JP4698662B2 - engine - Google Patents

Description

  The present invention operates by adding one or more pairs of pause strokes in which a piston is reciprocated without combustion in addition to four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke in one cycle. The present invention relates to an engine that performs an increased stroke cycle operation.

  As a conventional engine, one or more pairs of pause strokes that reciprocate the piston without combustion are added to one cycle including four strokes of intake, compression, combustion, and exhaust. It is known to perform an increased stroke cycle operation. For example, in the valve state in which the intake valve is open and the exhaust valve is closed, the intake stroke (intake) in which air is sucked from the intake passage as the piston descends, and in the valve state in which the intake valve is closed and the exhaust valve is closed, A first compression stroke that compresses the inside of the cylinder as it rises (first half pause stroke), and a first expansion stroke (the second half pause stroke) in which the piston is pushed back from top dead center by the pressure increase in the cylinder accompanying this compression, A second compression stroke (compression) in which the air-fuel mixture is ignited in the vicinity of the top dead center while the inside of the cylinder is compressed as the piston rises in the valve state in which the intake valve is closed and the exhaust valve is closed, and the high-temperature gas accompanying the combustion The second expansion stroke (combustion) in which the piston is pushed down by the expansion of the exhaust gas, and the exhaust stroke in which the expanded combustion gas is pushed out to the exhaust passage as the piston rises in the valve state in which the intake valve is closed and the exhaust valve is open , It proceeds in the order, is operable engine six stroke-cycle has been proposed (e.g., see Patent Document 1.) Of. If an increase stroke cycle operation in which a stroke called here a pause stroke is added, for example, a six stroke cycle operation is performed, the operation is performed without adding a pause stroke in one cycle as in a normal operation. Compared with the case where stroke cycle operation is performed, the shaft output can be reduced by adding one or more pairs of pause strokes that do not generate shaft output in one cycle, and the output is desired to be reduced at the same rotational speed. It is advantageous in situations where there is a demand.

JP 2004-116305 A (paragraph numbers 0014-0016)

  In the increase stroke cycle operation of the engine according to Patent Document 1, a reciprocating pause stroke (a pair of pause strokes) is performed with both the exhaust valve and the intake valve closed, so that the gas in the cylinder in the previous pause stroke (compression) When a part of the gas escapes as blow-by gas, a negative pressure is generated in the cylinder at the final stage of the post-pause stroke (expansion), leading to negative work and consequently force loss. In addition, the crank chamber (expansion) can be performed in the previous pause stroke even in the increase stroke cycle operation in which the pause stroke of the expansion is changed to the pre-pause stroke and the compression pause stroke is set to the post-pause stroke. When gas is flowed into the cylinder from the end, excessive pressure is generated in the cylinder at the final stage of the post-pause stroke (compression), which also leads to force loss.

  The present invention has been made in view of the above problems, and its purpose is to provide a piston without combustion in addition to four strokes consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke within one cycle. To provide an engine capable of suppressing a loss due to generation of a specific pressure such as a negative pressure or an excessive pressure in a cylinder when performing an increase stroke cycle operation in which one or more pairs of retreat strokes are added and operated. is there.

In order to achieve the above object, an engine according to the present invention includes a pair of reciprocating pistons in one cycle without combustion in addition to four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. An engine that performs an increased stroke cycle operation that operates by adding one or more pause strokes, the characteristic configuration of which is a pair of pause strokes consisting of a previous pause stroke and a subsequent pause stroke that follows the previous pause stroke, In the configuration in which the exhaust valve and / or the intake valve are instantaneously opened in the post-pause stroke, when either the exhaust valve or the intake valve is instantaneously opened alone, When the angular rotation angle is set to an open state in the range of 20 to 30 degrees, and both the exhaust valve and the intake valve are instantaneously opened, the crank angle rotation angle is 10 to 10. 5 ° range in that it is an open state.

  According to this characteristic configuration, the singular pressure such as a negative pressure or an excessive pressure that can be generated in the cylinder in the resting stroke after the pair of resting strokes in which the piston is reciprocated without combustion is generated immediately before or after the occurrence of the singular pressure. By instantaneously opening the exhaust valve and / or the intake valve, the gas is balanced through the release of the in-cylinder gas or the inflow of the out-cylinder gas, so that the loss due to the generation of the specific pressure is suppressed. .

