JP4546604B2 - Balancer shaft structure of internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the structure of the balancer shaft of an internal combustion engine including a balancer shaft that is rotationally driven by a crankshaft.
[0002]
[Prior art]
In a four-cycle engine that employs an OHC (overhead camshaft) type valve mechanism, rotation of the crankshaft is generally transmitted to the camshaft by a chain transmission mechanism, and intake and exhaust are caused by the rotation of the camshaft. The valve is opened and closed at a predetermined timing, and the required gas exchange is performed in the cylinder.
[0003]
By the way, there is proposed an internal combustion engine that adopts a configuration in which the rotation of the crankshaft is transmitted to the camshaft via the intermediate shaft due to the arrangement of auxiliary machinery. In this type of internal combustion engine, the intermediate shaft is used as a balancer shaft. It is also attempted to reduce vibrations by using them.
[0004]
[Problems to be solved by the invention]
Thus, transmission of the driving force to the balancer shaft that is driven to rotate by the crankshaft is made by gears, chains, timing belts, etc., but in particular, a system that transmits the rotation of the crankshaft to the balancer shaft via the gear is adopted. In this case, the torque fluctuation of the crankshaft is transmitted to the balancer shaft as it is and noise is generated, and the durability of the balancer shaft system is adversely affected. In particular, the above problem is remarkable when the rotational moment generated in the balance weight of the balancer shaft is large or when the auxiliary machines are driven by the balancer shaft.
[0005]
Accordingly, the object of the present invention is to provide a balancer shaft structure for an internal combustion engine that can reduce noise and improve the durability of the balancer shaft system by interrupting transmission of torque fluctuations of the crankshaft to the balancer shaft. There is to do.
[0006]
By the way, in an internal combustion engine that employs a configuration in which the rotation of the crankshaft is transmitted to the camshaft via the balancer shaft, a configuration in which the gear itself swings on the balancer shaft is adopted in order to ensure accurate opening and closing timings of the intake and exhaust valves. It is impossible to do.
[0007]
Accordingly, an object of the present invention is to provide a balancer shaft structure for an internal combustion engine that can block transmission of torque fluctuations of the crankshaft to the balancer shaft without causing a shift in the opening / closing timing of the intake / exhaust valves. It is to provide.
[0008]
[Means for Solving the Problems]
In order to achieve the above object , the present invention provides an internal combustion engine having a balancer shaft that is rotationally driven by a crankshaft, wherein the balancer shaft is divided into a weight portion and other non-weight portions, and a damper is provided between the two. It is characterized by interposing means.
[0009]
In one embodiment of the present invention, a sprocket for transmitting rotation to the gear and the camshaft for inputting the rotation of the pre-Symbol crankshaft may be provided in the non-weight portion of the balancer shaft.
[0010]
In one embodiment of the present invention, good but incorporates Shizasugiya the gear provided before Symbol balancer shaft.
[0011]
According to the present invention, the torque fluctuation of the crankshaft is effectively absorbed by the damper effect by the damper means interposed between the weight part of the balancer shaft and the other non-weight part. Transmission to the balancer shaft is cut off, reducing noise and improving the durability of the balancer shaft system.
[0012]
Further , according to the above aspect, in which the gear for inputting the rotation of the crankshaft and the sprocket for transmitting the rotation to the camshaft are provided in the non-weight portion of the balancer shaft, the rotation of the crankshaft bypasses the damper means and the balancer via the gear. Since the rotation of the non-weight part is transmitted to the camshaft via the sprocket and the chain, the rotation of the crankshaft is accurately transmitted to the camshaft and there is a phase difference between the two shafts. Therefore, no deviation occurs in the opening / closing timing of the intake / exhaust valve driven by the camshaft.
[0013]
Further, according to the embodiment incorporating Shizasugiya the gear provided on the balancer shaft, backlash does not occur between the balancer shaft side gear and the crankshaft side gears, precision rotation of crankshaft to the balancer shaft Is transmitted to.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
[0015]
FIG. 1 is a longitudinal sectional view of an internal combustion engine having a balancer shaft structure according to the present invention, and FIG. 2 is a broken sectional view showing configurations of an auxiliary machine drive system and a cam-crank drive system of the internal combustion engine.
