JPH11343921A - Front cover structure of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve compactness of an engine and prevent a front cover from contacting with a timing belt. SOLUTION: This cover structure comprises a cam pulley 36 provided toward the loosed side of a timing belt 39 and a pump pulley 38 toward the tightened side thereof. The corresponding portion to a predetermined range from the central position toward the pump side between both the pulleys 36, 38, in the side wall portions 64 and the like of a front cover (C) which face to the outer peripheral surface of the timing belt 39 between both the pulleys, is swelled outside so as to be separated from the timing belt 39. A torsional damper 50 is fitted to the cam pulley 36 and the belt tension of the timing belt 39 is adjusted by an auto-tensioner 51.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine in which a transmission mechanism for driving a valve operating system camshaft, accessories and the like of the engine by a crankshaft via an endless transmission member is accommodated in a front cover on the front side of the engine. Belongs to the technical field of front cover structure.

[0002]

2. Description of the Related Art Conventionally, as a front cover structure for an engine of this type, for example, as disclosed in Japanese Patent Application Laid-Open No. 8-326550, a cam pulley on a valve system camshaft and a cam pulley are disposed adjacent to the cam pulley. A pump pulley on the input shaft of the fuel injection pump and a timing belt for drivingly connecting these pulleys to a crank pulley on the crankshaft are arranged on the front of the engine, and these are accommodated in a front cover. It has been known. In this device, the belt transmission mechanism including the timing belt and the pulley is housed in the front cover in a substantially sealed state, so that the timing belt and the pulley are prevented from being deteriorated by rainwater and the reliability of the belt transmission mechanism is improved. Can be planned.

[0003] For example, Japanese Patent Application Laid-Open No. 57-198306 discloses that a front cover side wall portion facing an outer peripheral surface of a timing belt between a cam pulley and a pump pulley is stationary so that a substantially center position between both pulleys is a vertex. The timing belt in the state is bulged to the outer peripheral side. In this case, even if the timing belt spreads outward due to centrifugal force during traveling, contact with the side wall of the timing belt can be prevented.

[0004]

By the way, for example, a fuel injection pump of a diesel engine supplies high-pressure fuel to an injection nozzle of each cylinder, so that a reaction force from a plunger for discharging fuel is large, and the Input shaft 1
Angular velocity fluctuation during rotation is also likely to increase. On the other hand, since the valve system camshaft also has angular velocity fluctuation due to valve reaction force during one rotation, the timing belt between the cam pulley and the pump pulley receives the interaction of the different angular velocity fluctuations of the camshaft and the pump input shaft. Vibrates greatly (so-called string vibration).

[0005] However, the present inventors have found that the maximum amplitude position due to the resonance of the string vibration is not always at the center position between the cam pulley and the pump pulley. Therefore, in this case, in the above-described conventional front cover structure, the timing belt and the side wall of the front cover come into contact with each other at the maximum amplitude position of the string vibration, which causes problems such as generation of abnormal noise and reduction in the reliability of the belt. .

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and has as its object to determine the shape of the side wall of the front cover in consideration of the string vibration of an endless transmission member such as a timing belt. Accordingly, it is an object of the present invention to reduce the size of the engine and prevent problems caused by contact between the front cover and the endless transmission member.

[0007]

In order to achieve the above object, according to the present invention, the maximum amplitude position of the string vibration of the endless transmission member is set so that the position of the endless transmission member advances more than the center position between the two driven wheels. Paying attention to shifting to the front side in the direction, the shape of the front cover side wall portion is expanded outward at a portion corresponding to the maximum amplitude position of the string vibration.

More specifically, according to the first aspect of the present invention, a cam-side driven wheel with teeth on a valve system camshaft and a tooth on an input shaft of a fuel injection pump are provided at one end of the engine in the crankshaft direction. Pump driven wheels are disposed adjacent to each other, and are drivingly connected to toothed drive wheels on the crankshaft via endless transmission members, and at least both the driven wheels and the endless transmission members are provided in the front cover. The front cover structure of the housed engine is assumed. The front cover has a side wall extending in the crankshaft direction opposite to the outer peripheral surface of the endless transmission member between the cam side and the pump side driven wheel. The front corresponding portion corresponding to the front side in the traveling direction of the endless transmission member with respect to the center position of the endless transmission member of the endless transmission member expands outward away from the stationary endless transmission member in comparison with the rear corresponding portion corresponding to the rear side. Configuration.

According to this configuration, when the engine is operating,
The endless transmission member passes through the cam-side driven wheel and the pump-side driven wheel in order from the driving wheel on the crankshaft, and revolves around the driving wheel,
Thus, the camshaft and the pump input shaft are driven to rotate by the crankshaft. At this time, where the endless transmission member advances from the cam-side driven wheel, the separation between the two teeth is delayed, and a force toward the inner peripheral side may act on the endless transmission member. When the member enters the driven wheel on the pump side, the engagement between the two teeth may be delayed, and the endless transmission member may be pushed outward. For this reason, the endless transmission member that advances from the cam-side driven wheel to the pump-side driven wheel receives a force toward the inner periphery near the cam-side driven wheel, and receives a force toward the outer periphery near the pump-side driven wheel. As a result, the maximum amplitude position of the string vibration of the endless transmission member is shifted forward in the traveling direction of the endless transmission member from the center position between the driven wheels.

On the other hand, according to the present invention, the side wall of the front cover facing the outer peripheral surface of the endless transmission member between the cam-side and pump-side driven wheels is provided with the endless transmission member more than the center position between the two driven wheels. The front corresponding portion corresponding to the front side in the traveling direction is shaped to bulge outward compared to the rear corresponding portion on the opposite side. That is, of the side walls of the front cover,
By bulging the portion corresponding to the maximum amplitude position of the string vibration of the endless transmission member to the maximum, it is possible to prevent the endless transmission member from touching the side wall portion of the front cover even if the endless transmission member vibrates greatly due to resonance, Therefore, while minimizing the size of the engine by minimizing the amount of swelling of the front cover side wall portion, it is possible to prevent problems caused by contact between the front cover and the endless transmission member.

According to the second aspect of the present invention, the side wall of the front cover according to the first aspect of the present invention has a tangential line circumscribing the cam side and the pump side driven wheel and a driven wheel located rearward in the traveling direction of the endless transmission member. And gradually bulges outward from a portion corresponding to the contact point to a central portion corresponding to the center position of the tangent line, and a portion corresponding to a predetermined range from the center position of the tangent line to the front side in the traveling direction is the above-described portion. It is configured to bulge outward from the center part or larger than the center part. This embodies a desirable bulging state of the side wall portion of the front cover.

According to the third aspect of the present invention, the first or second aspect is provided.
In the described invention, both the cam-side and the pump-side driven wheels are arranged above the engine, and the pump-side driven wheels are
This is located at a position lower than the cam-side driven wheel and on the front side in the traveling direction of the endless transmission member, so that both the cam-side and pump-side driven wheels are arranged above the engine, and are located above both driven wheels. Since the side wall of the front cover bulges upward on the pump side at a relatively low position, the size of the front cover in the engine height direction does not increase due to the bulge.

According to a fourth aspect of the present invention, in the engine according to the third aspect of the present invention, the crankshaft extends in the left-right direction of the vehicle, and the pump-side driven wheel is located on the vehicle front side of the cam-side driven wheel. It is mounted horizontally.

That is, in general, the hood above the engine is shaped so as to gradually increase from the vehicle front side to the vehicle rear side in order to improve the aerodynamic characteristics of the vehicle. Therefore, in the present invention, the pump-side driven wheel, which is located at a lower position than the cam-side driven wheel, is located on the front side of the vehicle,
The side wall portion of the front cover located above both driven wheels can be shaped to follow the hood, thereby effectively utilizing the engine room space.

According to a fifth aspect of the present invention, the axis of the cam shaft of the engine according to the fourth aspect of the present invention is located at substantially the same height as the upper surface of the cylinder head, and the fuel injection pump is viewed from the vehicle front-rear direction. And at least a portion thereof is disposed so as to overlap the cylinder head. Thus, the fuel injection pump can be disposed at substantially the same height as the cylinder head at the top of the engine, and the space below the fuel injection pump can be used as an accessory arrangement space.

According to a sixth aspect of the invention, the engine according to the fourth aspect of the invention is provided with a total of four or more intake valves and exhaust valves for each cylinder.