According to a further characteristic configuration of the engine according to the invention, the pair of pause strokes are performed after the intake stroke, and the piston is closed in a closed state in which the exhaust valve and the intake valve are closed in the previous pause stroke. In the post-pause stroke, the piston is lowered in a closed state in which the exhaust valve and the intake valve are closed, and at the bottom dead center region, the exhaust valve and / or the intake valve are It is in the point which is made into an open state.

According to this characteristic configuration, in order to create an increased stroke cycle operation, when the pair of rest strokes are performed after the intake stroke, as a specific prescription for the above-mentioned singular pressure balancing, in the prior SL before resting stroke raising the piston in the closed state of the said intake valve and the exhaust valve closed, the said intake valve and the exhaust valve closed in the back rest stroke closed the intake valve at the bottom dead center region with lowering the piston can be momentarily opened state in the state. In this way, when a pair of pause strokes are interposed after the normal intake stroke, the piston rise in the previous pause stroke increases the in-cylinder pressure, and as a result, some in-cylinder gas escapes as blow-by gas, If the piston is lowered to the bottom dead center during the stroke, the cylinder becomes negative pressure and power loss occurs, but the intake valve is opened momentarily in the bottom dead center area before the piston reaches the bottom dead center. By doing so, it is avoided that gas flows in from the intake passage and negative pressure is generated in the cylinder, and as a result, force loss is also suppressed.

  In order to avoid the negative pressure in the cylinder during the post-pause stroke, the same effect can be obtained by instantaneously opening the exhaust valve in the bottom dead center region of the descending piston. When the exhaust valve is opened instantaneously and exhaust gas is allowed to flow from the exhaust passage, an internal EGR effect can be obtained as a result, which is advantageous. Of course, both the intake valve and the exhaust valve may be opened instantaneously in the bottom dead center region of the descending piston.

The engine according to the present invention is further characterized in that the pair of pause strokes are performed after the exhaust stroke, and the piston is in a closed state in which the exhaust valve and the intake valve are closed in the previous pause stroke. In the post-pause stroke, the piston is raised in a closed state in which the exhaust valve and the intake valve are closed, and the exhaust valve and / or the intake valve are both in the top dead center region. It is in the point that it is opened instantly.

According to this characteristic configuration, when the pair of pause strokes are performed after the exhaust stroke in order to create an increased stroke cycle operation, the exhaust valve and the intake valve are connected in the previous pause stroke. It lowers the piston in a closed state to the closed state, the intake valve and the intake valve and the exhaust valve in the post-dormancy stroke on top dead center region with raising the piston in the closed state to the closed state Can be instantaneously opened. In this way, when a pair of pause strokes are interposed after the normal exhaust stroke, the lowering of the piston in the previous pause stroke reduces the in-cylinder pressure, and as a result, in the state of sucking in gas from the crankcase, in the rear pause stroke When the piston is raised to the top dead center, the pressure inside the cylinder becomes excessive and power loss occurs, but the intake valve is opened instantly in the top dead center area before the piston reaches the top dead center. As a result, it is avoided that gas flows out to the intake passage and the inside of the cylinder becomes excessive pressure, and as a result, power loss is also suppressed.

  Even in this increased stroke cycle operation, the same effect can be obtained even if the exhaust valve is opened momentarily in the top dead center region of the ascending piston in order to avoid excessive pressure in the cylinder during the post-pause stroke. . Further, both the intake valve and the exhaust valve may be opened instantaneously in the upper point region of the ascending piston.

  An embodiment of an engine according to the present invention will be described with reference to the drawings. A schematic diagram of the engine is shown in FIG. As shown in this figure, the engine 50 includes a combustion chamber (in-cylinder chamber) 10 defined by the inner surface of the cylinder (cylinder) 3 and the top surface of the piston 4, and the combustion chamber 10 via the intake valve 1. A connected intake passage 13 and an exhaust passage 14 connected to the combustion chamber 10 via the exhaust valve 2 are provided.

  The piston 4 is swingably connected to the connecting rod 8, and the reciprocating motion of the piston 4 is obtained as a rotational movement of one crankshaft 9 by the connecting rod 8, and such a configuration is not different from a normal engine. .