[0016]
The internal combustion engine 1 shown in FIG. 1 is a four-cycle in-line five-cylinder engine for automobiles, and the cylinder block 2 has five cylinders 3 arranged in parallel in the direction perpendicular to the page of FIG. The piston 4 is slidably fitted. The piston 4 is connected via a connecting rod 6 to a crankshaft 5 that is long in the direction perpendicular to the plane of FIG. The crankshaft 5 is rotatably housed in a crank chamber 8 formed by the cylinder block 2 and an oil pan 7 attached to the lower part of the cylinder block 2.
[0017]
As shown in FIG. 1, an intake passage 10 and an exhaust passage 11 are formed for each cylinder in the cylinder head 9 attached to the upper portion of the cylinder block 2, and the intake passage 10 is formed in the cylinder head 9. An intake manifold 12 connected to the exhaust passage 11 is attached, and an exhaust manifold 13 connected to the exhaust passage 11 is attached. A surge tank 14 is attached to the tip of the intake manifold 12.
[0018]
The intake passage 10 and the exhaust passage 11 are opened to the cylinder 3 of each cylinder as an intake port 10a and an exhaust port 11a, respectively. The intake port 10a and the exhaust port 11a are respectively provided by an intake valve 15 and an exhaust valve 16. It is opened and closed at an appropriate timing. That is, the intake valve 15 and the exhaust valve 16 are respectively urged to the closed side by a valve spring (not shown), and these are cam shafts that are arranged on the upper part of the cylinder head 9 so as to be rotatable and are long in the direction perpendicular to the plane of FIG. The cam ports 17 and 18 are respectively in contact with the cams 17a and 18a formed integrally with the cam shafts 17 and 18, and the cam shafts 17 and 18 are rotationally driven to open and close the intake port 10a and the exhaust port 11a at appropriate timings as described above. Then perform the required gas exchange.
[0019]
As shown in FIG. 2, a crank damper 19 is attached to one end of the crankshaft 5, and a balancer serving as a first intermediate shaft is obliquely above the crankshaft 5 (leftward in FIG. 1). The shaft 20 is arranged to be rotatable in parallel with the crankshaft 5 and offset to the intake side with respect to the crankshaft 5. An auxiliary machine drive pulley 21 is attached to one end of the balancer shaft 20 on the side where the crank damper 19 is provided.
[0020]
As shown in FIG. 2, a large-diameter gear 22 and a small-diameter sprocket 23 are provided on one end side of the balancer shaft 20, and the large-diameter gear 22 is bound to an intermediate portion of the crankshaft 5. Meshed with a gear 24 having the same diameter.
[0021]
On the other hand, a second intermediate shaft 25 is arranged on the intake side of the cylinder head 9 so as to be parallel to and rotatable with respect to the crankshaft 5 and the balancer shaft 20, and a sprocket 26 is provided at one end of the second intermediate shaft 25. A sprocket 27 is attached to the other end. An endless chain 28 is wound between the sprocket 26 and the sprocket 23.
[0022]
Sprockets 29 and 30 are respectively attached to the end portions of the cam shafts 17 and 18, and an endless chain 31 is wound between the sprockets 29 and 30 and the sprocket 27. Yes. As shown in FIG. 2, a VVT (hydraulic variable valve timing device) 32 is attached to the end of the cam shaft 17 on the intake side. Further, as shown in FIG. 1, a sprocket 33 attached to an input shaft of a water pump (not shown) is pressed against the chain 31 from outside and meshed.
[0023]
By the way, as shown in FIG. 1, the chains 28 and 31 are seen from the outside of the cylinder 3 (intake side) so that they do not overlap the shilling 3 when viewed from the axial direction of the crankshaft 5 (that is, do not cross the cylinder 3). ). Further, as shown in FIG. 2, the chains 28 and 31 are arranged within the range of the axial length of the crankshaft 5.
[0024]
Thus, as shown in FIG. 1, a balancer shaft chamber 34 for accommodating the balancer shaft 20 is formed on the intake side of the cylinder block 2, and the balancer shaft chamber 34 is a side wall on the intake side of the cylinder block 2. The opening is covered with a detachable cover 35.
[0025]
By the way, in the internal combustion engine 1, as shown in FIG. 1, an alternator 36 and an air conditioner compressor 37, which are auxiliary machines, are disposed on one side of the intake side (the back side in FIG. 1). An endless belt 40 is wound between the idler pulley 38 and the tension pulley 39. In the embodiment, a power steering pump (not shown) is directly connected to the end of the second intermediate shaft 25.
[0026]
Here, the details of the structure of the balancer shaft 20 will be described with reference to FIGS. 3 is a broken side view of the balancer shaft (cross-sectional view taken along line AA in FIG. 4), FIG. 4 is a broken front view of the balancer shaft, FIG. 5 is a cross-sectional view taken along line BB in FIG. It is a disassembled perspective view of the balancer shaft.
[0027]
In the present embodiment, as shown in FIG. 3, the balancer shaft 20 is divided into a long weight portion 20A and a short non-weight portion 20B, and the non-weight portion 20B of the weight portion 20A. A flange 41 is integrally formed on the outer periphery of the opposite end, and a circular fitting hole 42 is formed at the center thereof.
[0028]
Further, three journal portions 20a, 20b, and 20c are formed at appropriate intervals in the axial direction on the outer periphery of the weight portion 20A of the balancer shaft 20, and a semi-cylindrical shape is formed between adjacent journal portions 20a and 20b. A balance weight 43 is integrally formed, and balance weights 44 and 45 are integrally formed with a phase difference of 180 ° with respect to the balance weight 43 before and after the other journal portion 20c. Here, one semi-cylindrical balance weight 44 is formed integrally with the outer periphery of the weight portion 20 </ b> A, and the other balance weight 45 is formed integrally with the flange 41. As shown in FIG. 6, two substantially rectangular grooves 46 and 47 are formed on the outer end surface of the flange 41 formed integrally with the end portion of the weight portion 20A. The three bolt holes 48 are formed at an equiangular pitch.
[0029]
On the other hand, the gear 22 is integrally formed at the intermediate portion in the axial direction of the non-weight portion 20B of the balancer shaft 20, and a small-diameter fitting shaft portion 49 is provided forward (leftward in FIG. 3) from the gear 22. Are integrally formed, and a journal portion 20 d is formed on the outer periphery of the rear portion of the gear 22. The sprocket 23 and a crank timing adjusting plate 50 are fitted to the end of the non-weight portion 20B.
[0030]
As shown in FIG. 6, the gear 22 has three elongated holes 51 extending in the circumferential direction at equal angular pitches, and is formed on the end surface of the gear 22 facing the flange 41 of the weight portion 20A. Each of the two rectangular grooves 52 and 53 is alternately formed at an equal angular pitch.
[0031]
Thus, as shown in FIG. 3, the balancer shaft 20 fits the fitting shaft portion 49 formed in the non-weight portion 20B into the fitting hole 42 of the weight portion 20A, and the flange 41 and the non-weight portion of the weight portion 20A. The 20B gear 22 is assembled, and a ring-shaped scissor gear 54 and a disc spring 65 are provided between the flange 41 and the gear 22 so as to mesh with the gear 24 on the crankshaft 5 side. . Two types of coil springs 55 and 56 and three cylindrical spacers 57 are interposed between the gear 22 and scissor gear 54 and the flange 41. The scissor gear 54 eliminates backlash that occurs when meshed with the gear 24 on the crankshaft 5 side, thereby reducing noise and the like. By eliminating the backlash, the rotation of the crankshaft 5 is increased to the balancer shaft 20. Communicated with accuracy. Here, the scissor gear 54 is urged in one rotation direction by the coil spring 55. As shown in FIG. 6, each of the scissor gear 54 has three long holes 58 and rectangular holes 59, 60 at an equal angular pitch. It is penetrated alternately.
[0032]
In the state where the balancer shaft 20 is assembled as shown in FIG. 3, the grooves 46 and 47 formed in the flange 41 of the weight portion 20A, the rectangular holes 59 and 60 penetrating the scissor gear 54, and the non-weight portion As shown in FIGS. 4 and 5, the coil springs 55 and 56 are arranged in the circumferential direction and stored in each rectangular space formed by the grooves 52 and 53 formed in the gear 22 of 20B. ing.
Caps 61 are attached to both ends of each coil spring 56.
[0033]
Thus, in the state where the coil springs 55 and 56 are accommodated in the spaces as described above, the bolts 63 are passed through the spacers 57 and the washers 62 by applying the washers 62 to the end surfaces of the spacers 57, The flange 41, the gear 22 and the scissor gear 54 are connected to each other by inserting the bolt 63 into the bolt hole 48 formed in the flange 41 by inserting into the long holes 51 and 58 formed in the gear 22 and the scissor gear 54, respectively. 20A and the non-weight portion 20B are integrated, whereby the balancer shaft 20 is assembled.
[0034]
As described above, when the balancer shaft 20 is assembled, the coil spring 55 is interposed between the flange 41 of the weight portion 20A, the gear 22 of the non-weight portion 20B, and the scissor gear 54 interposed therebetween. , 56 and a spacer 57 are interposed. Therefore, in the balancer shaft 20, the weight portion 20A and the non-weight portion 20B can be rotated relative to each other within a range in which the spacer 57 can move through the long holes 51 and 58 by compressive deformation of the coil spring 56 constituting the damper means. The desired damper effect is obtained by the elastic deformation of the coil spring 56, and the torque fluctuation of the crankshaft 5 is absorbed as will be described later.
[0035]
In the above, when the internal combustion engine 1 is operated and the crankshaft 5 is rotationally driven, the rotation of the crankshaft 5 is transmitted to the balancer shaft 20 via the gears 24 and 22 having the same diameter, and the balancer shaft 20 is In this embodiment, the balancer shaft 20 is divided into two parts, a weight part 20A and a non-weight part 20B, and a coil spring 56 constituting a damper means is interposed therebetween. Therefore, the torque fluctuation of the crankshaft 5 is absorbed by the damper effect of the coil spring 56, the transmission of the torque fluctuation to the balancer shaft 20 side is cut off, and noise is reduced and the durability of the balancer shaft 20 is improved.
[0036]
Thus, the rotation of the balancer shaft 20 is transmitted to the alternator 36 and the air conditioner compressor 37 via the accessory drive pulley 21 and the belt 40, and these are rotationally driven. The internal combustion engine 1 is also provided with an oil pump 64 as an auxiliary machine as shown in FIG. 1, but the rotation of the balancer shaft 20 is transmitted to the oil pump 64 via a transmission mechanism (not shown). Thus, the oil pump 64 is driven and oil is supplied to each part of the engine 1.
[0037]
The rotation of the balancer shaft 20 is decelerated via the sprocket 23, the chain 28 and the sprocket 26 and transmitted to the second intermediate shaft 25, and a power steering pump (not shown) directly connected to the second intermediate shaft 25 is driven. The Further, the rotation of the second intermediate shaft 25 is further decelerated via the sprocket 27, the chain 31, and the sprockets 29 and 30, and is also transmitted to the cam shafts 17 and 18, and these cam shafts 17 and 18 are rotationally driven. Thus, as described above, the intake valve 15 and the exhaust valve 16 open and close the intake port 10a and the exhaust port 11a at appropriate timings to perform the required gas conversion. The sprocket 33 is further rotated by driving the chain 31, thereby driving a water pump (not shown) to circulate the cooling water in the internal combustion engine 1. In the present embodiment, since the sprocket 23 is disposed in the vicinity of the journal portion 20d provided at one end of the balancer shaft 20, the swing of the sprocket 23 is suppressed to a small level and passes through the second intermediate shaft 25 from the balancer shaft 20. Rotational transmission to both the cam shafts 17 and 18 is performed reliably and with high accuracy.
