JP4543329B2 - Engine front structure - Google Patents

Description

  The present invention relates to a front structure of an engine, and in particular, includes an endless belt that drives a camshaft by the output of a crankshaft, an endless belt guide that guides the endless belt, and a timing cover. The present invention relates to an engine front structure in which an end portion and an intermediate portion are fastened to a front portion of an engine by bolts.

  In general, an endless belt, for example, a chain, is provided on the front portion of the engine body so that the camshaft is driven by the output of the crankshaft so that the intake and exhaust valves are opened and closed at a predetermined timing. Such a chain is stretched between a sprocket provided at the end of the crankshaft and a sprocket provided at the end of the camshaft, and transmits the output of the crankshaft to the camshaft. ing. The chain is stably driven by a tensioner lever for adjusting the tension on the loose side of the chain, a fixed chain guide for guiding the tension side of the chain, or the like.

  The engine front portion provided with these transmission mechanisms is generally covered with a timing cover, and the outer peripheral edge portion of the timing cover is fixed to the engine body with a plurality of bolts. Further, a bolt is also provided at the flat central portion of the timing cover to fix it to the engine body and to suppress membrane vibration of the timing cover.

  On the other hand, in order to mount the engine on the vehicle body, an engine mount bracket attached to an engine mount on the vehicle body side is generally provided on the front surface of the engine. As a structure of this engine mount bracket, a structure is known in which a mounting seat (mounting seat) for the bracket is provided on the timing cover, and the bracket is attached to the front portion of the engine body via the timing cover (for example, Patent Document 1). In the structure described in Patent Document 1, the intermediate portion of the timing cover is bolted to the engine body to support the bracket, and thus the intermediate portion is bolted to cause engine vibration. The membrane vibration of the timing cover is suppressed.

  On the other hand, a structure in which a mount seat (attachment portion) is provided on the front surface of the engine body and the engine mount bracket is directly attached to the engine front surface is also known (for example, Patent Document 2). In the structure described in Patent Document 2, an intermediate shaft for connecting the upper and lower two-stage chains is arranged offset to the engine side, and a mount seat for the engine mount bracket is formed at a position opposite to the offset position. is doing.

Japanese Patent No. 2770632 Japanese Patent No. 3142339

However, the above-described technique has the following problems.
First, in the structure in which the timing cover center portion as described above is bolted, it is necessary to prevent the bolt from interfering with the above-described tensioner lever, fixed chain guide, etc., in order to avoid such interference, If the position of the tensioner lever or fixed chain guide is changed, the chain tension may not be adjusted or the guide may not be reliably performed. On the other hand, if the bolt position is changed, the effect of suppressing the vibration of the timing cover is lowered, and further, the support performance of the engine may be lowered in the structure of Patent Document 1.
Further, in the structure of Patent Document 2, since the engine mount bracket is arranged offset with respect to the intermediate position in the width direction of the front portion of the engine, there is a possibility that the engine cannot be reliably supported with respect to the vehicle body. is there.

Therefore, the present invention has been made to solve the above-described problems of the prior art, and provides an engine front structure capable of suppressing the vibration of the timing cover while ensuring the function of the endless belt guide. The purpose is to do.
Furthermore, an object of the present invention is to provide an engine front structure that can ensure the support performance of the engine while ensuring the function of the endless belt guide.

In order to achieve the above object, the present invention provides an endless belt for driving a camshaft disposed in a cylinder head by the output of a crankshaft, a plurality of endless belt guides for guiding the endless belt, An endless belt and a timing cover that covers the endless belt guide, and an outer peripheral end portion and an intermediate portion of the timing cover are fastened to the engine front portion by bolts, respectively, and are at least one of the endless belt guide One has an opening that penetrates the endless belt guide in the longitudinal direction of the engine, and the bolt at the intermediate portion of the timing cover passes through the opening of the at least one endless belt guide and is fastened to the front surface of the engine It is characterized by.
In the present invention configured as described above, since the bolt at the intermediate portion of the timing cover passes through the opening formed in the endless belt guide and is fastened to the engine front portion, the fastening bolt of the timing cover and the endless belt guide Even if the positions overlap, the layout of the fastening bolt and the endless belt guide can be compatible. As a result, while securing the function of the endless belt guide, the intermediate portion of the timing cover can be fastened to the engine front portion to ensure the rigidity of the timing cover and to suppress vibration.

In the present invention, preferably, the endless belt guide includes a swingable tensioner lever disposed on the loose side of the endless belt, and the opening is formed in the tensioner lever so as to extend in the swinging direction of the tensioner lever. Has been.
In the present invention configured as described above, the loose side of the endless belt is guided by the swingable tensioner lever, so that the chain flapping can be suppressed, and the opening through which the bolt passes is the tensioner lever. The movement of the tensioner lever is not hindered and the rigidity of the tensioner lever is ensured.

In the present invention, it is preferable that the bolt at the intermediate portion of the timing cover includes a plurality of bolts arranged in the width direction with respect to the engine front portion, and a part of the plurality of bolts is within the opening of the endless belt guide. And is fastened to the front surface of the engine and the other part is fastened to the front surface of the engine in an area surrounded by an endless belt.
In the present invention configured as described above, a region in which a part of the plurality of bolts is fastened to the engine front part through the opening formed in the endless belt guide and the other part is surrounded by the endless belt. Thus, the layout of the endless belt guide and endless belt can be compatible with the layout of the bolts that fasten the timing cover to the front surface of the engine. Then, after achieving such a layout, the mounting rigidity of the timing cover to the engine front portion can be increased by a plurality of bolts arranged in the width direction.

