JP5120212B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine mounted on a vehicle such as an automobile. In this internal combustion engine, a plunger-type high-pressure fuel pump that supplies high-pressure fuel to an injector that directly injects high-pressure fuel into its combustion chamber, and this high-pressure fuel pump are driven using the rotational power of the crankshaft of the internal combustion engine. And a drive mechanism. A configuration in which the high-pressure fuel pump is mounted on the rear portion of the cylinder head of the internal combustion engine is a prerequisite of the present invention.

  Conventionally, a pump cam for driving a high-pressure fuel pump is provided on the outer diameter side in the longitudinal direction of a camshaft installed in a cylinder head of an internal combustion engine, and the pump cam is driven to rotate together with the camshaft by the driving force of the crankshaft. Is used to drive a high-pressure fuel pump (see, for example, Patent Document 1).

Further, a configuration in which a pump cam is connected to one shaft end of a camshaft via an Oldham coupling is known (for example, see Patent Document 2).
In such a configuration, the driving torque of the high-pressure fuel pump acts on the camshaft in addition to the driving torque of the intake valve or the exhaust valve. For example, a timing chain for transmitting power from the crankshaft to the camshaft There is a concern that it is necessary to make the product a high strength countermeasure product.

  In addition, for example, when a variable valve timing mechanism is attached to the camshaft, the driving torque of the high-pressure fuel pump becomes an operating load of the variable valve timing mechanism. Therefore, there is a concern that the operation of the variable valve timing mechanism becomes unstable.

  On the other hand, as shown in Patent Document 3, for example, a pump drive shaft is installed between the intake camshaft and the exhaust camshaft, and this pump drive shaft and one of the camshafts are connected to the crankshaft. There is known a configuration in which the rotational power is used to rotate and the remaining camshaft is driven by the rotational power of the pump drive shaft.

For example, as shown in Patent Document 4, a pump camshaft is attached to the outer diameter side of the front end of the camshaft so as to be relatively rotatable, and a timing chain is attached to a sprocket and a crankshaft provided on the pump camshaft. A configuration is known in which a high-pressure fuel pump disposed at the front portion of an internal combustion engine is driven by winding and rotationally driving a pump camshaft by a driving force of a crankshaft.
JP-A-8-14140 JP 2007-278205 A JP 2007-107504 A JP 2003-343181 A

  In the conventional examples according to Patent Documents 3 and 4, the driving torque of the high-pressure fuel pump does not act on the camshaft, but each has the following problems.

  First, in the conventional example according to Patent Document 3, it is pointed out that the internal combustion engine is enlarged in the width direction because of the relationship in which the pump drive shaft is disposed between the two camshafts.

  Moreover, in the conventional example which concerns on patent document 4, it is indispensable to install a high pressure fuel pump in the front part of an internal combustion engine, and it was pointed out that this high pressure fuel pump cannot be installed in the rear part of an internal combustion engine. The In recent years, it is necessary to install various types of auxiliary equipment at the front part of the internal combustion engine, and it may not be possible to secure a space for installing the high pressure fuel pump, and the high pressure fuel pump is installed at the rear part of the internal combustion engine. It is hoped that.

  In view of such circumstances, the present invention relates to a high-pressure fuel pump installed at a rear portion of a camshaft of an internal combustion engine and an internal combustion engine having a drive mechanism thereof, wherein the drive torque of the high-pressure fuel pump acts on the camshaft, The purpose is to make it possible to avoid an increase in the size of the engine.

The present invention provides a drive mechanism for driving a plunger-type high-pressure fuel pump that supplies high-pressure fuel to an injector that directly injects high-pressure fuel into a combustion chamber of the internal combustion engine using the rotational power of the crankshaft of the internal combustion engine. The valve mechanism of the internal combustion engine has an intake camshaft and an exhaust camshaft, the exhaust camshaft has a hollow shape, and the drive mechanism is inserted into an inner hole of the hollow exhaust camshaft. that includes a pump drive shaft, the pump camshaft for driving the high-pressure fuel pump installed in the rear end side of the integrally rotatably provided and the exhaust camshaft to the rear end side of the pump drive shaft, said A pump sprocket provided on the front end side of the pump drive shaft; an intake cam sprocket provided on the front end side of the intake camshaft; When the timing chain is wound around a crank sprocket provided on the front end side of the crankshaft, the pump drive shaft and the intake camshaft are rotated in the same direction by receiving the rotational power of the crankshaft, and the intake cam The sprocket and the exhaust camshaft are provided with gears that mesh with each other, whereby the exhaust camshaft is rotationally driven in the opposite direction by receiving the rotational power of the intake camshaft .