As a result, in the above engine, the valve reaction force to the camshaft becomes larger than that of an engine in which, for example, one intake valve and one exhaust valve are provided for each cylinder,
Since the angular velocity fluctuation per rotation of the camshaft tends to increase, the amplitude of the string vibration of the endless transmission member increases, and the contact with the front cover easily occurs. Therefore, in such a front cover structure of an engine, it is particularly effective to prevent the contact between the side wall portion and the endless transmission member by forming the swelling of the front cover side wall portion.

According to a seventh aspect of the present invention, in the first aspect of the present invention, the fuel injection pump discharges high-pressure fuel of 70 MPa or more.

As a result, the discharge pressure of the fuel injection pump is extremely high, and the angular velocity fluctuation of the pump input shaft becomes extremely large. Therefore, even in an engine equipped with the fuel injection pump, the contact between the endless power transmission member and the front cover is prevented. Easy to occur. Therefore, also in such a front cover structure of the engine, it is particularly effective to prevent the contact between the front cover side wall portion and the endless transmission member by forming the bulge of the front cover side wall portion, similarly to the invention of claim 6. Become.

According to an eighth aspect of the present invention, at least one of the camshaft and the cam-side driven wheel according to the seventh aspect of the present invention is provided with a torsional damper for attenuating angular velocity fluctuations of the camshaft. . Thus, the angular velocity fluctuation of the camshaft is attenuated by the torsional damper, so that the string vibration of the endless transmission member can be suppressed, and the degree of swelling of the front cover side wall portion can be reduced accordingly.

According to a ninth aspect of the present invention, in the invention of the seventh aspect, the tension of the endless transmission member is adjusted by pressing a loose side span of the span between the drive wheel and the driven wheel of the endless transmission member. An automatic tensioner is provided. As a result, the tension of the endless transmission member is constantly adjusted by the auto-tensioner, and the tension fluctuation of the endless transmission member is suppressed, and the string vibration is suppressed. Therefore, the degree of swelling of the front cover side wall is reduced accordingly. It becomes possible.

According to the tenth aspect of the present invention, a cam-side timing pulley on a valve system camshaft disposed on an upper portion of the engine at one end of the engine in the crankshaft direction and an input shaft of an auxiliary machine. A timing pulley adjacent to the auxiliary device and a driving pulley via a timing belt are connected to a timing pulley on a crankshaft disposed on a lower portion of the engine. In addition, it is assumed that the engine has a front cover structure in which the timing belt is housed in the front cover. An idler pulley for winding a timing belt between the pulleys is provided between the crank side and the auxiliary timing pulley, and a timing belt between the pulleys is provided between the crank side and the cam timing pulley. A tensioner that adjusts the belt tension by pressing is provided, and only the cam-side timing pulley of the cam-side and auxiliary-device-side timing pulleys is provided with a flange portion that regulates movement of the timing belt in the belt width direction. The front cover has a side wall portion extending in the crankshaft direction facing the outer peripheral surface of the timing belt between the cam side and the auxiliary device side timing pulley, and of the side wall portion, between the two timing pulleys. The auxiliary part on the accessory side with respect to the center position has a timing base in a stationary state compared with the cam side part on the cam side with respect to the center position. A configuration that bulges outward away from bets.

According to this configuration, when the engine is operating,
The timing belt passes through the cam-side timing pulley and the accessory-side timing pulley in order from the crank-side timing pulley to the crank-side timing pulley, whereby the camshaft and the accessory input shaft are rotationally driven by the crankshaft. You. At this time, a string vibration occurs in the timing belt between the cam-side and the accessory-side timing pulley due to the angular velocity fluctuation of the cam-side timing pulley. The belt receives the force on the inner circumference side of the belt due to the sliding frictional resistance between the flange and the flange.
The maximum amplitude position of the string vibration of the timing belt is shifted to the accessory side from the center position between the two timing pulleys. Note that the phase difference between the angular velocities of the timing pulleys on the cam side and the auxiliary machine side also causes the timing belt to reduce vibration.

On the other hand, in the present invention, similarly to the first aspect of the present invention, the side wall of the front cover facing the outer peripheral surface of the timing belt between the cam-side and auxiliary-device-side timing pulleys is provided between the two pulleys. Are bulged more than the cam-side portion at the accessory-side portion corresponding to the accessory side with respect to the center position. That is, by making the side wall portion of the portion corresponding to the maximum amplitude position of the string vibration of the timing belt maximum bulge, the size of the engine can be reduced while the front cover comes into contact with the endless transmission member. Failure can be prevented.

According to the eleventh aspect of the present invention, the side wall of the front cover according to the tenth aspect corresponds to a contact point between a tangent line circumscribing the pitch circle of the cam-side and auxiliary machine-side timing pulleys and the cam-side timing pulley. From the part that
Along with swelling outward gradually toward a central portion corresponding to the central position of the tangent, a portion corresponding to a predetermined range from the central position of the tangent to the accessory side is the same as or larger than the central portion outward. It has a bulging configuration. This embodies a desirable bulging state of the side wall portion of the front cover.

According to a twelfth aspect of the present invention, in the invention of the eleventh aspect, the crankshaft of the engine is supported by the cylinder block, the camshaft is supported by the cylinder head above the cylinder block, and the flange is formed by the cam. It is configured to be provided at both ends in the width direction of the side timing pulley.

That is, generally, there is an assembling error between the cylinder head and the cylinder block, so that the cam-side timing pulley and the crank-side timing pulley are also displaced in the crankshaft direction. On the other hand, according to the present invention, flanges are provided on both sides in the width direction of the cam-side timing pulley to restrict the movement of the timing belt in the belt width direction, and the displacement between the running timing belt and each timing pulley. Can be effectively suppressed. Further, since the accessory-side timing pulley is not provided with a flange portion, it is possible to prevent an increase in load on the timing belt due to sliding contact with the flange portion on the accessory side where string vibration of the timing belt is relatively large.

According to a thirteenth aspect of the present invention, in the engine according to the twelfth aspect, a total of four or more intake valves and exhaust valves are provided for each cylinder. This makes it particularly effective to prevent the contact between the side wall portion and the timing belt by the bulging formation of the front cover side wall portion, similarly to the invention of the sixth aspect.

In the fourteenth aspect, the tensioner according to the tenth aspect is an auto tensioner. As a result, similarly to the ninth aspect of the invention, the string vibration of the timing belt can be suppressed by the auto tensioner, so that the degree of bulging of the front cover side wall portion can be reduced accordingly.

According to a fifteenth aspect, in the tenth aspect or the fourteenth aspect, at least one of the camshaft and the cam-side timing pulley is provided with a torsional damper for attenuating the angular velocity fluctuation of the shaft. And
Thus, the string vibration of the timing belt can be suppressed by the torsional damper, as in the invention of claim 8, so that the degree of swelling of the front cover side wall can be reduced accordingly.

According to the sixteenth aspect, in the tenth aspect,
An auxiliary machine according to the invention described in any one of 14 and 15 is a fuel injection pump that discharges fuel by reciprocating a plunger via a cam mechanism by rotation of an input shaft.

As a result, the auxiliary machine is specified as a fuel injection pump having a large angular velocity fluctuation per one rotation of the input shaft, and the timing belt between the cam-side and the auxiliary machine-side timing pulley has an angular velocity fluctuation in addition to the camshaft angular velocity fluctuation. Fluctuation of the angular velocity of the pump input shaft causes a greater string vibration. Accordingly, in such a configuration, it is particularly effective to prevent the contact between the front cover side wall portion and the timing belt by the bulging formation of the front cover side wall portion.

Further, according to the seventeenth aspect,
While a crankshaft is supported by a cylinder block of the engine, a valve system camshaft is supported by a cylinder head above the cylinder block, and a fuel injection pump is attached to at least the cylinder head via a bracket. A cam-side timing pulley on the camshaft and a pump-side timing pulley on the input shaft of the fuel injection pump are arranged adjacent to the engine front side on one end side in the crankshaft direction, and the crank-side timing pulley on the crankshaft. It is assumed that the engine has a front cover structure in which at least the cam-side and auxiliary-device-side timing pulleys and the timing belt are housed in the front cover. And, only the cam-side timing pulley of the cam-side and pump-side timing pulleys is provided with a flange portion that regulates movement of the timing belt in the belt width direction, and is provided between the pump-side and crank-side timing pulleys. An idler pulley for winding the back of the timing belt is provided on the cam shaft side with respect to a plane connecting the rotation axes of both pulleys, and the front cover has a main wall portion superposed on the front surface of the cylinder block, A metal plate member having a side wall portion extending in the crankshaft direction so as to face the outer peripheral surface of the timing belt from the wall portion, and a resin cover member connected to the side wall portion of the plate member; In the side wall portion of the plate member, at least a portion below the pump-side timing pulley is located forward of a center position in the width direction of the pulley. Configuration and to which extend in.

