JP4311201B2 - Chain case structure - Google Patents

Description

  The present invention relates to a chain rotation transmission device that transmits rotation of a crankshaft of an engine to a valve operating system through a camshaft using an endless chain, and more particularly to a chain case structure that covers a chain tensioner that applies tension to the chain. .

  The engine uses a rotation transmission device to transmit a part of the rotational force of a crankshaft disposed in the lower part of the cylinder block to a valve operating system that drives an intake / exhaust valve via a camshaft provided on the cylinder head side. One of these rotation transmission devices requires a lubricating oil, but there is a chain rotation transmission device with relatively high durability. This chain rotation transmission device is usually housed in a chain housing chamber formed by attaching a chain case to one side wall surface of a cylinder block and a cylinder head that are integrally coupled to each other.

  Such a chain rotation transmission device includes a chain tensioner, which applies tension to the chain and suppresses noise generation. That is, the chain tensioner includes a chain tensioner body having a plunger that projects by receiving spring force or hydraulic pressure, and a chain guide that swings and receives tension from the plunger of the chain tensioner body to apply tension to the chain. ing. Of these, the chain tensioner body is housed in a casing that is bolted to one side wall surface of the cylinder block and cylinder head, and a spring that constantly applies a pressing force to the plunger, a hydraulic supply path, a relief valve that eliminates excess hydraulic pressure, etc. It is formed with relatively high accuracy and can function to automatically maintain the tension on the chain at a proper level.

  Japanese Patent Laid-Open No. 2003-35116 (Patent Document 1) discloses first and second rotations of a crankshaft pivotally supported on a cylinder block of a V-type engine, which are pivotally supported on first and second cylinder heads by a timing chain. A chain tensioner mechanism for transmitting to a camshaft is disclosed. Here, in one cylinder bank of the cylinder block, a tensioner member for applying a predetermined tension to the timing chain and a chain adjuster are disclosed.

Japanese Patent Laid-Open No. 2003-35116.

  By the way, when a chain or a chain tensioner is attached over the cylinder block and the cylinder head as in Patent Document 1, etc., these are accommodated in a chain accommodation chamber formed by attaching a chain case. However, when these chains or chain tensioners need to be replaced or regularly inspected, it is necessary to remove the chain case from the cylinder block or cylinder head side and open the chain housing chamber.

In particular, in order to check whether the chain tensioner is in normal condition and applying tension to the chain, check the protruding operation and the amount of protruding, or replace the chain tensioner body, the chain case should be Since it will be removed from the block and cylinder heads each time, the inspection workability is very low and improvement is desired.
The present invention has been made based on the above problems, and an object of the present invention is to provide a chain case structure in which a chain tensioner can be easily inspected and replaced without detaching the chain case.

A chain case structure according to claim 1 of the present invention is attached to the ends of a cylinder head and a cylinder block, and transmits a rotation of a crankshaft of an engine to a valve operating mechanism by a chain, and the cylinder block. a chain tensioner over applying tension to the chain attached to, to accommodate the chain rotation transmission device and the chain tensioner over, the engine width direction are end portions of the cylinder head and the sheet re Sunda block a chain case which forms a chain receiving chamber by being fastened via the connection flange to the left and right ends in a detachable the chain tensioner over a predetermined portion of the chain case opposite to the mounting site of the chain tensioner over a chain tensioner inspection hole having an opening area of a size And a normally-closed fastened with screws to the opening peripheral edge portion of the chain tensioner inspection hole, the screw of the screw boss of the chain tensioner which is mounted a below the chain tensioner inspection hole in the cylinder block It is arranged at a position deviating toward the center side of the chain housing chamber from an intermediate position in the engine lateral width direction, and is formed so as to project a predetermined amount in the chain housing chamber so as to prevent the chain tensioner from falling downward. , characterized in that.

  According to the first aspect of the present invention, when the normally closed opening of the chain case is opened, the chain tensioner can be detached from the chain housing chamber, so that the chain tensioner can be replaced or the chain tensioner can be removed without removing the chain case. It is possible to easily check whether tension is applied to the chain in a normal state.

In particular, even if the detached chain tensioner falls due to a mistake in work, the screw boss protruding on the back of the chain case can keep the fall to a minimum, and the chain housing chamber is opened by removing the chain case etc. This eliminates extra work such as removing the chain tensioner and reduces the number of parts and costs .

1 and 2 show a four-cycle gasoline engine (hereinafter simply referred to as engine 1) for a vehicle in which a chain case structure as an embodiment of the present invention is adopted.
The engine 1 has a cylinder head 3 and a head cover 4 on the upper side of the cylinder block 2, an oil pan 5 on the lower side, and a chain case 6 on one side wall surface thereof, which are integrally coupled to form an engine body. Has been. Further, a plurality of cylinders S are provided in the cylinder block 2 and the cylinder head 3. The intake and exhaust gas sucked into and discharged from the combustion chamber (not shown) of the cylinder S is controlled by the intake and exhaust components and the valve operating system (not shown), and the output energy received by the piston (not shown) in the combustion chamber is received. In response, the crankshaft 7 is formed to rotate.

