JP2011122510A - Valve driving device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lightweight and compact valve driving device for an internal combustion engine with a plurality of cylinders. <P>SOLUTION: The valve driving device for cylinder head valves of the plurality of cylinders 2, 3 includes first valve driving sprockets 21, 31 of the first cylinder 2; second valve driving sprockets 41, 51 of the second cylinder 3; a fuel pump sprocket 61 of a fuel pump 60; a first crank sprocket 11 and a second crank sprocket 12 arranged in an axial direction and fixed to a crankshaft 10; a first chain 80 for transmitting power from the first crank sprocket to the first valve driving sprocket; a second chain 90 for transmitting power from the second crank sprocket to the fuel pump sprocket; a first idler sprocket 71 driven by the second chain; a second idler sprocket 72 fixed to the first idler sprocket; and a third chain 100 transmitting power from the second idler sprocket to the second valve driving sprocket. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a valve drive apparatus for an internal combustion engine having a plurality of cylinders, and more particularly to a lightweight and compact device.

In a 4-stroke reciprocating internal combustion engine, generally, a camshaft provided in a cylinder head opens and closes valves (valves) provided in intake and exhaust ports, respectively. The camshaft is driven at a half speed of the crankshaft by a power transmission member such as a timing chain or a timing belt.
In the case of a horizontally opposed engine or a V-type engine having a plurality of cylinders (banks) distributed to different crankshaft phases, camshafts are provided in the cylinder heads of the banks.

  For example, in Patent Document 1, in a valve drive apparatus for a V-type internal combustion engine, left and right bank drive sprockets are provided on idler gears driven by a crank gear provided on a crankshaft. It is described that power is transmitted by a timing chain, and a tensioner for adjusting the tension of each timing chain is arranged between the left and right banks.

JP 2005-163583 A

When trying to drive a drive sprocket around which a timing chain is wound using a crank gear and an idler gear as in the prior art described above, the size and weight of the internal combustion engine increase due to the increase in the size of the idler gear. In particular, when the idler gear is decelerated and rotated with respect to the crank gear as in Patent Document 1, the idler gear is further increased in size.
Furthermore, if the two drive sprockets for the left and right banks are arranged concentrically with the idler gear, the axial length becomes long and the axial dimension of the valve drive device becomes large.

In addition, an oil pump that pressurizes and discharges the lubricating oil is provided at the crankshaft front end portion (the end portion opposite to the transmission side) of the internal combustion engine. As the oil pump, a trochoid pump having an inner rotor coupled to a crankshaft and an outer rotor that rotates in conjunction with the inner rotor is generally used.
In a configuration using a crank gear and an idler gear as in the prior art, it is difficult to dispose the oil pump closer to the transmission than the crank gear due to restrictions on the layout of the crank gear. For this reason, an oil pump will be arrange | positioned rather than a crank gear at the front-end | tip side of a crankshaft, and the full length of an internal combustion engine will become long.
An object of the present invention is to provide a valve drive apparatus for an internal combustion engine that drives valve valves of a plurality of cylinders with a lightweight and compact configuration.

The present invention solves the above-described problems by the following means.
The invention according to claim 1 is a valve drive apparatus for an internal combustion engine for driving a valve of a cylinder head provided in each of a plurality of cylinders, the first valve drive sprocket provided in the first cylinder, , A second valve drive sprocket provided in the second cylinder, a fuel pump sprocket provided in the fuel pump, and a first crank sprocket and a second crank fixed to the crankshaft and arranged in the axial direction A sprocket, a first chain for transmitting power from the first crank sprocket to the first valve drive sprocket, a second chain for transmitting power from the second crank sprocket to the fuel pump sprocket, and A first idler sprocket driven by a second chain and the first idler sprocket A second idler sprockets, a valve train drive system for an internal combustion engine, characterized in that it comprises a third chain of power transmission from the second idler sprocket to the second valve-operating drive sprocket.