According to this configuration, of the cam-side and pump-side timing pulleys, the pump-side timing pulley is not provided with a flange portion, and has a smaller diameter. In addition, the timing belt between the pump-side and crank-side timing pulleys is turned by an idler pulley, and the belt inner circumference extends at least to the camshaft side with respect to the plane connecting the rotation axes of the pump-side and crank-side timing pulleys. The layout has been moved to the side. This ensures a sufficient space for arranging auxiliary equipment below the pump-side timing pulley.

As a front cover for accommodating each of the timing pulleys and the timing belt, a metal plate member attached to the cylinder block,
Since a resin cover member is connected to the plate member, the timing belt and the timing pulley can be easily inspected simply by removing the cover member.

Further, the side wall portion of the plate member extends below the timing pulley on the pump side to the front side from the center position in the width direction of the pulley, whereby the side wall portion of the front cover below the timing pulley on the pump side is formed. It is constituted by the side wall of the plate member. That is, since the plate member is directly attached to the cylinder head, and the positional accuracy with respect to the cylinder head is higher than that of the cover member, the clearance between the side wall and the pump-side timing pulley can be set relatively small, In addition, the metal plate member can be formed thinner than the resin cover member. Therefore, the fuel injection pump and the auxiliary equipment can be arranged as close as possible.

According to the eighteenth aspect of the present invention, the side wall of the plate member according to the seventeenth aspect corresponds to a portion to be inspected of the timing belt extending from a portion surrounding above the cam-side timing pulley to above the pump-side timing pulley. In the inspection corresponding part, the cam side timing pulley is formed so as to be located behind the center position in the width direction of the cam-side timing pulley, and at least a portion of the cover member connected to the inspection corresponding part has a crankshaft direction. It is assumed that an extended cover side wall is formed.

With this, when the cover member is removed, the portion to be inspected of the timing belt from the portion wound around the cam-side timing pulley to the pump-side timing pulley is exposed. You can easily check the condition.

According to the nineteenth aspect of the present invention, the cover member according to the eighteenth aspect has a through-hole through which a crankshaft is inserted, and an auxiliary device driving pulley is provided on the crankshaft on the front side of the cover member. A first auxiliary device having a driven pulley on an input shaft projecting forward is disposed below the fuel injection pump, and the driven pulley is driven by a belt on the auxiliary device driving pulley. Are linked. The first auxiliary device has a substantially cylindrical casing, and the outer diameter of the casing is smaller on the front side than on the rear side.

Thus, the outer diameter of the casing of the first auxiliary device disposed below the fuel injection pump is smaller at the front portion located below the front cover than at the rear portion. Even if the engine is arranged as close as possible to the fuel injection pump, the clearance between the casing and the front cover can be ensured.

According to a twentieth aspect of the present invention, the engine according to the nineteenth aspect of the present invention is mounted horizontally with the crankshaft directed in the left-right direction of the vehicle, and the camshaft is located rearward of the vehicle with respect to the cylinder center line. On the other hand, the fuel injection pump is located on the front side of the vehicle with respect to the cylinder center line, and the pump input shaft is located at a position lower than the camshaft, and the crankshaft is located below the first accessory of the engine. The front cover above the cam-side and pump-side timing pulleys gradually lowers from the vehicle rear side to the vehicle front side along the hood hood inner surface of the vehicle. It is assumed that the configuration is as follows.

That is, generally, the hood above the engine is shaped so as to gradually increase from the vehicle front side to the vehicle rear side in order to improve the aerodynamic characteristics of the vehicle. On the other hand, in the present invention, the cam shaft
In addition, the fuel injection pump is positioned on the front side of the vehicle, and the pump input shaft is disposed lower than the cam shaft, and the front side of the cam side and the pump side timing pulley is disposed in accordance with the arrangement of the cam shaft and the pump input shaft. The cover is shaped along the inner surface of the hood, and
First and second accessories are arranged vertically below the fuel injection pump. In other words, the fuel injection pump is located as far as possible above the engine along the hood of the vehicle, and the two auxiliary machines are located vertically below the space secured below the engine to maximize the engine room space. We use effectively.

According to the twenty-first aspect, in the seventeenth aspect,
20. The plate member according to any one of the above items, wherein the plate member has a first fastening portion that is fastened to one of the cylinder block and an auxiliary machine fixed to the cylinder block, and a cylinder near the cam-side timing pulley. It is assumed that a second fastening portion fastened to one of the head and the cylinder head cover via a rubber mount and a third fastening portion fastened to the bracket of the fuel injection pump via the rubber mount are provided. .

As a result, the plate member is fastened to the cylinder block or the auxiliary machine fixed to the cylinder block at the first fastening portion, so that the positional accuracy of the plate member with respect to the cylinder block is extremely high. Moreover, if the plate member is directly superimposed on the cylinder block, the clearance between them can be minimized.

Further, the plate member is fastened to the cylinder head or the cylinder head cover and the bracket of the fuel injection pump via a rubber mount, and the mounting error of the cylinder head and the bracket with respect to the cylinder block is absorbed by the rubber mount. Therefore, the distortion can be reduced in a state where the plate member is mounted on the cylinder head side. Further, since the vibration of the engine transmitted to the plate member via each fastening portion is attenuated by the rubber mount at the first and second fastening portions, the film vibration of the plate member is attenuated, and the noise is reduced. Can be

[0046]

Embodiments of the present invention will be described below with reference to the drawings.

(Overall Configuration of Engine) FIG. 2 and FIG.
1 shows an appearance of a diesel engine E according to an embodiment of the present invention. As shown in FIG. 6, the engine E has a cylinder head 2 mounted on an upper surface of a cylinder block 1 and is integrated therewith. Inside the engine E, a front-rear direction of a crankshaft 3 supported by the cylinder block 1 extends ( This is an in-line four-cylinder engine in which four cylinders (cylinders) (not shown) are formed along the vertical direction in FIG. The engine E is mounted horizontally so that the crankshaft 3 extends in the left-right direction of the vehicle (not shown).

In this specification, for convenience of explanation, the longitudinal direction of the cylinder block 1, that is, the crankshaft 3
3 is referred to as the front side of the engine E, the lower side in FIG. 3 is referred to as the front side of the engine E, and the opposite side (the upper side in FIG. 3) is referred to as the rear side of the engine E. The engine E
In the left-right direction (left-right direction in FIGS. 2 and 3) orthogonal to the front-rear direction, the right side (left side in FIGS. 2 and 3) facing the front side of the engine E is called the right side of the engine E, and the opposite side (FIG. 2 and the right side of FIG. 3) will be referred to as the left side of the engine E.

At the front end of the engine E, a crankshaft 3
A belt transmission mechanism A described later that drives the camshaft 4 (see FIG. 4), the fuel injection pump 5 (see FIG. 7), and the like in synchronization with the rotation of
(See FIG. 1), and the belt transmission mechanism A
As shown in FIG. 2, a seal plate (plate member) 6 made of a steel plate and superposed on the front end surface of the cylinder block 1, and an upper cover 7 and a lower cover 8 fastened to the seal plate 6. And a resin-made belt cover (cover member). The front end of the crankshaft 3 has a V
A pulley 9 is attached. The V pulley 9 and a V pulley 10a provided on an input shaft of an alternator (first auxiliary machine) 10
And a V-pulley 11 provided on the input shaft of an air conditioner compressor (second auxiliary machine) (not shown).
(Only one is shown). Further, a connecting member 13 connected to an engine mount (not shown) is attached to the front end face of the cylinder block 1 by four bolts 14, 14,.

On the upper surface of the cylinder head 2,
As shown in FIG. 3, a cylinder head cover 18 is provided. Further, a resin sound insulation cover 20 that covers a part of the cylinder head cover 18, the fuel injection pump 5 and a fuel supply pipe 19 from the fuel injection pump 5 is provided. Is provided. As shown in FIG. 2, the sound insulation cover 20 also covers the upper part of the front cover C, and gradually lowers from the vehicle rear side to the vehicle front side along the hood line B of the vehicle.