In the present invention, it is preferable that the bolt at the intermediate portion of the timing cover includes a plurality of bolts arranged in the vertical direction with respect to the engine front portion, and the opening corresponds to the plurality of bolts arranged in the vertical direction. The plurality of bolts arranged in the vertical direction on the endless belt guide at the position, and the plurality of bolts arranged in the vertical direction are fastened to the engine front part through the plurality of openings arranged in the vertical direction of the endless belt guide. Has been.
In the present invention configured as above, the plurality of bolts arranged in the vertical direction are fastened to the engine front portion through the plurality of openings arranged in the vertical direction of the endless belt guide. The layout and the layout of the bolts that fasten the timing cover to the engine front can be made compatible. Then, after achieving such a layout, the mounting rigidity of the timing cover to the engine front portion can be increased by a plurality of bolts arranged in the vertical direction.

In the present invention, it is preferable that the endless belt is a chain, the timing cover is made of cast metal, and further has an engine mount mounting seat integrally formed on the front surface thereof. In the vicinity of the bolt at the intermediate portion of the timing cover.
In the present invention configured as described above, since the engine mount mounting seat is integrally formed on the front surface of the timing cover made of cast metal, the engine can be mounted to the vehicle body via the engine cover, and as a result, It is possible to achieve both the layout of the intangible belt and the intangible guide inside the timing cover and the layout of the engine mount mounting seat for mounting the engine on the vehicle body. Further, the mounting rigidity of the timing cover to the engine is increased by the bolt at the intermediate portion of the timing cover, and the engine mount mounting seat is disposed in the vicinity of the intermediate bolt having such increased mounting rigidity. Therefore, the support rigidity of the engine body can also be increased.

In the present invention, preferably, the endless belt guide includes a fixed endless belt guide disposed on a tension side of the endless belt, and a mounting bolt to the engine front portion of the fixed endless belt guide is surrounded by the endless belt. Is located in the area.
In the present invention configured as described above, the fixing bolt to the engine front portion of the fixed endless belt guide is disposed in the region surrounded by the endless belt, so that the space of the engine front portion can be effectively utilized. It is possible to suppress the engine front portion from spreading in the width.

In the present invention, preferably, the engine is a DOHC type engine in which two camshafts are arranged in a cylinder head, and the endless belt is driven by an upper endless belt that drives the two camshafts and a crankshaft. The engine further includes an intermediate shaft that transmits a driving force of the lower endless belt to the upper endless belt, and the intermediate shaft is a tension side of the endless belt in the width direction of the front surface of the engine. The tensioner lever is disposed in a region opposite to the offset direction with respect to the upper endless band in the width direction of the front surface of the engine.
In the present invention configured as above, the intermediate shaft that transmits the driving force of the lower endless belt driven by the crankshaft to the upper endless belt is offset to the tension side of the endless belt in the width direction of the engine front portion. Since the tensioner lever is disposed in the region opposite to the offset direction with respect to the upper endless belt in the width direction of the engine front surface portion, the tensioner lever is disposed on the engine front surface portion without increasing the width of the engine front surface portion. The endless belt can be efficiently routed and the endless belt guide can be arranged. In particular, since the intermediate shaft is arranged offset to the tension side of the endless belt in the width direction of the front surface of the engine, it is possible to secure a space on the opposite side of the offset side, and to this space the tensioner It becomes easy to arrange the lever.

  According to the present invention, it is possible to suppress the vibration of the timing cover while ensuring the function of the endless belt guide. Furthermore, the support performance of the engine can be ensured while ensuring the function of the endless belt guide.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
First, the schematic structure of an engine according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a front view of an engine according to an embodiment of the present invention, FIG. 2 is a side view of the engine according to an embodiment of the present invention, and FIG. 3 is a front view of a timing case.
First, as shown in FIGS. 1 and 2, the engine 1 according to the present embodiment is a common rail direct injection diesel engine, and covers the cylinder block 2, the cylinder head 4 attached to the upper surface thereof, and the cylinder head. A cylinder head cover 6 attached to the cylinder head 4, a lower block 8 attached to the lower surface of the cylinder block 2, an oil pan 10, and a timing case 12 attached to the front surface of the cylinder block 2 are mainly provided. Thus, the engine body is configured. As shown in FIG. 3, the timing case 12 is fixed to the cylinder block 2 with bolts through bolt through holes 12 b formed at six locations.

  Inside the cylinder block 2 and the cylinder head 4, four cylinders (not shown) are formed so as to be arranged in series in the front-rear direction. FIG. 1 shows a cylinder center line (engine width direction center line) C, and a crankshaft (crankshaft) 14 is disposed on an extension line of the cylinder center line C. In the present embodiment, the direction in which the cylinders are arranged, that is, the direction in which the crankshaft 14 extends is defined as the longitudinal direction of the engine, and the direction orthogonal to that direction is defined as the width direction of the engine. Further, the side of the engine 1 on which auxiliary machines and timing chains (to be described later) are provided is the front surface, and the side of the crankshaft 14 where the wheel driving force is output is the rear surface. And in this embodiment, a front view is the figure seen from the engine front side (direction which looks at a front part from the front).

As shown in FIG. 2, the crankshaft 14 extends in the front-rear direction below the cylinder block 2. Between the cylinder head 4 and the cylinder head cover 6, two camshafts (cam shafts) 16 (see FIG. 3 for the other camshaft 17) extend in the front-rear direction. It is a DOHC engine. One of the camshafts is an intake-side camshaft 16, and the other is an exhaust-side camshaft 17 (see FIG. 4).
As shown in FIG. 1, accessories such as an alternator 18, a water pump 20 (see FIG. 2), and an air compressor 22 are attached to the right side as viewed from the front of the engine 1. An endless belt 28 includes pulleys 18a, 20a, 22a attached to the front end of each auxiliary machine, a crankshaft pulley 14a, a pulley 24a of a tensioner lever 24 for adjusting the tension of the endless belt 28, and two idles. Auxiliary machine 18, 20, 22, 24 is operated by the power of crankshaft 14.