According to a second aspect of the present invention, the crankshaft is provided with an oil pump that is inserted into the crankshaft and pumps lubricating oil, and at least a part of the oil pump overlaps the third chain in the axial direction of the crankshaft. The valve drive apparatus for an internal combustion engine according to claim 1, wherein the valve drive apparatus is arranged.
The invention according to claim 3 is the internal combustion engine according to claim 2, wherein the first crank sprocket, the second crank sprocket, and the oil pump are sequentially arranged from the tip end side of the crankshaft. It is a valve drive device.

According to the present invention, the following effects can be obtained.
(1) By driving the fuel pump from the crankshaft by the second chain, it is not necessary to use a heavy idler gear, and the valve drive device can be reduced in weight and cost. Moreover, the fuel consumption rate is also improved by such weight reduction.
In addition, since each shaft has a configuration of two sprockets or less, the axial dimension of the valve drive device can be reduced.
(2) Utilizing an offset (so-called bank offset) between the first and second cylinders by driving the second valve drive sprocket from the idler sprocket driven by the second chain by the third chain Thus, a space can be secured in a region adjacent to the first and second crank sprockets around the crankshaft. And by arranging an oil pump in this space, the overall length of the internal combustion engine can be shortened.
(3) By disposing the first and second crank sprockets on the front end side of the crankshaft with respect to the oil pump, the oil pump is prevented from protruding from the front end portion of the internal combustion engine, and the degree of freedom in designing the vehicle body Can be improved.
Furthermore, the first crank sprocket, which is more required to have a smaller number of teeth and a smaller diameter than the second crank sprocket that drives the fuel pump, is disposed closer to the crankshaft tip than the second crank sprocket and the oil pump. This makes it easy to check the assembly of the chain. In addition, it is easy to secure a space (a depth of the screw hole) for the female screw formed at the front end portion of the crankshaft.

It is the figure which looked at the Example of the valve drive apparatus of the internal combustion engine to which this invention was applied from the axial direction (vehicle front side in the case of vertical installation) of a crankshaft. It is the II-II part arrow sectional drawing of FIG. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1. It is the figure which looked at the valve drive apparatus of the internal combustion engine which is a comparative example of this invention from the axial direction of the crankshaft. FIG. 5 is a cross-sectional view taken along line VV in FIG. 4. It is VI-VI part arrow directional cross-sectional view of FIG.

  It is an object of the present invention to provide a valve driving device for an internal combustion engine that drives a valve and a fuel pump of a plurality of cylinders with a lightweight and compact configuration, and a camshaft of one cylinder is directly chained from a first crank sprocket. This is solved by driving the camshaft of the other cylinder through an idler sprocket driven by a chain that transmits power from the second crank sprocket to the fuel pump.

Hereinafter, embodiments of a valve drive apparatus for an internal combustion engine to which the present invention is applied will be described. The valve drive apparatus according to the embodiment is provided in an engine that is mounted vertically in a front part of a vehicle body such as a passenger car.
As shown in FIG. 1, the engine 1 is a horizontally opposed engine having a right cylinder 2 and a left cylinder 3, for example, a 4-cylinder turbo diesel engine. The right cylinder 2 and the left cylinder 3 correspond to a first cylinder and a second cylinder, respectively, according to the present invention.

  The engine 1 includes a crankshaft 10, a right intake camshaft 20, a right exhaust camshaft 30, a left intake camshaft 40, a left exhaust camshaft 50, a fuel pump 60 (see FIGS. 2 and 3), an idler sprocket 70, The first chain 80, the second chain 90, the third chain 100, the oil pump 110, the water pump 120, and the like are provided.

The crankshaft 10 is an output shaft of the engine 1. The crankshaft 10 is formed with crank arms and crankpins corresponding to the number of cylinders, and each crankpin is connected to a piston of each cylinder (not shown) via a connecting rod. An end portion of the crankshaft 10 on the vehicle rear portion side (not shown) (hereinafter referred to as “rear end portion”) is provided with a flywheel and connected to the transmission.
The crankshaft 10 rotates clockwise in FIG. 1 when the engine 1 is operated. A first crank sprocket 11 and a second crank sprocket 12 are fixed to an end portion of the crankshaft 10 on the vehicle front side (hereinafter referred to as “front end portion”).
The first crank sprocket 11 is wound around the first chain 80 and drives an intake / exhaust valve provided on the right cylinder 2 side.
The second crank sprocket 12 is wound around the second chain 90 and drives the fuel pump sprocket 61 of the fuel pump 60 and the first idler sprocket 71 of the idler sprocket 70. The second crank sprocket 12 has a larger number of teeth and a larger diameter than the first crank sprocket 11.
As shown in FIGS. 2 and 3, the first crank sprocket 11 and the second crank sprocket 12 are sequentially arranged from the front end side of the crankshaft 10.