In FIG. 2, reference numeral 22 denotes an oil pan attached to the lower surface of the cylinder block 1, reference numeral 23 denotes a turbocharger, reference numeral 24 denotes an oil filter, and reference numeral 25 denotes one end (the left end in the figure) of the cylinder head 2. , While the other end is connected to a radiator (not shown). In FIG. 3, reference numeral 26 denotes a vacuum pump driven by the camshaft 4.

(Configuration of Cylinder Head) The engine E
Is a so-called SOHC (Single Over Head Cam) type engine. Although not shown, four cylinders are arranged at predetermined intervals in the front-rear direction at a position deviated leftward from the left-right center of the cylinder head 2. I have. on the other hand,
As shown in FIGS. 4 and 5, at a position deviated to the right side (left side in both figures) of the cylinder head 2, that is, at a position rearward of the cylinder with respect to the center line of the cylinder when the engine E is mounted on the vehicle, Six bearing portions 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, and 28 are arranged so that the camshaft 4 extends in the front-rear direction and the axis position is substantially the same as the upper surface of the cylinder head. Are rotatably supported by.

The cylinder head 2 is fastened to the cylinder block 1 by head bolts 29, 29,... Arranged so as to surround each cylinder at equal intervals in the circumferential direction at four locations. Are arranged so that the injection holes face the combustion chamber directly and extend along the cylinder center line. Also, the injection nozzles 30, 30,.
, Two intake valves 31, 31 and two exhaust valves 32, 32 are provided for each cylinder. The intake and exhaust valves 31, 32,... Are respectively provided with intake cams 4a, 4a,.
Are opened and closed via the rocker arms 33, 33,.

More specifically, as shown in FIG. 5 only, each of the exhaust rocker arms 33 is swingably supported by a rocker shaft 34 supported in parallel with the camshaft 4 in an obliquely upward direction. Cam roller 3 provided in the section
3a, while being in sliding contact with the exhaust cam 4b of the camshaft 4, substantially through a pressing bolt 33b provided at the other end.
It is in contact with the U-shaped pressing member 35. On the other hand, a cam pulley (cam-side timing pulley, cam-side driven wheel) 36 is attached to the front end of the camshaft 4 as shown in FIG. Crank pulley (crank side timing pulley, drive wheel) 37 and input shaft 5 of fuel injection pump 5
The pump pulley (pump-side timing pulley, pump-side driven wheel) 38 attached to a is driven and connected by a timing belt 39 having teeth on the inner peripheral side, thereby forming a belt transmission mechanism A.

When the camshaft 4 is rotated in synchronization with the rotation of the crankshaft 3, the exhaust cams 4b, 4b,.
Are rocked at a predetermined timing for each cylinder by the
Pushes down the pressing member 35, whereby the two exhaust valves 32, 32 are opened and closed in synchronization with the rotation of the crankshaft 3. Although not shown in detail, the intake valves 31, 3
Are opened and closed in the same manner as the exhaust valves 32, 32,. Since a single camshaft 4 is used to open and close a number of valves via the rocker arms 33, 33,..., In this engine E, the valve reaction force to the camshaft 4 becomes large. Accordingly, the angular velocity fluctuation of the camshaft 4 becomes extremely large.

(Attaching Structure of Fuel Injection Pump) As shown in FIGS. 6 and 7, the fuel injection pump 5 is located on the left side of the engine E, that is, on the vehicle front side of the cylinder center line in the vehicle mounted state, from the left and right direction of the engine. When viewed, at least a portion is arranged so as to overlap with the cylinder head 2, and is fixed to the engine side by a bracket 41 attached across the cylinder block 1 and the cylinder head 2.

That is, the bracket 41 has four flanges 43, 4 extending rearward along the left side surfaces of the cylinder block 1 and the cylinder head 2.
Fastened to the left side of the cylinder block 1 by 3, ...
The connecting portion 4 is fastened to the left side surface of the cylinder head 2 by one bolt 44 and extends from the front end of the flange portion 42 along the front end surface of the cylinder block 1.
2a is fastened to the front end face of the cylinder block 1 by bolts 14 together with the connecting member 13 of the engine mount. Further, the bracket 41 has a flange 42
Are integrally formed with a mounting flange portion 46 extending from the front end portion to the opposite side in the same plane as the front end surface of the cylinder block 1.

In the fuel injection pump 5, the input shaft 5a passes through the hole 46a of the mounting flange 46, and the position of the axis of the input shaft 5a is exactly the mating surface of the cylinder block 1 and the cylinder head 2. Is mounted to the mounting flange portion 46 with a bolt so that the height of the mounting flange portion is equal to the height. Although not shown, the fuel injection pump 5 is a distribution type pump that individually supplies fuel to the injection nozzle 30 of each cylinder by operating one plunger.
A cam mechanism for reciprocating the plunger with each of the two cam lobes, and a distributor for distributing the fuel from the plunger and individually supplying the fuel to the injection nozzles 30, 30,... By the fuel supply pipes 19, 19,. Have. The input shaft 5a is rotated in synchronization with the rotation of the crankshaft 3, and during one rotation of the input shaft 5a, the plunger is operated four times in total at a predetermined fuel injection timing for each cylinder, so that the amount of fuel supplied is By the pressure, the injection nozzles 30, 30,... Are opened, and high-pressure fuel is directly injected into each combustion chamber. Since the discharge pressure of the fuel injection pump 5 is set extremely high, for example, 70 MPa or more, the rotational torque fluctuation of the input shaft 5a for operating the plunger becomes large.
The angular velocity fluctuation of the pump pulley 38 becomes extremely large.

(Structure of Belt Transmission Mechanism) In the belt transmission mechanism A, as shown in FIG. 1, the timing belt 39 drives a water pump (not shown) in addition to the cam pulley 36, the crank pulley 37, and the pump pulley 38. While being wound around the water pump pulley 53,
The layout is directed to the inner circumferential side of the belt by the tensioner pulley 54 and the idler pulley 55 of the auto tensioner 51. When the crankshaft 3 rotates clockwise in the figure, the cam pulley 36, the crank pulley 37, the pump pulley 38, and the water pump pulley 53 rotate clockwise, and at the same time, the tensioner pulley 54 and the idler pulley 55. Is rotated counterclockwise.

The cam pulley 36 is provided with a timing belt 3 having a loose side span (left side in FIG. 1) having a relatively small tension.
The water pump pulley 38 and the tensioner pulley 54 are arranged in the middle of the loose side span. The cam pulley 36 is
The pitch circle has a diameter twice as long as the crank pulley 37, and as shown in FIGS. 8 and 9, a cylindrical boss portion 36a protruding on the inner peripheral side in the direction in which the axis x1 of the rotation shaft extends is provided. On the other hand, on the outer peripheral side, teeth that mesh with the teeth of the timing belt 39 are formed over the entire circumference.

Further, on the outer peripheral side of the cam pulley 36, flange portions 36b, 36b are provided at both ends in the direction of the axis x1.
b is provided to restrict the movement of the timing belt 39 in the belt width direction. That is, generally, there is a displacement in the engine front-rear direction due to an assembly error between the cylinder head 2 and the cylinder block 1, so that a displacement also occurs between the cam pulley 36 and the crank pulley 37. Therefore, the cam pulley 36 has a flange 36b,
6b and the same flange portion on the crank pulley 37 restrict the movement of the timing belt 39 in the belt width direction at two places separated from each other in the vertical direction of the engine E. Of the timing belt 39 from the pulleys 36, 37, 38 can be effectively suppressed.

The boss 36a of the cam pulley 36
, An annular torsion damper 50 is press-fitted from the front end side in an outer fitting state, and the cam pulley 36 and the torsion damper 5
0 rotates integrally. The torsion damper 50 includes an outer peripheral mass member 50 a and an inner peripheral side sleeve 5.
Ob and the vibration damping rubber 50c therebetween are integrally vulcanized and bonded, and the required damping characteristics can be obtained by setting the weight of the mass member 50a and the vibration absorption characteristics of the vibration damping rubber 50c. For example, the weight of the torsion damper 50 may be substantially the same as the weight of the cam pulley 36 as a single body.

In the cam pulley 36, two through holes 36c, 36c penetrating in the direction of the axis x1 are formed at symmetrical positions in the diameter direction, while the torsion damper 5 is formed.
0, the cam pulley 36 is provided with through holes 50d, 50d,... At positions corresponding to the through holes 36c. When the worker attaches the cam pulley 36 to the cam shaft 4, the through holes 50d, 36c The alignment mark (not shown) written on the side of the cylinder head 2 can be confirmed.

