JP2010150939A - Valve gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To set opening and closing timings of an intake valve and an exhaust valve such that situations of flowing of intake and returning of exhaust gas can be optimally maintained. <P>SOLUTION: Lift completion timings of an intake valve 13F and an exhaust valve 15F comprising a first valve set are set faster than lift completion timings of an intake valve 13R and an exhaust valve 15R of a second valve set, interference of intake and returning of exhaust are eliminated, and a large swirling flow is formed in an interior of a combustion chamber. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a valve gear for an internal combustion engine.

  A variable valve gear is known as a valve gear for an internal combustion engine. As a known example of the variable valve gear, for example, Patent Document 1 can be cited. In the variable valve mechanism disclosed in Patent Document 1, a rotor member integrated with an intake camshaft is provided on a sprocket on the intake camshaft side to which the driving force of the crankshaft is transmitted, and the rotor member is attached to the sprocket by hydraulic pressure. By rotating it, the phase of the rotation direction of the intake camshaft is changed with respect to the sprocket, and the rotation phase of the intake cam is changed. A technique for simultaneously changing the rotational phase of the exhaust cam using a similar mechanism is also known.

  By applying a variable valve mechanism, the phase of the camshaft rotation direction is changed to the advance side or the retard side according to the operating state of the internal combustion engine, that is, for each rotation speed of the internal combustion engine, and the intake valve / exhaust The opening / closing timing of the valve can be set as appropriate. For this reason, even if the situation of the pressure of the intake air differs from the rotational speed of the internal combustion engine, the volumetric efficiency can be increased and the output can be improved. In addition, by changing the amount that the intake valve opening timing overlaps with the exhaust valve, the internal EGR amount (exhaust gas return amount) is optimized to improve fuel efficiency and reduce pumping loss. This can contribute to fuel efficiency.

In recent years, when the variable valve mechanism is applied to change the opening and closing timing of both the intake valve and the exhaust valve, the characteristics of the variable valve mechanism are impaired by comprehensively considering the flow of intake air and the return of exhaust gas. Therefore, it has been required to improve output, improve fuel consumption, and reduce pumping loss.
JP 2008-25428 A

  The present invention has been made in view of the above situation, and provides a valve operating device capable of setting the opening and closing timings of both the intake valve and the exhaust valve so that the flow of intake air and the return of exhaust gas can be optimally maintained. The purpose is to provide.

  In order to achieve the above object, a valve operating apparatus according to a first aspect of the present invention includes a pair of intake valves and a pair of exhaust valves, a shaft that is rotated in synchronization with rotation of a crankshaft, and the shaft. An intake lift means for individually lifting the pair of intake valves; and an exhaust lift means for individually lifting the pair of exhaust valves provided on the shaft, wherein the pair of intake valves and the pair of exhaust valves are: The intake valve means and the exhaust lift means are constituted by a first valve set consisting of a combination of one side intake valve and one side exhaust valve and a second valve set consisting of a combination of the other side intake valve and the other side exhaust valve. The lift timing between the one-side intake valve and the one-side exhaust valve forming the first valve set, and the other-side intake valve forming the second valve set. The lift timing between the valve and the other side exhaust valve is in a state where there is no overlap in the lift timing, and the lift start timing of the one-side intake valve is set to be higher than the lift start timing of the other-side intake valve. It is characterized by being quick.

  In the first aspect of the present invention, the lift timing between the one-side intake valve and the one-side exhaust valve forming the first valve set, or between the other-side intake valve and the other-side exhaust valve forming the second valve set. As the state where at least one of the lift times does not overlap, the lift start timing of the one-side intake valve is set earlier than the lift start timing of the other-side intake valve. The intake (mixture) and exhaust return can be prevented from interfering with each other between the valves, and a large swirl flow can be formed. For this reason, the opening / closing timing of both the intake valve and the exhaust valve can be set so that the flow of intake air and the return state of exhaust gas can be optimally maintained.

  The valve operating apparatus of the present invention according to claim 2 is the valve operating apparatus according to claim 1, wherein the intake lift means and the exhaust lift means set the lift end timing of the one side exhaust valve to the other side. It is characterized by being earlier than the lift end timing of the exhaust valve.

  In the present invention according to claim 2, since the lift end timing of the exhaust valve on one side is made earlier than the lift end timing of the exhaust valve on the other side, interference of exhaust return can be eliminated.

  According to a third aspect of the present invention, there is provided the valve gear according to the first or second aspect, wherein the intake lift means and the exhaust lift means are on one side of the first valve set. The lift timing between the intake valve and the one side exhaust valve, and the other side intake valve and the other side exhaust valve forming the second valve set are both lifted in a state where no overlap occurs. To do.