The right intake camshaft 20 drives the intake valve of the right cylinder 2.
The right exhaust camshaft 30 drives the exhaust valve of the right cylinder 2.
The right intake camshaft 20 and the right exhaust camshaft 30 are arranged side by side in the vertical direction so that the right intake camshaft 20 faces upward.
A right intake cam sprocket 21 and a right exhaust cam sprocket 31 are fixed to front end portions of the right intake camshaft 20 and the right exhaust camshaft 30, respectively.
The right intake cam sprocket 21 and the right exhaust cam sprocket 31 correspond to a first valve drive sprocket according to the present invention.

The left intake camshaft 40 drives the intake valve of the left cylinder 3.
The left exhaust camshaft 50 drives the exhaust valve of the left cylinder 3.
The left intake camshaft 40 and the left exhaust camshaft 50 are arranged side by side in the vertical direction so that the left intake camshaft 40 is on the upper side.
A left intake cam sprocket 41 and a left exhaust cam sprocket 51 are fixed to front end portions of the left intake camshaft 40 and the left exhaust camshaft 50, respectively.
The left intake cam sprocket 41 and the left exhaust cam sprocket 51 correspond to a second valve drive sprocket according to the present invention.

As shown in FIG. 3, the fuel pump 60 is provided in the upper part of the engine 1 and pressurizes fuel such as light oil to a high pressure and supplies it to a common rail (not shown).
The fuel pump 60 includes an input shaft 60 a (see FIG. 3) whose main body is provided substantially above the crankshaft 10 and protrudes forward. A fuel pump sprocket 61 shown in FIG. 1 is fixed to the tip of the input shaft 60a. A second chain 90 is wound around the fuel pump sprocket 61.

The idler sprocket 70 is configured such that the first idler sprocket 71 and the second idler sprocket 72 are integrated to be rotatable about a rotation axis parallel to the crankshaft 10.
The first idler sprocket 71 is engaged with the tight side of the third chain 100 (the side returning from the fuel pump sprocket 61 side to the second crank sprocket 12 side) and the inside of the third chain 100 so as to mesh with the second crank sprocket 12. And on the lower side of the fuel pump sprocket 61 and offset to the left cylinder 3 side.
The second idler sprocket 72 is concentrically disposed on the rear side (transmission side) of the first idler sprocket 71. The second idler sprocket 72 has a smaller number of teeth and a smaller diameter than the first idler sprocket 71.

The first chain 80 is wound around the first crank sprocket 11, the right exhaust cam sprocket 31, and the right intake cam sprocket 21 in order.
The first chain 80 is provided with a chain tensioner 81, a chain tensioner lever 82, and a chain guide 83.
The chain tensioner 81 includes a plunger that presses the chain tensioner lever 82 against the chain.
The chain tensioner lever 82 is attached to the engine body so as to be swingable about a rotation axis parallel to the crankshaft 10, and is pressed against the first chain 80 by being pushed by the plunger of the chain tensioner 81. Adjust the tension so that it is within the appropriate range. The other chain tensioners and chain tensioner levers described below also have the same function.
The chain tensioner 81 and the chain tensioner lever 82 are disposed on the slack side of the first chain 80 (the side returning from the driven sprocket to the driving side sprocket; the lower side in the case of the first chain 80).
The chain guide 83 contacts the first chain 80 and guides the first chain 80. The chain guide 83 is disposed on the tight side of the first chain 80 (the side going from the driving-side sprocket to the driven-side sprocket; the upper side in the case of the first chain 80).

The second chain 90 is wound around the second crank sprocket 12, the first idler sprocket 71, and the fuel pump sprocket 61 in order.
A chain tensioner 91 and a chain tensioner lever 92 are provided on the slack side (right cylinder 2 side) of the second chain 90.

