JP2011069301A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability of bearings by preventing deflection of a crankshaft, in a type of an internal combustion engine in which a connecting rod only performs reciprocating motion without rotating. <P>SOLUTION: A crankshaft 4 has a rotational center shaft 6, a first crank portion 7, and a second crank portion 8, and the first crank portion 7 is interconnected to an eccentric position of the rotational center shaft 6 in a rotatable state. The rotational center shaft 6 is supported by an engine body 1 in a rotatable manner by a bearing 5, and a balance weight 15 is provided on the outside of the bearing 5. Furthermore, a planet gear 17 and an internal tooth gear 18 are arranged on the outside of the rotational center shaft 6. A balance weight 14 of a crank arm 9 is adjacent to the bearing 5. With both of the fact that a spacing between right and left bearings 5 can be made shorter, and the fact that the balance weight 15 of the rotational center shaft 6 does not act on the crank portions 7, 8 as a bending force, deflections of the crankshaft 4 can be prevented, and as a result, durability of the bearing 5 can be improved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a reciprocating internal combustion engine that extracts the reciprocating motion of a piston as rotational power, such as a gasoline engine or a diesel engine. More specifically, the present invention relates to an internal combustion engine of a type in which a connecting rod only reciprocates without rotating. Is.

  In an internal combustion engine, a crank mechanism is generally employed as a means for taking out the reciprocating motion of a piston as rotational power. In a normal internal combustion engine, the rotation axis of the crankshaft is rotatably held by the engine body, and the rotation is rotated. A crankpin is provided in a state of being eccentric from the shaft center, and the crankpin and the piston are connected by a connecting rod. Therefore, the connecting rod reciprocates while changing the angle, but the piston and cylinder bore are subject to wear because an external force is applied to the piston by changing the angle of the connecting rod. There were also problems such as large sliding resistance (energy loss).

  In view of this, a mechanism for obtaining a rotational motion by only reciprocating the connecting rod has been considered. As an example, Patent Document 1 discloses that a large-diameter eccentric collar (a kind of rotating damper) is rotated at the large end of the connecting rod. Insert the shaft freely, connect the eccentric collar to the crank pin of the crank shaft in an eccentric state, and set the eccentric dimension of the eccentric collar to the same dimension as the crank pin eccentric dimension. It is allowed to rotate around the axis of the crankpin while revolving, and furthermore, the eccentric collar is provided with a planetary gear concentric with the crankpin, while the engine body is provided with an internal gear that meshes with the planetary gear. By setting the number of teeth of the gear to twice the number of teeth of the planetary gear, the rotation collar is restricted to rotate in the direction opposite to the rotation direction of the crank portion, and thus the connecting rod does not rotate. The mechanism that reciprocates only is opened. It is.

  In Patent Document 1, a crankpin is connected to a rotation center shaft via a crank arm, and a balance weight for canceling centrifugal force is integrally provided on the crank arm. Further, a balance weight for canceling the centrifugal force is also provided integrally with the eccentric collar.

Japanese Patent Laid-Open No. 54-113775

  Now, in Patent Document 1, both the crank arm and the crank pin rotate (revolve) around the axis of the rotation center axis. Therefore, the crank shaft supports the rotation center axes at both ends thereof by bearings. Patent Document 1 employs a ball bearing as a bearing.

  However, although Patent Document 1 supports the crankshaft in a state where both ends are supported, since all members such as balance weights are arranged between the left and right bearings, the span between the left and right bearings only becomes long. In addition, the bending load on the crankshaft is inevitably increased, which may cause the crankshaft to bend easily and reduce the durability of the bearing.

  Further, in Patent Document 1, since the burden on the crankshaft increases due to the reciprocating movement of the eccentric collar having a large weight, it can be said that the problem of durability of the bearing is serious. Furthermore, when a plurality of connecting rods are connected to a crankpin by applying it to a multi-cylinder internal combustion engine, the span between the left and right bearings becomes longer and the bending load increases, resulting in bending (bending) of the crankshaft. It can be said that the harmful effects are conspicuous.

  The present invention has been made to improve such a current situation, and is intended to provide an internal combustion engine in which a connecting rod only reciprocates in an improved form.

  The present invention relates to an internal combustion engine, and the internal combustion engine includes a piston that reciprocates a cylinder bore, a connecting rod having one end connected to the piston, and a crankshaft that is driven by the reciprocating motion of the connecting rod. The crankshaft includes a rotation center shaft that is rotatably supported by the engine via a bearing, and a first crank portion that is rotatably connected to a portion of the rotation center shaft that is eccentric from the axis. And a second crank portion having a crank pin portion connected to the connecting rod so as to be rotatable relative to the connecting rod is eccentric from a rotation center of the first crank portion. Are integrally provided via a crank arm.

  Further, by setting the eccentric dimension of the first crank part with respect to the rotational axis of the rotation center shaft and the eccentric dimension of the second crank part with respect to the rotational axis of the first crank part to the same dimension, the second crank part When the shaft is revolved in the direction opposite to the rotation direction of the rotation center axis, the connecting rod is allowed to reciprocate without rotating, and either one of the second crank portion and the crank arm or Both and the rotation center shafts are each provided with a balance weight for canceling the centrifugal force.

