JP2009257330A - Reciprocating internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new reciprocating internal combustion engine capable of reducing a secondary vibration component with respect to crankshaft rotation synchronization, without causing increase in the overall height of the engine. <P>SOLUTION: The reciprocating internal combustion engine is provided with an upper link 5 connected to a piston pin 7 of a piston 8, a lower link 4 for interconnecting the upper link 5 and a crank pin 3 of a crankshaft 1, and a control link (third link) 10 having a lower end side swingably supported by a control shaft 12 on an engine body side and an upper end side connected to the lower link 4. Compared to other reciprocating internal combustion engines in which a piston pin and a crank pin are interconnected by a single link, this reciprocating internal combustion engine has a small vibration amplitude of a rotation secondary vibration component of piston movement while achieving the same piston stroke and cylinder height. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an improvement of a reciprocating internal combustion engine that is suitably used for automobiles and the like.

  In a general reciprocating internal combustion engine, a crankpin of a crankshaft and a piston pin of a piston are connected by a single link (connecting rod). In such a single link type reciprocating engine, since the length of the connecting rod is finite, higher-order vibration components other than the rotation primary vibration component are included in the motion of the piston.

  FIG. 9 is a graph showing piston acceleration (thick solid line) and fluctuations of each order component in a single link type reciprocating engine. As shown in the figure, in the conventional general single link type reciprocating engine, in addition to the primary component of the piston acceleration corresponding to the primary rotational vibration component of the piston motion, a relatively large amplitude (the amplitude of the primary component). It can be seen that a secondary component of about 1/3 of the above is included. For this reason, an excitation force caused mainly by the primary and secondary vibration components acts on the engine body side.

  The primary vibration caused by the rotational primary vibration component can be sufficiently suppressed by providing a counterweight at a position opposite to the crankpin of the crankshaft. In a multi-cylinder engine, primary vibration can be sufficiently suppressed by devising the arrangement of cylinders.

  However, the secondary vibration caused by the secondary vibration component with respect to the crankshaft rotation synchronization cannot be eliminated by the cylinder arrangement in many cases, and this secondary vibration is likely to cause a vehicle interior noise. The longer the connecting rod is, the closer the piston motion becomes to a single vibration, and the secondary component of the piston acceleration can be reduced. However, since the overall height of the engine increases, the weight tends to increase and the in-vehicle property tends to deteriorate.

  An object of the present invention is to provide a novel reciprocating internal combustion engine that can effectively reduce a secondary vibration component with respect to crankshaft rotation synchronization without increasing the overall engine height by connecting a crank pin and a piston pin with a plurality of links. Is to provide.

  Note that a reciprocating internal combustion engine itself in which a crank pin and a piston pin are connected by a plurality of links is known from Japanese Patent Laid-Open No. 9-228858 and the like. None reduce the secondary vibration component.

  A reciprocating internal combustion engine according to the present invention is supported by an upper link connected to a piston pin of a piston, a lower link connecting the upper link and a crank pin of a crankshaft, and one end swingably toward the engine body side. The other end has a third link connected to the upper link or the lower link.

  The first invention achieves the same piston stroke and cylinder height as compared with other reciprocating internal combustion engines in which the piston pin and the crank pin are connected by a single link, while the crankshaft rotation of the piston motion is achieved. It is characterized in that the amplitude of the secondary vibration component with respect to the synchronization is small.

  In other words, the size, shape, layout, etc. of each link member constituting the multi-link reciprocating engine are set so that the amplitude of the rotational secondary vibration component of the piston motion is sufficiently small.

  Further, the second invention is characterized in that the amplitude of the secondary vibration component and the amplitude of the tertiary vibration component with respect to the crankshaft rotation synchronization of the piston motion are substantially equal.

  In other words, the dimensions, shapes, layouts, etc. of the link members constituting the multi-link reciprocating engine are set so that the amplitude of the secondary rotational vibration component of the piston motion is suppressed to the same extent as the amplitude of the rotational tertiary vibration component. It is set.