The third chain 100 is wound around the second idler sprocket 72, the left intake cam sprocket 41, and the left exhaust cam sprocket 51 sequentially.
A chain tensioner 101 and a chain tensioner lever 102 are provided on the slack side (upper side) of the third chain 100, and a chain guide 103 is provided on the tension side (lower side).

The oil pump 110 pressurizes and discharges the lubricating oil of the engine 1.
The oil pump 110 is, for example, a trochoid pump having an inner rotor fixed to the crankshaft 10 and an outer rotor that rotates in conjunction with the inner rotor.
As shown in FIGS. 2 and 3, the oil pump 110 has the crankshaft 10 inserted therein, and is disposed between the second crank sprocket 12 and the crank journal 10 a on the engine front end side.

  The water pump 120 circulates the cooling water of the engine 1. The position of the water pump 120 as viewed from the axial direction of the crankshaft 10 is disposed below the left cylinder 3 between the crankshaft 10 and the left exhaust camshaft 50.

Hereinafter, the effect of the above-described embodiment will be described in comparison with a valve drive apparatus of a comparative example of the present invention described below. In the description of the comparative example, portions that are substantially the same as those of the embodiment are denoted by the same reference numerals, description thereof is omitted, and differences are mainly described.
The engine 1A of the comparative example shown in FIG. 4 includes the first crank sprocket 11, the second crank sprocket 12, the fuel pump sprocket 61, the idler sprocket 70, the first chain 80, the second chain 90, and the third chain 100 of the embodiment. Instead, a crank gear 13, a fuel pump gear 62, an idler gear 130, a right chain 140, a left chain 150 and the like described below are provided.

The crank gear 13 is a helical gear provided near the front end of the crankshaft 10.
The fuel pump gear 62 is a helical gear fixed to the input shaft 60 a of the fuel pump 60.
The idler gear 130 is provided between the crank gear 13 and the fuel pump gear 62, meshes with these gears, and transmits power from the crank gear 13 to the fuel pump gear 62.

A first idler sprocket 131 and a second idler sprocket 132 are provided on the vehicle front side of the idler gear 130 in order from the vehicle front side. The first idler sprocket 131 and the second idler sprocket 132 are fixed so as to rotate integrally with the idler gear 130.
For example, the idler gear 130 has twice as many teeth as the crank gear 13, and the first idler sprocket 131 and the second idler sprocket 132 have the same number of teeth as the sprocket of each camshaft.

  The right chain 140 is wound around the first idler sprocket 131, the right exhaust cam sprocket 31, and the right intake cam sprocket 21, and transmits power among them. The right chain 140 is provided with a chain tensioner 141, a chain tensioner lever 142, and a chain guide 143.

  The left chain 150 is wound around the second idler sprocket 132, the left intake cam sprocket 41, and the left exhaust cam sprocket 51, and transmits power among them. The left chain 150 is provided with a chain tensioner 151, a chain tensioner lever 152, and a chain guide 153.

  In the comparative example, the oil pump 110 is disposed on the front end side of the crankshaft 10 with respect to the crankgear 13 due to the layout restriction of the crankgear 13 provided on the crankshaft 10. (See FIGS. 5 and 6)

In the comparative example described above, the weight of the gear train such as the idler gear 130 is increased, and the weight and cost of the engine 1A are increased.
Further, in the idler gear 130, since it is necessary to arrange one gear and two sprockets on the same axis, the dimension (thickness) in the axial direction of the valve driving device is increased, and the overall length of the engine 1A is increased. Become.
Furthermore, due to the layout constraints of the crank gear 13, the oil pump 110 protrudes toward the front end portion of the engine 1A, further increasing the overall length of the engine 1A and reducing the degree of freedom in designing the vehicle body.