  In the invention of claim 1, in addition to the above configuration, the rotation center shaft is supported by the bearing at a portion between the balance weight provided on the rotation center shaft and the crank arm. According to a second aspect of the present invention, in the first aspect, the bearing is a ball bearing or a metal bearing, and the crank arm is provided with a balance weight in a state of being close to the bearing.

  In the present invention, since the balance weight of the rotation center shaft is located outside the bearing, the span between the left and right bearings can be shortened, and the balance weight of the rotation center shaft can act as a bending force on the crankshaft. Therefore, the bending force acting on the crankshaft can be reduced. As a result, the durability of the bearing can be significantly improved by preventing or significantly suppressing the bending of the crankshaft.

  Conventionally, ball bearings and metal bearings are frequently used as bearings for the crankshaft. In any case, if the bearing is provided close to the balance weight of the crank arm as in claim 2, the balance weight of the crank arm is provided. Since the kinetic energy does not act as a bending force on the second crank portion, it is possible to more reliably prevent the crankshaft from being bent while ensuring smooth rotation.

(A) is a longitudinal front view of the embodiment, (B) is a schematic diagram of the structure, (C) is a schematic diagram showing the movement. It is a vertical front view. 2A is a cross-sectional view taken along the line A-A in FIG. 2, FIG. 2B is a cross-sectional view taken along the line B-B in FIG. 2, and FIG. (D) is a DD sectional view of FIG. 2, (E) is an EE sectional view of FIG.

  Next, an embodiment of the present invention will be described with reference to the drawings. In the following description, the terms “left and right” and “front and back” are used to specify the direction. This is a state seen from a direction orthogonal to the axis of the main axis (ie, FIG. 1A and FIG. Is the standard).

(1). Structure The internal combustion engine of the present embodiment is a two-cylinder four-cycle system. Therefore, the engine body (crankcase) 1 is formed with two cylinder bores 2 in parallel, and each cylinder bore 2 has a piston 3. Is slidably fitted.

  A crankshaft 4 having an axis extending along the direction in which the pistons 3 are arranged is disposed below the piston 3. The crankshaft 4 includes two left and right rotation center shafts 6 rotatably held by the engine body 1 via bearings (ball bearings) 5 and two left and right first crank portions 7 eccentric from the rotation center shaft 6. And a second crank portion 8 positioned between the left and right first crank portions 7.

  The first crank portion 7 is rotatably fitted to a portion of the rotation center shaft 6 that is eccentric from the rotation axis O1 by an appropriate dimension E. On the other hand, the first crank portion 7 and the second crank portion 8 are integrally connected via a crank arm 9. A pair of left and right true circular crankpin portions 10 are formed in the second crank portion 8, and the crankpin portion 10 and the piston 3 are connected by a connecting rod 11.

  The lower end portion of the connecting rod 11 is a large-diameter lower bearing portion 11 a that holds the crankpin portion 10, and the lower half of the lower bearing portion 11 a is constituted by a lower member 11 b of another part. It is concluded. The upper end of the connecting rod 11 is connected to the piston 3 by a piston pin (not shown). The eccentric dimension of the axis O2 of the first crank portion 7 with respect to the axis O1 of the rotation center shaft 6 is the same as the eccentric dimension of the axis O3 of the crankpin portion 10 with respect to the axis O2 of the first crank portion 7. Is set.

  The portion of the second crank portion 8 of the crankshaft 4 that is sandwiched between the left and right crankpin portions 10 has a slightly larger diameter than the crankpin portion 10, and the first balance weight 13 is provided integrally therewith. Yes. The first balance weight 13 projects in the same direction as the projecting direction of the crank arm 9 when viewed from the axis O3 of the second crank portion 8 (when viewed from the first crank portion 7, the first balance weight 13 Is protruded from the second crank portion 8 in a direction opposite to the direction in which the crank arm 9 protrudes from the first crank portion 7.

  The crank arm 9 is provided with a second balance weight 14 extending in the direction opposite to the protruding direction of the second crank portion 8. The second balance weight 14 is close to the bearing 5. On the other hand, the left and right rotation center shafts 6 have an exposed portion that protrudes outside the bearing 5, and a third balance weight 15 and a main drive gear 16 are provided in the exposed portion. In the drawing, the third balance weight 15 is located on the inner side and the main driving gear 16 is located on the outer side. However, the arrangement may be reversed in the inside and outside. The third balance weight 15 protrudes in the opposite direction to the first crank portion 7 with the axis O1 of the rotation center shaft 6 interposed therebetween.

  The tip of one of the first crank parts 7 (the right first crank part 7 in FIGS. 1A and 2) is completely hidden by the rotation center shaft 6, but the other (left) second crank. The tip of the portion 7 is an exposed portion 7a protruding from the rotation center shaft 6. The planetary gear 17 is fixed to the exposed portion 7a so as not to be relatively rotatable, and the planetary gear 17 is meshed with the internal gear 18. (It is also possible to arrange the planetary gear 17 and the internal gear 18 on the left and right.) The internal gear 18 is disposed concentrically with the rotation center shaft 6 and is fixed to the engine body 1 so as not to rotate. The number of teeth of the internal gear 18 is set to twice the number of teeth of the planetary gear 17.