  Further, as shown in FIG. 2, a high-pressure fuel pump (supply pump) 30 is provided on the right side as viewed from the front of the engine 1 as an auxiliary machine, below the water pump unit 20. The high-pressure fuel pump 30 is a pump for feeding high-pressure fuel into a direct-injection common rail fuel injector (not shown) provided in the cylinder head 4 in order to inject diesel fuel into the cylinder at a high pressure. It is driven by a chain drive mechanism 42 (see FIG. 3) described later. This pump is of a type that pressurizes fuel by the action of a cam and a plunger, and high-pressure fuel is delivered from two fuel delivery ports 30a.

  In the present embodiment, the front end portion of the high-pressure fuel pump 30 is attached to the timing case 12. As shown in FIGS. 1 and 3, the timing case 12 is formed with a protruding portion 12a protruding rightward with respect to the cylinder block 2 and the like below the water pump 20, and the rear surface side of the protruding portion 12a (engine A high pressure fuel pump mounting seat 12c is formed on the rear side. That is, as shown in FIG. 2, the high-pressure fuel pump 30 is fixed to the rear surface portion of the protruding portion 12a by the bolt. The thickness of the mounting seat 12c is higher than that of other portions, and the support rigidity of the high-pressure fuel pump 30 is increased. The high-pressure fuel pump 30 may be directly attached to the side surface of the cylinder block 2 via a bracket or the like, and the timing case 12 may be integrally formed with the cylinder block 2.

  Thus, various auxiliary machines (30 etc.), belts (28), etc. are arranged in the front part of engine 1. As shown in FIGS. 1 and 2, a timing cover 40 is provided at the front portion of the engine 1 between the belt 28, the pulley 14a, and the like and the engine body. A chain transmission mechanism 42 that transmits the power of the crankshaft 14 to the high-pressure fuel pump 30 and the camshaft 16 and drives them is provided inside the timing cover 40.

Next, the chain transmission mechanism 42 provided at the front of the engine will be mainly described with reference to FIG. FIG. 4 is a front view of the engine for explaining the chain transmission mechanism according to the embodiment of the present invention. Components such as the cylinder head cover 6, the timing cover 40, and the belt 28 ahead of the timing cover shown in FIG. It is shown excluding.
As shown in FIG. 4, the chain transmission mechanism 42 transmits the output of the crankshaft 14 to the above-described high-pressure fuel pump 30 and the crankshafts 16 and 17 through the lower chain 44 and the upper chain 46, and the like. It is a mechanism to drive.

First, a crankshaft sprocket 48 is attached to the front end portion of the crankshaft 14. The high-pressure fuel pump 30 (see FIG. 2) includes a fuel pump shaft 50 extending in the front-rear direction. The fuel pump shaft 50 passes through a hole 12d formed in the pump mounting seat 12c of the timing case 12 shown in FIG. As shown in FIG. 4, a fuel pump shaft sprocket 52 is attached to the front end portion of the pump shaft 50.
An intermediate shaft 54 for transmitting power from the lower chain 44 to the upper chain 46 is provided on the front surface of the engine 1. An intermediate shaft lower sprocket 56 is attached to the front end of the intermediate shaft 54. It has been. The intermediate shaft 54 is fixed to both the cylinder block 2 and the timing case 12.

  The lower chain 44 is stretched over the sprockets 48, 52 and 56, and the output of the crankshaft 14 is transmitted to the fuel pump 30 and the intermediate shaft 54. Here, the crankshaft 14 rotates clockwise as viewed from the front side of the engine 1. Accordingly, the portions between the sprockets 48, 52, and 56 of the lower chain 44 become the tension side portions 44a and 44b or the loose side portion 44c, respectively.

  Next, an intermediate shaft upper sprocket 58 for the upper chain 46 is attached to the front end portion of the intermediate shaft 54 on the further front side (front side in FIG. 1) of the intermediate shaft lower sprocket 56. The upper chain 46 is stretched over the intermediate shaft upper sprocket 58 and the camshaft sprockets 60 and 62 attached to the front end portions of the camshafts 16 and 17, and the output of the crankshaft 14 passes through the intermediate shaft 54. Via the camshafts 16 and 17. According to the rotation direction of the crankshaft 14 described above, the portions between the sprockets 58, 60, 62 of the upper chain 46 become the tension side portions 46a, 46b or the loose side portions 46c, respectively.

  The chains 44 and 46 spanned in this way are so-called timing chains, and the rotation timing of the camshafts 16 and 17 with respect to the rotation of the crankshaft 14 is determined in advance. In the present embodiment, since the load of the high-pressure fuel pump 30 is very large, the chain pitch of the lower chain 44 is made larger than that of the upper chain 46 to increase the strength of the chain.

Next, the arrangement of the chains 44 and 46 and the shafts 14, 50, 54, 16, and 17 will be described with reference to FIG.
As shown in FIG. 4, the lower chain 44 is disposed on the engine body side, that is, the rear side with respect to the upper chain 46. In the present embodiment, the lower chain 44 is arranged in a position close to the high-pressure fuel pump 30 with a very large load in this way, so that the pump 30 can be driven reliably. That is, the moment force applied to the fuel pump shaft 50 is made as small as possible so that the load applied between the lower chain 44 and the high-pressure fuel pump 30 is made as small as possible.