  In short, in consideration of the fact that a large number of auxiliary machines are arranged in front of the internal combustion engine, the rotational power of the crankshaft is supplied to the front of the internal combustion engine while installing the high-pressure fuel pump at the rear part of the internal combustion engine. It is devised to transmit to the high-pressure fuel pump via the timing chain arranged in the cylinder or the drive mechanism.

  In particular, the pump drive shaft for driving the high pressure fuel pump is driven by the rotational power of the crankshaft independently of the camshaft, and the high pressure fuel pump is attached to the camshaft of the valve mechanism as in the conventional example. There is no configuration in which a pump cam for driving or a pump cam for driving a high-pressure fuel pump is connected to the camshaft of the valve mechanism.

  As a result, it is possible to avoid the drive torque of the high-pressure fuel pump from acting on the camshaft of the valve operating mechanism, thereby reducing the load on the means for transmitting the drive force to the camshaft.

  Further, since the pump drive shaft of the drive mechanism for transmitting rotational power from the front to the rear of the internal combustion engine as described above is inserted into the inner hole of the hollow cam shaft, the pump drive shaft is inserted into the intake cam. Unlike the conventional example installed between the shaft and the exhaust camshaft, the internal combustion engine can be kept compact in the width direction, for example, because it is not necessary to design the internal combustion engine to be wide.

In the present invention, the timing chain is connected to the pump sprocket provided on the front end side of the pump drive shaft, the intake cam sprocket provided on the front end side of the intake camshaft, and the crank sprocket provided on the front end side of the crankshaft. Is wound so that the pump drive shaft and the intake camshaft are rotationally driven in the same direction by receiving the rotational power of the crankshaft.

  The sprocket may be a gear, and the timing chain may be a timing belt.

In such a configuration, for example, even when it is necessary to increase or decrease the rotational power of the crankshaft and transmit it to the pump drive shaft, the pump sprocket diameter and the number of teeth are set to the crank sprocket diameter and the number of teeth. However, it is not necessary to use a transmission gear for speeding up or decelerating. Therefore, for example, when using a transmission gear, it is necessary to make the timing chain a high-strength product. However, in the above-described configuration , such a need is not required, which increases useless equipment costs and installation space. Can be avoided. Thus, the rotation ratio of the pump drive shaft to the crankshaft can be arbitrarily set without adding extra parts.

  Preferably, the pump drive shaft and the pump camshaft are coupled together by an Oldham coupling so as to be integrally rotatable.

  In this configuration, the type of coupling that connects the pump drive shaft and the pump camshaft is specified. As is well known, this Oldham coupling has a high ability to absorb axial misalignment between the two shafts to be connected. Therefore, even when the accuracy of the support position of the two shafts is low, the two shafts can be connected without hindrance.

  The present invention makes it possible to avoid the drive torque of the high-pressure fuel pump from acting on the camshaft in the drive mechanism of the high-pressure fuel pump installed at the rear portion of the camshaft of the internal combustion engine. It is possible to avoid an increase in size.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  1 to 4 show an embodiment of the present invention. In these drawings, reference numeral 1 denotes an internal combustion engine (engine). The internal combustion engine 1 in this embodiment is an in-cylinder direct fuel injection (so-called in-cylinder direct injection) engine of, for example, an in-line 4-cylinder DOHC type.

  Since the basic configuration and operating principle of the internal combustion engine 1 are generally known, in this embodiment, portions related to the features of the present invention will be described in detail, and portions not directly related to the features of the present invention. The detailed explanation about is omitted.

  Although not shown, an upper portion (cylinder head) of the internal combustion engine 1 is equipped with an intake valve for opening and closing an intake port and an exhaust valve for opening and closing an exhaust port, and for opening and closing the intake valve. An intake camshaft 2 and an exhaust camshaft 3 for opening and closing the exhaust valve are mounted. The intake valve, exhaust valve, intake side camshaft 2, exhaust side camshaft 3 and the like are referred to as a valve operating mechanism.

  The internal combustion engine 1 of this embodiment is configured such that the intake camshaft 2 is driven by the rotational power of the crankshaft 4 and the exhaust camshaft 3 is rotationally driven by the rotational power of the intake camshaft 2. Thereby, the intake camshaft 2 rotates in the same direction as the crankshaft 4, and the exhaust camshaft 3 rotates in the opposite direction to the intake camshaft 2 and the crankshaft 4.

  A crank sprocket 5 is provided at the front end side of the crankshaft 4, an intake cam sprocket 6 with an intake cam gear 7 is provided at the front end side of the intake camshaft 2, and an exhaust cam gear 8 is provided at the front end side of the exhaust camshaft 3. , Each is attached.