[0038]
Thus, in the present embodiment, since the gear 22 and the sprocket 23 are provided in the non-weight portion 20B of the balancer shaft 20, the rotation of the crankshaft 5 bypasses the coil spring 56 that constitutes the damper means, And the rotation of the non-weight portion 20B is transmitted to the second intermediate shaft 25 via the sprocket 23, the chain 28 and the sprocket 26, and the rotation of the second intermediate shaft 25 is transmitted to the sprocket 27 and the chain. 31 and the sprockets 29 and 30 are transmitted to the camshafts 17 and 18. Therefore, the rotation of the crankshaft 5 is accurately transmitted to the camshafts 17 and 18 so that no phase difference occurs between the two shafts. Therefore, the intake / exhaust valves 15 and 15 driven by the camshafts 17 and 18 are prevented. No deviation occurs at the opening and closing timing of 16.
[0039]
Although the present invention has been described with respect to the embodiment in which the present invention is applied particularly to the balancer shaft of a five-cylinder engine, the present invention is similarly applied to the balancer shaft of any other internal combustion engine having a balancer shaft that is rotationally driven by a crankshaft. It is applicable to.
[0040]
In the above embodiment, the coil spring is used as the damper means. However, any other absorber including an elastic body such as rubber can be used as the damper means.
[0041]
【The invention's effect】
As apparent from the above description, according to this onset bright, torque fluctuation of the crankshaft effectively absorbed by the damper effect of the damper means is interposed between the non-weight portion of the rest and the weight portion of the balancer shaft Therefore, transmission of the crankshaft torque fluctuation to the balancer shaft is cut off, so that the effect of reducing noise and improving the durability of the balancer shaft system can be obtained.
[0042]
In addition , since a gear for inputting the rotation of the crankshaft and a sprocket for transmitting the rotation to the camshaft are provided in the non-weight portion of the balancer shaft, the rotation of the crankshaft bypasses the damper means and the balancer shaft Since the rotation of the non-weight part is transmitted to the camshaft via the sprocket and the chain, the rotation of the crankshaft is accurately transmitted to the camshaft and a phase difference occurs between the two shafts. In this way, it is possible to prevent the occurrence of deviation in the opening / closing timing of the intake / exhaust valve driven by the camshaft.
[0043]
Moreover, since incorporating Shizasugiya the gear provided on the balancer shaft, backlash does not occur between the balancer shaft side gear and the crankshaft side gear, the rotation of the crankshaft is transmitted to the high precision balancer shaft The effect is obtained.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an internal combustion engine having a balancer shaft structure according to the present invention.
FIG. 2 is a broken sectional view showing configurations of an auxiliary machine drive system and a cam-crank drive system of an internal combustion engine having a balancer shaft structure according to the present invention.
FIG. 3 is a cutaway side view of the balancer shaft (a cross-sectional view taken along line AA in FIG. 4).
FIG. 4 is a cutaway front view of a balancer shaft.
5 is a cross-sectional view taken along line BB in FIG.
FIG. 6 is an exploded perspective view of a balancer shaft.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Internal combustion engine 5 Crankshaft 20 Balancer shaft 20A Weight part 20B Non-weight part 22 Gear 23 Sprocket 54 Scissor gear 56 Coil spring (damper means)

Claims (3)

In an internal combustion engine comprising a balancer shaft that is rotationally driven by a crankshaft,
And the weight portion of the balancer shaft, a non-weight portion other than it, with the length in the axial direction is divided into a shorter than the weight part the non-weight portion of the balancer shaft, the damper means between them Intervening,
The non-weight portion is provided with a gear that meshes with the gear of the crankshaft, and a sprocket that rotates integrally with the gear and transmits the rotation to the camshaft ,
The weight part, and the sprocket is the located on the opposite side of the gear of the non-weight portion, wherein the axially opposed to the gear and the balancer shaft of the non-weight portion, a larger diameter than the balancer shaft Provide a flange,
Between the flange and the gear of the non-weight portion, a plurality of springs constituting the damper means are arranged in a circumferential direction surrounding the balancer shaft ,
A plurality of grooves for receiving the plurality of springs are formed at equal intervals in a circumferential direction surrounding the balancer shaft on an end surface of the flange facing the gear and an end surface of the gear facing the flange. An internal combustion engine characterized by the above.   The internal combustion engine according to claim 1, wherein a balance weight is formed on the flange. The internal combustion engine according to claim 1, wherein a scissor gear is incorporated in the gear provided on the balancer shaft.

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