  In the present invention according to claim 3, the lift timing between the one side intake valve and the one side exhaust valve forming the first valve set, and the other side intake valve and the other side exhaust valve forming the second valve set are set. Since both lift timings are in a state in which no overlap occurs in the lift timing, it is possible to reliably achieve a state in which intake (mixture) and exhaust return do not interfere with each other between the opposing intake valve and exhaust valve. it can.

  A valve operating device according to a fourth aspect of the present invention is the valve operating device according to any one of the first to third aspects, wherein the intake lift means and the exhaust lift means are the first valve. The valve opening start timing of the one side intake valve forming the set is set earlier than the valve closing end timing of the other side exhaust valve forming the second valve set so that the overlap occurs.

  In the present invention according to claim 4, since an overlap is formed between the intake valve in the first valve set and the exhaust valve in the second valve set, the flow of intake (mixture) and the return flow of exhaust are in the same direction. Can be.

  A valve operating device according to a fifth aspect of the present invention is the valve operating device according to any one of the first to fourth aspects, wherein the shaft includes an intake camshaft and an exhaust camshaft. The intake lift means is two intake cams that lift the one side intake valve of the first valve set and the other side intake valve of the second valve set according to the cam profile, respectively, and the exhaust lift means One exhaust valve of one valve set and the other exhaust valve of the second valve set are two exhaust cams that lift each according to the cam profile.

  In the present invention according to claim 5, the lifts of the opposing intake valve and exhaust valve can be operated by the two intake cams of the intake camshaft and the two exhaust cams of the exhaust camshaft.

  A valve operating apparatus according to a sixth aspect of the present invention is the valve operating apparatus according to the fifth aspect, further comprising an intake cam phase changing means for arbitrarily changing the phase of the intake cam in the rotational direction. And

  According to a seventh aspect of the present invention, the valve gear of the present invention is the valve gear according to the sixth aspect, further comprising exhaust cam phase changing means for arbitrarily changing the phase in the rotational direction of the exhaust cam. And

  In the present invention according to claim 6, the phase in the rotational direction of the intake cam can be arbitrarily changed by the intake cam phase changing means. According to the seventh aspect of the present invention, the exhaust cam phase changing means can arbitrarily change the phase of the exhaust cam in the rotational direction.

  The valve gear of the present invention can set the opening / closing timing of both the intake valve and the exhaust valve so that the flow of intake air and the return state of exhaust gas can be maintained optimally.

  FIG. 1 shows the appearance of a camshaft equipped with a valve gear according to an embodiment of the present invention, FIG. 2 shows the concept of the relationship between the combustion chamber and the valve, and FIG. 3 shows the line III-III in FIG. FIG. 4 shows a valve operation time chart, and FIG. 5 shows a flow state in the cylinder (combustion chamber). FIG. 6 shows a flow state in the cylinder (combustion chamber) in a state where the intake air and the exhaust gas interfere with each other.

  The main part of the internal combustion engine provided with the valve operating device will be described with reference to FIGS.

  As shown in FIGS. 1 and 2, an intake camshaft 1 and an exhaust camshaft 2 are arranged parallel to each other along the cylinder arrangement direction on the cylinder head side, and end portions of the intake camshaft 1 and the exhaust camshaft 2 are arranged. Are provided with sprockets 3 and 4. A timing chain 7 is wound around the sprocket 3 and the sprocket 6 on the crankshaft 5 side, and the power of the crankshaft 5 is supplied to the intake camshaft 1 and the exhaust cam via the timing chain 7 and the sprockets 3 and 4. It is transmitted to the shaft 2.

  The intake camshaft 1 is fixed with intake cams 11F and 11R for each cylinder, and is provided with intake valves 13F and 13R corresponding to the intake cams 11F and 11R. The intake valves 13F and 13R are lifted according to the cam surfaces of the intake cams 11F and 11R through the valve lifter 14 by the rotation of the intake camshaft 1 (intake lift means). The intake cams 11F and 11R can be integrally formed on the intake camshaft 1.

  Exhaust cams 12F and 12R are fixed to the exhaust camshaft 2 for each cylinder, and exhaust valves 15F and 15R are provided corresponding to the exhaust cams 12F and 12R. The exhaust valves 15F and 15R are lifted according to the cam surfaces of the exhaust cams 12F and 12R through the valve lifter 16 by the rotation of the exhaust camshaft 2 (exhaust lift means). It is also possible to integrally form the exhaust cams 12F and 12R on the exhaust cam shaft 2.