  With such a configuration, as in the third aspect of the invention, the piston stroke is changed by moving the position of the pivot axis of the third link relative to the engine body in accordance with the operating state of the engine. It is possible to change the compression ratio of the engine.

  In the configuration in which the compression ratio is changed by changing the piston stroke as described above, the amplitude of each component of the piston acceleration changes with the change of the compression ratio. Therefore, preferably, the high-order component amplitude of the piston acceleration is set to be small when the high compression ratio is set during the low and medium speed rotation operation that requires quietness.

  In other words, the fourth aspect of the present invention provides a secondary vibration component for the crankshaft rotation synchronization of the piston motion when the compression ratio is low and the amplitude of the secondary vibration component for the crankshaft rotation synchronization of the piston motion is a low compression ratio. It is characterized by being smaller than the amplitude of.

  If the swing axis of the third link is configured to be movable as described above, the swing axis of the third link is movably supported in the vicinity of the top dead center and the bottom dead center of the piston where the piston acceleration is maximized. A large load acts on the portion to be applied, and a large holding force is required to face this load.

  Therefore, in the fifth aspect of the invention, in order to effectively suppress the load acting on the portion supporting the swing axis of the third link at least near the top dead center of the piston, the shaft center of the crankpin and the piston are effectively suppressed. The distance from the reciprocating axis of the pin is made smaller than the distance between the pivot axis of the third link and the reciprocating axis of the piston pin.

  In the sixth aspect of the invention, in order to effectively suppress the load acting on the portion supporting the pivot axis of the third link at least near the bottom dead center of the piston, the reciprocation of the crankpin axis and the piston pin is performed. The distance to the axis is made smaller than the distance between the swing axis of the third link and the reciprocating axis of the piston pin.

  According to a seventh aspect of the present invention, the rotation center of the crankshaft is the origin, the x-axis is parallel to the direction orthogonal to the piston pin and its reciprocating axis, the y-axis is parallel to the reciprocating axis of the piston pin, and the crankshaft When the rotation direction is defined as the counterclockwise direction, the x-coordinate of the swing axis of the third link is positive and the x-coordinate of the reciprocating axis of the piston pin is negative.

In an eighth aspect of the invention, the distance between the axis of the crankshaft and the axis of the crankpin is L1;
The distance between the axis of the crankpin and the first axis of the portion where the lower link and the third link are connected so as to be relatively rotatable is L2;
The link length of the third link is L3;
The distance between the axis of the crank pin and the second axis of the portion where the upper link and the lower link are connected to each other so as to be relatively rotatable is L4;
The distance between the first axis and the second axis is L5;
The link length of the upper link is L6;
The coordinate position of the pivot axis of the third link is (XC, YC);
The x coordinate of the reciprocating axis of the piston pin is x4;
Defined as

(Equation 2)
L1: L2: L3: L4: L5: L6: XC: YC: x4
≈ 1: 2.4: 2.65 to 3.5: 0.69: 3.0 to 3.4: 3.3 to 3.55: 3.2 to 3.55: -2 to -1.35 : -1 to -0.6
It is characterized by that.

  According to the first and second aspects of the invention, in the multi-link type reciprocating internal combustion engine in which the compression ratio can be changed, the secondary vibration caused by the secondary vibration component with respect to the crankshaft rotation synchronization of the piston motion is reduced. Vehicle interior noise caused by secondary vibration can be sufficiently suppressed.

  In particular, according to the fourth aspect of the invention, the amplitude of the higher-order component of the piston acceleration can be effectively suppressed, for example, during low and medium speed rotation operation that requires quietness.