On the other hand, in the embodiment, the fuel pump 60 is a chain drive using the second chain 90, so that even when the idler sprocket 70 is provided, the gear drive as in the comparative example is used. As a result, the valve drive device can be made lighter and the cost can be reduced. Furthermore, the fuel consumption rate of the engine 1 is improved by reducing the weight.
Moreover, since each shaft can be configured to have a maximum of two sprockets, the axial dimension of the valve drive device can be reduced and the overall length of the engine 1 can be shortened.
Further, the left intake camshaft 40 and the left exhaust camshaft 50 are chain-driven from the second idler sprocket 72 using the third chain 100, so that the left and right intake camshafts 40 and A space formed due to the cylinder offset (bank offset) can be secured, and by accommodating the oil pump 110 here, the internal thread length of the front end of the crankshaft 10 is secured while the engine 1 of the engine 1 is secured. The overall length can be further shortened. Thereby, the freedom degree of vehicle body design improves.
In addition, since the first crank sprocket 11 having a small diameter with respect to the second crank sprocket 12 is disposed in front of the second crank sprocket 12 and the oil pump 110, it is easy to check the assembly of the chain to each sprocket.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) The internal combustion engine of the embodiment is, for example, a horizontally opposed 4-cylinder DOHC turbo diesel engine, but the present invention can also be applied to other types of internal combustion engines. The present invention can be applied to, for example, a V-type engine, a multi-cylinder engine having 6 or more cylinders, an SOHC engine in which intake and exhaust valves are driven by a common camshaft, and engines other than diesel. Also, the mounting direction and mounting position of the engine are not particularly limited.
(2) The shape, structure, arrangement and the like of each element constituting the valve drive device are not limited to those of the above-described embodiments, and can be changed as appropriate. For example, the number of teeth of each sprocket can be appropriately set so that each camshaft is half the number of revolutions of the crankshaft and the number of revolutions of the fuel pump is appropriate. In the case of a V-type engine, the fuel pump can be arranged either in the left and right (front and rear) banks or outside the bank.

1 Engine (Example) 1A Engine (Comparative example)
2 Right Cylinder 3 Left Cylinder 10 Crankshaft 10a Crank Journal 11 First Crank Sprocket 12 Second Crank Sprocket 13 Crank Gear 20 Right Intake Camshaft 21 Right Intake Cam Sprocket 30 Right Exhaust Camshaft 31 Right Exhaust Cam Sprocket 40 Left Intake Camshaft 41 Left intake cam sprocket 50 Left exhaust camshaft 51 Left exhaust cam sprocket 60 Fuel pump 60a Input shaft 61 Fuel pump sprocket 62 Fuel pump gear 70 Idler sprocket 71 First idler sprocket 72 Second idler sprocket 80 First chain 81 Chain tensioner 82 Chain Tensioner lever 83 Chain guide 90 Second chain 91 Chain tensioner 92 Chain tensioner lever 100 Third chain 101 Chain tensioner 102 Chain tensioner lever 103 Chain guide 110 Oil pump 120 Water pump 130 Idler gear 131 First idler sprocket 132 Second idler sprocket 140 Right chain 141 Chain tensioner 142 Chain tensioner lever 143 Chain guide 150 Left Chain 151 Chain tensioner 152 Chain tensioner lever 153 Chain guide

Claims (3)

A valve drive apparatus for an internal combustion engine for driving a valve of a cylinder head provided in each of a plurality of cylinders,
A first valve drive sprocket provided in the first cylinder;
A second valve drive sprocket provided in the second cylinder;
A fuel pump sprocket provided in the fuel pump;
A first crank sprocket and a second crank sprocket fixed to the crankshaft and arranged in an axial direction;
A first chain for transmitting power from the first crank sprocket to the first valve drive sprocket;
A second chain for transmitting power from the second crank sprocket to the fuel pump sprocket;
A first idler sprocket driven by the second chain;
A second idler sprocket secured to the first idler sprocket;
And a third chain for transmitting power from the second idler sprocket to the second valve drive sprocket. The crankshaft is inserted into the inside and includes an oil pump that pumps lubricating oil,
The valve drive apparatus for an internal combustion engine according to claim 1, wherein at least a part of the oil pump is arranged such that a position of the crankshaft in an axial direction overlaps the third chain. The valve drive apparatus for an internal combustion engine according to claim 2, wherein the first crank sprocket, the second crank sprocket, and the oil pump are sequentially arranged from the tip end side of the crankshaft.

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