  That is, the one side intake valve that forms the first valve set is the intake valve 13F, and the one side exhaust valve that forms the first valve set is the exhaust valve 15F. The other side intake valve forming the second valve set is an intake valve 13R, and the other side exhaust valve forming the second valve set is the exhaust valve 15R.

  The sprocket 3 at the end of the intake camshaft 1 is provided with an intake valve varying device 51 as intake cam phase changing means. In the intake valve variable device 51, a rotor member integral with the intake camshaft 1 is rotatably arranged on the sprocket 3, and the rotor member is rotated with respect to the sprocket 3 by, for example, hydraulic pressure, so that the sprocket 3 is rotated. The rotation direction phase of the intake camshaft 1 is changed, and the rotation phases of the intake cams 11F and 11R are continuously changed.

  The sprocket 4 at the end of the exhaust camshaft 2 is provided with an exhaust valve variable device 52 as exhaust cam phase changing means. In the exhaust valve variable device 52, a rotor member integral with the exhaust camshaft 2 is rotatably arranged on the sprocket 4, and the rotor member is rotated with respect to the sprocket 4 by, for example, hydraulic pressure. The rotational phase of the exhaust camshaft 2 is changed, and the rotational phases of the exhaust cams 12F and 12R are continuously changed.

  It is also possible to adopt a configuration in which the rotational phases of the intake cams 11F and 11R and the exhaust cams 12F and 12R are fixed without providing the intake valve variable device 51 and the exhaust valve variable device 52.

  The configuration of the cylinder head portion will be specifically described with reference to FIG. FIG. 3 shows a cross-section of the intake valve 13F and the exhaust valve 15F. Reference numerals in the following description and drawings are the intake valve 13 and the exhaust valve 15, respectively.

  A surface forming the upper wall of the combustion chamber 22 is formed on the lower surface of the cylinder head 21, and two intake openings 24 of the intake port 23 and two exhaust openings 26 of the exhaust port 25 are formed on the surface forming the upper wall. Is provided. The intake valve 13 is arranged to communicate and block the intake opening 24 and the combustion chamber 22, and the exhaust valve 15 is arranged to communicate and block the exhaust opening 26 and the combustion chamber 22.

  The intake valve 13 includes an umbrella portion 13a formed in accordance with the opening shape of the intake opening 24, and a stem portion 13b is provided at the upper portion of the central portion of the umbrella portion 13a. A cylindrical stem guide 27 is press-fitted into the cylinder head 21, and a stem portion 13 b of the intake valve 13 is slidably supported on the stem guide 27.

  A disc-shaped retainer 29 is connected to the upper end of the stem portion 13b via a cotter 28, and a spring 31 is provided between the lower surface of the retainer 29 and the seat 30 on the cylinder head 21 side. That is, the stem portion 13 b is biased upward by the spring 31 via the retainer 29, and the intake valve 13 is biased in the valve closing direction (the direction in which the intake opening 24 and the combustion chamber 22 are blocked).

  A cylindrical valve lifter 14 is arranged on the upper portion of the stem portion 13b, and the inner side of the upper end surface of the valve lifter 14 is attached to the upper portion of the stem portion 13b, so that the outer side of the spring 31 is covered with the cylindrical surface of the valve lifter 14. Has been. A shim 32 is provided on the outer side (upper surface) of the upper end surface of the valve lifter 14, and the shim 32 is in contact with the intake cam 11.

  Similarly, the exhaust valve 15 includes an umbrella portion 15 a and a stem portion 15 b, and is supported by the cylinder head 21 with the same configuration as the intake valve 13. For this reason, the description which attaches | subjects the same code | symbol with respect to a supporting member and overlaps is abbreviate | omitted.

  Corresponding to the upper end surface of the valve lifter 14 of the intake valve 13, the intake camshaft 1 is disposed above the cylinder head 21, and the intake camshaft 1 is rotatably supported by the cylinder head 21 via a cam cap 41. . Corresponding to the upper end surface of the valve lifter 14 of the exhaust valve 15, the exhaust camshaft 2 is arranged on the upper portion of the cylinder head 21, and the exhaust camshaft 2 is rotatably supported by the cylinder head 21 via a cam cap 41. .

  Therefore, the intake valve 11 and the exhaust valve 15 are opened (lifted) against the urging force of the spring 31 by the rotation of the intake cam 11 and the exhaust cam 12 via the valve lifter 14 according to the cam surface.

  The state of the lift timing of the intake valves 13F and 13R and the exhaust valves 15F and 15R will be described with reference to FIGS.

