JP4586519B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine capable of changing a valve lift amount of an intake valve in accordance with an engine load.

A variable valve operating apparatus for an internal combustion engine that variably controls the valve lift characteristic of the intake valve in accordance with the engine operating state is conventionally known from Patent Document 1 and the like.
JP 2002-89303 A

  By the way, when the engine load is controlled by controlling the throttle opening and the valve lift amount of the intake valve, there is a problem that the pumping loss increases and the fuel consumption deteriorates because the suction negative pressure is generated downstream of the throttle. In order to solve this problem, there is a method of reducing the pumping loss and improving the fuel consumption by using non-throttle and precisely controlling the valve lift amount of the intake valve. However, in order to perform stable load control by controlling the valve lift amount of the intake valve, precise control of the valve lift amount of the intake valve at the time of the intake valve minimum lift is required. In other words, it is necessary to reduce the variation range of the intake air amount between cylinders by reducing the variation range of the valve lift amount of the intake valve between the cylinders and for each cylinder at the time of manufacturing the variable valve operating device, which increases the manufacturing cost. There was a problem to do.

  The present invention has been made paying attention to such a conventional problem, and by reducing the variation range of the intake air amount caused by the variation of the valve lift amount of the intake valve at the time of the intake valve minimal lift, the intake valve is reduced. It is intended to reduce the manufacturing cost of the variable valve operating device by expanding the allowable valve lift amount variation.

Accordingly, the present invention provides an internal combustion engine capable of changing the valve lift amount of the intake valve in accordance with the engine load, and the valve lift amount of the intake valve is a minimum lift on the combustion chamber wall surface on the outer peripheral side of the valve seat of the intake valve. The valve lift amount of the intake valve is higher than the intake valve maximum lift amount during the operation state where the intake valve is minimally lifted, and the valve lift amount of the intake valve is a small lift so that the intake air amount in the operation state becomes relatively small. The first wall portion that is lower than the maximum lift amount of the intake valve in the operating state is formed so as to surround the outer periphery of the valve seat of the intake valve over the entire periphery . As a result, the intake air amount at the time of the intake valve minimum lift is relatively reduced, the change in the intake air amount that changes due to the change in the intake valve opening area is reduced, and the variation in the intake air amount at the time of the intake valve minimum lift is reduced. Will be.

  According to the present invention, it is possible to expand the allowable range of lift variation width at the time of the minimum lift of the intake valve, omitting or simplifying the part selection process that was necessary to reduce the lift variation of the intake valve after manufacture. Therefore, the cost can be reduced.

  An embodiment of the present invention will be described in detail with reference to the drawings. Each embodiment described below is based on an internal combustion engine including a variable valve mechanism that can continuously vary the valve lift amount of the intake valve according to the engine load. The valve lift amount is controlled to be smaller than that during high load, and the lift amount is controlled to be even smaller during idle operation. Further, by controlling the valve lift amount of the intake valve in the minimum lift region, it is possible to perform engine load control without performing precise control of the throttle opening. The variable valve mechanism that can change the valve lift characteristic of the intake valve is already known from Japanese Patent Application Laid-Open No. 11-107725 previously proposed by the present applicant. Description is omitted.

  Normally, when the valve lift amount of the intake valve is a minimum lift, the intake flow flows in a direction in contact with the combustion chamber wall around the valve seat through a slight gap between the intake valve and the valve seat on which the intake valve is seated. On the other hand, when the valve lift amount of the intake valve is small, the valve lift amount is larger than that of the minimum lift, and the intake flow flows along the intake port wall surface, the intake valve valve head upper surface, and the valve seat surface direction. The flow separates from the wall of the combustion chamber, unlike during the minimal lift. In the present invention, the intake flow smoothly flows into the cylinder during the intake stroke at the time of the small lift, but the intake valve and the exhaust valve so that the flow of the intake flow into the cylinder is disturbed at the intake stroke at the time of the minimum lift. Combustion chamber, piston and valve seat are configured.

  FIG. 1 is an explanatory view schematically showing the internal combustion engine according to the first embodiment of the present invention, showing the shape of the combustion chamber of the internal combustion engine viewed from the piston side, in other words, the shape of the combustion chamber on the cylinder head side. It is explanatory drawing.

