can be obtained.

Further, an oil gear rally 71 for the intake side valve train is disposed to extend in the longitudinal direction of the cylinder head H outside the bucket portion 28 of the intake valve 3 on the opposite exhaust side. and,
The oil gear rally 71 for the intake valve system includes a first lubricating oil passage 72 that supplies lubricating oil to the bucket portion 28 of the intake valve 3 on the opposite exhaust side, a camshaft 32 for the intake valve on the opposite exhaust side, and a camshaft 32 for the intake valve on the opposite exhaust side. A second lubricating oil passage 73 that supplies lubricating oil is connected to the journal portion of the valve bearing 53 .

The downstream end of the first lubricating oil passage 72 is connected to an annular oil groove 74 formed in an annular shape along the inner peripheral surface of the packet hole for the bucket throat portion 28 . and,
This annular oil groove 74 is provided with the first and second exhaust side intake valves 1.
, the third bucket part 19 supplies lubricating oil to the bucket parts 19 of the second buckets. A fourth lubricating oil passage 75,76 is connected. Furthermore, a fifth lubricating oil passage 77 that supplies lubricating oil to the journal portions of the exhaust-side intake valve camshaft 22 and the exhaust-side intake valve bearing 48 is connected to the annular oil groove 74 .

Further, an exhaust side valve train oil gear rally 81 is provided for the exhaust side valve train. 6. Supplying lubricating oil to the packet 38 for the second exhaust valve 11.12. Seventh oil passage 82.
83 and an eighth oil passage 84 that supplies lubricating oil to the journal portions of the exhaust valve camshaft 42 and the exhaust valve bearing 56 are connected.

The drive mechanism of each cam shirt 22, 32, and 42 will be explained below.

As shown in FIGS. 1 and 2, the camshaft 32 for the intake valve on the opposite exhaust side, the camshaft 22 for the exhaust side intake valve, and the FJ
Near a part of the front side of the F air valve air force camshaft 42,
A camshaft pulley 86 for the opposite-exhaust side intake valve, a camshaft pulley 87 for the exhaust side intake valve, and a camshaft pulley 88 for the exhaust valve are provided, respectively. As is clear from FIG. 2, the camshaft pulley 86 for the intake valve on the opposite exhaust side and the camshaft pulley 88 for the exhaust valve are arranged at the same position when viewed in the longitudinal direction of the cylinder head II. The camshaft pulley 87 for the exhaust side intake valve has a distance d from this point.
It is located only on the front side.

An intermediate boolean set 90 is provided at a substantially intermediate position between the crankshaft 89 and the upper end surface of the crank throat F1 when viewed in the downward direction. This intermediate boolean set 90 is connected to a deceleration main pulley 9 that has twice the diameter of a crank pulley 91 attached to a crankshaft 89.
2, and a first drive pulley 93 and a second drive pulley 93 which are coaxially fixed in close proximity to the front and rear sides of the main deceleration pulley 92 and have the same diameter as each camshaft boob 986, 87, 88. , 94.

Then, crank pulley 9I and deceleration main boo 'J
A main belt 95 is placed across the first drive boob 993 and the camshaft pulley 87 for the exhaust side intake valve, and a first drive belt 96 is placed across the first drive boob 993 and the camshaft pulley 87 for the intake valve on the exhaust side. A second drive belt 97 is stretched across the valve camshaft pulley 86 and the exhaust valve camshaft pulley 88.

Therefore, first, the deceleration main pulley 92 is operated by the crank boot 991 via the main belt 95.
The camshaft pulley 87 for the exhaust side intake valve is rotated synchronously at a rotation speed of /2.
6, the first drive boob 1793 rotates at the same rotation speed as this, and the opposite-exhaust side intake valve camshaft pulley 86 and the exhaust valve camshaft pulley 8
8 is connected to the second drive pulley 94 via the second drive belt 97.
It is rotated at the same rotation speed as this. In this way, each camshaft 22, 32, 42 rotates synchronously at 1/2 the rotation speed of the crankshaft 89.