  A pair of intake / exhaust cam shafts 8 i and 8 e (see FIGS. 2 and 5) forming a part of a valve system (not shown) are pivotally supported by a plurality of bearings (not shown) inside the cylinder head 3 and the head cover 4. Cam shaft sprockets 9i and 9e (see FIG. 2) are integrally coupled to one ends of the intake and discharge cam shafts 8i and 8e. In particular, the intake-side camshaft sprocket 9i is connected to the intake camshaft 8i via a timer 11 (see FIG. 1). As a result, the timer 11 that has received the crank rotation via the chain 29 (see FIG. 2) is configured to transmit the rotation to an intake cam (not shown) after the opening / closing timing has been advanced and retarded.

  As shown in FIG. 1, the cylinder block 2 is formed with a plurality of cylinders S and a block-side water jacket 16 that cools around the cylinders S, and its lower opening is closed by an oil pan 5 to form a crank chamber. It is formed as an aluminum alloy casting. A crankshaft 7 pivotally supported by a plurality of bearings (not shown) is disposed in the crank chamber, and a crank sprocket 12, an inner rotor (not shown) of an oil pump 13 (to be described later), and a crank pulley 14 are integrally coupled to one end of the crankshaft 7. Has been.

  The cylinder head 3 is formed as an aluminum alloy casting, and a head-side water jacket 15 and an inner chamber 17 are formed therein. The inner chamber 17 accommodates a main part VD of a valve operating system such as intake and exhaust camshafts 8i and 8e. Is done. As shown in FIG. 5, an end inner wall 301 is formed on one end side of the cylinder head 3, extending portions 302 project from the left and right ends of the end inner wall 301, and the flange portion of the extending end 302 is a chain case. 6 overlaps with the upper connection flange 601 and is fastened with bolts (not shown).

  An end inner wall 18 is formed at one side end of the cylinder block 2, and an extended portion 18 g is projected from the left and right ends of the end inner wall 18. A flange portion of the extended end 18 g is formed on the lower side of the chain case 6. It overlaps with the connection flange 601 and both are fastened with bolts (not shown). The upper end inner wall 301 and the lower end inner wall 18 have the same flat cross-sectional shape and are integrally joined to each other. Here, a protruding wall portion 21 extending in the engine lateral width direction Y is formed in the vicinity of the intersecting portion of the extending portion 18g of the cylinder block 2 and the rear outer wall 19.

The protruding wall portion 21 is formed with a flat one-side facing surface F (a part of the outer wall surface of the block) facing the one side end, and the same surface is also continuously formed on the left and right extending portions 18g. The case back wall surface fc (see FIG. 3) of the chain case 6 is formed so as to overlap the one side facing surface F.
As shown in FIGS. 1 to 3, the chain case 6 has a front wall 602 and left and right connecting flanges 601 that are substantially continuous vertically, have a concave cross section in plan view, and are chained in the center when joined to the one-side facing surface F. The storage chamber 22 is formed and is manufactured by aluminum die casting.

  As shown in FIG. 5, in the chain case 6, the insertion hole 23 (see FIG. 3) through which the crankshaft 7 is inserted at the center lower part of the front wall 602 is a part of the chain rotation transmission device of the present invention at the upper part. A chain tensioner inspection hole 24 as a closed opening is formed. A chain tensioner main body 31 to be described later is mounted on the inner side of the chain tensioner inspection hole 24, that is, on a portion facing the chain tensioner inspection hole 24 of the end inner wall 18 of the cylinder block 2. Here, the chain tensioner inspection hole 24 has an opening area that allows the chain tensioner main body 31 to be attached and detached, and a normally closed lid 32 that normally closes the chain tensioner inspection hole 24 is stacked on the peripheral edge of the opening. It is formed so that it can be stopped. Here, a plurality of bolts for fastening the normally closed lid 32 to the peripheral edge of the opening are employed, and among them, a screw boss portion 33 (FIGS. 1 to 3) that forms a screw hole of the bolt located below the chain tensioner inspection hole 24 Is larger than the other screw bosses and protrudes into the chain housing chamber 22. Moreover, the screw boss portion 33 is set such that the interval B with the inner wall surface of the right connection flange 601 is slightly smaller than the front, rear, left and right outer widths of the casing 34 of the chain tensioner body 31. Thus, both the screw boss portion 33 and the inner wall surface of the right connection flange 601 can function as a stopper, and the chain tensioner main body 31 can be prevented from dropping downward.