Since the fuel pump 30 is provided on the side surface of the engine main body as described above, the fuel pump shaft 50 is in a position protruding in the width direction with respect to the engine main body. On the other hand, the intermediate shaft 54 is provided at a position offset inward from the fuel pump shaft 50 in the width direction of the front surface of the engine and offset toward the fuel pump shaft 50 from the engine width direction center line C described above. Yes. The intermediate shaft 54 is disposed above the crankshaft 14 and the fuel pump shaft 50. With such an arrangement of the intermediate shaft, the tight side portions 44a and 44b of the lower chain 44 extend obliquely in a direction close to the width direction of the engine front portion.
Here, the camshafts 16 and 17 are equally arranged in the width direction with respect to the center line C in the engine width direction. The intermediate shaft 54 is disposed below the intake camshaft 16 and on a vertical line passing through the intake camshaft 16 among the camshafts 16 and 17. Accordingly, the upper chain 46 has a tight side portion 46a extending substantially in the vertical direction and a loose side portion 46c extending obliquely.

Next, referring to FIGS. 4 to 6, the guide mechanism provided for the chains 44 and 46 in the chain drive mechanism 42 will be described. FIG. 5 is a view showing a cross-sectional structure of the adjuster mounting seat taken along the line VV in FIG. 3, and FIG. 6 is a view showing the upper tensioner lever adjuster according to the present embodiment.
As shown in FIG. 4, each chain 44, 46 is provided with a lower fixed chain guide 70, an upper fixed chain guide 72, a lower tensioner lever 74, and an upper tensioner lever 76 as chain guides.
First, the lower fixed chain guide 70 is fixed to the timing case 12 with bolts inside the lower chain 44. The lower fixed chain guide 70 has two guide surfaces 70a and 70b, and each guide surface 70a and 70b is slightly curved outward, and the tension side portions 44a and 44b are respectively formed from the inside thereof. It is designed to guide you.

  Next, the upper fixed chain guide 72 is attached to the timing case 12 by bolts 73 at two locations inside the upper chain 46, and the rear side of the chain 46 (between the chain 46 and the engine body) from these attachment portions. The guide surface 72 a is formed on the outer side of the chain 46. The guide surface 72 a is curved toward the inner side of the chain 46, and the tension side portion 46 a is guided so as to travel along a path curved toward the inner side of the chain 46. Here, as described above, the upper chain 46 is disposed at a position on the front side of the lower chain 44, that is, at a position away from the engine body. It is easy to pass through.

  Next, the lower tensioner lever 74 and the upper tensioner lever 76 can swing around a common swinging shaft 78 attached to the timing case 12, and the arrangement in the front-rear direction is different for each chain. 44, 46, the upper tensioner lever 76 is on the front side and the lower tensioner lever 74 is on the rear side (engine body side). The chain guide surfaces 74a and 76a of the tensioner levers 74 and 76 are curved inwardly of the chains 44 and 46, and the loose side portions 44c and 46c are inwardly of the chains 44 and 46, respectively. The vehicle is guided to travel along a curved path.

  Here, since the intermediate shaft 54 is in the offset position as described above, the slack side portions 44c and 46c of the chains 44 and 46 extend obliquely so as to pass through the center line C in the engine width direction. Therefore, a space is secured in the front side of the engine main body in the region on the left side of the center line C when viewed from the front, so that the tensioner levers 74 and 76 are within the region in the width direction of the front surface of the engine main body. It has become.

As a guide mechanism, each tensioner lever 74, 76 is provided with a lower tensioner lever adjuster 80 and an upper tensioner lever adjuster 82.
Each tensioner lever adjuster 80, 82 is provided on the back side of each tensioner lever 74, 76 (opposite the guide surface), and applies a predetermined pressure to each tensioner lever 74, 76. That is, the adjusters 80 and 82 are operated by hydraulic pressure and have a function of adjusting the tension of the chains 44 and 46 by applying pressure to the tensioner levers 74 and 76.
As a specific structure, the adjusters 80 and 82 include plungers (movable end portions) 80b and 82b that can move in the axial direction by hydraulic pressure with respect to the main body portions 80a and 82a, and these plungers 80b and 82b. The front end of each of the tensioner levers 74 and 76 is in contact with the receiving surface portions 74b and 76b of the tensioner levers 74 and 76 so as to apply pressure to the tensioner levers 74 and 76.

  A main body 80a of the lower tensioner lever adjuster 80 is attached to an adjuster mounting seat 12e of the timing case 12 shown in FIG. As shown in the cross section of the mounting seat 12e in FIG. 5, an oil passage 12f is formed in the adjuster mounting seat 12e from the cylinder block 2 to the timing case 12, so that the plunger 80b receives oil pressure through the oil passage 12f. It has become.

  As shown in FIG. 6, the upper tensioner lever adjuster 82 is mainly composed of a main body portion 82a and a plunger 82b. The main body portion 82a has a threaded portion 82c, a head portion 82d, and an oil passage as will be described later. A groove 82e to be formed and an oil inlet 82f are formed, and the plunger 82b receives hydraulic pressure through the groove 82d and the oil inlet 82e. The adjuster 82 is attached to the timing cover 40 as will be described later.