  In the intake passage 13, an air-fuel mixture I of circulating air and fuel that is a natural gas city gas is formed, and the air-fuel mixture I has a crank angle from about TDC (top dead center) to BDC (bottom dead center). In the intake stroke in which the intake valve 1 is opened to the vicinity, the combustion chamber 10 is inhaled.

  The engine 50 compresses the mixture I taken into the combustion chamber 10 by the piston 4 ascending in the compression stroke in which both the intake valve 1 and the exhaust valve 2 are closed. I is ignited by a known ignition method such as spark ignition or compression ignition by an ignition plug (not shown), and further, in the expansion stroke, the piston 4 is pushed down by combustion of the air-fuel mixture I to obtain a shaft output. Has been. Further, after the expansion stroke, the exhaust gas E in the combustion chamber 10 is discharged to the exhaust passage 14 in the exhaust stroke in which the exhaust valve 2 is opened from the vicinity of the BDC to the vicinity of TDC.

  Further, the engine 50 is provided with a known valve mechanism 20 such as a cam type, an electromagnetic actuator type or a hydraulic actuator type for opening and closing the intake valve 1 and the exhaust valve 2. The valve mechanism 20 is provided with a variable valve timing mechanism 21 capable of adjusting at least the closing timing of the intake valve 1 by changing the phase of cam rotation or periodic operation of the actuator.

  The engine 50 includes four strokes including the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke described above in one cycle, and is operated without adding a stroke different from the four strokes. And an increased stroke cycle operation in which the number of stroke cycles included in one cycle is increased to a value larger than 4 and the operation is performed, for example, a 6 stroke operation in which the number of stroke cycles is increased to 6. By switching between cycle operation, the number of one-cycle strokes can be changed. Hereinafter, a detailed configuration for performing each operation will be described.

(4-stroke cycle operation)
When the engine 50 performs the above-described four-stroke cycle operation, the intake stroke, the compression / ignition stroke (compression stroke), the explosion / expansion stroke (expansion stroke) is accompanied by the reciprocation between the TDC and BDC of the piston 4. ), One cycle including only the exhaust stroke in order is operated repeatedly. Here, the intake valve 1 is opened in the vicinity of the start time of the intake stroke so that the air-fuel mixture I is sucked into the combustion chamber 10 from the intake passage 13 as the piston 4 descends from TDC to BDC in the intake stroke. In the vicinity of the end of the intake stroke, the valve is closed. On the other hand, the exhaust valve 2 is opened near the start of the exhaust stroke in order to discharge the exhaust gas E in the combustion chamber 10 to the exhaust passage 14 as the piston 4 rises from BDC to TDC in the exhaust stroke. Closed near the end of the stroke. In this four-stroke cycle operation, the number of strokes included in one cycle is four (four strokes), and in one expansion stroke in the four strokes constituting one cycle, the mixture I The piston 4 is pushed down by combustion to generate shaft output.

(First embodiment of 6-stroke cycle operation)
A pair of resting strokes in which the piston 4 is reciprocated without combustion in addition to the four strokes of the intake stroke, compression / ignition stroke (compression stroke), explosion / expansion stroke (expansion stroke), and exhaust stroke within one cycle. FIG. 2 shows an explanatory diagram of a first embodiment of a six-stroke cycle operation in which one is added. FIG. 2 (a) is a schematic diagram showing each stroke constituting the six stroke cycle operation in a schematic engine operation diagram, and FIG. 2 (b) shows the intake valve 1 in the six stroke cycle operation. FIG. 2 is a timing chart showing an open / closed state of the exhaust valve 2, and FIG. 2B is a graph showing a crank angle and a piston position in the six-stroke cycle operation.

  In this six-stroke cycle operation, a pair of pause strokes for reciprocating the piston 4 without combustion is inserted after the intake stroke, and the pair of pause strokes before functioning as a compression stroke in which the piston 4 rises. It consists of a resting stroke and a subsequent resting stroke that functions as an expansion stroke in which the piston 4 descends following the previous resting stroke.