On the other hand, the pump pulley 38 is arranged so that the timing belt 39 on the tight side span (the right side in FIG. 1) advances, and the diameter of the pitch circle is twice as large as that of the crank pulley 37 like the cam pulley 36. Although the length is set, the diameter is smaller than the cam pulley 36 as a whole because the flange is not provided. In addition, in the present embodiment, the weight of the pump pulley 38 is substantially the same as the weight of the cam pulley 36 having substantially the same diameter. , The angular velocity fluctuation of the pump pulley 38 is reduced. Further, an idler pulley 55 disposed between the pump pulley 38 and the crank pulley 37 is disposed on a side of the camshaft 4 with respect to a line connecting a rotation axis of the pulleys 37 and 38 with a rotating shaft. The timing belt 39 is largely moved inward. Thus, a relatively large space is secured below the pump pulley 38.

As shown in FIGS. 10 and 11, the automatic tensioner 51 includes a tensioner pulley 5 which is engaged with the loose side span of the timing belt 39 from the outer peripheral side of the belt.
4 and a rotation arm 56 that cantileverably supports the tensioner pulley 54 from the front end side of the engine (one side in the axial direction of the rotation shaft) and rotates around a rotation shaft (rotation fulcrum) 51a. The hydraulic arm 57 is fastened and fixed to the cylinder block 1 side.
6 is urged to rotate toward the timing belt 39 side.

That is, the hydraulic cylinder 57 is connected to the turning arm 56 by a piston rod 57b provided to be able to advance and retreat to the cylinder body 57a. Although not shown, a coil spring provided inside the cylinder body 57a is provided. Thereby, the piston rod 57b is moved to the extension side. The hydraulic cylinder 57 causes the tensioner pulley 54 to move the timing belt 3
9. Following the movement of No. 9, the timing belt 39 is pressed,
Adjust the tension constantly. The hydraulic cylinder 57
Is provided with a hydraulic damper structure for restricting the movement of the piston rod 57b to the contraction side by the flow resistance of the pressure oil in the cylinder body 57a, and the timing belt 39 transmitted through the rotating arm 56 and the tensioner pulley 54. To attenuate the reaction force.

In the belt transmission mechanism A having the above configuration,
When the engine is in operation and the crankshaft 3 is rotated, the timing belt 39 is sequentially moved from the crank pulley 37 to the tensioner pulley 54 and the water pump pulley 5.
3, via the cam pulley 36, the pump pulley 38, and the idler pulley 55, to the crank pulley 37. At this time, the timing belt 39 between the cam pulley 36 and the pump pulley 38 spreads to the outer peripheral side due to centrifugal force, and vibrates in a string due to the interaction between the angular velocity fluctuation of the cam shaft 4 and the angular velocity fluctuation of the pump input shaft 5a. .

Also, when the timing belt 39 advances from the cam pulley 36, the separation of the two teeth is delayed, and a force toward the inner peripheral side may act on the timing belt 39. When the shaft enters the pump pulley 38, the engagement between the two teeth may be delayed, and the timing belt 39 may be pushed outward. In other words, the timing belt 39 that travels from the cam pulley 36 to the pump pulley 38 is applied with a force toward the inner periphery near the cam pulley 36, while a force toward the outer periphery is applied near the pump pulley 38. As a result, The maximum amplitude position of the string vibration is shifted to the pump side from the center position between the cam pulley 36 and the pump pulley 38. In addition, since a sliding frictional force acts on the timing belt 39 with the flange portion 36b of the cam pulley 36, string vibration is restricted in the vicinity of the cam pulley 36. The maximum amplitude position of the string vibration is shifted to the pump side from the center position between the two pulleys 36 and 38.

(Configuration of Front Cover) In this embodiment, the front cover C that houses the belt transmission mechanism A is taken into consideration in consideration of the string vibration of the timing belt 39 as described above.
Has been determined. Hereinafter, the configuration of the front cover C will be described in detail with reference to FIG. 1 and FIGS.

As shown in FIG. 1, the front cover C
Mainly, a seal plate 6 disposed from the cylinder block 1 to the cylinder head 2, the cylinder head cover 18 and the bracket 41 of the fuel injection pump 5 (see FIG. 6), and a cylinder block lower than the seal plate 6. 1, a cylinder block cover 62 having a through-hole formed in the center thereof and through which the crankshaft 3 passes, an upper cover 7 fastened to the seal plate 6 (see FIGS. 2 and 3), and the seal plate 6 And the lower cover 8 fastened to the cylinder block cover 62.

The seal plate 6 is formed by press-forming a thin steel plate as shown in each of FIGS. 12 to 14, and includes a main wall portion 63 superposed on the front end surface of the cylinder block 1 and the like, An outer peripheral side wall portion (side wall portion) 64 extending in the engine front-rear direction from the main wall portion 63 so as to surround an outer periphery of the belt 39, and a substantially central portion of the main wall portion 63 surrounding the periphery of the engine mount connecting member 13. An annular inner peripheral side wall portion 65 extending in the front-rear direction of the engine is provided.

The seal plate 6 has a first fastening portion 6a directly fastened to the cylinder block 1 side (specifically, a water pump case 1a fixedly provided on the right side surface of the cylinder block), and a cam pulley 36. The second fastening portion 6b fastened to the front cover portion 18a of the cylinder head cover 18 at the outer peripheral side wall portion 64 located in the vicinity
And a third fastening portion 6c and a fourth fastening portion 61d fastened to the bracket 41 of the fuel injection pump 5. That is, the seal plate 6 is connected to the first fastening portion 6.
a, the water pump case 1a
And is directly superimposed on the front end face of the cylinder block 1, so that the clearance between the seal plate 6 and the cylinder block 1 is minimized, and the cylinder block of the seal plate 6 1
Is extremely high.

On the other hand, in the second, third and fourth fastening portions, the seal plate 6 is attached via a rubber mount 67 by bolts 66 as shown in FIG. That is, since the seal plate 6 is mounted via the rubber mount 67 to the cylinder head cover 18 or the bracket 41 having a positional deviation due to an assembly error between the seal plate 6 and the cylinder block 1, the above-described assembly is performed by the rubber mount 67. The displacement caused by the error is absorbed, and the distortion of the seal plate 6 in the assembled state is reduced. This allows the cam pulley 36
Also, the clearance between the pump pulley 38 and the seal plate 6 can be made extremely small, whereby the dimension in the engine front-rear direction can be reduced.

The main wall 63 of the seal plate 6 has
The pump pulley 38 is provided at a position corresponding to the pump pulley 38.
A substantially circular hole 63 a having a slightly smaller diameter is formed, and a substantially central position of the hole 63 a is positioned at the input shaft 5 of the fuel injection pump 5.
a penetrates. Similarly, the water pump pulley 53
A circular hole 63b having a diameter larger than that of the water pump pulley 53 is formed at a position corresponding to the water pump pulley 53, and an input shaft of the water pump penetrates a substantially central position of the hole 63b. A portion of the main wall 63 corresponding to the cam pulley 36 is cut out so as to open upward. As shown in FIGS. 16 and 17, the front cover 18a of the cylinder head cover 18 is And constitutes a part of the front cover C.

The outer peripheral side wall 64 of the seal plate 6
Are connected to the pump pulley 3 with the notch 63c of the main wall 63 as a boundary.
It is divided into two on the 8 side and the cam pulley 36 side. As a first characteristic part of the present invention, the protruding height of the outer peripheral side wall 64 from the main wall 63 differs depending on the location. That is, as shown in FIG. 13, in the portion surrounding the outer periphery from directly above the pump pulley 38 to the lower end of the seal plate 6, the front end of the outer peripheral side wall 64 has the pump pulley 38.
Of the pump pulley 38 is formed high so as to cover the pump pulley 38 in the front-rear direction of the engine.

That is, below the pump pulley 38, the side wall of the front cover C is constituted by the outer peripheral side wall 64 of the seal plate 6, and the positional accuracy of the seal plate 6 with respect to the cylinder block 1 is extremely high. Even if the clearance between the side wall portion 64 and the pump pulley 38 is set sufficiently small, they do not come into contact due to an assembly error or the like. Moreover, the seal plate 6 made of a steel plate can be formed thinner than the lower cover 8 made of a resin. Therefore, the fuel injection pump 5 and the alternator 10 can be arranged as close as possible.