Here, the other structure of the chain drive mechanism 42 is demonstrated with reference to FIG.
As shown in FIG. 4, a balancer shaft 64 and its sprocket 65 are provided on the oil pan 10 below the crankshaft 14. Here, only one of the pair of left and right balancer shafts is shown. A balancer chain 66 is stretched over the sprocket 65 of the balancer shaft 64 and the second sprocket 49 of the crankshaft 14, and this balancer chain 66 extends in the vertical direction of the engine, and more than the lower chain 44 described above. It is arranged on the rear side, that is, on the side close to the engine body. The balancer chain 66 is also provided with a fixed chain guide 67 on its tension side portion 66a, and a balancer chain tensioner lever 68 and its adjuster 69 on its loose side portion 66b. The fixed chain guide 67, the tensioner lever 68 and the adjuster 69 are all attached to the cylinder block 2.

Next, the entire structure of the timing cover 40 will be described with reference to FIGS. 1, 2, and 7. FIG. 7 is a front view of the timing cover according to the present embodiment.
As shown in FIGS. 1, 2, and 7, the timing cover 40 covers the above-described chain drive mechanism 42, and extends from the flat surface portion 40 a and the peripheral portion of the flat surface portion 40 a toward the engine body side. The wall portion 40b has a U-shaped cross section as a whole. On the other hand, the wall 40b is not formed on the upper edge 40c of the cover 40 and is opened upward. As shown in FIGS. 1 and 2, the cylinder head cover 6 is attached to the upper surface portion of the timing cover 40 so as to cover the open portion of the upper edge portion 40 c, and as a result, almost the entire chain drive mechanism 42. Is covered with a timing cover 40, and a part of each of the camshafts 16, 17, their sprockets 60, 62 and the upper chain 46 is covered with a cylinder head cover 6. The timing cover 40 is preferably integrally formed of cast metal, and is made of an aluminum alloy in this embodiment.

As shown in FIG. 7, a plurality of bolt through holes 40d are formed at predetermined intervals on the peripheral wall surface portion 40b of the timing cover 40. As shown in FIG. 1, the timing cover 40 has these bolt through holes. A bolt passing through 40d, and a screw hole 106c (see FIG. 4) formed in the peripheral portion of the timing case 12 and the cylinder block 2 at a position corresponding to the bolt through hole 40d (a part is common with a screw hole 106d described later). Thus, the cylinder block 2 and the timing case 12 are fixed. Seals (not shown) are provided on the periphery of the timing cover 40 and the portion that contacts the timing case 12 or the cylinder block 2. As will be described later, an intermediate portion of the timing cover 40 is also fixed to the engine body by a bolt.
In addition, a mounting seat 40e for the crankshaft pulley 14a and a mounting seat 40f for the idle pulley 26a in which a hole through which the crankshaft 14 (see FIGS. 1 and 2) is formed are formed on the flat surface portion 40a.

Next, a structure for attaching the upper tensioner lever adjuster 82 to the timing cover 40 will be described with reference to FIGS. 8 is a cross-sectional view of the adjuster mounting portion of the timing cover as viewed along line VIII-VIII in FIG. 7, and FIG. 9 is an adjuster mounting portion of the timing cover as viewed along line IX-IX in FIG. It is sectional drawing which shows an oil path.
As shown in FIG. 7, the mounting portion 90 for the upper tensioner lever adjuster 82 described above is formed integrally with the timing cover 40 above the timing cover 40.

As shown in FIG. 8 and FIG. 9, the mounting portion 90 is formed with a cylindrical portion 90 a in which a thread groove is formed on the inner surface, and two ribs 90 b for increasing the rigidity of the mounting portion 90. Yes. These ribs 90b are formed integrally with an engine mount bracket mounting seat portion 100, which will be described later, so as to increase the rigidity of the timing cover 40 itself.
As shown in FIG. 6, the screw portion 82c of the upper tensioner lever adjuster 82 is screwed into the cylindrical portion 90a from the outside of the timing cover 40 and fixed. When the head 82d is screwed in until it comes into contact with the cylindrical portion 90a, a closed space is formed by the head portion 82d and the groove portion 82e, and this becomes an oil passage.
As shown in FIG. 9, the cylindrical portion 90a is formed with an oil passage 90c that communicates with the formed oil passage. The oil passage 90c communicates with an oil passage (not shown) formed in the cylinder head 4, and the plunger 82b of the adjuster 82 receives oil pressure through these oil passages.

Next, an engine mount bracket mounting seat portion formed on the timing cover 40 and a structure for mounting the engine to the vehicle body will be described with reference to FIGS.
10 is a cross-sectional view taken along line XX in FIG. 7, FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. 7, and FIG. 12 is indicated by XII in FIG. FIG. 13 is a front view similar to FIG. 1 for explaining a structure for mounting the engine to the vehicle body.
First, as shown in FIGS. 1 and 7, an engine mount bracket mounting seat portion 100 is formed above the timing cover 40 adjacent to the adjuster mounting portion 90 described above. As shown in FIGS. 10 and 11, the mount bracket mounting seat portion 100 is formed so as to gradually increase in thickness from the lower side to the upper side, and the upper surface thereof is the engine mount bracket 110 (see FIG. 13). The mounting seat surface 100a is attached. Thus, by increasing the thickness, the rigidity of the timing cover 40 itself and the support rigidity of the engine 1 are increased. As shown in FIG. 10, the common shaft 78 of the tensioner levers 74 and 76 described above is also attached to the timing cover 40, so that the tensioner levers 74 and 76 are surely supported. It has become.