Here, the camshaft pulley 87 for the exhaust side intake valve
is in contact with the first drive belt 96 over about 1/2 of its entire circumference, so the driving force of the first drive belt 96 is reliably transmitted to the exhaust-side intake valve camshaft pulley 87. Further, since the opposite-exhaust side intake valve camshaft pulley 86 and the exhaust valve camshaft pulley IJ88 are in contact with the second drive belt 97 over 1/4 or more of their entire circumference, the driving force of the second drive belt 97 is It is reliably transmitted to the intake valve camshaft pulley 86 and the exhaust valve camshaft pulley 88 on the opposite exhaust side.

Therefore, each camshaft 22.32.42 can be reliably driven, and each intake and exhaust valve I, 2°3.11.1
2 can be opened and closed with precise timing.

In the first embodiment, a timing belt is used as the winding power transmission means, but a timing chain may be used instead.

<Embodiment of the Pond> In the first embodiment, the intermediate boolean set 90 is provided, but as in the second embodiment shown in FIG. The pulley 87 is directly rotationally driven by the crank pulley 91 via the first drive belt 96, and the camshaft pulley 86 for the intake valve and the camshaft pulley 88 for the exhaust valve on the opposite exhaust side are rotated.
and may be directly rotationally driven by the crank boot 991 via the second drive belt 97. At this time, the diameter of each camshaft boob 986, 87, 88 is set to twice the pulley diameter of the crank pulley 91.

Also in this embodiment, each camshaft pulley 86, 8
A sufficient circumferential length of contact with the 7.88 drive belt 96°97 can be ensured, and each intake and exhaust valve 1°2.3.11.12 can be opened and closed at accurate timing.

Further, the distribution of the camshaft pulley connected to the first drive belt 96 and the camshaft pulley connected to the second drive belt 97 is determined by the distribution of the camshaft pulley connected to the first drive belt 96 and the second drive belt 97. The allocation method is not limited to that of the second embodiment, and the allocation may be as shown in FIGS. 5 to 9, for example.

Further, in the embodiments shown in FIGS. 5 to 9, the intermediate boolean set 90 is provided, but it is of course possible to use a type that is directly driven by the crank pulley as in the second embodiment. be.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view of a cylinder of a multi-valve engine equipped with a valve train according to the present invention. 2 is an explanatory side view of the drive mechanism of the valve train of the engine shown in FIG. 1. FIG. FIG. 3 is an explanatory plan view of the combustion chamber of the engine shown in FIG. 1, showing the arrangement of an intake boat and an exhaust boat. FIG. 4 is a schematic diagram of an engine equipped with a valve gear drive mechanism in which each camshaft booster is directly driven by a crank pulley without providing an intermediate booster set, and is a second embodiment of the present invention. Give an example. FIGS. 5 to 9 are diagrams showing embodiments in which the distribution of the camshaft boot on the first drive belt and the camshaft boot on the second drive belt is variously changed. CE...Engine, H...Cylinder navel)', 1.
2... 1st. 2nd exhaust side intake valve, 3... counter-exhaust side intake valve, 4-6... 1st to 3rd intake boat, 7... combustion chamber, 11.12... 1st. 2nd exhaust valve, 13.14...
・First. Second exhaust boat, 22... Camshaft for exhaust side intake valve, 23... Cam for exhaust side intake valve, 32...
- Camshaft for intake valve on the opposite exhaust side, 33... Cam for intake valve on the opposite exhaust side, 42... Camshaft for exhaust valve, 43
...Cam for exhaust valve, 86...Camshaft pulley for intake valve on opposite exhaust side, 87...Camshaft pulley for intake valve on exhaust side, 88...Camshaft pulley for exhaust valve, 89
... Crankshaft, 90 ... Intermediate boolean set, 91 ... Crank pulley, 95 ... Main belt, 96 ... First drive belt, 97 ... Second drive belt. Figure 3

Claims (1)

[Claims] (1) In an engine in which a plurality of intake and exhaust valves are provided in one combustion chamber, three or more camshafts are provided to drive the intake and exhaust valves, and some of these camshafts and the remaining camshafts are connected to each other. A valve operating device for a multi-valve engine, characterized in that the driving force of the crankshaft is transmitted independently through winding type power transmission means.