  The cylinder head 1 is provided with two intake valves 2 that are controlled to open and close so that the valve lift amount is variable according to the engine load, and two exhaust valves 3 are arranged per cylinder. Yes.

  The intake valve 2 and the exhaust valve 3 are respectively connected to an intake valve valve seat 6 and an exhaust valve valve seat 7 arranged on an upper wall surface 5 of a pent roof type combustion chamber 4 (see FIGS. 2 and 3 to be described later). Sit down.

  The intake valve valve seat 6 is provided at a connection portion between an intake port 8 (see FIGS. 2 and 3 described later) formed in the cylinder head 1 and the combustion chamber 4. The exhaust valve valve seat 7 is provided at a connection portion between an exhaust port 9 (see FIGS. 2 and 3 described later) formed in the cylinder head 1 and the combustion chamber 4.

  The upper wall surface 5 of the combustion chamber 4 is formed with a wall portion 10 as a first wall portion surrounding the outer peripheral side of the intake valve valve seat 6 over the entire circumference for each intake valve 2. .

  2 and 3 are cross-sectional views taken along the line AA in FIG. 1. FIG. 2 shows the idle operation state after warm-up in which the valve lift amount of the intake valve 2 is a minimum lift, and FIG. The low load operation state excluding the idle operation after warm-up in which the valve lift amount of the valve 2 is a small lift is shown.

  2 and 3, the height M of the wall surface 10a of the wall 10 facing the side surface 11a of the valve head 11 of the intake valve 2, that is, the protrusion amount of the wall 10 in the valve lift direction. M is higher than the maximum lift amount Pmax of the intake valve 2 in the idle operation state after warm-up when the valve lift amount of the intake valve 2 is a minimum lift, and warm-up when the valve lift amount of the intake valve 2 is a small lift It is formed to be lower than the maximum lift amount Rmax of the intake valve 2 in the low load operation state excluding the post-idle operation. In addition, 12 in FIG. 1 is a spark plug.

  In the first embodiment as described above, the wall portion 10 provided on the outer peripheral side of the valve seat 6 for the intake valve causes the intake flow to flow through the wall portion 10 during the intake stroke when the valve lift amount of the intake valve 2 is the minimum lift. Colliding with the wall surface 10a, the flow of the intake flow into the cylinder is disturbed, so that the intake flow does not flow smoothly into the cylinder compared to when the intake valve is small lifted.

  Therefore, the amount of intake air at the time of minimum lift of the intake valve is relatively reduced, the change of the amount of intake air that changes due to the change of the opening area of the intake valve is reduced, and the variation in the amount of intake air at the time of minimum lift of the intake valve is reduced. Will be.

  That is, it is possible to reduce the intake air amount change ratio corresponding to the intake valve lift change during the intake valve minimum lift without reducing the intake flow during the intake valve small lift.

  As a result, when the engine load is controlled by controlling the valve lift amount when the intake valve is minimally lifted, the allowable range of the lift variation width of the intake valve 2 can be expanded. It is possible to reduce the manufacturing accuracy standards and to omit or simplify the part selection process to reduce the lift variation of the intake valve after the manufacture of the variable valve operating system, thus reducing the overall cost. Is possible.

  Furthermore, since the intake air amount control accuracy can be maintained even if the accuracy of the valve lift amount control of the intake valve 2 is lowered, the valve lift amount control can be simplified. In addition, since the intake flow smoothly flows into the cylinder during the small intake valve lift, it is possible to improve combustion and reduce fuel consumption and unburned HC emissions by enhancing the intake flow.

  Hereinafter, other embodiments of the present invention will be sequentially described. However, the same reference numerals are given to components common to the above-described first embodiment, and redundant description will be omitted.

  4 to 6 show a second embodiment of the present invention. FIG. 4 is an explanatory view schematically showing the internal combustion engine in the second embodiment of the present invention, and shows the shape of the combustion chamber of the internal combustion engine viewed from the piston side, in other words, the shape of the combustion chamber on the cylinder head side. It is explanatory drawing. 5 and 6 are cross-sectional views taken along the line BB in FIG. 4. FIG. 5 shows the idle operation state after warm-up in which the valve lift amount of the intake valve 2 is a minimal lift, and FIG. The low load operation state excluding the idle operation after warm-up in which the valve lift amount of the valve 2 is a small lift is shown.