  As shown in FIGS. 11 and 12, screw holes 100b are formed in three places on the mounting seat surface 100a, and stud bolts 102 for attaching the engine mount bracket (see FIGS. 1 and 2) are formed in these screw holes 100b. (See FIG. 13). As shown in FIG. 13, an engine mount bracket 110 is attached to the mounting seat surface 100 a by a stud bolt 102 and a nut, and an engine mount unit 112 is attached to the engine mount bracket 110. The engine mount unit 112 is attached to a vehicle body side bracket 116 fixed to a front side frame 114 extending in the longitudinal direction of the vehicle body in the engine room. In this way, the engine 1 is attached to the vehicle body. In the present embodiment, the engine 1 is placed horizontally, and the front portion of the engine 1 is attached to the front side frame 114 in this way.

Next, referring to FIGS. 4, 7, and 10, the mounting structure of the timing cover 40 to the engine body in the mounting seat portion 100 and the layout of each component associated therewith are described.
First, as shown in FIG. 7, the mount bracket mounting seat portion 100 is formed with a total of five mounting portions 100d to 100f arranged side by side in the width direction and the vertical direction for mounting the timing cover 40 to the engine body. Of these, the two attachment portions 100d are arranged at the peripheral edge portion of the timing cover 40, and the remaining three attachment portions 100e and 100f are formed at the intermediate portion in the width direction of the engine body.
As shown in FIG. 10, these attachment portions 100 d to f have a boss-shaped cylindrical portion 100 g, and the boss-shaped cylindrical portion 100 g has a length that contacts the timing case 12. Then, from the outside of the timing cover 40, a bolt 104 (see FIG. 1) is passed through the hollow portion of the boss-shaped cylindrical portion 100 g and fastened to the cylinder block 2 and the timing case 12. The part is attached to the engine body. In this way, the attachment rigidity of the timing cover 40 to the engine body is increased and the membrane vibration of the timing cover 40 is suppressed.

Here, the above-described chain drive mechanism 42 is provided inside the timing cover 40, and the boss-like cylindrical portion 100g of the three attachment portions 100e and 100f formed at the intermediate portion in the width direction of the engine body. And bolt 104 should not interfere with its mechanism 42.
Therefore, in this embodiment, the following configuration is adopted.
That is, as shown in FIG. 4, screw holes 106 d to 106 d to which the bolts 104 are fastened are formed in the timing case 12 and the cylinder block 2 behind the timing case 12 at positions corresponding to the mounting portions 100 d to f of the timing cover 40. Has been. And the opening part 76e is formed in the position of two places corresponding to the attaching part 100e and the screw hole 106e in the upper tensioner lever 76 mentioned above. These opening portions 76e are larger than the outer diameter of the cylindrical portion 100g and the swinging of the tensioner lever 76 so as not to interfere with the boss-shaped cylindrical portion 100g (bolt 104) even when the upper tensioner lever 76 swings. It is formed to extend in the direction.
On the other hand, the attachment portion 100f, its bolt 104, and screw hole 106f are disposed inward of the upper chain 46 so as not to interfere with the upper chain 46 and the like.

Next, main effects of the present embodiment will be described.
First, the operation and effects relating to the intermediate shaft 54 and the upper and lower two-stage chains 44 and 46 will be described.
In this embodiment, as described above, the fuel pump 30 is driven by the output of the crankshaft 14 and the intermediate shaft 54 for transmitting power to the upper chain 46 is separately provided. The intermediate shaft 54 is provided at a position offset inward from the fuel pump shaft 50 in the width direction of the engine front portion and offset toward the fuel pump shaft 50 from the engine width direction center line C described above. The tight side portions 44a and 44b of the lower chain 44 can be relatively extended in the width direction. As a result, it is possible to suppress the front portion of the engine 1 from being widened.

  For example, as shown in FIG. 14 with a virtual upper chain indicated by phantom lines, if the fuel pump shaft 50 is provided with the function of an intermediate shaft and the upper chain is passed over, the engine body is The width of will spread. That is, as shown in FIG. 14, the auxiliary machine region H to which the high-pressure fuel pump 30 or the like is attached is difficult to narrow further, but the other parts should not be wider than the engine body region E. It is preferable in arranging other auxiliary machines such as the alternator 18 or mounting the engine on the vehicle body. In the present embodiment, by providing the intermediate shaft 54 and arranging the intermediate shaft 54 as described above, it is possible to eliminate such a widening of the width, and as a result, it is possible to reduce restrictions on the arrangement of the auxiliary machines or the engine 1. The degree of freedom of mounting in the engine room can be increased.

  Furthermore, the engine of the present embodiment is a common rail direct injection diesel engine, and a large force (load) is required to drive the high-pressure fuel pump 30. Therefore, it is desirable to use the output of the crankshaft 14. . In such an engine, by using the two upper and lower chains 44 and 46 and providing the intermediate shaft 54, even if both the fuel pump 30 and the camshafts 16 and 17 are driven, the above-described configuration causes the engine This is effective in that the front portion can be prevented from spreading in the width direction.

That is, by configuring the chain in two stages of the lower chain 44 and the upper chain 46, even if the driving load of the high-pressure fuel pump 30 is large, only the lower chain 44 receives the load. , 17 drive timing error can be reduced. If both the auxiliary machine and the camshaft are driven by a single chain, the chain becomes long and errors are likely to occur. Therefore, in order to obtain the timing as designed, the strength of the chain must be increased. However, by configuring in two stages as in the present embodiment, the strength of the lower chain 44 is increased, and the strength of the upper chain 46 does not have to be increased as much as the lower chain 44, so that the cost can be reduced.
In this embodiment, since the chain pitch of the lower chain 44 is larger than the chain pitch of the upper chain 46, it is possible to more reliably withstand the high load of the high-pressure fuel pump 30. On the other hand, since the upper chain 46 is not as heavily loaded as the lower chain 44, a lower strength than the lower chain 44 can be used, and the cost can be reduced.

