JP2005207372A - Auxiliary machine drive structure for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simultaneously achieve prevention of tooth strike noise in a gear train, sure support of a fuel pump 51 , and reduction of the number of articles while keeping total length of the engine not to be extended in an auxiliary machine drive structure of the engine 1 combining gear drive and belt drive. <P>SOLUTION: A pump gear 52 and a pump pulley 91 are attached to a pump shaft 51a of a fuel pump 51. A scissors gear 8 is arranged in a front cover 21b side of the pump gear 52, an end surface of a bearing 25 provided in a housing of the front cover 21b is abutted on the scissors gear 8. Consequently, the scissors gear 8 is pressed and supported on the pump gear 52 side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an engine accessory drive structure.

  A structure that transmits the driving force of the crankshaft to the fuel pump via the idle gear while transmitting the output of the pump shaft of the fuel pump to the camshaft via the timing belt as one of the auxiliary drive structures of the engine Is known (see, for example, Patent Document 1).

Patent Document 2 discloses a configuration in which a scissors gear is disposed in the idle gear in order to prevent rattling noise in a gear train including a crank gear, an idle gear, and a pump gear.
Utility Model Registration No. 2581022 JP 2002-195387 A

  Incidentally, as disclosed in Patent Document 2, when a scissors gear is provided, a pressing member that presses the scissors gear against the main gear (idle gear in Patent Document 2) is separately required. For this reason, the number of parts increases, and an arrangement space is required in the axial direction of the gear by the amount of the pressing member, resulting in an inconvenience that the overall length of the engine becomes long.

  Further, in the structure disclosed in Patent Document 1, the pump gear is disposed on the base end side and the pump pulley is disposed on the distal end side with respect to the pump shaft of the fuel pump, and the gear and the pulley are arranged side by side in the axial direction. As the pump shaft becomes longer, belt tension acts on its tip. Moreover, since a high fuel pressure is required in a direct injection diesel engine, the driving load of the fuel pump is high. As described above, the long pump shaft of the fuel pump and the high driving load of the fuel pump make it necessary to sufficiently support the pump shaft.

  Further, in the structure disclosed in Patent Document 1, the gear train including the crank gear, the pump gear, and the idle gear is covered with the gear cover, while the belt mechanism including the pump pulley, the timing pulley, and the timing belt is covered with the belt cover. Here, at the position where the fuel pump is disposed, an oil seal is provided between the pump gear and the pump pulley and a gear cover is interposed. However, since the belt cover is usually formed of synthetic resin or the like, the rattling sound of the pump gear is not generated. The oil seal is likely to leak to the outside through the belt cover. Therefore, it is effective to prevent the rattling noise by disposing the scissors gear in the pump gear. In this case, as described above, the pump shaft that becomes longer by disposing the pump gear and the pump pulley is the scissor gear. And the holding member thereof are further lengthened, making the engine more compact and disadvantageous in terms of supporting the pump shaft.

  The present invention has been made in view of the above points, and an object of the present invention is to reduce the overall length of the engine and reduce the gear striking in the gear train in an engine accessory drive structure combining a gear drive and a belt drive. The object is to simultaneously achieve the prevention of noise, the reliable support of the fuel pump, and the reduction in the number of articles.

  The engine accessory drive structure according to the present invention is an accessory drive structure for a direct injection diesel engine that injects fuel into the cylinder from an injector facing the cylinder.

  The structure includes a fuel pump supported by a cylinder block and supplying fuel to the injector, a pump gear attached to a pump shaft of the fuel pump, a crank gear attached to a crankshaft, and the pump gear and crank gear. Between the idle gear for transmitting the driving force of the crankshaft to the fuel pump, the scissor gear disposed in the pump gear, and the crank block fixed to the cylinder block, the crank gear, the pump gear, the scissors gear, And a gear cover covering the gear train including the idle gear, a pump pulley attached to the front end side of the pump gear in the pump shaft, a timing pulley attached to a camshaft disposed on the cylinder head, and the pump pulley and timing Between the pulley Only passed by, comprises a timing belt for drivingly connecting the pulleys, the pump pulley, timing pulley, and a belt cover for covering the belt mechanism comprising a timing belt, a bearing for supporting the pump shaft, a.

  The gear cover has an oil seal interposed between the pump gear and the pump pulley to hold the gap between the pump shaft and the pump shaft, and the gear cover covers the bearing closer to the pump gear than the oil seal. The scissors gear is disposed on the end surface of the pump gear on the gear cover side, and the pump gear side end surface of the bearing abuts against the pump gear to support the pump gear. To do.