  The lift timings of the intake valves 13F and 13R and the exhaust valves 15F and 15R are set as follows depending on the attachment status of the intake cams 11F and 11R and the exhaust cams 12F and 12R.

  As shown in the figure, the intake valve 13F and the exhaust valve 15F forming the first valve set are set in a state in which no overlap occurs in the lift timing. The lift end timing of the intake valve 13F and the exhaust valve 15F in the first valve set (see the solid line in FIG. 4) is from the lift end timing of the intake valve 13R and the exhaust valve 15R in the second valve set (see the dotted line in FIG. 4). Is set too early. Further, the lift timing of the intake valve 13R and the exhaust valve 15R forming the second valve set is also set to a state where no overlap occurs.

  The opening timing of the intake valve 13F of the first valve set is set earlier than the closing end timing of the exhaust valve 15R of the second valve set. That is, an overlap is formed between the intake valve 13F of the first valve set and the exhaust valve 15R of the second valve set.

  In this state, by arbitrarily operating the intake valve variable device 51 and the exhaust valve variable device 52, the lift timing of the intake valves 13F, 13R and the lift timing of the exhaust valves 15F, 15R can be arbitrarily set according to the driving state of the vehicle. It can be changed continuously.

  It should be noted that there is no overlap between the lift timing of the intake valve 13F and the exhaust valve 15F forming the first valve set, and the lift timing of the intake valve 13R and the exhaust valve 15R forming the second valve set. Is possible.

  By setting the lift timing of the intake valves 13F, 13R and the exhaust valves 15F, 15R as described above, for example, the volume efficiency is increased to improve the output, or the intake valve 13F is connected to the exhaust valves 15F, 15R. The amount of overlap of the valve opening timing of 13R is changed to optimize the internal EGR amount, thereby improving the fuel consumption and reducing the pumping loss, thereby reducing the fuel consumption. In addition, the intake air inflow time can be changed.

  That is, as shown in FIG. 5A, immediately after the intake valve 13F is opened, the opposing exhaust valve 15F is closed, and the intake opening 24 on the intake valve 13R side is closed, so that the exhaust valve is closed. The state immediately before the exhaust opening 26 on the 15R side is closed (open state) is set. That is, an overlap is formed by the intake valve 13F and the exhaust valve 15R.

  The air-fuel mixture inside the combustion chamber 22 forms a large swirl flow S1 from the intake valve 13F side in the left-turned state in the figure. Further, the exhaust return flow forms a swirl flow from the exhaust valve 15R side in the left-turned state in the figure. Since the swirl flow S1 of the air-fuel mixture and the swirl flow returning from the exhaust gas are in the same direction, they grow into a larger swirl flow. Since the air-fuel mixture flows from the intake valve 13F on one side, the flow of the air-fuel mixture does not weaken due to interference on the exhaust valves 15F and 15R side. Further, there is no interference with the return of the exhaust.

  When the intake valves 13F and 13R and the exhaust valves 15F and 15R are opened and closed in the same phase and the intake valve 13 and the exhaust valve 15 are overlapped, as shown in FIG. At the same time, the air-fuel mixture flows in from the 13F and 13R sides in opposite directions, and at the same time, the exhaust flows in from the exhaust valves 15F and 15R in the opposite directions. For this reason, the inflowing air-fuel mixture and the returned exhaust gas interfere with each other to cancel the flow, and the turbulence in the cylinder flow is attenuated. By setting the lift timing of the intake valves 13F, 13R and the exhaust valves 15F, 15R as described above, the flow of the mixture does not interfere with the returned exhaust gas and the flow is not canceled out.

  Returning to FIG. 5A, after that, the air-fuel mixture flows from the intake opening 24 on the intake valve 13R side, but the large swirl flow S1 is maintained until the latter half of the compression stroke (see FIG. 4).

  As shown in FIG. 5B, the intake opening 24 on the intake valve 13R side is open immediately before the intake valve 13F is closed (when the intake valve 13F is shifted to the compression stroke). It increases at the intake opening 24 on the valve 13R side, and the inside of the combustion chamber 22 forms a large swirl flow S2 toward the intake valve 13R in the left-turned state in the figure. The swirl flow S2 having a large blowback from one side prevents the air-fuel mixture from interfering and weakening on the intake valves 13F and 13R side.

  As shown in FIG. 5C, when the intake opening 24 on the intake valve 13R side is closed with a delay and the piston reaches top dead center (immediately before ignition), the swirl flow S is strongly disturbed in the vicinity of the spark plug 40. Change to S3. Thereby, the combustion reaction after ignition can be accelerated | stimulated.