On the other hand, as shown in FIG. 13, FIG. 14 and FIG. 17, the outer peripheral side wall portion 64 is exposed at a predetermined portion from the periphery of the cam pulley 36 to the pump side. It is formed to be lower in the front-rear direction. In addition, corresponding to this portion, as shown by the phantom line in FIG.
Side wall portion 7a is formed deep in the front-rear direction. That is, for example, the side wall portion of the front cover C corresponding to the above-mentioned inspected portion so that the operator can press the inspected portion of the timing belt 39 between the cam pulley 36 and the pump pulley 38 to easily inspect its tension. Is mostly constituted by the side wall portion 7a of the upper cover 7, so that the timing belt 39 of the inspected portion can be exposed and easily inspected simply by removing the upper cover 7. I have a good hand.

As a second characteristic part of the present invention, a front cover C opposing the outer peripheral surface of the timing belt 39 stretched between the cam pulley 36 and the pump pulley 38.
, Ie, the side wall portion 7a of the upper cover 7 and the outer peripheral side wall portion 64 of the seal plate 6 located above the cam pulley 36 and the pump pulley 38,
A shape in which a pump-side portion on the pump side (right side in the drawing) with respect to the center position between the belts 38 bulges outward (upper side in the drawing) with respect to the timing belt 39 compared to a cam-side portion on the cam side (left side in the drawing) It has been.

More specifically, the outer peripheral side wall 64 of the seal plate 6 will be described. As shown in FIG. 12, the outer peripheral side wall 64 above the cam pulley 36 and the pump pulley 38 is formed by a pitch circle O1 of the pulleys 36 and 38. , O2 as a reference, a central portion corresponding to a center position m of the tangent L from a portion corresponding to a contact point P1 between the tangent L and the pitch circle O1 of the cam pulley 36 (a vertical portion of the tangent L shown in FIG. (The part on the bisector M), and gradually bulges upward, and a portion corresponding to a predetermined range W from the center position m of the tangent line L to the pump side is substantially the same as the center portion on the outer circumferential side. It is shaped to bulge out.

That is, the predetermined range W is experimentally determined so as to correspond to the maximum amplitude position due to resonance when the timing belt 39 vibrates in a string as described above during running, and corresponds to the predetermined range W. The outer peripheral side wall portion 64 of the seal plate 6 has a shape which swells to the maximum. As a result, as shown in FIG. 1, the interval between the timing belt 39 in the stationary state between the cam pulley 36 and the pump pulley 38 and the outer peripheral side wall portion 64 is such that the interval d1 at the pump side portion is larger than the interval d2 at the cam side portion. Is always getting bigger. Although not shown in detail, the side wall 7a of the upper cover 7 also
9 corresponds to the predetermined range W.
9 is bulged outwardly. That is, since the side wall portion of the front cover C is formed so as to bulge toward the outer peripheral side in correspondence with the maximum amplitude position of the string vibration of the timing belt 39, the timing belt 39 is not susceptible to string vibration due to resonance. The side wall of the cover C is not contacted.

(Arrangement of Alternator) FIGS. 18 and 19
As shown in FIG. 3, the alternator 10 disposed below the fuel injection pump 5 is connected to a fuel injection pump 5 at a connecting portion 80a integrally provided on one side of a substantially cylindrical casing 80.
Of the casing 8
0 is fastened to the strap 81 at a connecting portion 80b integrally provided on the other side. And the other side connecting portion 8
By changing the position of 0b up and down within the range of the long hole 81a formed in the strap 81, the alternator 10 can be rotated around the one-side connecting portion 80a to adjust the fixed position. .

The front end of the casing 80 (FIG. 1)
9, an input shaft (not shown) protrudes from the input shaft, and a V pulley 10a attached to the input shaft is driven by a V belt 12 (see FIG. 2) on a V pulley 9 on a crankshaft 3 of an engine E. Are linked. Then, the tension of the V-belt 12 can be adjusted by rotating and adjusting the position of the alternator 10 around the connecting portion 80a.

Further, the front end of the casing 80 of the alternator 10 is located below the pump pulley 38 and is close to the outer peripheral side wall 64 of the seal plate 6 constituting the side wall of the front cover C. The outer diameter of the front end side of the casing 80 is gradually reduced toward the front side, and a sufficient space is secured between the casing 80 and the lower cover 8 provided on the upper seal plate 6 and the joining flange. That is, the casing 80 is connected to the fuel injection pump 5
Even if the other side connecting portion 80b of the casing 80 is fixed to the uppermost position of the long hole 81a so as to be as close as possible to the maximum, there is sufficient clearance between the front end side of the casing 80 and the seal plate 6 thereabove. Is secured.

(Effects of Embodiment) Therefore, according to the engine front cover structure of this embodiment, the string vibration of the timing belt 39 between the cam pulley 36 and the pump pulley 38 is taken into account as described above. Since the side wall portion of the front cover C above the pulleys 36 and 38 has a shape that bulges maximally at a portion corresponding to the maximum amplitude position of the string vibration of the timing belt 39, the external dimensions of the front cover C are increased unnecessarily. Without
Even if the timing belt 39 vibrates greatly due to resonance, the timing belt 39 can be prevented from contacting the side wall of the front cover C. Therefore, while miniaturizing the engine, it is possible to prevent problems such as noise generation and reliability deterioration due to the contact between the front cover C and the timing belt 39.

In particular, in the diesel engine E according to this embodiment, four valves 31, 32,.
The angular velocity fluctuation per rotation of the camshaft 4 is likely to be large, and the discharge pressure of the fuel injection pump 5 is extremely high, and the angular velocity fluctuation of the pump input shaft 5a is also extremely large. Are also likely to be large. Therefore, in such an engine E, the effect that the contact between the side wall and the timing belt 39 can be prevented by the bulging formation of the side wall of the front cover C is particularly effective.

In this embodiment, in the belt transmission mechanism A, the tension of the timing belt 39 is constantly adjusted by the auto tensioner 51, and the cam pulley 3
Since the string vibration of the timing belt 39 is suppressed by attenuating the angular velocity fluctuation of the camshaft 4 by the torsional damper 50 disposed in 6, the degree of bulging of the front cover side wall portion can be reduced accordingly.

Further, the engine E of this embodiment is mounted horizontally on a vehicle, and the camshaft 4 and the cam pulley 36, and the fuel injection pump 5 and the pump pulley 38 are all located at the upper part of the engine in a vehicle-mounted state. A pump pulley 38 located on the vehicle front side with respect to the cam pulley 36 is located lower than the cam pulley 36. In addition, since the upper portion of the front cover C is formed along the inner surface of the hood hood B corresponding to the above arrangement, the front cover C is formed to bulge upward on the pump side at a relatively low position. However, the overall height of the engine does not increase.

In addition, the sound insulation cover 20 above the front cover C is disposed substantially parallel to the hood hood B, while the side wall of the front cover C is sealed below the pump pulley 38 by the seal plate 6. The alternator 10 and the compressor for the air conditioner are vertically arranged in a space secured below the fuel injection pump 5 with the clearance between the side wall and the pump pulley 38 being set to a minimum while being thin. That is, the fuel injection pump 5 is arranged at the uppermost position in the engine room, and two auxiliary machines are arranged in a space secured below the fuel injection pump 5, thereby effectively utilizing the engine room space.

(Other Embodiments) The present invention is not limited to the above-described embodiment, but includes various other embodiments. That is, in the belt transmission mechanism A of the embodiment, the torsional damper 50 is attached to the cam pulley 36.
And the auto tensioner 51 is used, but either one or none of them may be used. Further, a fixed tensioner for adjusting the initial tension may be used instead of the automatic tensioner.

In the above embodiment, the present invention is applied to the shape of the portion of the side wall of the front cover C which faces the outer peripheral surface of the timing belt 39 between the cam pulley 36 and the pump pulley 38 of the fuel injection pump 5. However, the present invention is not limited to this, and the present invention can be applied to any part other than the fuel injection pump 5 as long as the auxiliary part has an angular velocity fluctuation on the input shaft between the pulley provided on the input shaft of the auxiliary part and the cam pulley.