The insertion hole 23 through which the crankshaft 7 is inserted is provided with an oil pump 13 of the oil circulation system OS at the peripheral edge of the inner wall, and a thickened bulging portion 27 in which a water pump 26 is formed at a portion facing the protruding wall portion 21. Are continuously formed.
As shown in FIG. 3, the oil pump 13 at the center lower portion of the front wall 602 includes a pump housing 46 that protrudes outward around the insertion hole 23 of the front wall 602, and a pump plate 47 is provided on the inner end surface of the pump housing 46. Are tightened with overlapping bolts, an oil pump chamber (not shown) is formed inside, and an inner rotor (not shown) rotated by the crankshaft 7 and an outer rotor (not shown) are rotatably incorporated therein. The oil pump 13 communicates with an oil strainer (not shown) in the oil pan 5 through a suction passage 48 and communicates with a relief valve 51 and each sliding portion provided in the engine body through a discharge passage 49.

  A chain receiving member 28 protrudes below the insertion hole 23 at the end of the pump housing 46 in the chain housing chamber 22. The chain receiving member 28 serves as a movement restricting member for an endless timing chain (hereinafter simply referred to as a chain 29) that constitutes a main part of the chain rotation transmission device of the present invention. That is, the chain receiving member 28 has a function of preventing the chain 29 from moving excessively downward from the state where the chain 29 is wound around the crank sprocket 12. In a normal state, the chain receiving member 28 is held at a steady position p1 away from the chain 29 wound around the crank sprocket 12 by a predetermined gap.

  As shown in FIGS. 3 and 5, a pump chamber 261 of the water pump 26 is formed in the thickened bulging portion 27 of the chain case 6. The water pump 26 is integrally coupled to a pump shaft 263 having a pump impeller 262 fitted in the pump chamber 261, a pump outer lid 264 that is pivotally attached to the pump shaft 263 and fastened to the front wall surface fd, and a protruding end of the pump shaft 263. And a pump pulley 265. The pump chamber 261 communicates with the thermostat 36 on the cylinder block 2 side, and the discharge passage 266 extending from the pump chamber 261 communicates with the block-side discharge passage 37. The block-side discharge path 37 reaches the block-side water jacket 16 and the head-side water jacket 15, the communication path 38 of the cylinder head 3, and the outlet 39. The outlet 39 is connected to the thermostat 36 via the short circuit 42 when the cooling water temperature is relatively low during warm-up, and via the radiator 41 after completion of the relatively high warm-up.

  In such a chain case 6 of the engine 1, the upper part of the left and right side walls 601 is integrally joined to the left and right extending parts 302 of the head cover 4, and the lower part is integrally joined to the left and right extending parts 18 g of the cylinder block 2. As a result, the chain housing chamber 22 is maintained in a hermetically sealed state, and is communicated with the upper and lower internal spaces of the oil pan 5 and the head cover 4 so that oil supply to the chain 29 is facilitated. A chain 29 is housed in the chain housing chamber 22 in a state of being spanned over the crank sprocket 12 and the intake / exhaust camshaft sprockets 9i and 9e. A chain tensioner A including a chain tensioner main body 31 and a pair of chain guides 43 is disposed opposite to the chain 29.

As shown in FIGS. 2 and 5, the pair of chain guides 43 are bolted to the end inner wall 301 of the cylinder head 3 and the end inner wall 18 of the cylinder block 2, and only one (left side in FIG. 2) is at the upper end. The pivot bolt 57 can be swung as a fulcrum.
The chain tensioner main body 31 includes a plunger 55 in a housing 34 that is bolted to the inner wall 18 of the end, a spring 53 that constantly applies a pressing force to the plunger 55, a hydraulic chamber 54, and a check valve 56. The hydraulic chamber 54 is connected to the discharge passage 49 of the oil circulation system OS via a check valve 56, and can project the plunger 55 by the hydraulic pressure received when the engine is driven. Here, a convex body 61 is integrally coupled to an intermediate portion of one of the chain guides 43 (left side in FIG. 2). The convex body 61 can come into contact with the plunger 55, and the pressing force from the plunger 55 is applied to the chain guide 43, and this swings and displaces, thereby pressing the chain 29 and automatically applying tension to the chain 29. To do. An example of the hydraulic chain tensioner body is also disclosed in Japanese Patent Application Laid-Open No. 2002-156013.

The operation of the engine 1 having such a chain case structure of the engine will be described.
When a key switch (not shown) is turned on and the engine 1 enters an operating state, the oil pump 13 is driven in conjunction with the rotation of the crankshaft 7, the oil in the oil circulation system OS flows, and each slide in the engine body flows. Lubricate and cool moving parts and heating parts. At this time, the chain tensioner body 31 receives the hydraulic pressure reaching the hydraulic chamber 54 from the discharge passage 49, and the plunger 55 protrudes and operates to swing the plunger 55 and one of the chain guides 43. Apply tension. At this time, the tension of the chain 29 fluctuates up and down, and a reaction force is applied to the hydraulic pressure in the hydraulic chamber 54 via the plunger 55, but the check valve 56 prevents excessive oil discharge from the hydraulic chamber 54, Excessive shake and noise can be prevented. At the same time, the water pump 26 is driven to circulate the cooling water according to the engine cooling water temperature and perform the engine cooling process.

  It is assumed that such an engine 1 is subjected to periodic inspection. At this time, the normally closed lid 32 is removed from the chain case 6, and the chain tensioner inspection hole 24 as a normally closed opening is opened. As a result, the chain tensioner main body 31 can be detached from the chain housing chamber 22 through the chain tensioner inspection hole 24, and the deterioration and damage of each component inside the chain tensioner main body 31 are checked, and then bolted to the end inner wall 18 side again. it can. Furthermore, it is assumed that the operator releases the chain tensioner body 31 by mistake during this work. In this case, the chain tensioner main body 31 descends between the screw boss portion 33 as a stopper and the inner wall surface of the right connection flange 601 and is locked to the same portion. That is, the fall can be kept to a minimum, and the chain tensioner main body 31 locked to the screw boss portion 33 side can be easily taken out from the chain tensioner inspection hole 24. For this reason, the chain tensioner main body 31 falls to the bottom of the chain housing chamber 22, and the extra work such as removing the chain case 6 and opening the chain housing chamber 22 and taking out the chain tensioner main body 31 can be eliminated. In addition, in the normal inspection work in which only the chain tensioner 31 is in a normal state and tension is applied to the chain, it is only necessary to remove the normally closed lid 32 and open the chain tensioner inspection hole 24. It can be done easily.

Further, here, the screw boss portion 33 formed on the inner wall of the chain case 6 is also used as a stopper, so that the number of parts and the manufacturing cost can be reduced.
It should be noted that a plurality of such screw boss portions 33 may be provided to more reliably prevent the chain tensioner 31 from falling during the attaching / detaching operation. In addition, a stopper plate (not shown) is provided below the chain tensioner inspection hole 24 and is bolted to the inner wall of the chain case 6 so that the chain tensioner 31 can be more reliably dropped during the detaching operation. You may make it prevent.

  In the above, the chain case 6 of FIG. 1 integrally formed the oil pump 13 and the water pump chamber 261, but these are eliminated, and the chain tensioner inspection hole 24 is formed in the simplified chain case. In this case, substantially the same operation and effect as the chain case structure of the engine shown in FIG. 1 can be obtained.

  In the above description, the chain case in the chain case structure of the present invention has been described as being made of aluminum die casting, but the present invention can be similarly applied to a cast product made of an aluminum alloy.

It is an engine outline rear view to which the chain case structure as one embodiment of the present invention was applied. It is a schematic side view of the engine of FIG. It is a reverse view of the chain case of FIG. It is an enlarged front view of the chain tensioner main body in FIG. FIG. 2 is an exploded cutaway perspective view of one end side of the chain case, cylinder head, and cylinder block of FIG. 1.

Explanation of symbols

1 Engine 2 Cylinder block 3 Cylinder head 6 Chain case 601 Left and right side walls (peripheral flange)
602 Front wall (case main part)
7 Crankshaft 301, 18 End inner wall (one side wall surface)
8i, 8e Camshaft 22 Chain storage chamber 24 Chain tensioner inspection hole (opening)
29 Chain 31 Chain tensioner body 32 Normally closed lid 33 Screw boss part X Engine longitudinal direction Y Engine lateral width direction

Claims (1)

A chain rotation transmission device that is attached to the ends of the cylinder head and the cylinder block and transmits the rotation of the crankshaft of the engine to the valve operating mechanism with a chain;
A chain tensioner over which imparts tension to attached the chain to the cylinder block,
To accommodate the chain rotation transmission device and the chain tensioner chromatography, chain receiving by being fastened via the connection flange to the right and left ends of the engine width direction are end portions of the cylinder head and the sheet re Sunda block A chain case forming a chamber ;
A chain tensioner inspection hole with a size opening area of the detachable the chain tensioner over a predetermined portion of the chain case opposite to the mounting site of the chain tensioner over,
A normally closed lid fastened with a screw to the opening peripheral edge of the chain tensioner inspection hole ,
The screw boss of the screw located below the chain tensioner inspection hole is disposed at a position that is biased toward the center side of the chain housing chamber with respect to the intermediate position of the chain tensioner in the engine lateral width direction, and A chain case structure characterized in that a distance from the inner wall surface is smaller than the outer width of the chain tensioner, and a predetermined amount projects from the chain housing chamber so as to prevent the chain tensioner from falling downward .

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