  By setting the lift end timing of the intake valve 13F and the exhaust valve 15F in one valve set earlier than the lift end timing of the intake valve 13R and the exhaust valve 15R in the other valve set, interference between the intake air and intake and exhaust Thus, a large swirl flow can be formed inside the combustion chamber 22. As a result, a strong turbulence can be generated immediately before ignition, and combustion can be promoted to achieve low fuel consumption by improving combustion.

  For this reason, it is possible to set the opening and closing timing of both the intake valve and the exhaust valve so that the intake flow and the exhaust gas return state can be optimally maintained. It becomes possible to maintain the return state of the exhaust gas optimally.

  Further, by forming an overlap between the intake valve 13F and the exhaust valve 15R, the internal EGR amount (exhaust gas return amount) is optimized without hindering the formation of swirl inside the combustion chamber 22, thereby improving fuel consumption and pumping. Loss can be reduced.

  In addition, by arbitrarily operating the intake valve variable device 51 and the exhaust valve variable device 52, the lift timing of the intake valves 13F, 13R and the lift timing of the exhaust valves 15F, 15R are determined as the vehicle operating state (engine speed, load). It can be changed arbitrarily and continuously depending on. For this reason, output improvement and fuel consumption improvement can be aimed at.

  In addition, since the lift timing of the intake valves 13F, 13R and the exhaust valves 15F, 15R can be set by setting the intake cams 11F, 11R and the exhaust cams 12F, 12R, the apparatus can be configured without cost.

  The present invention can be used in the field of valve operating devices for internal combustion engines.

1 is an external view of a camshaft provided with a valve operating device according to an embodiment of the present invention. It is a conceptual diagram of the relationship between a combustion chamber and a valve. It is the III-III arrow directional view in FIG. It is a time chart of valve operation. It is a conceptual diagram showing the flow condition in a cylinder (combustion chamber). It is a conceptual diagram showing the flow condition in a cylinder (combustion chamber).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Intake cam shaft 2 Exhaust cam shaft 11 Intake cam 12 Exhaust cam 13 Intake valve 15 Exhaust valve 21 Cylinder head 22 Combustion chamber

Claims (7)

A pair of intake valves and a pair of exhaust valves;
A shaft that is rotated in synchronization with the rotation of the crankshaft;
Intake lift means provided on the shaft for individually lifting the pair of intake valves;
An exhaust lift means provided on the shaft for individually lifting the pair of exhaust valves;
The pair of intake valves and the pair of exhaust valves include a first valve set comprising a combination of one side intake valve and one side exhaust valve, and a second valve set comprising a combination of the other side intake valve and the other side exhaust valve. Consists of
The intake lift means and the exhaust lift means are:
At least one of lift timing between the one side intake valve and the one side exhaust valve forming the first valve set, and lift time between the other side intake valve and the other side exhaust valve forming the second valve set In a state where no overlap occurs during the lift time of
The valve operating device characterized in that the lift start timing of the one side intake valve is made earlier than the lift start timing of the other side intake valve. The valve gear according to claim 1,
The intake lift means and the exhaust lift means are:
The valve operating apparatus characterized in that the lift end timing of the one side exhaust valve is made earlier than the lift end timing of the other side exhaust valve. In the valve operating apparatus according to claim 1 or 2,
The intake lift means and the exhaust lift means are:
Both the lift timing between the one side intake valve and the one side exhaust valve forming the first valve set, and the lift timing between the other side intake valve and the other side exhaust valve forming the second valve set, A valve operating device characterized in that no overlap occurs. In the valve gear as described in any one of Claims 1-3,
The intake lift means and the exhaust lift means are:
The valve opening start timing of the one-side intake valve that forms the first valve group is set earlier than the valve closing end timing of the other-side exhaust valve that forms the second valve group, so that overlap occurs. A valve operating device. In the valve gear as described in any one of Claims 1-4,
The shaft comprises an intake camshaft and an exhaust camshaft,
The intake lift means is two intake cams that lift the one side intake valve of the first valve set and the other side intake valve of the second valve set, respectively, according to the cam profile,
The exhaust lift means includes two exhaust cams that lift the one side exhaust valve of the first valve set and the other side exhaust valve of the second valve set according to the cam profile, respectively. . The valve gear according to claim 5,
A valve operating device comprising intake cam phase changing means for arbitrarily changing the phase of the intake cam in the rotational direction. The valve gear according to claim 6,
A valve operating apparatus comprising exhaust cam phase changing means for arbitrarily changing a phase in a rotation direction of the exhaust cam.

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