  In the second embodiment, as shown in FIG. 4, the upper wall surface 5 is processed with a cutting tool around a position eccentric from the center of the valve seat 6 for the intake valve in the direction of the exhaust valve 3. As a result, a wall portion 10 corresponding to a first wall portion is formed between the intake valve valve seat 6 and the intake valve valve seat 6 which is on the side opposite to the intake air introduction direction (the intake valve valve seat 6 Wall surface 10a is formed on the outer peripheral side of the left half in FIG.

  Here, the anti-intake air introduction direction is specifically the left side in the left-right direction in FIG. This is because the intake port 8 is connected to the combustion chamber 4 from the right in the left-right direction in FIG. 4 with respect to the center of the combustion chamber 4, and the opening of the intake port 8 to the combustion chamber 4 is on the right side in FIG. This is because the portion is relatively positioned on the side where the intake air is introduced. Therefore, in the upper wall surface 5 of the combustion chamber 4, the right side in the left-right direction in FIG. 4 is defined as the intake air introduction direction, and the left side in the left-right direction in FIG.

  In addition, the height M of the wall surface 10a in 2nd Embodiment is set similarly to 1st Embodiment mentioned above.

  Also in the second embodiment, the intake flow collides with the wall surface 10a of the wall portion 10 in the intake stroke when the valve lift amount of the intake valve 2 is the minimum lift, and the flow of the intake flow into the cylinder is disturbed, The intake flow is prevented from flowing smoothly into the cylinder as compared with the case of small lift of the intake valve.

  Therefore, in the second embodiment, the wall surface 10a is formed only on the outer peripheral side of the portion on the anti-intake introduction direction side of the intake valve valve seat 6, so that the entire outer peripheral side of the intake valve valve seat 6 is formed. Although it is more disadvantageous than the first embodiment in which the wall surface 10a is formed over the circumference, the same effect as the first embodiment described above can be obtained.

  7 to 9 show a third embodiment of the present invention. FIG. 7 is an explanatory view schematically showing the internal combustion engine in the third embodiment of the present invention, showing the shape of the combustion chamber of the internal combustion engine viewed from the piston side, in other words, the shape of the combustion chamber on the cylinder head side. It is explanatory drawing. 8 and 9 are cross-sectional views taken along the line CC of FIG. 7. FIG. 8 shows the idle operation state after warm-up in which the valve lift amount of the intake valve 2 is a minimum lift, and FIG. The low load operation state excluding the idle operation after warm-up in which the valve lift amount of the valve 2 is a small lift is shown.

  As shown in FIG. 7, the third embodiment provides a step on the upper wall surface between the intake valve 2 and the exhaust valve 3, resulting in a first difference between the intake valve 2 and the exhaust valve 3. A wall portion 10 corresponding to the wall portion is formed, and a wall surface 10 a is formed between the intake valve 2 and the exhaust valve 3. Note that the height M of the wall surface 10a in the third embodiment is set in the same manner as in the first embodiment described above.

  Also in the third embodiment, the intake flow collides with the wall surface 10a of the wall portion 10 in the intake stroke when the valve lift amount of the intake valve 2 is the minimum lift, and the flow of the intake flow into the cylinder is disturbed. The intake flow is prevented from flowing smoothly into the cylinder as compared with the case of small lift of the intake valve.

  Therefore, in such a third embodiment, although it is disadvantageous compared to the first embodiment described above in that the wall surface 10a is not formed over the entire outer periphery of the intake valve valve seat 6, The same effect as the first embodiment described above can be obtained.

  10 to 12 show a fourth embodiment of the present invention. FIG. 10 is an explanatory view schematically showing the internal combustion engine in the fourth embodiment of the present invention, showing the shape of the combustion chamber of the internal combustion engine viewed from the piston side, in other words, the shape of the combustion chamber on the cylinder head side. It is explanatory drawing. 11 and 12 are cross-sectional views taken along the line D-D in FIG. 10. FIG. 11 shows the idle operation state after warm-up in which the valve lift amount of the intake valve 2 is a minimum lift, and FIG. The low load operation state excluding the idle operation after warm-up in which the valve lift amount of the valve 2 is a small lift is shown.