  In the pre-pause stroke, the piston 4 moves upward from BDC to TDC. At this time, the intake valve 1 and the exhaust valve 2 are held in the closed state, so the cylinder is closed. As the gas rises, the in-cylinder gas is compressed, and a part of the in-cylinder gas leaks out of the cylinder as blow-by gas. In the subsequent post-stop stroke, the piston 4 performs a lowering operation from TDC to BDC. However, since the intake valve 1 and the exhaust valve 2 are held closed, the in-cylinder pressure decreases as the piston 4 descends. Go. When a part of the cylinder gas leaks during the previous pause stroke, the cylinder becomes negative pressure before the piston 4 reaches BDC. In this six stroke cycle operation, the BDC (900 degrees, Before the lowering to (see FIG. 2C), the intake valve 1 is instantaneously opened, for example, in a range of 20 to 30 degrees at a timing before BDC. Thereby, the air-fuel mixture I enters from the intake passage 13 and the specific pressure in the cylinder is balanced. As a result, inconveniences in which a negative pressure is generated in the cylinder in the bottom dead center region of the piston 4 and a loss in the shaft output is avoided.

  Next, two modifications of the first embodiment of the six-stroke cycle operation will be described with reference to FIGS. 3 and 4 corresponding to FIG. In the modification shown in FIG. 3, before the piston 4 reaches BDC in the post-pause stroke, the exhaust valve 2 is not instantaneously moved, for example, in the range of 20 to 30 degrees at the timing before BDC. Open. Thereby, the exhaust gas E enters from the exhaust passage 14, and the specific pressure in the cylinder is balanced. In the modification shown in FIG. 4, before the piston 4 reaches BDC in the post-rest process, both the intake valve 1 and the exhaust valve 2 are instantaneously set, for example, in the range of 10 to 15 degrees at the timing before BDC. Open. As a result, the air-fuel mixture I flows from the intake passage 13 and the exhaust gas E enters from the exhaust passage 14, and the specific pressure in the cylinder is balanced.

(Second embodiment of 6-stroke cycle operation)
In the first embodiment described above, the piston 4 is not accompanied by combustion in one cycle, in addition to the four strokes of the intake stroke, the compression / ignition stroke (compression stroke), the explosion / expansion stroke (expansion stroke), and the exhaust stroke. In the second embodiment shown in FIG. 5, the pair of pause strokes are reconciled with one exhaust stroke after the intake stroke. However, the second embodiment shown in FIG. This is a six-stroke cycle operation in which one is added later. Here, FIG. 5A is a schematic diagram showing each stroke constituting the six stroke cycle operation as a schematic engine operation diagram, and FIG. 5B is an intake air intake in the six stroke cycle operation. FIG. 5 is a timing chart showing the open / closed state of the valve 1 and the exhaust valve 2, and FIG. 5B is a graph showing the crank angle and the piston position in the six-stroke cycle operation.

  In this six-stroke cycle operation, since a pair of pause strokes that reciprocate the piston 4 without combustion is inserted after the exhaust stroke, the pair of pause strokes functions as an expansion stroke in which the piston 4 descends. It consists of a pre-pause stroke and a post-pause stroke that functions as a compression stroke in which the piston 4 rises following this pre-pause stroke.

  In the pre-pause stroke, the piston 4 performs the lowering operation from TDC to BDC. However, since the intake valve 1 and the exhaust valve 2 are held in the closed state, the in-cylinder pressure decreases as the piston 4 descends. In the subsequent post-pause stroke, the piston 4 moves up from BDC to TDC due to the return force due to the reduced in-cylinder pressure. However, when the piston 4 approaches TDC, the in-cylinder pressure rises and shaft output loss is possible. Sex occurs. Therefore, before the piston 4 reaches TDC (720 degrees, see FIG. 5C), that is, when the piston 4 reaches the top dead center region, the pressure in the cylinder that has become excessive pressure is slightly released. The intake valve 1 is instantaneously opened, for example, in a range of 20 to 30 degrees at a timing before TDC. Thereby, a part of in-cylinder gas escapes to the intake passage 13, and the excess pressure (singular pressure) in the cylinder is balanced. In addition, in the intake stroke following the rest stroke, the intake valve 1 is opened. Therefore, the instantaneous opening state of the intake valve 1 in the previous rest stroke and the open state in the intake stroke may be continued. . In other words, it is advantageous to advance the intake valve open state in the intake stroke to the rear rest stroke region to contribute to the balancing of excess pressure generated at the end of the rear rest stroke.