  Next, since the intermediate shaft 54 is provided at a position offset toward the fuel pump shaft 50 side from the center line C in the engine width direction, the space on the left side of the center line C is widened. In the present embodiment, the tensioner levers 74 and 76 for guiding and adjusting the tension of the slack side portions 44c and 46c of the chains 44 and 46 can be effectively arranged in the left region. There is no need to increase the width.

Next, functions and effects relating to the arrangement of the upper tensioner lever 76 and the adjuster 82 will be described.
First, since the upper tensioner lever adjuster 82 is attached to the timing cover 40, even if there is no space for attaching the tensioner lever adjuster on the front surface portion of the engine body, an attachment portion protruding in the width direction is not formed on the engine body. Further, an adjuster 82 can be provided. In particular, in the present embodiment, since the upper chain 46 is disposed in front of the lower chain 44, the adjuster 82 can be easily attached to the timing cover 40 instead of the engine front portion.

  A cylindrical portion 90 a is formed in the attachment portion 90 for the adjuster 82 formed on the timing cover 40, and the adjuster 82 can be attached from the outside of the timing cover 40 by the cylindrical portion 90 a. Yes. Accordingly, when the engine 1 is assembled, the timing cover 40 is attached to the engine body and then the adjuster 82 is assembled to the timing cover 40. Alternatively, the timing cover 40 is attached to the engine body after the adjuster 82 is assembled to the timing cover 40. It can also be attached, and the assembling property of the upper tensioner lever adjuster 82 is improved.

  In particular, when the adjuster 82 is assembled to the timing cover 40 after the timing cover 40 is attached to the engine body, the adjuster 82 is simply inserted into the attachment portion 90 and fastened to the receiving surface portion 76b of the upper tensioner lever 76. Can be ensured with high accuracy. Further, compared with the case where the timing cover 40 is attached to the engine body after the adjuster 82 is assembled to the timing cover 40, the possibility of interference between the adjuster 82 and the tensioner lever 72 or the chain 46 is reduced.

  Next, the tensioner levers 74 and 76 are disposed so as to be displaced in the front-rear direction and can be swung by a common swinging shaft 78. Therefore, the tensioner levers 74 and 76 are disposed in a compact manner. In addition, the space formed by the offset of the intermediate shaft 54 described above can be used effectively.

Next, the function and effect of the fixed chain guides 70 and 72 will be described.
The fixed chain guide is generally fixed outside the chain. On the other hand, in this embodiment, since the upper fixed chain guide 72 is fixed to the engine body inside the upper chain 46, the space can be used effectively. In particular, by offsetting the intermediate shaft 54 as in the present embodiment, the space for handling the upper chain 46 is reduced, and even if the space for installing the chain guide outside the chain is reduced accordingly, Thus, by fixing the fixed chain guide inside the chain, the fixed chain guide can be attached effectively without increasing the width of the engine.

  Furthermore, in this embodiment, since the upper chain 46 is disposed on the front side of the lower chain 44, the upper fixed chain guide 72 is connected to the rear side of the chain 46 from the mounting portion (between the chain 46 and the engine body). ) To extend out of the chain 46. In the present embodiment, a chain guide surface 72a is formed on the outer side of the chain 46, and the guide surface 72a guides the chain 46 by curving it inward. Therefore, the upper chain 46 can be easily routed in the front portion of the engine body as the upper chain 46 is not curved outward. Further, the spread in the width direction of the engine can be suppressed by preventing the upper chain 46 from interfering with the timing case 12 and the edge in the width direction of the engine. Furthermore, contact with the timing case 12 due to the upper chain 46 flapping and being displaced outward can also be prevented.

  Further, since the lower fixed chain guide 46 is provided inward of the lower chain 44, the space on the front surface of the engine is effectively utilized, and both the two tension side portions 44a and 44b of the lower chain 44 are 1 Can be guided by two fixed chain guides.

Next, the effects of the attachment structure of the timing cover 40 to the engine body and the attachment structure of the engine to the vehicle body via the timing cover 40 will be described.
First, in the intermediate portion of the timing cover 40, the mounting portions 100e and 100f, the boss-shaped cylindrical portion 100g, and a plurality of fastening bolts 104 corresponding thereto are provided, so that the timing cover 40 is attached to the engine body. The mounting rigidity can be increased and the membrane vibration of the timing cover 40 can be suppressed. Further, since the mounting rigidity of the timing cover 40 is increased, it is possible to ensure the rigidity of the engine mounted on the vehicle body by the engine mount bracket mounting seat portion 100 formed on the timing cover 40. Furthermore, by providing a plurality of bolts 104 in the width direction or the vertical direction, it is possible to increase the degree of freedom of the fastening position while securing the mounting rigidity.

Further, since the upper tensioner lever 76 is formed with an opening 76e through which the bolt 104 and the boss-like cylindrical portion 100g pass, restrictions on the arrangement of the bolt 104 (cylindrical portion 100g) provided in the middle portion thereof. As a result, the support rigidity of the timing cover 40 can be more reliably ensured. Since the bolt 104 (cylindrical portion 100g) provided in the intermediate portion is disposed inside the upper chain 46 or in the opening 76e formed in the upper tensioner lever 76, the bolt 104 (cylindrical portion 100g) is disposed in the timing cover 40. Further, the layout of the chain drive mechanism 42 can be prevented from being hindered.
Furthermore, since the opening 76e is larger than the outer diameter of the cylindrical portion 100g and extends in the swinging direction of the tensioner lever 76, the cylindrical portion 100g or the like does not hinder the swinging of the tensioner lever 76, and the tensioner lever 76 If the size of the opening 76e is made as small as possible so that the above-described interference does not occur, the rigidity of the tensioner lever 76 itself can be ensured.