  In the fourth embodiment, as shown in FIGS. 11 and 12, the intake valve valve seat 6 is retracted to the intake upstream side of the upper wall surface 5 of the combustion chamber 4, resulting in the first wall portion. Is formed, and the outer peripheral side of the intake valve valve seat 6 is surrounded by the wall surface 10a of the wall 10 over the entire circumference. In addition, the height M of the wall surface 10a in 4th Embodiment is set similarly to 1st Embodiment mentioned above.

  Also in the fourth embodiment, the intake flow collides with the wall surface 10a of the wall portion 10 in the intake stroke when the valve lift amount of the intake valve 2 is the minimum lift, and the flow of the intake flow into the cylinder is disturbed, The intake flow is prevented from flowing smoothly into the cylinder as compared with the case of small lift of the intake valve.

  Therefore, in the fourth embodiment, it is possible to obtain substantially the same operational effects as those of the first embodiment described above.

  13 to 15 show a fifth embodiment of the present invention. FIG. 13 is an explanatory view schematically showing the internal combustion engine in the fifth embodiment of the present invention, and shows the shape of the combustion chamber of the internal combustion engine viewed from the piston side, in other words, the shape of the combustion chamber on the cylinder head side. It is explanatory drawing. 14 and 15 are cross-sectional views taken along the line E-E in FIG. 13. FIG. 14 shows the idle operation state after warm-up in which the valve lift amount of the intake valve 2 is a minimum lift, and FIG. The low load operation state excluding the idle operation after warm-up in which the valve lift amount of the valve 2 is a small lift is shown.

  This fifth embodiment is the same as the second embodiment described above on the outer peripheral side of the portion of the intake valve valve seat 6 that is relatively on the intake introduction direction side (the right half in FIG. 13 of the intake valve seat 6). A second wall portion 21 that protrudes along the intake valve lift direction is formed.

  The height N of the wall surface 21a of the second wall 21 facing the side surface 11a of the valve head 11 of the intake valve 2, that is, the protrusion amount N of the second wall 21 in the valve lift direction is the intake valve 2 seating position. Is set to be slightly larger than the maximum lift amount (small lift amount Rmax) in a low-load operation state excluding idle after warm-up.

  In addition, the height M of the wall surface 10a in 5th Embodiment is set similarly to 1st Embodiment mentioned above.

  In the fifth embodiment, by providing the second wall portion 21 on the outer peripheral side of the intake valve valve seat 6 on the intake introduction direction side, when the valve lift amount of the intake valve 2 is minimal lift or small lift, The intake valve opening area can be reduced and high-speed directional intake flow can be generated.

  Therefore, in addition to the same effects as the first embodiment described above, the intake flow is enhanced by the second wall portion 21, so that it is possible to improve the combustion when the valve lift amount of the intake valve 2 is the minimum lift or the small lift. Become.

  16 to 18 show a sixth embodiment of the present invention. FIG. 16 is an explanatory view schematically showing the internal combustion engine in the sixth embodiment of the present invention, showing the shape of the combustion chamber of the internal combustion engine viewed from the piston side, in other words, the shape of the combustion chamber on the cylinder head side. It is explanatory drawing. 17 and 18 are cross-sectional views taken along the line FF in FIG. 16. FIG. 17 shows the idle operation state after warm-up in which the valve lift amount of the intake valve 2 is a minimum lift, and FIG. The low load operation state excluding the idle operation after warm-up in which the valve lift amount of the valve 2 is a small lift is shown.

  In the sixth embodiment, when the exhaust valve 3 is closed, that is, when the exhaust valve 3 is seated on the exhaust valve valve seat 6, the protrusion amount S from the upper wall surface 5 of the exhaust valve 3 is the valve of the intake valve 2. Low load excluding the warm-up idle operation state in which the lift amount is larger than the maximum lift amount Pmax of the intake valve 2 during the warm-up idle operation state where the lift amount is a minimal lift and the valve lift amount of the intake valve 2 is a small lift The intake valve 2 is set to be smaller than the maximum lift amount Rmax in the operating state.