  Next, two modifications of the second embodiment of the six-stroke cycle operation will be described with reference to FIGS. 6 and 7 corresponding to FIG. In the modification shown in FIG. 6, before the piston 4 reaches TDC in the post-pause stroke, the exhaust valve 2 is not instantaneously moved, for example, in a range of 20 to 30 degrees at a timing before TDC. Open. Thereby, a part of in-cylinder gas escapes to the exhaust passage 14, and the specific pressure in the cylinder is balanced. In the modification shown in FIG. 7, before the piston 4 reaches TDC in the post-rest process, both the intake valve 1 and the exhaust valve 2 are instantaneously set, for example, in a range of 10 to 15 degrees at a timing before TDC. Open. Thereby, a part of in-cylinder gas escapes to the intake passage 13 and the exhaust passage 14, and the specific pressure in the cylinder is balanced.

  In the two embodiments described above, a pair of pause strokes in which the piston 4 is reciprocated without combustion in addition to the four strokes of an explosion / expansion stroke, an exhaust stroke, an intake stroke, and a compression / ignition stroke within one cycle. However, it is possible to add two pairs of pause strokes in succession to obtain an 8-stroke cycle operation, or to perform a multi-stroke cycle operation beyond that. Moreover, it is good also as 8 stroke cycle driving | operation combining the said 1st Embodiment and 2nd Embodiment. By performing switching control between these multi-stroke cycle operation and normal six-stroke cycle operation, appropriate engine operation control corresponding to the engine load is realized.

  The engine according to the present invention includes a pair of rest strokes in which a piston is reciprocated without combustion, in addition to four strokes including an explosion / expansion stroke, an exhaust stroke, an intake stroke, and a compression / ignition stroke within one cycle. Even in an increased stroke cycle operation in which one or more are additionally operated, the engine can be effectively used as an engine capable of suppressing a loss due to generation of a specific pressure such as a negative pressure or an excessive pressure in the cylinder.

Schematic configuration diagram of the engine (A) Operation diagram of engine in first embodiment of 6 stroke cycle operation, (b) Opening / closing timing chart of intake valve and exhaust valve, (c) Explanatory drawing showing a graph showing crank angle and piston position Explanatory drawing which shows the 1st modification of 1st Embodiment. Explanatory drawing which shows the 2nd modification of 1st Embodiment. (A) Operation diagram of engine in second embodiment of 6 stroke cycle operation, (b) Opening / closing timing chart of intake valve and exhaust valve, (c) Explanatory drawing showing a graph showing crank angle and piston position Explanatory drawing which shows the 1st modification of 2nd Embodiment. Explanatory drawing which shows the 2nd modification of 2nd Embodiment.

1: Intake valve 2: Exhaust valve 4: Piston 9: Exhaust passage 10: In-cylinder chamber (combustion chamber)
13: Intake path 14: Exhaust path 20: Valve mechanism 21: Valve timing variable mechanism

Claims (3)

Incremental stroke cycle that is operated by adding one or more pairs of pause strokes that reciprocate the piston without combustion separately from the four strokes consisting of the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke within one cycle. An engine for driving,
The pair of pause strokes includes a pre-pause stroke and a post-pause stroke following the previous pause stroke, and the exhaust valve or the intake valve or both are instantaneously opened in the post-pause step .
When either one of the exhaust valve or the intake valve is instantaneously opened, it is opened in the range of 20 to 30 degrees in terms of the rotation angle of the crank angle,
When both the exhaust valve and the intake valve are opened instantaneously, the engine is opened within a range of 10 to 15 degrees in terms of a crank angle rotation angle . The pair of pause strokes are performed after the intake stroke, the piston is raised in a closed state in which the exhaust valve and the intake valve are closed in the pre-pause stroke, and the exhaust in the post-pause stroke. The piston is lowered in a closed state in which the valve and the intake valve are closed, and the exhaust valve and / or the intake valve are instantaneously opened in the bottom dead center region. The engine according to claim 1. The pair of pause strokes are performed after the exhaust stroke, the piston is lowered in a closed state in which the exhaust valve and the intake valve are closed in the pre-pause stroke, and the exhaust in the post-pause stroke. The piston is raised in a closed state in which the valve and the intake valve are closed, and the exhaust valve and / or the intake valve are instantaneously opened in the top dead center region. The engine according to claim 1.

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