  The left and right main drive gears 16 are respectively engaged with driven gears 19, and the left and right driven gears 19 are integrally connected by a constant speed shaft 20. Therefore, the driven gear 19 constitutes a constant speed mechanism that rotates the crankshaft 4 in a state without twisting. The rotation center shaft 6 located on the opposite side of the planetary gear 17 is provided with a boss protruding outside the main driving gear 16, and the flywheel 21 is fixed thereto.

(2) Summary In the above configuration, one cylinder bore 2 performs explosion / exhaust / intake / compression every 4 cycles in which the piston 3 makes two reciprocations. The cycle (360 degrees of crankshaft rotation angle) is off.

  Then, the first crank portion 7 revolves around the axis of the rotation center shaft 6 while rotating by the pressing and pulling action by the connecting rod 11, but due to the restriction action by the meshing between the planetary gear 17 and the internal gear 18, The rotation direction of the rotation center shaft 6 and the rotation direction of the first crank portion 7 are opposite to each other. Since the eccentric dimension E of the first crank part 7 with respect to the axis of the rotation center shaft 6 is the same as the eccentric dimension E of the second crank part 8 with respect to the first crank part 7, FIG. ), The second crank portion 8 rotates while revolving. Thereby, rotational power can be obtained only by reciprocating movement of the connecting rod 11.

  The second crank portion 8 needs a certain length because the two connecting rods 11 are connected, but the bearing 5 supports the end portion of the rotation center shaft 6 near the crank arm 9. Therefore, the distance between the left and right bearings 5 can be made as short as possible. Moreover, since the third balance weight 15 is located outside the bearing 5, the load of the third balance weight 15 does not act as a bending force on the first crank portion 7 and the second crank portion 8. By reducing the support span and suppressing the bending load, the crankshaft 4 can be prevented from being bent and the durability of the bearing 5 can be remarkably improved.

  Further, since the second balance weight 14 of the crank arm 9 is close to the bearing 5, the centrifugal force accompanying the rotation of the second balance weight 14 hardly acts as a bending force on the first crank portion 7. In this respect, the effect of preventing the crankshaft 4 from being bent is promoted.

  When providing the 1st balance weight 13 in the 2nd crank part 8, as shown by the dashed-two dotted line in FIG. 2, it provides as far as possible from the left-right intermediate point of the 2nd crank part 8 (as close as possible to the crankpin part 10). It is also possible to adopt this configuration, and it is more preferable in terms of prevention of bending.

(3). Others The present invention can be embodied in various ways other than the above embodiment. For example, the number of cylinders is not limited to two, but can be applied to an internal combustion engine having a single cylinder or three or more cylinders. The first crank portion, the crank arm, and the second crank portion do not necessarily have to be integrated as a whole, and those manufactured separately may be assembled and integrated. In the case of a multi-cylinder internal combustion engine, it is also possible to provide a plurality of second cranks (in this case, three or more rotation center shafts are provided). Needless to say, a metal bearing can be used for the bearing of the rotation center shaft.

  The present invention can be applied to an internal combustion engine to exhibit its usefulness. Therefore, it can be used industrially.

1 Engine Body 2 Cylinder Bore 3 Piston 4 Crankshaft 5 Bearing (Ball Bearing)
7 First crank portion 8 Second crank portion 9 Crank arm 10 Crank pin portion 11 Connecting rod 13 First balance weight 14 Second balance weight 15 Third balance weight 17 Planetary gear 18 Internal gear

Claims (2)

A piston that reciprocates a cylinder bore, a connecting rod having one end connected to the piston, and a crankshaft driven by the reciprocating motion of the connecting rod;
The crankshaft includes a rotation center shaft that is rotatably supported by the engine via a bearing, and a first crank portion that is rotatably connected to a portion of the rotation center shaft that is eccentric from the axis. And a second crank part having a crank pin part connected to the first connecting part so as to be rotatable relative to the connecting rod is eccentric from a rotation center of the first crank part. It is provided integrally through
The second crank part is rotated by setting the eccentric dimension of the first crank part with respect to the rotational axis of the rotation center axis to the same dimension as the eccentric dimension of the second crank part with respect to the rotational axis of the first crank part. When revolving in the direction opposite to the rotation direction of the central axis, the connecting rod is allowed to reciprocate without rotating,
Furthermore, any one or both of the second crank portion and the crank arm, and the rotation center shaft are provided with balance weights for canceling centrifugal force, respectively.
The structure
The rotation center shaft is supported by the bearing at a portion between a balance weight provided on the rotation center shaft and the crank arm.
Internal combustion engine. The bearing is a ball bearing or a metal bearing, and the crank arm is provided with a balance weight in a state close to the bearing.
The internal combustion engine according to claim 1.

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