In the belt transmission mechanism A of the above-described embodiment, the cam pulley 36 is arranged closer to the loose side of the timing belt 39 and the pump pulley 38 is arranged closer to the tension side.
9 and the pump pulley 38 may be arranged closer to the loose side. In this case, it is desirable that the pump pulley 38 be positioned higher than the cam pulley 36 and on the rear side of the vehicle when the engine E is mounted on the vehicle. Further, it is desirable to provide a flange only on the pump pulley 38 of the cam pulley 36 and the pump pulley 38.

In the belt transmission mechanism A of the above embodiment, the cam pulley 36 is provided with the flange 36b, while the pump pulley 38 is not provided with the flange. However, neither of the pulleys may be provided with the flange. Good.

In the above embodiment, the camshaft 4 and the fuel injection pump 5 are driven via the timing belt 39. However, the present invention is not limited to this. For example, the camshaft 4 and the fuel injection pump 5 may be driven via a sprocket and a chain.

The engine E of the above embodiment is provided with four valves 31, 32,... For each cylinder. However, the present invention is not limited to this. For example, two or three valves are provided for each cylinder. The present invention may be applied to an engine provided with 31, 32,... Or an engine provided with five or more valves for each cylinder. Further, the engine E of the above embodiment is a direct injection type diesel engine, but is not limited to this, and the present invention is also applicable to, for example, a sub-chamber type diesel engine or a gasoline engine.

[0095]

As described above, according to the engine front cover structure according to the first aspect of the present invention, the side wall portion of the front cover opposed to the outer peripheral surface of the endless transmission member between the cam side and the pump side driven wheel. A shape corresponding to the front side corresponding to the front side in the traveling direction of the endless transmission member relative to the center position between the driven wheels, that is, the shape corresponding to the maximum amplitude position of the string vibration of the endless transmission member. Thus, while minimizing the size of the engine by minimizing the outer dimensions of the front cover, it is possible to prevent noise generation and reduction in reliability due to contact between the front cover and the endless transmission member.

According to the third aspect of the present invention, the side wall portion of the front cover is expanded on the pump side, which is located at a relatively low position, of the cam side and the pump side driven wheels arranged above the engine. It is possible to prevent an increase in the height of the front cover due to the formation of the protrusion, and an increase in the overall height of the engine.

According to the fourth aspect of the present invention, the pump-side driven wheel located at a position lower than the cam-side driven wheel is positioned on the front side of the vehicle, and the front cover side walls above both driven wheels are arranged along the hood of the vehicle. The shape can be made, so that the effective use of the engine room space is achieved.

According to the fifth aspect of the present invention, the fuel injection pump is arranged above the engine, and a space for disposing auxiliary equipment can be secured below the fuel injection pump.

According to the sixth aspect of the invention, in an engine in which the angular velocity of the camshaft varies greatly due to the reaction force of the valve, the effect of preventing the contact with the endless transmission member by forming the front cover to be bulged is particularly effective. become.

According to the eighth aspect of the invention, the degree of swelling of the front cover side wall can be reduced by attenuating the angular velocity fluctuation of the camshaft by the torsional damper and suppressing the string vibration of the endless transmission member.

According to the ninth aspect of the present invention, the tension of the endless transmission member is constantly adjusted by the auto tensioner to suppress the string vibration of the endless transmission member, so that the degree of bulging of the front cover side wall can be reduced.

According to the engine front cover structure of the tenth aspect of the present invention, similarly to the first aspect of the present invention, the portion of the side wall of the front cover corresponding to the maximum amplitude position of the string vibration of the timing belt. The maximum swelling shape minimizes the amount of swelling of the front cover side wall to minimize the size of the engine while reducing noise and noise generated by contact between the front cover and the endless transmission member. It is possible to prevent a decrease in reliability.

According to the twelfth aspect of the present invention, by providing flange portions on both sides in the width direction of the cam-side timing pulley, the displacement between the running timing belt and each pulley can be effectively suppressed, and the timing belt has a string vibration. On the auxiliary machine side where the load is relatively large, it is possible to prevent the load on the timing belt from increasing due to sliding contact with the flange.

According to the thirteenth aspect, the sixth aspect is provided.
As in the case of the described invention, the effect of preventing contact between the front cover and the timing belt is particularly effective.

According to the fourteenth aspect, according to the ninth aspect,
The same effects as those of the described invention can be obtained.

According to the fifteenth aspect, the eighth aspect is provided.
The same effects as those of the described invention can be obtained.

According to the sixteenth aspect of the present invention, in an engine equipped with a fuel injection pump having a large torque fluctuation, the effect of preventing the contact with the timing belt by forming the front cover to be bulged becomes particularly effective. .

Further, according to the engine front cover structure of the present invention, since the front cover is provided with the plate member and the cover member, the timing belt and the like can be easily inspected simply by removing the cover member. it can. Further, by providing the pump-side timing pulley with a small diameter without providing a flange, and by moving the timing belt below the pulley to the inner peripheral side, a sufficient space for arranging auxiliary equipment can be secured. Further, the side wall of the front cover below the pump-side timing pulley is constituted by a metal plate member, which makes it relatively thin and minimizes the clearance with the pump-side timing pulley. The lower auxiliary equipment can be arranged as close as possible.

According to the eighteenth aspect of the present invention, the side wall portion of the plate member is formed to be lower at a portion corresponding to the inspection from the portion surrounding the cam-side timing pulley to the pump side, so that the cover member is simply removed. The timing belt is exposed for easy inspection.

According to the nineteenth aspect of the present invention, even if the first auxiliary device below the fuel injection pump is arranged as close as possible to the fuel injection pump, the casing of the first auxiliary device and the upper part thereof are disposed. Clearance with the front cover can be secured.

According to the twentieth aspect of the present invention, the fuel injection pump is arranged at the maximum position above the engine along the hood, and two auxiliary machines are arranged vertically below the engine, so that the engine room The space can be used effectively to the maximum.

According to the twenty-first aspect, the clearance between the plate member and the cylinder block can be minimized, and the positional accuracy can be extremely high. Further, the rubber mount can absorb an error in assembling the cylinder head and the like to the cylinder block, thereby reducing the distortion of the plate member and attenuating the membrane vibration of the plate member, thereby reducing the noise.

[Brief description of the drawings]

FIG. 1 is a front view showing a front cover structure according to an embodiment of the present invention.

FIG. 2 is a front view of an engine to which the front cover structure of FIG. 1 is applied.

FIG. 3 is a plan view of FIG. 2;

FIG. 4 is a front view showing a configuration of a cylinder head in a state where a rocker shaft and the like are omitted.

FIG. 5 is an explanatory view showing a configuration in which a rocker arm opens and closes an exhaust valve.

FIG. 6 is a front view showing a configuration in which a bracket of the fuel injection pump is mounted on an engine side.

FIG. 7 is a left side view of FIG.

FIG. 8 is a front view showing a configuration of a cam pulley and a torsion damper.

9 is a sectional view taken along line IX-IX in FIG.

FIG. 10 is a front view showing a configuration of the auto tensioner.

11 is a sectional view taken along line XI-XI in FIG.

FIG. 12 is a front view showing a configuration of a seal plate.

FIG. 13 is a plan view of FIG.

FIG. 14 is a right side view of FIG.

FIG. 15 is a cross-sectional view illustrating a configuration of a rubber mount.

FIG. 16 is a front view showing an arrangement configuration of a cylinder head, a cylinder head cover, and a seal plate.

FIG. 17 is a plan view showing an arrangement configuration of a cylinder head cover, a seal plate, and an upper cover.

FIG. 18 is a front view showing the arrangement of the alternator.

FIG. 19 is a diagram showing a positional relationship between an alternator and a seal plate.