  According to this configuration, the gear train is formed by the crank gear, the idle gear, and the pump gear attached to the base end side of the pump shaft of the fuel pump, and the driving force of the crankshaft is transmitted to the fuel pump by the gear train. To drive the fuel pump. The pump pulley attached to the tip end side of the pump shaft and the timing pulley of the camshaft are drivingly connected by a timing belt. The gear train is covered with a gear cover, and the belt mechanism including each pulley and the timing belt is covered with the belt cover. At this time, the gear cover is interposed between the pump gear and the pump pulley, and the pump pulley is accommodated between the gear cover and the belt cover. Further, the inside of the gear cover is oil-tightly held by the oil seal disposed between the pump shaft.

  The pump shaft of the fuel pump supported by the cylinder block is supported by a bearing disposed in the housing of the gear cover at a position between the pump gear and the pump pulley. Thus, by disposing the bearing on the relatively distal end side of the pump shaft, it becomes possible to resist the belt tension acting via the pump pulley, and the fuel for the direct injection engine that requires high fuel pressure. It becomes possible to cope with a high driving load of the pump.

  And the scissors gear is arrange | positioned at the said pump gear, Thereby, a rattling sound is prevented. At the position where the pump gear is disposed, the gear cover and the belt cover are separated by an oil seal, and when a rattling noise is generated, sound leaks easily through the oil seal and the belt cover. By preventing the rattling noise of the pump gear with the scissor gear, the occurrence of sound leakage is prevented in advance.

  The scissors gear is disposed on the end face of the pump gear on the gear cover side, and is pressed and supported when the end face of the bearing on the pump gear side contacts. As described above, the bearing serves both as a support for the pump shaft and a restraining member for the scissors gear. As a result, it is not necessary to separately provide a scissors gear pressing member, the number of parts can be reduced, and the total length of the engine can be suppressed by the amount of omitting the pressing member.

  The bearing includes an inner race that is externally fitted to the pump shaft and an outer race that is internally fitted to the peripheral wall of the housing, and an annular surface that abuts the end surface of the inner race on the end surface on the bearing contact side of the scissor gear. A convex portion and a concave portion that is recessed at the radially outer position of the annular convex portion and that is not in contact with the outer race may be formed.

  According to this configuration, the annular convex portion formed on the scissors gear contacts the inner race of the bearing, and thereby the scissors gear is pressed toward the pump gear. On the other hand, the outer race of the bearing is located in an annular recess formed in the scissor gear, so that the outer race is not in contact with the scissor gear. As a result, the scissor gear rotates integrally with the pump gear, and the rotation is not hindered.

  Two idle gears may be interposed between the crank gear and the pump gear, and a gear rattle noise prevention mechanism may be provided on the crank gear.

  In this configuration, a gear train is formed by the crank gear, the two idle gears, and the pump gear, and the drive input side is the crank gear and the output side is the pump gear. Further, by disposing a scissors gear on the pump gear, rattling noise is prevented on the output side of the gear train. Further, by providing the crank gear with a rattling noise prevention mechanism (including a scissors gear and a friction gear), rattling noise is prevented on the input side of the gear train. In this way, by preventing rattling noise on both the drive input side and output side of the gear train, the number of mechanisms for preventing rattling noise is unnecessarily increased in a gear train composed of a large number of gears. Therefore, the rattling noise can be effectively prevented.

  As described above, the auxiliary drive structure of the present invention is a structure in which the scissors gear provided in the pump gear is pressed by the bearing that supports the pump shaft, and the pressing member for the scissors gear is not required, so the number of parts is reduced. In addition, rattling noise can be prevented while suppressing the overall length of the engine.

  Further, since the bearing supports the pump shaft on the tip side of the pump gear, the bearing reliably supports the pump shaft against a belt tension acting on the tip side of the pump shaft and a high driving load of the fuel pump. be able to.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a plan view of an in-cylinder direct injection diesel engine 1 according to an embodiment of the present invention. In this engine 1, the first, second, third, and fourth four cylinders 2, 2,... Are in front (left side in the figure) in the longitudinal direction of the main body (the left and right direction in the figure). Are in-line four-cylinder engines arranged in order from the rear side (right side in the figure), with the intake system on the right side (upper side in the figure) and exhaust on the left side (lower side in the figure). Each system is provided.

  On the intake side of the engine 1, an intake manifold 3 for supplying intake air to the combustion chamber of each cylinder 2 and a common rail for distributing and supplying high-pressure fuel to the injectors 4, 4,. 5 are arranged. The common rail 5 is supplied with fuel from a fuel pump 51 (not shown in FIG. 1) and supplies fuel to each of the injectors 4 through independent fuel pipes 41.