  That is, in the sixth embodiment, the valve head 14 of the exhaust valve 3 protruding from the upper wall surface 5 when the exhaust valve 3 is seated corresponds to the first wall portion.

  In such a sixth embodiment, the intake flow collides with the side surface 14a of the valve head 14 of the exhaust valve 3 protruding from the upper wall surface 5 during the intake stroke when the valve lift amount of the intake valve 2 is the minimum lift, and the intake flow As a result, the flow of air into the cylinder is disturbed, so that the intake flow does not flow smoothly into the cylinder as compared to when the intake valve is small lifted.

  Therefore, in such a sixth embodiment, although it is more disadvantageous than the first embodiment described above, it is possible to obtain the same effects as the first embodiment described above.

  The technical ideas of the present invention that can be grasped from the above embodiments will be listed together with the effects thereof.

  (1) In an internal combustion engine in which the valve lift amount of the intake valve can be changed according to the engine load, the intake flow smoothly flows into the cylinder during the intake stroke when the valve lift amount of the intake valve is small. In the intake stroke when the valve lift amount is a minimum lift, the flow of the intake flow into the cylinder is disturbed.

  As a result, the intake air amount at the time of the intake valve minimum lift is relatively reduced, the change in the intake air amount that changes due to the change in the intake valve opening area is reduced, and the variation in the intake air amount at the time of the intake valve minimum lift is reduced. Will be. Therefore, it is possible to expand the allowable range of the lift variation width at the time of the minimum lift of the intake valve, and it is possible to omit or simplify the part selection process that was necessary to reduce the lift variation of the intake valve after manufacturing. This makes it possible to reduce costs.

  (2) In the internal combustion engine described in (1) above, specifically, the flow of the intake air into the cylinder during the intake stroke when the valve lift amount of the intake valve is the minimum lift is disturbed by the shape of the wall surface of the combustion chamber. The

  (3) In the internal combustion engine described in the above (1) or (2), specifically, the valve lift amount of the intake valve is increased by the first wall portion formed on the wall surface of the combustion chamber near the valve seat of the intake valve. The flow of the intake flow into the cylinder during the intake stroke during the minimum lift is disturbed.

  (4) In the internal combustion engine according to (3), more specifically, the first wall portion is higher than the intake valve maximum lift amount in an operation state in which the valve lift amount of the intake valve is a minimum lift, And it is formed so that the valve lift amount of the intake valve is lower than the maximum lift amount of the intake valve in the operation state where the lift is small.

  (5) In the internal combustion engine according to any one of (1) to (4), when the valve lift amount of the intake valve is a small lift or a minimal lift, the intake valve opening area is reduced and high speed directing is performed. A second wall portion is formed on the outer peripheral side of the valve seat of the intake valve so as to generate a characteristic intake flow. This makes it possible to improve the combustion when the valve lift amount of the intake valve is a minimum lift or a small lift.