  According to the fifth and sixth inventions, when the swing axis of the third link is configured to be movable, the load acting on the portion that supports the swing axis of the third link so as to be movable is particularly large. The load can be effectively suppressed near the bottom dead center on the piston.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram (a) and decomposition | disassembly block diagram (b) which show the multiple link type reciprocating internal combustion engine which concerns on one Example of this invention. The link figure in each crankshaft rotational position which concerns on a present Example. The graph which shows a piston stroke when it is set as the high compression ratio and low compression ratio which concern on a present Example. The graph which shows the piston acceleration when setting it as the high compression ratio which concerns on a present Example, and the amplitude of each order component. The graph which shows the piston acceleration when setting it as the low compression ratio which concerns on a present Example, and the amplitude of each order component. The schematic block diagram which shows the link attitude | position of the piston top dead center vicinity (a) and bottom dead center vicinity (b) which concern on a present Example. The graph which shows the amplitude of the secondary component of the piston acceleration in the piston top dead center vicinity which concerns on a present Example. The graph which shows the amplitude of the secondary component of piston acceleration in the piston bottom dead center vicinity which concerns on a present Example. The graph which shows the piston acceleration and each order component which concern on the conventional single link type reciprocating type internal combustion engine.

  Hereinafter, the above-mentioned and other configurations and effects according to the present invention will be described in detail with reference to specific examples and drawings.

  FIG. 1 is a schematic configuration diagram (a) and an exploded configuration diagram (b) showing a multi-link type reciprocating internal combustion engine according to an embodiment of the present invention. The crankshaft 1 is provided with a crank journal 2 rotatably supported by a main bearing (not shown) of a cylinder block (not shown) constituting the engine body. Each crank journal 2 has an axis O that coincides with the axis (rotation center) of the crankshaft 1 and constitutes a rotating shaft portion of the crankshaft 1.

  Further, the crankshaft 1 includes a crankpin 3 that is eccentric from the axis O and provided for each cylinder, a crank arm 3a that connects the crankpin 3 to the crank journal 2, and a crankpin 3 that is connected to the axis O. The counter weight 3b is disposed on the opposite side and mainly reduces the rotational primary vibration component of the piston motion. In this embodiment, the crank arm 3a and the counterweight 3b are integrally formed.

  In this embodiment, the piston 8 slidably fitted to the cylinder 9 formed for each cylinder and the crank pin 3 are composed of a plurality of link members, that is, the upper link 5 and the lower link 4. It is mechanically linked. The upper end side of the upper link 5 is externally fitted to a piston pin 7 fixedly provided on the piston 8 so as to be relatively rotatable around the axis Oc. Further, the lower end side of the upper link 5 and the main body 4a of the lower link 4 are connected to each other around the axis Od by a connecting pin 6 that passes through both of them.

  The lower link 4 is configured by attaching a cap 4b to the main body 4a so as to sandwich the crank pin 3, and is connected to the crank pin 3 and the axis Oe so as to be relatively rotatable at this sandwiching portion. . The lower link body 4a and the upper end side of the control link (third link) 10 are connected to each other around the axis Of by a connecting pin 11 that passes through both of them.

  The lower end side of the control link 10 is externally fitted and supported by a large-diameter portion 12a of the control shaft 12 that is rotatably supported by the cylinder block so as to be swingable around the axis Oa. That is, a large diameter portion 12a is fixedly provided on the outer periphery of the small diameter portion 12b of the control shaft 12, and the axis Oa of each large diameter portion 12a is offset by a predetermined amount with respect to the axis Ob of the small diameter portion 12b. I have a heart. The control shaft 12 is controlled to rotate according to the operating state of the engine by a compression ratio control actuator (not shown) and is held at an arbitrary rotation position.

  Here, as shown in FIG. 1A, the rotation center of the crankshaft 1 (the axis of the crank journal 2) O is the origin, and the direction orthogonal to the piston pin 7 and its reciprocating axis 1 (thrust-anti-thrust direction). ) In parallel with the reciprocating axis l of the piston pin 7 and the rotation direction of the crankshaft 1 is defined as the counterclockwise direction, the axis Oc of the piston pin 7 is Set so that the x-coordinate of the reciprocal axis passing through (≈the axis of the cylinder 9) l becomes a negative value and the x-coordinate of the axis Oa of the large-diameter portion 12a serving as the pivot axis of the control link 10 becomes a positive value. Has been.

More specifically,
The distance between the axis O of the crankshaft 1 and the axis Oe of the crankpin 3 is L1;
The distance between the axis Oe of the crank pin 3 and the axis (first axis) Of of the connecting pin 11 that connects the lower link 4 and the control link 10 so as to be relatively rotatable is L2;
The link length of the control link 10 is L3;
The distance between the axis Oe of the crank pin 3 and the axis (second axis) Od of the connecting pin 6 that connects the upper link 5 and the lower link 4 so as to be relatively rotatable is L4;
The distance between the axis Of and the axis Od is L5;
The link length of the upper link 5 is L6;
The coordinate position of the swing axis Oa of the control link 10 is (XC, YC);
The x coordinate of the reciprocating axis 1 of the piston pin 7 is x4;
Is defined so that the following ratio holds.

(Equation 3)
L1: L2: L3: L4: L5: L6: XC: YC: x4
≈ 1: 2.4: 2.65 to 3.5: 0.69: 3.0 to 3.4: 3.3 to 3.55: 3.2 to 3.55: -2 to -1.35 : -1 to -0.6
Note that XC and YC vary depending on the rotational position of the control shaft 12, but in this embodiment, the above ratio is always established when the rotational position of the control shaft 12 is within the control range. ing.

  With such a configuration, as the crankshaft 1 rotates, the piston 8 moves up and down in the cylinder 9 via the crankpin 3, the lower link 4, the upper link 5 and the piston pin 7, and is connected to the lower link 4. The control link 10 swings around the swing axis Oa on the lower end side. As a reference, FIG. 2 schematically shows the link posture of each crankshaft 1 at the rotational angle θ (FIG. 1) position.

  In addition, by controlling the rotation of the control shaft 12 by the compression ratio control actuator, the axis Oa of the large-diameter portion 12a serving as the pivot axis of the control link 10 rotates around the axis Ob of the small-diameter portion 12b. That is, the swing center position Oa of the control link 10 moves with respect to the engine body (and the crankshaft rotation center O). As a result, the stroke of the piston 8 changes, and the compression ratio of each cylinder of the engine is variably controlled. For reference, FIG. 3 shows each piston stroke (y coordinate of the piston pin axis Oc) in a state where the rotation position of the control shaft 12 is held so as to obtain a high compression ratio and a low compression ratio.

  4 and 5 show the piston acceleration (thick solid line) and its respective order components in the multi-link type reciprocating engine of the present embodiment, and each of these order components corresponds to the vibration component of each rotational order of the piston motion. is doing. FIG. 4 shows a state when the compression ratio is high, and FIG. 5 shows a state when the compression ratio is low.

  As shown in FIG. 4, when the compression ratio is at least high, the amplitude of the high-order vibration component is suppressed to 10% or less with respect to the amplitude of the rotation primary vibration component. The occurrence of vibration and noise due to this can be sufficiently reduced.

  Further, when the low compression ratio shown in FIG. 5 is used, the amplitude of the high-order vibration component is slightly larger than that at the high compression ratio of FIG. (In detail, the amplitude of the secondary component is 7% or less, the amplitude of the tertiary component is 9% or less, and the amplitude of the quaternary component is 7% or less). The occurrence of vibration and noise due to this can be sufficiently reduced.

  4 and 5, the multi-link type reciprocating engine of this embodiment has substantially the same piston stroke and substantially the same cylinder height (crank journal) as compared to the single-link type reciprocating engine as shown in FIG. The y-coordinate of the axis Oc of the piston pin at the piston top dead center position when the axis O is the origin is realized, and the secondary component for crankshaft rotation synchronization is greatly reduced. In other words, the amplitude of the rotational secondary vibration component of the piston motion is suppressed to approximately the same level as the amplitude of the rotational tertiary vibration component. For this reason, without increasing the overall engine height, the secondary vibration caused by the rotational secondary vibration component of the piston motion can be reduced and the vehicle interior noise caused by this secondary vibration can be sufficiently suppressed. it can.

  By the way, in an engine having a variable compression ratio mechanism, in general, a high compression ratio is often set during low and medium speed rotation operation, and a low compression ratio is often set during high speed rotation operation. In the mechanism for changing the compression ratio by changing the piston stroke as in this embodiment, as shown in FIGS. 4 and 5, the amplitude of each order component of the piston acceleration also changes as the compression ratio is changed. Therefore, in the present embodiment, the amplitude of the higher order component of the piston acceleration is relatively smaller than that at the low compression ratio during the low and medium speed rotation operation (at the time of the high compression ratio) that requires more quietness. It is set to.

  FIG. 6 shows link postures in the vicinity of the piston top dead center (a) and in the vicinity of the piston bottom dead center (b) in the multi-link engine of the present embodiment.

  When the piston 8 is at the top dead center or near the bottom dead center, the acceleration of the piston 8 becomes the largest, and the load acting on the control shaft 12 via the piston pin 7, the upper link 5, the lower link 4, and the control link 10. Is the largest. When the piston 8 is in the vicinity of the compression top dead center, the reaction force of the combustion pressure received by the piston 8 is applied to the control shaft 12.

  The load acting on the control shaft 12 from the control link 10 side substantially acts on the shaft center Oa of the large-diameter portion 12a. The shaft center Oa is the small-diameter portion 12b that is the rotation center of the control shaft 12. Therefore, the load from the control link 10 acts as a torque for rotating the control shaft 12. When this torque becomes larger than the rotational position holding torque of the compression ratio control actuator, the control shaft 12 rotates against the control, causing a problem that the compression ratio changes arbitrarily.

  Therefore, in this embodiment, the distance in the x-axis direction between the axis Oe of the crank pin 3 and the axis Oc of the piston pin 7 at least near the bottom dead center on the piston where the load applied to the control shaft 12 from the control link 10 increases. α is smaller than the distance β in the x-axis direction between the axis Oa of the control shaft large-diameter portion 12a, which is the pivot axis of the control link 10, and the axis Oc of the piston pin 7, that is, α <β. Thus, the load applied to the control shaft 12 is reduced by the lever ratio. Thereby, the rotational position holding torque of the compression ratio control actuator can be effectively reduced.

  In addition, it has been confirmed by calculation that the amplitude of the secondary component of the piston acceleration suddenly increases when β / α is smaller than 1 (FIGS. 7 and 8). preferable. 7 and 8 show the relationship between β / α and the amplitude of the secondary component of piston acceleration near the piston top dead center and piston bottom dead center, respectively.

  Further, in this embodiment, as described above, the x coordinate of the axis Oa of the large diameter portion 12a serving as the swing axis of the control link 10 is positive, and the x coordinate of the reciprocating axis 1 of the piston pin 7 is negative. Since the position is set, a downward combustion load on the piston 8 which is a power source of the internal combustion engine can be effectively applied to the crankpin 3 and the dimension of the engine body in the x-axis direction (width direction) can be set. It is possible to reduce the size of the engine body.

  This point will be described in detail. If the x-coordinate of the axis Oa of the large-diameter portion 12a is positive and the x-coordinate of the reciprocating axis 1 of the piston pin 7 is positive, the x-coordinate of the reciprocating axis 1 and Since the deviation from the x-coordinate of the crankpin axis Oe (when the y-coordinate of the axis Oe of the crankpin 3 is reduced) increases, the downward combustion load on the piston 8 can be effectively applied to the crankpin 3. In addition, in order to ensure a large difference between α and β, the x coordinate of the axis Oa of the large diameter portion 12a must be set large (in other words, greatly separated in the positive direction of the x axis). As a result, the width direction dimension of the engine body is increased.

  If the x-coordinate of the axis Oa of the large-diameter portion 12a is negative and the X-coordinate of the reciprocating axis 1 of the piston pin 7 is negative, the x-coordinate of the reciprocating axis 1 and the piston descending position (of the crank pin 3 Since the deviation from the x-coordinate of the crankpin axis Oe (when the y-coordinate of the axis Oe is reduced) is small, the downward combustion load on the piston 8 can be effectively applied to the crankpin 3. In order to ensure a large difference between α and β, the x coordinate of the axis Oa of the large diameter portion 12a must be set sufficiently small (in other words, greatly separated in the negative direction of the x axis). As a result, the width direction dimension of the engine body is increased.