[Explanation of symbols]

Reference Signs List A belt transmission mechanism B bonnet hood C front cover E diesel engine 1 cylinder block 2 cylinder head 3 crankshaft 4 camshaft 5 fuel injection pump 5a input shaft of fuel injection pump 6 seal plate (plate member) 6a first fastening of seal plate Part 6b Second fastening part of seal plate 6c Third fastening part of seal plate 7 Upper cover (cover member) 7a Side wall part of upper cover (cover side wall part) 8 Lower cover (cover member) 9 V pulley (for driving auxiliary equipment) Pulley) 10 Alternator (first accessory) 31 Intake valve (intake valve) 32 Exhaust valve (exhaust valve) 36 Cam pulley (cam-side driven wheel) 36b Cam pulley flange 37 Crank pulley (drive wheel) 38 Pump pulley (pump-side pulley) ) 39 Timing belt (No Transmission member) 41 outer peripheral side wall portion of the main wall portion 64 seals the plate of the mounting bracket 50 torsional damper 51 auto-tensioner 55 idler pulley 63 seal plate of a fuel injection pump (side wall portion) 67 rubber mount 80 alternator casing

Claims (21)

[Claims] 1. A toothed cam-side driven wheel on a valve train camshaft and a toothed pump-side driven wheel on an input shaft of a fuel injection pump are adjacent to one end of an engine in a crankshaft direction.
And in the front cover structure of the engine is disposed and connected to the toothed drive wheels on the crankshaft via an endless transmission member, at least both the driven wheels and the endless transmission member are housed in the front cover, The front cover has a side wall extending in the crankshaft direction facing an outer peripheral surface of an endless transmission member between the cam side and the pump side driven wheel, and an endless portion between the two driven wheels among the side wall. The front corresponding portion corresponding to the front side in the traveling direction of the endless transmission member with respect to the center position of the transmission member bulges outward so as to be away from the stationary endless transmission member as compared to the rear corresponding portion corresponding to the rear side. The front cover structure of the engine. 2. The front cover according to claim 1, wherein the side wall of the front cover is formed from a portion corresponding to a contact point between a tangent line circumscribing the cam side and the pump side driven wheel and a driven wheel located rearward in the traveling direction of the endless transmission member. , While gradually bulging outward toward a central portion corresponding to the central position of the tangent, and a portion corresponding to a predetermined range from the central position of the tangent to the front side in the traveling direction is equal to or larger than the central portion. The front cover structure of the engine, characterized in that it bulges out. 3. The cam-side driven wheel according to claim 1, wherein the cam-side driven wheel and the pump-side driven wheel are both disposed at an upper portion of the engine, and the pump-side driven wheel is at a position lower than the cam-side driven wheel and the endless transmission member advances. The front cover structure of the engine, which is located on the front side in the direction. 4. The engine according to claim 3, wherein the engine is mounted laterally so that the crankshaft extends in the left-right direction of the vehicle, and the driven wheel on the pump side is located on the vehicle front side of the driven wheel on the cam side. Characteristic engine front cover structure. 5. The engine according to claim 4, wherein the axis of the camshaft of the engine is located at substantially the same height as the upper surface of the cylinder head, and at least a part of the fuel injection pump overlaps the cylinder head when viewed from the vehicle longitudinal direction. The front cover structure of the engine, which is arranged as follows. 6. The front cover structure for an engine according to claim 4, wherein a total of four or more intake valves and exhaust valves are provided for each cylinder. 7. The engine front cover structure according to claim 1, wherein the fuel injection pump discharges high-pressure fuel of 70 MPa or more. 8. The engine front cover structure according to claim 7, wherein at least one of the camshaft and the cam-side driven wheel is provided with a torsional damper for attenuating angular velocity fluctuations of the camshaft. 9. An auto-tensioner according to claim 7, wherein an auto-tensioner for adjusting a tension of the endless transmission member by pressing a loose side span of a span between a drive wheel and a driven wheel of the endless transmission member is provided. The engine front cover structure characterized by the following. 10. An engine having one end in a crankshaft direction.
A cam-side timing pulley on a valve operating system camshaft disposed on the upper part of the engine and an accessory-side timing pulley on an input shaft of the auxiliary machine are adjacent to each other, and a crankshaft disposed on a lower part of the engine is disposed on a crankshaft. In a front cover structure of an engine, which is drivingly connected to a crank-side timing pulley via a timing belt and at least the cam-side and accessory-side timing pulleys and the timing belt are housed in a front cover, An idler pulley for wrapping the timing belt between the two pulleys is provided between the timing pulleys on the accessory and the timing pulley between the crank side and the cam side. A tensioner for adjusting the timing is provided. Only the cam-side timing pulley is provided with a flange portion that regulates movement of the timing belt in the belt width direction, and the front cover faces the outer peripheral surface of the timing belt between the cam-side and auxiliary device-side timing pulleys. And a side wall extending in the crankshaft direction. Of the side wall, an auxiliary machine side portion on the auxiliary machine side with respect to a center position between the timing pulleys and a cam side portion on a cam side with respect to the center position. In comparison, the engine front cover structure swells outward so as to be separated from the stationary timing belt. 11. The tangent line according to claim 10, wherein the side wall of the front cover extends from a portion corresponding to a contact point between the tangent line circumscribing the pitch circle of the cam-side and auxiliary device-side timing pulleys and the cam-side timing pulley. While gradually bulging outward toward the central portion corresponding to the position, a portion corresponding to a predetermined range from the central position of the tangent line to the accessory side bulges outward to the same extent or larger than the central portion. A front cover structure for an engine, characterized in that: 12. The engine according to claim 11, wherein the crankshaft of the engine is supported by the cylinder block, the camshaft is supported by the cylinder head above the cylinder block, and the flanges are provided at both ends in the width direction of the cam-side timing pulley. An engine front cover structure, which is provided. 13. The engine front cover structure according to claim 12, wherein a total of four or more intake valves and exhaust valves are provided for each cylinder. 14. The engine front cover structure according to claim 10, wherein the tensioner is an automatic tensioner. 15. The front cover of an engine according to claim 10, wherein at least one of the camshaft and the cam-side timing pulley is provided with a torsional damper for attenuating a variation in angular velocity of the camshaft. Construction. 16. The fuel injection pump according to claim 10, wherein the auxiliary machine reciprocates a plunger via a cam mechanism by rotation of an input shaft to discharge fuel. The engine front cover structure characterized by the following. 17. A crankshaft is supported by a cylinder block of an engine, a valve system camshaft is supported by a cylinder head above the cylinder block, and a fuel injection pump is mounted on at least the cylinder head via a bracket. A cam-side timing pulley on the camshaft and a pump-side timing pulley on the input shaft of the fuel injection pump are arranged adjacent to the engine front side on one end side in the crankshaft direction, and on the crankshaft. Wherein the cam-side and the auxiliary-device-side timing pulleys and the timing belt are housed in a front cover, and the cam-side and the pump-side timings are arranged. Only for the cam-side timing pulley of the pulleys Flange portion is provided for restricting the movement of the belt width direction of the timing belt, between the pump side and the crank timing pulley, the camshaft with respect to a plane connecting the rotation axis of the pulleys,
An idler pulley is provided around the back of the timing belt. A metal plate member having an extending side wall portion; and a resin cover member connected to the side wall portion of the plate member. The side wall portion of the plate member has at least a portion below a pump-side timing pulley. A front cover structure for an engine, wherein the pulley extends to a front side from a center position in a width direction of the pulley. 18. The inspection corresponding portion according to claim 17, wherein the side wall portion of the plate member corresponds to a portion to be inspected of a timing belt extending from a portion surrounding above the cam-side timing pulley to above the pump-side timing pulley. A cover side wall portion extending in the crankshaft direction is formed at least at a portion of the cover member that is connected to the inspection corresponding portion, the cover timing member being formed at a position behind the center position in the width direction of the side timing pulley. The front cover structure of the engine. 19. The fuel injection pump according to claim 18, wherein a through hole through which the crankshaft is inserted is formed in the cover member, and an auxiliary drive pulley is provided on the crankshaft on the front side of the cover member. A first auxiliary device having a driven pulley on the input shaft projecting forward is disposed below, and the driven pulley is drivingly connected to the auxiliary device driving pulley by a belt. The front cover structure of an engine, wherein the machine has a substantially cylindrical casing, and an outer dimension of the casing is smaller on a front side than on a rear side. 20. The engine according to claim 19, wherein the engine is mounted horizontally with the crankshaft directed to the left and right direction of the vehicle, and the camshaft is located on the rear side of the vehicle with respect to the cylinder center line. A second auxiliary machine driven by the crankshaft is located below the first auxiliary machine of the engine, and the pump input shaft is located at a position lower than the camshaft relative to the cylinder center line. The front cover above the cam-side and pump-side timing pulleys is shaped so as to be gradually lowered from the rear side of the vehicle to the front side of the vehicle along the inner surface of the hood of the vehicle. Engine front cover structure. 21. The cam member according to any one of claims 17 to 20, wherein the plate member has a first fastening portion fastened to one of a cylinder block and an auxiliary machine fixed to the cylinder block. A second fastening portion fastened to one of the cylinder head and the cylinder head cover via a rubber mount near the timing pulley, and a third fastening portion fastened to the bracket of the fuel injection pump via the rubber mount are provided. The front cover structure of the engine, which is characterized in that: