JP2016121706A - Balancer shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure compactness in mounting to an engine, and generate a sufficient unbalance amount for vibration suppression of the engine.SOLUTION: A balancer shaft includes: a shaft part 1 in which a first spiral groove 1b having a predetermined inclination angle to a rotational shaft, and a second spiral groove 1c having the inclination angle and extending while rotating in a direction reverse to the rotation direction of the first spiral groove 1b are formed; a first unbalance weight 2 and a second unbalance weight 3 that move in mutually opposite directions to a circumferential direction so as to take synchronization, and have a centroid eccentric to the shaft center of the shaft part 1; and a movement mechanism 6 that moves the unbalance weights 2, 3 in the axial direction of the shaft part 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a balancer shaft that rotates in synchronization with rotation of a crankshaft of an engine and suppresses vibration of the engine.

  In an engine such as a four-cylinder engine of an automobile, in order to suppress vibration (secondary vibration) generated due to the inertial force and moment generated by the reciprocating motion of the piston and connecting rod, the engine is synchronized with the rotation of the crankshaft of the engine. A rotating balancer shaft may be added. This balancer shaft has a structure in which the weight is eccentric with respect to the rotation axis. Specifically, when the piston and connecting rod are displaced toward the top dead center, the center of gravity of the weight of the balancer shaft is It is displaced in the opposite direction to the displacement, and acts to cancel out vibrations generated by reciprocating motion of the piston or the like.

  The vibration generated by the reciprocating motion of the piston or the like becomes more conspicuous as the engine speed is higher, and is not so problematic when the engine speed is low. On the other hand, the balancer shaft is mainly focused on reducing vibrations when the engine speed is high, and an unbalance amount (an eccentric amount of the center of gravity of the weight) is often set large. For this reason, when the number of rotations is low, the amount of unbalance becomes excessive, and the vibration becomes larger than when no balancer shaft is provided, which may cause problems such as a reduction in fuel consumption.

  Thus, for example, Patent Document 1 discloses a configuration in which a weight is provided inside the balancer shaft so as to be movable in the radial direction of the shaft. As shown in FIG. 4 of this document, when the crankshaft is stopped or in a low-speed rotation state, the weight is substantially at the center of the balancer shaft and the unbalance amount is small. For this reason, the balancer shaft itself does not become a vibration source. On the other hand, as shown in FIG. 5 of this document, when the crankshaft is in a high-speed rotation state, the weight is displaced in one direction against the urging force of the urging means due to centrifugal force, and the unbalance amount Will increase. In this way, by making the unbalance amount variable according to the rotation speed of the crankshaft, the vibration caused by the balancer shaft in the low speed rotation state is suppressed, and the vibration of the engine in the high speed rotation state is controlled by the balancer shaft. It can be canceled out reliably.

Japanese Patent No. 4421958

  In the balancer shaft according to Patent Document 1, since the weight is housed inside the balancer shaft, the weight can be displaced only within the range of the inner diameter of the balancer shaft. For this reason, when a large vibration occurs during high-speed rotation of the crankshaft, it is necessary to expand the balancer shaft to expand the range in which the weight can be displaced, which may cause a problem in engine layout.

  Accordingly, an object of the present invention is to generate an unbalance amount sufficient for suppressing vibration of the engine while ensuring compactness when mounted on the engine.

  In order to solve this problem, according to the present invention, the balancer shaft that rotates in synchronization with the rotation of the crankshaft of the engine and suppresses vibration of the engine has a predetermined inclination angle with respect to the rotation axis on the outer peripheral surface. A first spiral groove extending in one direction of the rotary shaft while rotating around the axis, and the predetermined axis with respect to the rotary shaft on the axis symmetric side with respect to the first spiral groove. A shaft portion having an inclination angle and forming a second spiral groove extending in the one direction of the rotation axis and rotating around the axis in a direction opposite to the rotation direction of the first spiral groove; A center of gravity that is eccentric with respect to the shaft center of the portion, and is provided so as to face the outer peripheral surface of the shaft portion so as to be movable in the axial direction along the shaft portion and rotatable about the shaft. First unbalanced wedge with pin insertion holes And a center of gravity that is eccentric with respect to the axis of the shaft portion, and in synchronization with the first unbalance weight, in the axial direction along the shaft portion and in the same direction as the first unbalance weight. A second unbalance that is movable and has a second pin insertion hole formed so as to face the outer peripheral surface of the shaft portion so as to be rotatable about the axis in the opposite direction to the first unbalance weight. A weight, a first pin inserted into the first pin insertion hole and the first spiral groove, a second pin inserted into the second pin insertion hole and the second spiral groove, the first unbalance weight, A moving mechanism for moving the second unbalance weight in the axial direction of the shaft portion, and when the crankshaft stops rotating or rotates at a rotational speed smaller than a predetermined rotational speed. When the crankshaft rotates at a rotational speed greater than the predetermined rotational speed so that the center of gravity of the first unbalanced weight and the second unbalanced weight is opposite to the shaft center of the shaft portion. The first unbalanced weight and the second unbalanced weight so that the centers of gravity of the first unbalanced weight and the second unbalanced weight are directed from the opposite side to the same side with respect to the axis of the shaft portion. The balancer shaft is characterized in that the unbalance weight is moved in the axial direction of the shaft portion by the moving mechanism.

  As described above, when the crankshaft stops rotating or rotates at a rotational speed smaller than a predetermined rotational speed, the center of gravity of the first unbalanced weight and the second unbalanced weight is opposite to the shaft center of the shaft portion. By doing so, the amount of unbalance of the balancer shaft can be almost eliminated, and the balancer shaft itself can be prevented from becoming a vibration source. On the other hand, when the crankshaft rotates at a rotational speed greater than the predetermined rotational speed, the center of gravity of both unbalanced weights is directed from the opposite side to the same side with respect to the shaft center of the shaft portion. The center of gravity of the balancer shaft can be decentered radially outward to generate a large unbalance amount, and engine vibration can be suppressed.

  Further, by providing both unbalance weights so as to face the outer peripheral surface of the shaft portion, and by displacing both the unbalance weights along the outer peripheral surface of the shaft portion, the unbalance amount is changed, whereby the balancer is changed. It is not necessary to increase the outer diameter of the shaft (shaft portion) itself, and the compactness can be ensured.

  In the above configuration, the first unbalance weight and the second unbalance weight have a cylindrical portion inserted through the shaft portion, and a fan-shaped portion that rises radially outward from the cylindrical portion, and the crank It is preferable that the fan-shaped portions of the unbalanced weights can contact each other in the circumferential direction when the shaft rotates at a rotational speed greater than the predetermined rotational speed.

  In this way, if fan-shaped portions are formed on both unbalance weights, the unbalance weight necessary to suppress engine vibration can be secured without increasing the radial outward protrusion amount of the unbalance weight so much. It is possible to achieve further downsizing.

  In the structure which forms the said fan-shaped part, it is preferable that the angle of the said fan-shaped part is 90 degrees or less.

  When the angle of the fan-shaped portion exceeds 90 degrees, in the state where the fan-shaped portions formed on both unbalanced weights are in contact with each other, the total angle of the fan-shaped portions exceeds 180 degrees and one of the displaced unbalanced weights The part protrudes to the opposite side beyond the center line of the shaft part. In this case, a centrifugal force in the direction opposite to that of the other portions acts on the protruding portion, and there arises a problem that the unbalance amount decreases as the protruding portion increases. On the other hand, when the angle of the fan-shaped portion is 90 degrees or less, the above-mentioned protrusion does not occur. Therefore, the centrifugal force of both unbalance weights acts only in one direction, and is necessary and sufficient for suppressing vibration of the engine. A balance amount can be generated.

  In each of the above configurations, it is preferable that the moving mechanism is a hydraulic or electric actuator.

  Thus, by using the actuator, both unbalance weights can be smoothly moved in the axial direction of the shaft portion, and can be rotated around the axis in accordance with this movement, corresponding to the number of rotations of the crankshaft. Thus, it is possible to reliably generate an unbalance amount necessary for suppressing vibrations of the engine.

  In the present invention, the first spiral groove having a predetermined inclination angle with respect to the rotation axis and extending around the axis in one direction of the rotation axis and the first spiral groove are formed on the outer peripheral surface. It has the predetermined inclination angle with respect to the rotation axis on the axis-symmetrical side, and rotates in the one direction of the rotation axis and in the direction opposite to the rotation direction of the first spiral groove. And a second spiral groove that extends while having a center of gravity that is eccentric with respect to the axis of the shaft, is movable in the axial direction along the shaft, and rotates about the axis. A first unbalanced weight provided to face the outer peripheral surface of the shaft portion and having a first pin insertion hole; and a center of gravity decentered with respect to the shaft center of the shaft portion; Axis along the shaft while synchronizing with the unbalanced weight The first unbalanced weight is movable in the same direction as the first unbalanced weight, and can be rotated around the axis in the opposite direction to the first unbalanced weight so as to face the outer peripheral surface of the shaft portion. A second unbalanced weight formed with a pin insertion hole; a first pin inserted into the first pin insertion hole and the first spiral groove; and a second pin insertion hole and the second spiral groove. A balancer shaft including a second pin, the first unbalance weight, the second unbalance weight, and a moving mechanism for moving the shaft portion in the axial direction is configured.

  With this configuration, when the crankshaft stops rotating or rotates at a rotational speed smaller than a predetermined rotational speed, the center of gravity of the first unbalanced weight and the second unbalanced weight is set to the axis of the shaft portion. By setting the opposite side, the balancer shaft unbalance amount can be substantially eliminated, and the balancer shaft itself can be prevented from becoming a vibration source.

  On the other hand, when the crankshaft rotates at a rotational speed greater than the predetermined rotational speed, the center of gravity of the first unbalance weight and the second unbalance weight is the same from the opposite side with respect to the shaft center of the shaft portion. The first unbalanced weight and the second unbalanced weight are moved in the axial direction of the shaft portion by a moving mechanism so that the unbalanced amount of a desired size is displaced in the displacement direction of both unbalanced weights. It was made to produce. For this reason, the vibration of the engine can be reliably suppressed by the balancer shaft.

It is a perspective view which shows embodiment of the balancer shaft which concerns on this invention, Comprising: (a) at the time of a stop or low speed rotation, (b) at the time of high speed rotation Front view of the balancer shaft shown in FIG. 2 is a longitudinal sectional view taken along line III-III in FIG. 2 of the balancer shaft shown in FIG. Front view of the balancer shaft shown in FIG. FIG. 4 is a longitudinal sectional view taken along line VV in FIG. 4 of the balancer shaft shown in FIG. 1 is a longitudinal sectional view showing the main part of the balancer shaft shown in FIG. 1 is an exploded perspective view of the balancer shaft shown in FIG.

  An embodiment of a balancer shaft according to the present invention will be described with reference to the drawings. The balancer shaft rotates in synchronization with the rotation of a crankshaft (not shown) of the engine and suppresses vibration of the engine. As shown in FIGS. The first unbalance weight 2, the second unbalance weight 3, the first pin 4, the second pin 5, and the moving mechanism 6 are the main components. Generally, it is integrally attached to the lower part of the engine. FIGS. 1A and 1B are perspective views of a balancer shaft according to the present invention, FIGS. 2 and 4 are front views, FIGS. 3, 5 and 6 are longitudinal sectional views, and FIG. 7 is an exploded perspective view.

  The shaft portion 1 is connected to the engine crankshaft via a gear (not shown) so as to rotate in synchronization with the rotation of the crankshaft. The shaft portion 1 and the crankshaft are arranged in parallel to each other. Both ends of the shaft portion 1 are reduced diameter portions 1a that are slightly reduced in diameter from the vicinity of the center.

  A first spiral groove 1 b and a second spiral groove 1 c are formed on the outer peripheral surface near the center of the shaft portion 1. The first spiral groove 1b has a predetermined inclination angle with respect to the rotation axis of the shaft portion 1, and extends in one direction of the rotation axis while rotating around the axis. The second spiral groove 1c has the same predetermined inclination angle as that of the first spiral groove 1b with respect to the rotational axis of the shaft portion 1 on the axis symmetric side with respect to the formation of the first spiral groove 1b. In one direction of the shaft, it extends while rotating around the axis in the direction opposite to the rotation direction of the first spiral groove 1b.

  The first unbalance weight 2 and the second unbalance weight 3 are formed from cylindrical portions 2a and 3a inserted through the shaft portion 1 and fan-shaped portions 2b and 3b that stand radially outward from the cylindrical portions 2a and 3a. Composed. Both unbalance weights 2 and 3 have the same shape, and both unbalance weights 2 and 3 are in contact with each other in the axial direction. Moreover, the fan-shaped parts 2b and 3b are configured such that the angle is 90 degrees. A first pin insertion hole 2c and a second pin insertion hole 3c are formed in the cylindrical portions 2a and 3a of the first unbalance weight 2 and the second unbalance weight 3, respectively. By forming the fan-shaped parts 2b and 3b in this way, the center of gravity of the first unbalance weight 2 and the second unbalance weight 3 is decentered from the axis of the shaft part 1 in the direction of the fan-shaped parts 2b and 3b. Become. Moreover, the unbalance amount by both the unbalance weights 2 and 3 can be changed suitably by changing the radial thickness of the fan-shaped parts 2b and 3b.

  The first pin 4 is inserted into the first pin insertion hole 2c and the first spiral groove 1b, and is freely guided by the first spiral groove 1b. The second pin 5 is inserted into the second pin insertion hole 3c and the second spiral groove 1c, and is freely guided by the second spiral groove 1c. The first pin 4 is covered from the outer diameter side by the fan-shaped portion 3b of the second unbalanced weight 3 and the second pin 5 is covered by the fan-shaped portion 2b of the first unbalanced weight 2, so that the shaft portion 1 There is no possibility that the pins 4 and 5 will drop off with the rotation.

  The moving mechanism 6 is for moving the first unbalance weight 2 and the second unbalance weight 3 in the axial direction of the shaft portion 1. In this embodiment, a hydraulic actuator (hereinafter, the same reference numeral 6 as that of the moving mechanism 6 is used) is employed. A hydraulic oil supply port 6a through which hydraulic oil is passed is formed in the actuator 6. The hydraulic oil supplied from the hydraulic oil supply port 6 a is an oil chamber 7 surrounded by the shaft portion 1, end portions of the cylindrical portions 2 a and 3 a of the first unbalance weight 2 or the second unbalance weight 3, and the actuator 6. Is sent to. Each oil chamber 7 on the first unbalance weight 2 side and the second unbalance weight side 3 is filled with hydraulic oil in advance. It is of course possible to employ an electric actuator instead of using the hydraulic actuator 6 as in this embodiment.

  When the crankshaft is stopped or rotates at a low speed less than a predetermined speed, the first unbalance weight 2 and the second unbalance as shown in FIGS. 1 (a), 2 and 3. The center of gravity of the weight 3 is opposite to the axis of the shaft portion 1. As described above, both the unbalance weights 2 and 3 have the same shape, and the eccentric state with respect to the shaft center of the shaft shaft 1 is the same, so that both the unbalance weights 2 and 3 are opposite to the shaft center. By being located on the side, the weight balance in the circumferential direction is just balanced. For this reason, the unbalance amount as the whole balancer shaft is very small, and vibration of the balancer shaft itself can be prevented.

  On the other hand, when the crankshaft rotates at a higher speed than the predetermined speed, as shown in FIGS. 1B, 4 and 5, the first unbalance weight 2 and the second unbalance weight 2 are used. The balance weight 3 is moved so that the center of gravity of the balance weight 3 is directed from the opposite side (see FIG. 2) toward the same side with respect to the axis of the shaft portion 1. In this movement, hydraulic oil is supplied from the hydraulic oil supply port 6a of the actuator 6 to the oil chamber 7 on the cylindrical portion 3a side of the second unbalance weight 3, and the second unbalance weight 3 and the first abutting against the second unbalance weight 3 are contacted. One unbalance weight 2 is urged to one side in the axial direction (leftward in FIG. 5), and hydraulic oil is drawn from the oil chamber 7 on the cylindrical portion 2a side of the first unbalance weight 2 through the hydraulic oil supply port 6a. (See the arrow in FIG. 5).

  Thus, when the first unbalance weight 2 and the second unbalance weight 3 are urged in one of the axial directions, the first pin insertion hole 2c formed in the first unbalance weight 2 as shown in FIG. The inserted first pin 4 is guided by the first spiral groove 1 b, and the first unbalance weight 2 moves to the one side and rotates around the shaft portion 1. On the other hand, the second pin 5 inserted into the second pin insertion hole 3c formed in the second unbalance weight 3 is guided to the second spiral groove 1c, and the second unbalance weight 3 is moved to the one side. As it moves, it rotates around the axis of the shaft portion 1 in the direction opposite to the first unbalanced weight 2 so that the fan-shaped portions 2b and 3b of the unbalanced weights 2 and 3 are in contact with each other in the circumferential direction.

  Thus, when both the unbalance weights 2 and 3 are eccentric to one side of the shaft 1, an unbalance amount is generated in the eccentric direction. For this reason, the vibration of the engine can be reliably suppressed by the balancer shaft. Moreover, as described above, by setting the angle of the fan-shaped parts 2b and 3b to 90 degrees, the angle when the fan-shaped parts 2b and 3b abut on each other in the circumferential direction becomes 180 degrees. For this reason, a part of the fan-shaped portions 2b and 3b does not protrude beyond the center line of the shaft portion 1 and the centrifugal force of the unbalanced weights 2 and 3 is unidirectional (eccentric side). Acts only on For this reason, it is possible to generate an unbalance amount having an appropriate size necessary for suppressing vibrations of the engine.

  The predetermined rotational speed is preferably the rotational speed of the crankshaft when, for example, engine vibration starts to become a problem. The balancer shaft unbalance amount is extremely small in the low-speed rotation region than this predetermined rotational speed, and the balancer shaft itself is prevented from vibrating, and the balancer shaft functions in the high-speed rotation region. This is because the vibration of the engine due to can be surely suppressed.

  The maximum unbalance amount can be freely changed by changing the radial thickness of the fan-shaped portions 2b and 3b. In this case, since both the unbalance weights 2 and 3 are provided on the outer peripheral side of the shaft portion 1, it is not necessary to change the outer diameter of the shaft portion 1, and even a space in the movable range of the fan-like portions 2b and 3b is secured. do it. For this reason, the compactness as the whole balancer shaft is securable.

  As described above, the crankshaft and the shaft portion 1 are configured to rotate in synchronism, and in the case of a four-cylinder engine, the rotation ratio of the crankshaft and the shaft portion 1 is set to 1: 2. The shaft portion 1 rotates twice while the shaft rotates once. The reason is as follows. That is, in the four-cylinder engine, four pistons are reciprocated by connecting rods, but two of the four pistons are driven in a state where the phases are shifted from each other by 180 degrees. That is, when the two pistons are at top dead center, the remaining two pistons are at bottom dead center. When the crankshaft rotates halfway, the positions of the top dead center and the bottom dead center of each piston are switched.

  In this reciprocation of the piston, it has been found that a particularly large vibration occurs when the piston reaches the top dead center. In a 4-cylinder engine, there are two timings when the piston reaches the top dead center during one revolution of the crankshaft. Therefore, the shaft portion 1 is rotated twice during one revolution of the crankshaft so that the piston is at the top dead center. At the timing of reaching, the center of gravity of the balancer shaft is moved to the opposite side to synchronize, thereby suppressing vibration when the piston reaches top dead center.

  This vibration suppression effect by the balancer shaft is noticeable in a 4-cylinder engine or a V8 engine, but can also be adopted for other engines. At that time, the rotation ratio between the crankshaft and the shaft portion 1 is appropriately changed in accordance with the phase shift of the reciprocating motion of each piston.