  Here, since the tensioner levers 74 and 76 have functions of guiding the chains 44 and 46 and adjusting the tension, a predetermined rigidity is required. In this embodiment, the upper tensioner lever 76 is provided with two openings 76e. However, since the overall dimension of the upper tensioner lever 76 is larger than the dimension of the lower tensioner lever 74, the rigidity is more reliably ensured. Is secured. Accordingly, it is possible to achieve both the securing of the function of the tensioner lever 76 and the freedom of layout of the bolts 104 and the like by the opening 76e.

  Next, an engine mount bracket mounting seat portion 100 with increased rigidity is formed at an intermediate portion in the width direction of the timing cover 40, and the engine 1 uses the mounting seat portion 100 to mount the timing cover 40. Therefore, it is possible to achieve both an efficient layout of the chain drive mechanism 42 in the timing cover 40 and an efficient layout of the mounting structure to the vehicle body.

1 is a front view of an engine according to an embodiment of the present invention. 1 is a side view of an engine according to an embodiment of the present invention. It is a front view of the timing case by embodiment of this invention. It is a front view of the engine for demonstrating the chain transmission mechanism by embodiment of this invention. It is a figure which shows the cross-section of the adjuster mounting seat seen along the VV line of FIG. It is a figure which shows the upper tensioner lever adjuster by embodiment of this invention. It is a front view of the timing cover by the embodiment of the present invention. It is sectional drawing of the adjuster attaching part of the timing cover seen along the VIII-VIII line of FIG. It is sectional drawing which shows the adjuster attaching part and oil path of a timing cover seen along the IX-IX line of FIG. It is sectional drawing seen along the XX line of FIG. It is sectional drawing seen along the XI-XI line of FIG. It is the arrow line view seen from the direction of the arrow shown by XII of FIG. It is a front view shown like FIG. 1 for demonstrating the attachment structure to the vehicle body of the engine by embodiment of this invention. It is the schematic of the front part structure of the engine for demonstrating the effect by this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder block 4 Cylinder head 12 Timing case 14 Crankshaft 16, 17 Camshaft 30 High pressure fuel pump 40 Timing cover 42 Chain drive mechanism 44 Lower chain 44a, 44b Tight side part 44c Loose side part 46 Upper chain 46a, 46b Tension Side portion 46c Loose side portion 48, 49, 52, 56, 58, 60, 62, 65 Sprocket 50 Fuel pump shaft 54 Intermediate shaft 70, 72 Lower or upper fixed chain guide 74, 76 Lower or upper tensioner lever 76e Opening Part 78 Common swing shafts 80, 82 Lower or upper tensioner lever adjuster 90 Upper tensioner lever adjuster mounting part (timing cover)
100 Engine mount bracket mounting seat 100d to f Timing cover mounting portion to engine body

Claims (7)

An endless belt for driving a camshaft disposed on the cylinder head by the output of the crankshaft, a plurality of endless belt guides for guiding the endless belt, and a timing cover for covering the endless belt and the endless belt guide Provided, and the front end structure of the engine in which the outer peripheral end portion and the intermediate portion of the timing cover are respectively fastened to the engine front portion by bolts,
At least one of the endless belt guides has an opening that penetrates the endless belt guide in the engine longitudinal direction,
The engine front structure, wherein a bolt at an intermediate portion of the timing cover is fastened to the front surface of the engine through the opening of the at least one endless belt guide. The endless belt guide includes a swingable tensioner lever disposed on the loose side of the endless belt,
2. The engine front structure according to claim 1, wherein the opening is formed in the tensioner lever so as to extend in a swinging direction of the tensioner lever. The bolt at the intermediate portion of the timing cover includes a plurality of bolts arranged in the width direction with respect to the engine front portion,
Some of these bolts are fastened to the engine front part through the opening of the endless belt guide, and the other part is fastened to the engine front part in the region surrounded by the endless belt. The front structure of the engine according to claim 1 or 2. The bolt at the intermediate portion of the timing cover includes a plurality of bolts arranged in the vertical direction with respect to the front surface of the engine.
The opening includes a plurality of openings lined up and down in the endless belt guide at positions corresponding to the plurality of bolts lined up and down in the vertical direction,
The engine according to any one of claims 1 to 3, wherein the plurality of bolts arranged in the vertical direction are fastened to the engine front portion through the plurality of openings arranged in the vertical direction of the endless belt guide. Front structure. The endless belt is a chain,
The timing cover is made of cast metal, and further has an engine mount mounting seat integrally formed on the front surface thereof, and the engine mount mounting seat is disposed in the vicinity of the bolt at the intermediate portion of the timing cover. The front structure of an engine according to any one of claims 1 to 4. The endless belt guide includes a fixed endless belt guide disposed on the tension side of the endless belt,
The engine front structure according to any one of claims 1 to 5, wherein a mounting bolt of the fixed endless belt guide to the engine front portion is disposed in a region surrounded by the endless belt. The engine is a DOHC type engine in which two camshafts are arranged on the cylinder head.
The endless belt includes an upper endless belt for driving the two camshafts and a lower endless belt driven by the crankshaft,
The engine further includes an intermediate shaft that transmits the driving force of the lower endless belt to the upper endless belt,
The intermediate shaft is arranged to be offset to the tension side of the endless belt in the width direction of the engine front portion, and the tensioner lever is arranged in the offset direction with respect to the upper endless belt in the width direction of the engine front portion. The engine front structure according to claim 2, wherein the engine is disposed in an opposite region.

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