  Further, if the x-coordinate of the axis Oa of the large-diameter portion 12a is negative and the x-coordinate of the reciprocating axis 1 of the piston pin 7 is positive, the x-coordinate of the reciprocating axis 1 of the piston pin 7 Since the deviation from the x coordinate of the crankpin axis Oe (when the y coordinate of the axis Oe of the pin 3 is reduced) increases, the downward combustion load on the piston 8 can be effectively applied to the crankpin 3. It will disappear.

  As described above, the present invention has been described based on specific embodiments. However, the present invention is not limited to the above embodiments, and various modifications and changes can be made without departing from the spirit of the present invention. is there.

DESCRIPTION OF SYMBOLS 1 ... Crankshaft 3 ... Crankpin 4 ... Lower link 5 ... Upper link 7 ... Piston pin 8 ... Piston 10 ... Control link (third link)

Claims (8)

An upper link connected to the piston pin of the piston;
A lower link that connects the upper link and the crank pin of the crankshaft;
A reciprocating internal combustion engine having one end supported swingably toward the engine body side and the other end connected to the upper link or the lower link;
Compared to other reciprocating internal combustion engines in which the piston pin and crank pin are connected by a single link, the same piston stroke and cylinder height are achieved, and the amplitude of the secondary vibration component with respect to the crankshaft rotation synchronization of the piston motion A reciprocating internal combustion engine characterized by having a small value. An upper link connected to the piston pin of the piston;
A lower link that connects the upper link and the crank pin of the crankshaft;
A reciprocating internal combustion engine having one end supported swingably toward the engine body side and the other end connected to the upper link or the lower link;
A reciprocating internal combustion engine characterized in that the amplitude of a secondary vibration component and the amplitude of a tertiary vibration component with respect to crankshaft rotation synchronization of piston motion are substantially equal. The reciprocating internal combustion engine according to claim 1 or 2, wherein the compression ratio of the engine is changed by moving the position of the swing axis of the third link with respect to the engine body. The amplitude of the secondary vibration component with respect to the crankshaft rotation synchronization of the piston motion when the compression ratio is high is smaller than the amplitude of the secondary vibration component with respect to the crankshaft rotation synchronization of the piston motion when the compression ratio is low. The reciprocating internal combustion engine according to claim 3. The distance between the axis of the crank pin and the reciprocating axis of the piston pin is smaller than the distance between the pivot axis of the third link and the reciprocating axis of the piston pin at least near the top dead center of the piston. The reciprocating internal combustion engine according to any one of 1 to 4. The distance between the center axis of the crank pin and the reciprocating axis of the piston pin is smaller than the distance between the swing axis of the third link and the reciprocating axis of the piston pin at least near the bottom dead center of the piston. A reciprocating internal combustion engine according to any one of 1 to 5. Taking the rotation center of the crankshaft as the origin, taking the x axis parallel to the direction perpendicular to the piston pin and its reciprocating axis, taking the y axis parallel to the reciprocating axis of the piston pin, and counterclockwise the rotation direction of the crankshaft When defined as the direction of rotation,
The reciprocating internal combustion engine according to any one of claims 1 to 6, wherein the x-coordinate of the swing axis of the third link is positive and the x-coordinate of the reciprocating axis of the piston pin is negative. organ. The distance between the crankshaft axis and the crankpin axis is L1;
The distance between the axis of the crankpin and the first axis of the portion where the lower link and the third link are connected so as to be relatively rotatable is L2;
The link length of the third link is L3;
The distance between the axis of the crank pin and the second axis of the portion where the upper link and the lower link are connected to each other so as to be relatively rotatable is L4;
The distance between the first axis and the second axis is L5;
The link length of the upper link is L6;
The coordinate position of the pivot axis of the third link is (XC, YC);
The x coordinate of the reciprocating axis of the piston pin is x4;
Defined as
(Equation 1)
L1: L2: L3: L4: L5: L6: XC: YC: x4
≒ 1: 2.4: 2.65-3.5: 0.69: 3.0-3.4: 3.3-3.55: 3.2-3.55: -2 to -1.35 : -1 to -0.6
The reciprocating internal combustion engine according to claim 7, wherein:

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