  The balancer shaft according to each of the above embodiments is merely an example, and solves the problem of the present invention of generating an unbalance amount sufficient for suppressing vibration of the engine while ensuring compactness when mounted on the engine. As long as it is obtained, the shape of the shaft portion 1, the shapes of the unbalanced weights 2 and 3, the mechanism for moving the unbalanced weights 2 and 3 in synchronization can be appropriately changed.

DESCRIPTION OF SYMBOLS 1 Shaft part 1a Diameter reduction part 1b 1st spiral groove 1c 2nd spiral groove 2 1st unbalance weight 2a Cylindrical part 2b Fan-shaped part 2c 1st pin insertion hole 3 2nd unbalance weight 3a Cylindrical part 3b Fan-shaped part 3c 2nd Pin insertion hole 4 First pin 5 Second pin 6 Moving mechanism (actuator)
6a Hydraulic oil supply port 7 Oil chamber

Claims (4)

In the balancer shaft that rotates in synchronization with the rotation of the crankshaft of the engine and suppresses the vibration of the engine,
A first spiral groove (1b) and a first spiral groove (1b) having a predetermined inclination angle with respect to the rotation axis and extending in one direction of the rotation axis while rotating around the axis on the outer peripheral surface. The rotation axis of the first spiral groove (1b) around the axis has the predetermined inclination angle with respect to the rotation axis on the side symmetrical with the axis of rotation, and has the predetermined inclination angle with respect to the rotation axis. A second spiral groove (1c) that extends while rotating in the reverse direction, and a shaft portion (1) that forms a shaft part (1),
The shaft portion (1) has a center of gravity that is eccentric with respect to the axis of the shaft portion (1), is movable in the axial direction along the shaft portion (1), and is rotatable about the axis. A first unbalance weight (2) provided so as to face the outer peripheral surface and having a first pin insertion hole (2c);
The center of gravity is eccentric with respect to the axis of the shaft portion (1), and the first unbalance is axially along the shaft portion (1) while synchronizing with the first unbalance weight (2). Provided so as to face the outer peripheral surface of the shaft portion (1) so that it can move in the same direction as the balance weight (2) and can turn around the axis in the opposite direction to the first unbalance weight (2). A second unbalance weight (3) in which a second pin insertion hole (3c) is formed,
A first pin (4) to be inserted into the first pin insertion hole (2c) and the first spiral groove (1b);
A second pin (5) to be inserted into the second pin insertion hole (3c) and the second spiral groove (1c);
A moving mechanism (6) for moving the first unbalance weight (2) and the second unbalance weight (3) in the axial direction of the shaft portion (1);
And the center of gravity of the first unbalance weight (2) and the second unbalance weight (3) is the shaft when the crankshaft stops rotating or rotates at a rotational speed smaller than a predetermined rotational speed. When the crankshaft rotates at a rotational speed greater than the predetermined rotational speed so as to be opposite to the axis of the portion (1), the first unbalance weight (2) and the second The first unbalance weight (2) and the second unbalance weight (2) are arranged so that the center of gravity of the unbalance weight (3) is directed from the opposite side to the same side with respect to the axis of the shaft portion (1). The balancer shaft is characterized in that 3) is moved in the axial direction of the shaft portion (1) by the moving mechanism (6).   The first unbalanced weight (2) and the second unbalanced weight (3) have a cylindrical portion (2a, 3a) inserted through the shaft portion (1) and a diameter from the cylindrical portion (2a, 3a). The fan-shaped portions (2b, 3b) that stand up outward in the direction, and the fan-shaped portions of the unbalanced weights (2, 3) when the crankshaft rotates at a rotational speed greater than the predetermined rotational speed. The balancer shaft according to claim 1, wherein (2b, 3b) can contact each other in the circumferential direction.   The balancer shaft according to claim 2, wherein the angle of the fan-shaped part (2b, 3b) is 90 degrees or less.   The balancer shaft according to any one of claims 1 to 3, wherein the moving mechanism (6) is a hydraulic or electric actuator (6).

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