  (6) In the internal combustion engine according to any one of (1) to (5), the amount of protrusion of the exhaust valve from the combustion chamber wall surface of the valve head when the exhaust valve is closed is the minimum lift of the intake valve. It is set to be larger than the maximum lift amount of the intake valve in the operating state, and smaller than the maximum lift amount of the intake valve in the operating state where the valve lift amount of the intake valve is a small lift.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed typically the internal combustion engine in 1st Embodiment of this invention. Sectional drawing in alignment with the AA of FIG. 1 at the time of an idle driving | running state after warming-up. Sectional drawing in alignment with the AA of FIG. 1 at the time of the low load driving | running state except idle operation after warming-up. Explanatory drawing which showed typically the internal combustion engine in 2nd Embodiment of this invention. Sectional drawing in alignment with the BB line of FIG. 4 at the time of idle operation state after warming-up. Sectional drawing along the BB line | wire of FIG. 4 at the time of the low load driving | running state except idle operation after warming-up. Explanatory drawing which showed typically the internal combustion engine in 3rd Embodiment of this invention. Sectional drawing along CC line of FIG. 7 at the time of idle operation state after warming-up. Sectional drawing along CC line of FIG. 7 at the time of the low load driving | running state except idle operation after warming-up. Explanatory drawing which showed typically the internal combustion engine in 4th Embodiment of this invention. Sectional drawing in alignment with the DD line | wire of FIG. 10 at the time of idle operation state after warming-up. Sectional drawing along the DD line | wire of FIG. 10 at the time of the low load driving | running state except idle operation after warming-up. Explanatory drawing which showed typically the internal combustion engine in 5th Embodiment of this invention. Sectional drawing along the EE line | wire of FIG. 13 at the time of idle operation state after warming-up. Sectional drawing along the EE line | wire of FIG. 13 at the time of the low load driving | running state except idle operation after warming-up. Explanatory drawing which showed typically the internal combustion engine in 6th Embodiment of this invention. Sectional drawing in alignment with the FF line | wire of FIG. 16 at the time of an idle driving | running state after warming up. Sectional drawing along the FF line | wire of FIG. 16 at the time of the low load driving | running state except idle operation after warming-up.

Explanation of symbols

2 ... Intake valve 5 ... Upper wall surface 6 ... Valve seat for intake valve 10 ... Wall portion 21 ... Second wall portion

Claims (5)

In an internal combustion engine that can change the valve lift amount of the intake valve according to the engine load,
The intake valve valve lift amount is minimally lifted on the combustion chamber wall on the outer periphery of the valve seat of the intake valve so that the intake air amount is relatively reduced during the operation state in which the valve lift amount of the intake valve is minimal lift. The first wall portion, which is higher than the intake valve maximum lift amount in the operating state and becomes lower than the intake valve maximum lift amount in the operating state where the intake valve valve lift amount is a small lift, is the valve of the intake valve An internal combustion engine characterized in that the outer periphery of the seat is formed so as to surround the entire periphery . In an internal combustion engine that can change the valve lift amount of the intake valve according to the engine load,
  When the side where the intake port is connected in the combustion chamber is the intake introduction direction side, and the side where the exhaust port is connected in the combustion chamber is the anti-intake introduction direction side,
  The intake valve valve lift amount is minimally lifted on the combustion chamber wall on the outer periphery of the valve seat of the intake valve so that the intake air amount is relatively reduced during the operation state in which the valve lift amount of the intake valve is minimal lift. The first wall portion, which is higher than the intake valve maximum lift amount in the operating state and becomes lower than the intake valve maximum lift amount in the operating state where the intake valve valve lift amount is a small lift, is the valve of the intake valve An internal combustion engine characterized by being formed so as to surround a portion of the outer periphery of the seat on the side opposite to the intake direction. In an internal combustion engine that can change the valve lift amount of the intake valve according to the engine load,
  On the upper wall surface of the combustion chamber, a linear step is formed passing between the intake valve and the exhaust valve. The height of the step in the intake valve lift direction is such that the valve lift amount of the intake valve is a minimum lift. In order to relatively reduce the intake air amount during the operation state, the valve lift amount of the intake valve is higher than the intake valve maximum lift amount during the operation state where the lift valve is a minimum lift, and the valve lift amount of the intake valve is a small lift. An internal combustion engine configured to be lower than a maximum lift amount of the intake valve in an operating state.   The second wall part, which is higher than the intake valve maximum lift amount in the operating state where the valve lift amount of the intake valve is a small lift, is formed so as to surround the portion on the intake valve introduction side on the outer periphery of the valve seat of the intake valve The internal combustion engine according to claim 2, wherein the internal combustion engine is provided. In an internal combustion engine that has a pent roof type combustion chamber and can change the valve lift amount of the intake valve according to the engine load,
  When the exhaust valve is closed, the amount of protrusion of the valve head of the exhaust valve from the combustion chamber wall surface is larger than the maximum lift amount of the intake valve in the operating state where the valve lift amount of the intake valve is a minimum lift, and the valve lift of the intake valve An internal combustion engine characterized by being set to be smaller than an intake valve maximum lift amount in an operating state in which the amount is a small lift.

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