  On the other hand, an exhaust manifold 15 for discharging burned gas from the fuel chamber in the cylinder 2 is disposed on the exhaust side of the engine 1.

  The injector 4 is disposed along the center line of each cylinder 2 and is supported upright with respect to the cylinder head 14. Although not shown, the nozzle hole at the tip of the injector 4 faces the cylinder 2. The base end portion of the cylinder head cover 11 protrudes upward through a common opening 12 formed at a substantially central portion in the width direction of the cylinder head cover 11.

  FIG. 2 is a front view of the engine 1 as seen from the front side with some members such as an intake system and an exhaust system removed. In the figure, 13 is a cylinder block, 14 is a cylinder head disposed above the cylinder block 13, and 21 is a gear case attached to the lower part of the cylinder block 13.

  The gear case 21 is a case for accommodating a gear train to be described later. As shown in FIG. 3, the gear case 21 includes a rear cover 21a disposed on the cylinder block 13 side and a front cover 21b disposed on the front side of the rear cover 21a. Thus, both the covers 21a and 21b are fixed to the cylinder block 13 with a plurality of bolts in a state where the covers 21a and 21b overlap in the longitudinal direction of the engine.

  As shown in FIGS. 2 and 3, a crank gear 61 that rotates integrally with the crankshaft 6 is attached to the front end side of the crankshaft 6 extending in the cylinder row direction at the lower position of the cylinder block 13. Yes. A fuel pump 51 for supplying fuel to the common rail 5 is disposed at the intake side upper position of the gear case 21. The fuel pump 51 is supported by the cylinder block 13 via a rear cover 21a. . A pump gear 52 is attached to the base end side of the pump shaft 51a of the fuel pump 51, and the pump gear 52 rotates integrally with the pump shaft 51a.

  First and second idle gears 62 and 63 are disposed between the pump gear 52 and the crank gear 61. The first idle gear 62 meshes with the pump gear 52, while the second idle gear 63 is Engages with the crank gear 61. The first and second idle gears 62 and 63 are rotatably supported by the shaft portions 62a and 63a in a state of being extrapolated to the shaft portions 62a and 63a fixed to the cylinder block 13, respectively. The driving force of the crankshaft 6 is transmitted to the pump shaft 51a via the first and second idle gears 62 and 63.

  A vacuum pump gear 64 attached to a drive shaft of a vacuum pump (not shown) is disposed at a position below the engine of the pump gear 52, and a hydraulic pressure for a power steering device is disposed at a position obliquely below the intake side of the vacuum pump gear 64. A hydraulic pump gear 65 attached to a pump (not shown) is provided. The vacuum pump gear 64 meshes with the first idle gear 62, and the hydraulic pump gear 65 meshes with the vacuum pump gear 64.

  The crank gear 61 is further attached to a third idle gear 66 disposed obliquely above the exhaust side of the crank gear 61 and a drive shaft of an oil pump (not shown). Positioned oil pump gears 67 mesh with each other.

  A right balance shaft (not shown) on the intake side with respect to the crankshaft 6 and a left balance shaft (not shown) on the exhaust side are rotatably supported by the cylinder block 13 in parallel with the crankshaft 6. The right balancer gear 68 attached to the front end portion of the right balance shaft meshes with the first idle gear 62, while the left balancer gear 69 attached to the front end portion of the left balance shaft meshes with the crank gear 61. Mesh with the third idle gear 66.

  The crank gear 61, the pump gear 52, the vacuum pump gear 64, the hydraulic pump gear 65, the oil pump gear 67, the left and right balancer gears 68, 69, and the first to third idle gears 62, 63, 66 are all housed in the gear case 21. ing.

  In the gear train composed of the crank gear 61, the pump gear 52, and the first and second idle gears 62 and 63, the crank gear 61, which is the drive input side gear, has a friction gear 71 as a rattling noise prevention mechanism. Is attached. The friction gear 71 is a gear having one fewer tooth than the crank gear 61 and is pressed against the front end surface of the crank gear 61 by a baffle plate 72 and a spring 73. The friction gear 71 meshes with the second idle gear 63, but does not mesh with the third idle gear 66.

  As will be described in detail later, a scissors gear 8 is disposed in the pump gear 52 which is a gear on the drive output side of the gear train.

  In the pump shaft 51a of the fuel pump 51, a pump pulley 91 is attached to the front end side (front side of the engine 1) of the pump gear 52. The pump pulley 91 rotates integrally with the pump shaft 51a.

  The cylinder head 14 has two camshafts (not shown) on the intake side and the exhaust side that are arranged in the left-right direction of the engine 1 and extend in the front-rear direction of the engine 1, respectively. As shown in FIG. 2, intake-side and exhaust-side timing pulleys 92 and 93 are attached to the front end portions of the two camshafts.

  The pump pulley 91 and the timing pulleys 92 and 93 are drivingly connected by a timing belt 94. The timing belt 94 rotates from the pump pulley 91 to the pump pulley 91 via the exhaust side timing pulley 93 and the intake side timing pulley 92, and the timing belt 94 is loosened (the right side in FIG. 2) span. On the other hand, an auto tensioner 95 is disposed, and an idler pulley 96 is disposed on the tension side (left side in FIG. 2) span.

  The belt mechanism constituted by the pulleys 91 to 93, the timing belt 94, the tensioner 95, and the idler 96 is a belt made of, for example, synthetic resin or the like attached to the front end surface of the engine 1 as shown in FIGS. Covered with a cover 22. The belt cover 22 is in contact with the front end surface of the front cover 21b at the position where the pump pulley 91 is disposed, whereby the pump pulley 91 is accommodated between the belt cover 22 and the front cover 21b. .

  Next, the arrangement structure of the pump gear 52 and the pump pulley 91 will be described in detail with reference to FIGS. As described above, the pump gear 52 is attached to the base end side of the pump shaft 51a of the fuel pump 51, and is externally fitted to the gear body portion 53 having teeth formed on the outer periphery thereof and the pump shaft 51a. The front end of the front cover 21b includes a boss portion 54 that protrudes forward from the opening formed in the front cover 21b.

  An annular groove 53a is formed on the end surface of the gear body 53 on the engine front side, and a torsion spring 83 is accommodated in the groove 53a.

  The scissors gear 8 is disposed on the end surface of the gear main body 53 on the front cover side (the engine 1 front side). The scissor gear 8 is a relatively thin annular body and has the same number of teeth as the pump gear 52 on the outer periphery thereof. On the end surface of the scissors gear 8 on the front cover side (the front side of the engine 1), an annular convex portion 81 protruding toward the front side of the engine is formed at the radially inner position, and the radially outer side of the annular convex portion 81 is formed. An annular recess 82 that is recessed at a position is formed.

  As shown in FIG. 4A, the torsion spring 83 is an end-arc-shaped member in which a part of the annular body is cut out, and one of the two ends is fixed to the pump gear 52 side. The other engaging portion engages with the pin 85 fixed on the scissors gear 8 side. The torsion spring 83 urges the pump gear 52 and the scissors gear 8 that are superposed on each other so as to be displaced relative to each other in the circumferential direction, and thereby the teeth of the drive gear (here, the first idle gear 62). However, it is sandwiched between the teeth of the pump gear 52 and the teeth of the scissors gear 8 to prevent rattling noise.

  An inner race 25a of the bearing 25 is fitted on the boss portion 54 of the pump gear 52, and the outer race 25b of the bearing 25 is a peripheral wall of the housing 23 that is recessed on the gear main body 53 side of the front cover 21b. Is fitted inside. Thus, the boss portion 54 of the pump gear 52, in other words, the pump shaft 51 a of the fuel pump 51 is supported on the front end side of the gear main body portion 53 by the bearing 25 disposed in the housing 23.

  The inner race 25 a of the bearing 25 is in contact with an annular convex portion 81 formed on the scissors gear 8, and the scissors gear 8 is pressed toward the gear main body 53 by the bearing 25. At this time, the outer race 25 b of the bearing 25 is located in an annular recess 82 formed in the scissors gear 8, and the outer race 25 b is not in contact with the scissors gear 8. Thus, the scissors gear 8 rotates integrally with the pump gear 52 so that the rotation is not hindered by the bearing 25.

  An oil seal 24 is disposed in an opening of the front cover 21b through which the boss portion 54 penetrates. The oil seal 24 holds the boss portion 54 in an oil-tight manner. A pump pulley 91 is arranged coaxially with the pump gear 52 on the front end surface of the boss portion 54 of the pump gear 52 protruding forward of the engine from the front cover 21b. The boss portion 54 and the pump pulley 91 are mutually connected by bolts. Are combined. Thus, the front cover 21b is in a state of being interposed between the gear body 53 of the pump gear 52 and the pump pulley 91.

  As described above, in the engine 1 described above, the bearing 25 that supports the pump shaft 51a is housed in the bearing 25 housing chamber that is recessed in the front cover 21b, and the bearing 25 supports the relatively distal end side of the pump shaft 51a. Is done. As a result, the pump pulley 91 is disposed on the front end side of the pump shaft 51a, so that the belt tension acting on the front end portion of the pump shaft 51a can be resisted, and the common rail type direct injection engine 1 is provided. Further, it is possible to cope with a high driving load of the fuel pump 51 that requires a high fuel pressure.

  The scissors gear 8 is provided on the front end face of the pump gear 52 (gear body 53) attached to the pump shaft 51a, and the scissors gear 8 is pressed against the gear body 53 by the bearing 25. As a result, it is not necessary to separately provide a pressing member for the scissors gear 8, and the number of parts can be reduced and the overall length of the engine 1 can be suppressed. Further, by providing the scissors gear 8 in the pump gear 52, rattling noise is prevented.

  Further, the pump shaft 51a of the fuel pump 51 protrudes from the front cover 21b into the belt cover 22 via the oil seal 24. When a rattling noise is generated in the pump gear 52, the oil seal and synthetic resin are used. However, since the rattling noise of the pump gear 52 is prevented by providing the scissors gear 8, it is possible to prevent the occurrence of sound leakage.

  Further, in the gear train composed of the crank gear 61, the first and second idle gears 62 and 63, and the pump gear 52, by providing the friction gear 71 on the crank gear 61 on the input side, the input side and the output side of the gear train are provided. In both cases, rattling noise is prevented. As a result, it is possible to effectively prevent the occurrence of rattling noise without unnecessarily increasing the mechanism for preventing rattling noise.

  The present invention is not limited to the DOHC engine. For example, it can be applied to a SOHC engine.

It is a top view of the engine which concerns on embodiment. It is a front view of an engine in the state where members, such as an intake and exhaust system, were removed. It is AA sectional drawing of FIG. 2 which shows a gear train. (A) The top view which shows the pump gear which provided the scissors gear, (b) It is the BB sectional drawing.

Explanation of symbols

1 Engine 13 Cylinder block 14 Cylinder head 21b Front cover (gear cover)
22 Belt cover 23 Housing 24 Oil seal 25 Bearing 25a Inner race 25b Outer race 51 Fuel pump 51a Pump shaft 52 Pump gear 6 Crankshaft 61 Crank gear 62 First idle gear 63 Second idle gear 71 Friction gear (tooth rattling noise prevention mechanism)
8 Scissor gear 81 Annular convex part 82 Annular concave part 91 Pump pulleys 92, 93 Timing pulley 94 Timing belt

Claims (3)

An auxiliary drive structure for a direct-injection diesel engine that injects fuel into the cylinder from an injector facing the cylinder,
A fuel pump supported by a cylinder block for supplying fuel to the injector;
A pump gear attached to the pump shaft of the fuel pump;
A crank gear attached to the crankshaft;
An idle gear interposed between the pump gear and the crank gear to transmit the driving force of the crankshaft to the fuel pump;
A scissor gear disposed on the pump gear;
A gear cover fixed to the cylinder block and covering a gear train including the crank gear, pump gear, scissor gear, and idle gear;
A pump pulley attached to the tip side of the pump gear in the pump shaft;
A timing pulley attached to a camshaft disposed on the cylinder head;
A timing belt that is spanned between the pump pulley and the timing pulley and drives and connects the pulleys;
A belt cover covering a belt mechanism including the pump pulley, the timing pulley, and the timing belt;
A bearing for supporting the pump shaft,
The gear cover is interposed between the pump gear and a pump pulley, and has an oil seal that holds the pump shaft in an oil-tight manner;
The bearing is disposed in a housing recessed in the gear cover on the pump gear side from the oil seal,
The scissor gear is disposed on an end surface of the pump gear on the gear cover side, and is an auxiliary machine drive structure that is pressed and supported on the pump gear side by contacting the end surface of the bearing on the pump gear side. In the auxiliary machine drive structure according to claim 1,
The bearing includes an inner race that fits externally on the pump shaft, and an outer race that fits internally on the peripheral wall of the housing,
An end surface on the bearing contact side of the scissor gear has an annular convex portion that contacts the end surface of the inner race, and an annular concave portion that is recessed at a radially outer position of the annular convex portion and is not in contact with the outer race. Auxiliary machinery drive structure is formed. In the accessory drive structure according to claim 1 or 2,
Two idle gears are interposed between the crank gear and the pump gear,
An auxiliary machine drive structure in which the crank gear is provided with a rattling noise prevention mechanism.

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