  A timing chain (or timing belt) 9 is wound around the crank sprocket 5 and the intake cam sprocket 6, and the intake cam gear 7 and the exhaust cam gear 8 are engaged with each other. The tension of the timing chain 9 is adjusted by the damper 10 and the tensioner 11.

  The intake camshaft 2 and the exhaust camshaft 3 are set to rotate once every time the crankshaft 4 rotates twice. That is, the crank sprocket 5, the intake cam sprocket 6 and the timing chain 9 constitute a power transmission mechanism from the crankshaft 4 to the intake camshaft 2.

  In general, in the internal combustion engine 1 mounted on a vehicle such as an automobile, it goes without saying that the side on which the timing chain 9 is arranged is expressed as the front. Therefore, in the internal combustion engine 1, the front and the rear are clear.

  Although not shown, generally, an auxiliary machine such as an air compressor, an alternator, or a water pump driven by a serpentine belt is installed in front of the crank sprocket 5.

  Since the internal combustion engine 1 illustrated in this embodiment has four cylinders, an injector (not shown) provided for each cylinder during one cycle of the internal combustion engine 1, that is, while the crankshaft 4 rotates twice. Thus, a total of four fuel injections are performed once each.

  In addition, the internal combustion engine illustrated in this embodiment is a cylinder direct injection engine, so that the fuel pressure is generally higher than the pressure in the combustion chamber (not shown) of the internal combustion engine 1. It is necessary to inject fuel. Therefore, the fuel sent from the fuel tank (not shown) is pressurized by the high-pressure fuel pump 12 and stored in the delivery pipe (not shown), and is supplied from the injector (not shown) to the combustion chamber as necessary. It has become.

  The high-pressure fuel pump 12 has a known configuration called, for example, a plunger type (see, for example, Japanese Patent Application Laid-Open No. 2007-285209), and illustration and description of the detailed configuration are omitted. Briefly speaking, the operation of the high-pressure fuel pump 12 is such that fuel is pressurized and discharged by linearly reciprocating a plunger (not shown).

  The high-pressure fuel pump 12 is installed at the rear portion of the internal combustion engine 1, more specifically, at the rear end side of the exhaust camshaft 3, and a drive mechanism for driving the high-pressure fuel pump 12 installed at such a location. This will be described in detail below.

  The drive mechanism mainly includes a pump cam shaft 21, a pump drive shaft 22, and a coupling 23.

  The pump camshaft 21 includes a pump cam 21a for driving the plunger (not shown) of the high-pressure fuel pump 12 up and down. The pump cam shaft 21 is installed on the rear end side of the exhaust cam shaft 3, and the pump cam 21 a is brought into contact with the outer end portion of the plunger of the high-pressure fuel pump 12. From this relationship, the high-pressure fuel pump 12 is attached above the pump cam 21a, that is, for example, to a cylinder head cover (not shown) of the internal combustion engine 1.

  The pump drive shaft 22 is inserted into the inner hole of the exhaust camshaft 3 so as to be relatively rotatable, and protrudes from both the front end and the rear end of the exhaust camshaft 3. That is, the exhaust camshaft 3 is formed in a hollow shape, and the pump drive shaft 22 is inserted through the inner hole thereof.

  A pump sprocket 24 is attached to the front end side of the pump drive shaft 22, and the timing chain 9 is wound around the pump sprocket 24. As a result, the rotational power of the crankshaft 4 is transmitted to the pump drive shaft 22 via the timing chain 9. Accordingly, the pump drive shaft 22 is directly driven by the crankshaft 4 and the pump drive shaft 22 is rotationally driven in the same direction as the rotation direction of the crankshaft 4.

  The pump sprocket 24 has the same diameter and the same number of teeth as, for example, the crank sprocket 5 and the number of teeth. This is because the discharge operation from the high-pressure fuel pump 12 is performed once for every rotation of the crankshaft 4, for example. In other words, during one cycle of the internal combustion engine 1, the high pressure fuel is discharged from the high pressure fuel pump 12 twice, and each fuel injection is performed from each injector (not shown) provided for each cylinder. This is to make it happen. However, the diameter and the number of teeth of the pump sprocket 24 are arbitrary, and can be appropriately changed according to the required number of high-pressure fuel discharge operations from the high-pressure fuel pump 12.

  The coupling 23 connects the pump camshaft 21 and the pump drive shaft 22 so as to be integrally rotatable, and is called a so-called Oldham coupling. As is well known, this Oldham coupling has a high ability to absorb axial misalignment between the two shafts 21 and 22 to be connected.

  Specifically, for example, as shown in FIG. 4, the coupling 23 is provided with a rectangular through hole 23 a penetrating in the thickness direction in the center of an elliptical plate, and a straight line in the elliptical plate. The projecting pieces 23b and 23c projecting outward are provided on the two sides.

  At one end of the pump camshaft 21, a rectangular convex portion 21a that can be fitted into the through hole 23a of the coupling 23 is provided. Further, a cylindrical portion 22a is provided at the rear end of the pump drive shaft 22, and a notch in which the projecting pieces 23b and 23c of the coupling 23 can engage with each other at a position opposed to the cylindrical portion 22a by 180 degrees. 22b and 22c are provided. An elliptical main body portion of the coupling 23 is fitted into the inner hole of the cylindrical portion 22a.

  That is, the through hole 23a of the coupling 23 is fitted to the convex portion 21a of the pump cam shaft 21, and the projecting pieces 23b and 23c of the coupling 23 are engaged with the notches 22b and 22c of the pump drive shaft 22. The coupling 23 itself is inserted into the inner hole of the cylindrical portion 22 a of the pump drive shaft 22. As a result, the pump cam shaft 21 and the pump drive shaft 22 are integrally connected by the coupling 23 and can be rotated integrally.

  Next, the operation will be described. Here, the rotation direction of the crankshaft 4 and the timing chain 9 is set to the clockwise direction as shown by the arrow in FIG. 2, the intake camshaft 2 is disposed upstream of the power transmission direction of the timing chain 9, and the pump drive shaft 22 Is arranged downstream.

  When the crankshaft 4 is rotationally driven with the operation of the internal combustion engine 1, the rotational power of the crankshaft 4 is first transmitted to the intake camshaft 2 via the timing chain 9, and the intake camshaft 2 rotates in the direction of rotation of the crankshaft 4. And then transmitted to the pump drive shaft 22, and the pump drive shaft 22 is driven to rotate in the same direction as the rotation direction of the crankshaft 4.

  Then, the rotational power of the intake camshaft 2 is transmitted from the intake cam gear 7 to the exhaust cam gear 8, and the exhaust cam gear 8 and the exhaust camshaft 3 are rotationally driven in the direction opposite to the rotational direction of the intake camshaft 2.

  Further, as the pump drive shaft 22 is rotated, the pump cam shaft 21 is rotationally driven integrally therewith. Therefore, the plunger (not shown) of the high pressure fuel pump 12 is displaced up and down by the pump cam 21a of the pump cam shaft 21. Thus, the high-pressure fuel is discharged from the high-pressure fuel pump 12 at a predetermined timing.

  Incidentally, during the operation of the internal combustion engine 1, the lubricating oil supplied to the valve operating mechanism is supplied to the facing gap between the exhaust camshaft 3 and the pump drive shaft 22. For this reason, the sliding portions of these both are lubricated and cooled with lubricating oil.

  Since the exhaust camshaft 3 and the pump drive shaft 22 rotate in opposite directions, the drag resistance due to the viscosity of the lubricating oil interposed between the exhaust camshaft 3 and the pump drive shaft 22 gives a damping characteristic to both rotational motions. . As a result, fluctuations in rotational torque between the exhaust camshaft 3 and the pump drive shaft 22 are attenuated, so that rattling noise between the intake cam gear 7 and the exhaust cam gear 8 can be reduced. Therefore, in order to prevent the rattling noise, it is not necessary to take measures such as widening the gear or using a scissor gear, which is advantageous in reducing the equipment cost and the installation space. It becomes.

  As described above, in the embodiment to which the features of the present invention are applied, the high pressure fuel pump 12 is installed at the rear portion of the internal combustion engine 1 in consideration of the fact that a large number of auxiliary machines are arranged in front of the internal combustion engine 1. However, the rotation power of the crankshaft 4 is devised so as to be transmitted to the high-pressure fuel pump 12 via the timing chain 9 disposed in front of the internal combustion engine 1 or the drive mechanism described above. An effect is obtained.

  First, in this embodiment, the pump drive shaft 22 for driving the high-pressure fuel pump 12 is driven by the timing chain 9 wound around the crank sprocket 5. The camshaft (2, 3) is not provided with a pump cam for driving the high-pressure fuel pump 12, or the camshaft (2, 3) is not connected with a pump cam for driving the high-pressure fuel pump 12.

  As a result, it is possible to avoid the drive torque of the high pressure fuel pump 12 from acting on the camshafts (2, 3) of the valve operating mechanism. ) Can be reduced.

  Further, since the pump drive shaft 22 of the drive mechanism for transmitting the rotational power from the front to the rear of the internal combustion engine 1 as described above is inserted through the inner hole of the hollow exhaust camshaft 3, the pump drive Unlike the conventional example in which the shaft 22 is installed between the intake camshaft 2 and the exhaust camshaft 3, it is not necessary to design the internal combustion engine 1 to be wide. it can.

  Further, even when the rotational power of the crankshaft 4 needs to be increased or decreased and transmitted to the pump drive shaft 22, the diameter and the number of teeth of the pump sprocket 24 attached to the pump drive shaft 22 can be changed. The diameter and the number of teeth can be appropriately set, and there is no need to use a transmission gear for speeding up or slowing down. Therefore, for example, when a transmission gear is used, it is necessary to make the timing chain 9 a high-strength product. However, in this embodiment, such a necessity is not required, so that an unnecessary equipment cost and an installation space are increased. Can be avoided.

  Thus, in the embodiment to which the features of the present invention are applied, it is possible to avoid the drive torque of the high-pressure fuel pump 12 from acting on the camshafts (2, 3) and the external shape of the internal combustion engine 1 from being increased in size. The rotation ratio of the pump drive shaft 22 to the crankshaft 4 can be arbitrarily set without adding extra parts.

  In addition, this invention is not limited only to the said embodiment, All the deformation | transformation and application included in the range equivalent to the claim and the said range are possible. Examples are given below.

  (1) In the above embodiment, the exhaust camshaft 3 is made hollow and the pump drive shaft 22 is inserted into the inner hole. However, the intake camshaft 2 is made hollow and the inner hole is inserted. It is also possible to adopt a configuration in which the pump drive shaft 22 is inserted through the shaft.

  (2) In the above embodiment, an example is given in which the pump drive shaft 22 is driven after the intake camshaft 2 is driven, but the reverse is also possible.

  (3) In the above embodiment, an example in which the coupling 23 that connects the pump camshaft 21 and the pump drive shaft 22 is an Oldham coupling is used. However, the type of the coupling 23 is arbitrary and publicly known. Various types of joints can be used.

  (4) In the above embodiment, an example is given in which the internal combustion engine 1 to which the present invention is applied is an in-line four-cylinder DOHC engine, but the number of cylinders and the type of valve operating mechanism are arbitrary.

  (5) In the above-described embodiment, the present invention can be applied even if the camshafts 2 and 3 are each provided with a variable valve timing mechanism.

1 is a plan view showing a schematic configuration of an embodiment of an internal combustion engine according to the present invention. FIG. 2 is a view of the internal combustion engine of FIG. 1 as viewed from the front, showing a power transmission system to the drive mechanism of the high-pressure fuel pump. FIG. 3 is a cross-sectional view taken along line (3)-(3) in FIG. 2. FIG. 4 is a perspective view showing the Oldham coupling, the pump drive shaft, and the pump cam shaft shown in FIGS. 1 and 3 separately.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake cam shaft 3 Exhaust cam shaft 4 Crankshaft 5 Crank sprocket 6 Intake cam sprocket 7 Intake cam gear 8 Exhaust cam gear 9 Timing chain 12 High pressure fuel pump 21 Pump camshaft 21a Pump cam 22 Pump drive shaft 23 Coupling

Claims (2)

A plunger-type high-pressure fuel pump that supplies high-pressure fuel to an injector that directly injects high-pressure fuel into the combustion chamber of the internal combustion engine, using a rotational power of a crankshaft of the internal combustion engine;
The valve mechanism of the internal combustion engine has an intake camshaft and an exhaust camshaft, and the exhaust camshaft is hollow.
The drive mechanism is provided on the rear end side of the pump drive shaft, and is provided on the rear end side of the exhaust camshaft. The pump drive shaft is inserted into the inner hole of the hollow exhaust camshaft. A pump camshaft for driving the high-pressure fuel pump
A timing chain is wound around a pump sprocket provided on the front end side of the pump drive shaft, an intake cam sprocket provided on the front end side of the intake camshaft, and a crank sprocket provided on the front end side of the crankshaft. The pump drive shaft and the intake camshaft are rotationally driven in the same direction by receiving the rotational power of the crankshaft,
The intake cam sprocket and the exhaust camshaft are provided with gears that mesh with each other, so that the exhaust camshaft is rotated in the reverse direction by receiving the rotational power of the intake camshaft. Internal combustion engine. The internal combustion engine according to claim 1,
The internal combustion engine, wherein the pump drive shaft and the pump camshaft are connected together by an Oldham coupling so as to be integrally rotatable .

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